Handbook of Practical Electrotherapy

i

Handbook of Practical Electrotherapy


Pushpal Kumar Mitra Lecturer in Physiotherapy NIOH, Kolkata

JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD New Delhi

Published by

Jitendar P Vij Jaypee Brothers Medical Publishers (P) Ltd EMCA House, 23/23B Ansari Road, Daryaganj New Delhi 110 002, India Phones: +91-11-23272143, +91-11-23272703, +91-11-23282021, +91-11-23245672 Fax: +91-11-23276490, +91-11-23245683 e-mail: [email protected] Visit our website: www.jaypeebrothers.com Branches

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© 2006, Pushpal Kumar Mitra All rights reserved. No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the author and the publisher. This book has been published in good faith that the material provided by author is original. Every effort is made to ensure accuracy of material, but the publisher, printer and author will not be held responsible for any inadvertent error(s). In case of any dispute, all legal matters are to be settled under Delhi jurisdiction only. First Edition : 2006

ISBN 81-8061-620-7 Typeset at JPBMP typesetting unit Printed at

Gopsons Papers Ltd., A 14, Sector 60, Noida

To My dear departed Mother, in her memory

Preface The scientific art of Physiotherapy has grown by leaps & bounds over the last few decades, gaining credibility as an established drug-less discipline of modern medicine. The public at large, especially in India, has become wary of the indiscriminate use of potentially harmful drugs for even trivial complaints. More and more people are being drawn towards physiotherapy, recognising it as an effective alternative to conventional drug based treatment. Though the discipline of physiotherapy has been in practice for over half a century, physicians, particularly in India, had been traditionally recommending physiotherapy, only as a supplementary measure to the drug based regime of disease management. Of late, due to wide coverage given by the media to such issues like the free availability of over the counter drugs and the dangers of unmonitored use of such potentially harmful agents, have created awareness among the population regarding the dangers of excessive dependence on drugs. Physicians have of late begun to realize that physiotherapy can be extremely effective for the treatment of many disorders, as a complementary force-multiplier to their own efforts. The role of physiotherapy in diverse areas of patient care, such as rheumatology, orthopaedics, sports medicine, paediatrics, neonatology, geriatrics, neurology, gynaecology, obstetrics, pulmonology, cardiology, etc. is now established beyond doubt and is accepted by the medical fraternity worldwide. So much so, it has led to a change in the definition of physiotherapy by the World Health Organisation . This acceptance has led to a boom in physiotherapy education in India. Physiotherapy has come of age as a viable career option, either as a self employed professional or as a part of healthcare infrastructure, in India or abroad, drawing the best and the brightest students in India. Major universities all over the nation are now offering physiotherapy as speciality training, at undergraduate and postgraduate level. In my capacity as a teacher and examiner spanning over two decades, I have had the opportunity to interact closely with a wide spectrum of student community. The feedback given by these students regarding problems that they face in pursuing a course curriculum in Physiotherapy unanimously boils down to the lack of precise volumes that cover relevant details of the subject, highlighting the applied aspect of the science in a format and language that can be easily understood by them. This problem is easy to understand, since most of the publications available on the subject are by foreign authors. Though very well researched and descriptive, contents of these volumes are usually expressed in an English that is far beyond the comprehension of the average Indian student, particularly if he/ she have had his/her basic education in vernacular medium. The genesis of this hand book on practical aspect of electrotherapy owes its origin to the need among students for simple volumes, oriented to the practical application of the science,

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with adequate text, backed up with plenty of illustrations, in easily understood format and language. Happily enough, several young authors, involved with undergraduate teaching in India, being actively encouraged by publishers with the vision, like the J.P.Brothers, are now coming forward with excellent volumes that will go a long way to encourage many teachers like me to do their bit for this noble cause. This is volume is a humble attempt to bridge the gap between the text and the applied aspect of Electrotherapy. With no pretence of being a magnum opus, it may provide an easy updater for the student or practitioner working in a clinical setting. The entire gamut of electrotherapeutics has been divided into three major sections, i.e. therapeutic electrical stimulation, thermo therapy and actino therapy. Each section commences with a review of the relevant biophysics. The applied aspects of the modalities considered under each section have been listed under the headings of Points to Ponder,’ for quick review of the essential information. This will be useful for bus stop revisions at exam time. The text in this volume has been deliberately kept simple and short, with liberal use of illustrations to project a word picture of the essentials in electrotherapy. Every effort has been made to make the contents of this volume easy to understand and framed to stimulate the reader to try using the techniques in a step-by-step manner during practice/clinical sessions. It is also expected to help fledgling teachers of Physiotherapy, to impart basic training in electrotherapy, with confidence, projecting the fundamentals firmly in front of their pupil, without too much technical jargon, which often tends to confuse the teacher and the taught alike. Among many unique features presented in this volume, I would like to highlight the sections on precise dosing parameters for each modality. This can be an excellent guide for the beginner in clinical practice. Each section concludes with a comprehensive chart that details all aspects of practical application for individual modalities. Placement of electrodes, optimum dosage, equipment settings, patient position, etc. has been detailed for each region of the body or for specific clinical condition. Several advanced applications of electrotherapy, yet to be mainstreamed in clinical practice in India, such as functional electrical stimulation or the combination therapy, have been presented for the appraisal of the reader. The volume also contains a section on frequently asked questions during the viva examinations, along with short and to the point answers. The students can use this section as a means of complete revision at exam time, since each modality has been explored separately through short question and answers. My effort has been directed towards de-mystifying the science and makes it user friendly for the budding professionals in physiotherapy. I have made every effort to make the volume as free of factual errors as possible. However, I realise that there is still a lot of scope for improvement in this volume. I shall be indebted to the reader for any valuable input to make the further editions more useful. Pushpal Kumar Mitra

Acknowledgements This volume would not have seen the light of the day without active participation of my students in this project. My students, past and present, have been the friend, philosopher and guide in this maiden venture. Their feedback, advice and quality assessment, though not always flattering, have been the prime mover behind this effort. In this context I would like to convey my sincere thanks to Ms. Bani Laha, my erstwhile pupil and present assistant, for the motivation, backup support and secretarial assistance. I would also like to put on record my appreciation for Mr. Devidutt Pathak, Mr. Ravishankar, Ms. Richa Kashyap and Mr. Prosenjit Patra and Mr. Sapan Kumar, all Internees of physiotherapy at NIOH, for literature review proof reading and research, to make this volume as foolproof as possible. Special mention must be made for Ms. Divya and Ms. Suravi, visiting internees from GNDU, Amritsar for organising the photo shoots. Finally I wish to convey my appreciation and thanks to my teachers, colleagues and patients for their inspiration.

Contents 1. Review of Basic Concepts in Electricity

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2. Introduction to Electrotherapy

10

3. Therapeutic Electrical Stimulation

15

4. Low Frequency Stimulation of Nerves and Muscles (NMES)

24

5. Getting Started with Low Frequency Electrical Stimulation

30

6. Pain Modulation — Transcutaneous Electrical Nerve Stimulation (TENS)

50

7. Advanced Applications of Low Frequency Electrical Stimulation

57

8. Medium Frequency Currents

65

9. Therapeutic Heat

76

10. Deep Heat Therapy

85

11. Therapeutic Ultrasound (US Therapy)

98

12. Therapeutic Cold

119

13. Therapeutic Light (Actinotherapy/Heliotherapy)

130

14. Frequently Asked Questions in Practical: Viva Examination

142

Index

149

1 Review of Basic Concepts in Electricity Definition

Electricity is a form of physical energy that exists in nature due to excess or deficit of electrons in any living or non-living object. In modern times, electricity is the lifeline of human civilisation. Our world is so dependent on electrical energy, that failure in the power grid assumes proportions and significance of a national disaster. It will be wise to remember that the living cell also works on definite electrical principles like a car battery. Electrical potentials are generated across the membrane of a living cell, which governs movement of essential ions in and out of the cell. Such ionic movements control the physiology and therefore the life of the cell. Physical principles of electricity remain the same in either context. In order to understand the effect of electrical energy on the living cell it is important to review the fundamentals of electricity once again. Electrical energy exists in nature in two forms—static electricity and electrical current

• • •

• •

•

•

•

.

Points to Ponder

• Static electricity is the charge that develops in any object that has free electrons, other

•

than a conductor. The nature of static charge may be positive (+) or negative (–). The objects capable of loosing electrons develop positive charge. The objects capable of accepting loose electrons develop negative charge. Static electric charge tends to distribute uniformly over a spherical surface and concentrate on pointed surfaces of the charged objects (Fig. 1.1). Like charges repel and opposite charges attract each other (Fig. 1.2) Static electric charge creates a sphere of influence around itself. This is known as an electrical field. The direction of the line of forces is directed away from the positively-charged body and towards the negatively-charged body. Static electricity does not mean its stationary. A bolt of lightening strikes the earth when the static electric Charge generated in a body of cloud becomes too great for the cloud to hold, generating intense heat that creates the thunderclap by overheating the air in the atmosphere. An electrical current is the flow of electrons through a conductor, from a region of

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Fig. 1.1: Static electricity & electrical field—Static electric charge tends to spread over the surface of the charged objects. Concentrations of charge are greater on any pointed area. Positively-charged objects have deficiency of electrons, hence try to attract electrons. Negatively-charged objects have surplus electrons; hence try to give up the excess electrons. This imbalance in electron content creates a sphere of influence around the charged objects, which is known as the electrical field

•

• •

•

•

higher concentration to a zone of lower concentration. By convention, the direction of flow of electrons is opposite to the direction of flow of the current (Fig. 1.2) The rate of flow of electrons is measured in Amperes. The force that drives electrons through a conductor is known as Electromotive Force (EMF), arises from the difference of potential between two points in a conductor and is measured in Volts. The force opposing the flow of electrons through a medium is known as resistance or impendence and is measured in Ohms. The domestic electric supply is an Alternating Current (AC) having a sine wave at 50 Hz frequencies.

Fig. 1.2: Behaviour of electrical fields—Opposite charges attract each other, thus flow of electron takes place from negatively-charged pole to the positivelycharged pole, which is known as electric current. The direction of flow of the electric current by convention is opposite to the direction of flow of electrons, i.e. positive to negative pole

• The supply line has a phase, a neutral and an earth connection. • The phase carries the current, the neutral completes the circuit and the earth provides the escape route for any electrons from that may have escaped the circuit. A fuse or circuit breaker is essential as a safety feature in any circuit to break the flow of current in case of any over load. INTRODUCTION TO BIOELECTRICITY AND ELECTROPHYSIOLOGY Definition

Bioelectricity can be defined as the inherent electrical energy present in a living cell and the manifestation of this electrical energy in day-to-day functions of the cell is called electrophysiology. Have you ever thought why the fire fly glows in the dark? Or how can the electric eel

Review of Basic Concepts in Electricity 3

kill its prey with a shock? Or for that matter tial. Such changes of electrical potentials are why does the physician order an ECG for a greater and more frequent in sensitive cells heart patient? like nerves or muscles. All have one common answer—BioelectriFor ease of understanding, here after all references to cellular potentials, will be in city. All living cells are like miniature batteries, context of a human nerve cell, since these cells constantly charging and discharging as it goes has the highest excitability among all the cells about living. All of the cell’s physiological in the body. The neuron is composed of four functions revolve around its electrical status. basic parts: the soma or cell body, the axon, A healthy cell is the one that can hold a normal presynaptic terminals and the dendrites level of electrical charge and sustain a fixed (Fig. 1.3). The soma surrounds the nucleus. potential difference between the cell and its The axon can be part of the spinal cord, environment. Any change in this normal connect with muscle nerves or sensory nerves, electrical charge can render the cell, like a or branch into small fibres. The presynaptic battery—dead terminals branch off from the axon and send The mystery behind this electrical pheno- the action potential to nearby neurons. Dendmenon is hidden in the composition of the cell. rites sense information from neighbouring Nearly 90 per cent of a living cell is made up cells. of water, in which are dissolved a number of RESTING MEMBRANE POTENTIAL salts. Like the acid solution in a storage battery, the dissolved salts in the cellular fluid Definition provide the ions, which give the cell its requisite electrical charge. Throughout its life At rest, every living cell tries to maintain an this electrical potential of the cell changes electrical equilibrium across its cell membrane simultaneously with all life sustaining that allows it carry out common minimum processes, always to regain its resting poten- physiological functions. The potential diffe.

Fig. 1.3: A typical nerve cell

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Fig. 1.4: Resting membrane potential in a nerve cell—The relative concentration of positively-charged ions like Na+ and K+ is greater outside the cell membrane than the inside of the cell. The inside of the cell has a large number of negatively-charged ions like Cl– etc. This makes the intracellular environment negatively-charged and the extracellular environment positivelycharged. Hence -70 mV potential difference exists across the cell membrane of a nerve cell at rest

rence thus existing across the cell membrane of a resting cell is called resting membrane potential. Points to Ponder

• The cell membrane is selectively more permeable to K+ ions, as compared to Na + ions. • K + ions can enter or leave the cell by diffusion while the Na+ ions cannot do so. • At rest, K + ions and other negatively charged protein ions are concentrated inside the cell giving it a net negative charge and Na+ ions in the fluid outside giving it a net positive charge. • In a living cell, the number of Na+ ions are far greater than K+ ions

• The inside of the cell becomes progressively more negative as compared to the outside as the K+ ions gradually diffuse out. • This creates a difference of potential across the cell membrane, which is known as resting membrane potential, which is –70 mV in case of a nerve cell and -90 mV for a muscle (Fig. 1.4) • Due to passive diffusion, the cell constantly looses K+ ions and some Na+ ions gain entry to maintain the electrical equilibrium. • The cell again expels these Na+ ions and the lost K+ ion is reabsorbed through active transport mechanism of sodium-potassium pump mechanism, at the expense of ATP.


• The resting membrane potential creates an electrical field that allows the cell to draw essential elements and throwout or avoid unwanted elements. A cell with normal resting membrane potential (-70 mV in case of nerves and -90 mV in case of muscle cell) is regarded as healthy and one with abnormal resting membrane is regarded as sick. ACTION POTENTIAL (AP) Definition

An action potential may be defined as the momentary electrical activity taking place in a cell, as a result of a stimulus, signifying a sudden reversal of resting membrane potential (Fig. 1.5). 1 A typical action potential has threshold potential, depolarisation, repolarization and sometimes hyperpolarisation. An AP is an all or none phenomenon. Once a nerve approaches threshold potential, depolarisation occurs. Open channels for sodium to rush into the cell characterize depolarisation. An increase in the conductance of sodium is observed and the sodium is driven to Nernst potential. The membrane voltage peaks and is repolarised by the outward movement of potassium ions through open channels. An action potential is often referred to as a spike because on time scales greater than millisecond they appear as a vertical line. Any excitable cell like the nerve or muscle cannot maintain its resting membrane potential indefinitely, since it’s bombarded continuously with environmental stimuli, progressively lowering its state of polarisation. When such stimuli of sufficient intensity hits the cell, a critical threshold of the potential difference is crossed that leads to sudden depolarisation of the cell. The sudden depola-

Fig. 1.5: Action potential: An action potential is generated when the resting membrane potential is reversed due to any stimulus that upsets the resting ionic balance of the cell Stage 1. Resting membrane potential (RMP)-70 mV. Stage 2. A weak stimulus causes partial depolarisation of the cell till it reaches critical threshold of –55 mV. Stage 3. Sudden depolarisation of the cell takes place, with rapid reversal of the RMP. Stage 4. The cell is completely depolarised and reversal of the RMP takes place from -70 to +30 mV. This change is instantaneous creating a sharp spike potential. Stage 5. The cell begins the process of recovery to its RMP Stage 6. The momentum of repolarisation makes the cell hyperpolarised. Stage 7, 8, 9, 10. The cell searches for the mean RMP by losing or gaining ions as required through the selectively permeable cell membrane

risation of the cell creates a spike of electrical potential called the action potential. Points to Ponder

• All excitable cells try to retain normal resting membrane potential (Fig. 1.5, stage 1) • Any stimulus, mechanical or electrical, makes the cell membrane more permeable to Na+ ions. • As the gates at the cell membrane open, Na+ ions rush into the cell, trying to change its polarity (Fig. 1.5, stage 2).

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• If the stimulus is of small duration and and the phase of relative refraction (Fig. 1.5, stage 5). intensity, the degree of depolarisation is • The K+ channels remain open long enough minimal and the cell soon regains its to repolarise the cell to 10 to 20 mV below resting membrane potential by throwing the resting potential value of -70 mV. This out excess Na + ions to reduce its +ve process is called the phase of hyperpolaricharge (Fig. 1.5, stage 8 to 10). sation (Fig. 1.5, stage 6) • An action potential is generated only when + the intensity and the duration of the • K channels soon close and through passive diffusion the cell returns to its stimulus is such that sufficient number of normal resting potential (Fig. 1.5, stage 7). Na+ ions enter the cell to reduce the resting membrane potential to a critical threshold PROPAGATION OF ACTION value (-55 mV in case of nerve cell). Such POTENTIAL (AP) a stimulus is called liminal stimulus (Fig. Definition 1.5, stage 3) • At this point, the voltage sensitive Na+ An action potential tends to move along the channels open wide to allow a flood of Na+ body a nerve or a muscle cell, from its point ions to enter the cell, completely reversing of origin, like a wave or ripple in a pool of the resting membrane potential from-70 water. This is called the propagation of action mV to +35 mV. This process is called potential. An action potential generated in a nerve depolarisation (Fig. 1.5, stage 2 to 4) • The inside of the cell becomes positively may propagate along the axon of the nerve in charged as compared to the outside, as a either direction (Fig. 1.6). In a motor nerve, propagation of action result of flow of ions. • This state of reversal of potential lasts for potential takes place proximally towards the a very short time (1msec) and the electrical CNS (anterior horn cells in the spinal cord) changes are reflected as a sharp spike and distally towards the peripheral end organ potential when seen through an oscillo- i.e. the muscle. Action potentials travelling proximally towards the CNS are known as scope. The spikes in an ECG are a common antidromic conduction and those travelling example of the action potential generated in the distally towards the neuromuscular junction heart muscle (Fig. 1.5, stage 4) are known as orthodromic conduction. • Once the depolarisation starts the cell does In a sensory nerve, the orthodromic propanot respond to any stimulus till the cell has gation of action potential takes place towards repolarised to certain extent (Fig. 1.5, stage the sensory cortex and the antidromic conduc2 to 5). This state of the nerve is called tion takes place towards the peripheral absolute refractory phase. sensory receptors on the skin. • Sooner the peak of the action potential is The orthodromic propagation of action + + reached the Na channels close and the K potential produces the desired effect in its channels open wide, letting the cell loose target end organ where as the antidromic K+ ions rapidly, making the trans-memb- conduction is believed to be blocked at the rane potential progressively more nega- next node of Ranvier from its point of origin. tive. This process is called repolarisation The character of conduction of an action


Fig. 1.6: Propagation of action potential: An action potential (AP) generated in a non-myelinated nerve cell spreads throughout the nerve cell membrane by cyclic local circuit depolarisation. The AP is conducted through the axon to the motor neuron junction from where it is passed on to the muscle fibres, causing them to contract. In a myelinated nerve the AP jumps from one node of Ranvier to the next, increasing the nerve conduction velocity considerable. This is known as staltatory conduction

potential along a nerve varies according to the type of the nerve being stimulated. In a myelinated nerve, the action potential tends to jump from one node of ranvier to the next . Jumping conduction of the action potential from node to node makes it travel very fast and such conduction is called staltatory conduction. In a non-myelinated nerve, the action potential travels by successive and progressive depolarisation of the nerve membrane adjacent to its point of origin. Such conduction is known as local circuit conduction and is much slower as compared to that in a myelinated nerve. Any action potential is a message. Messages are sent to contract desired muscles, to signal pain, or to maintain ideal temperature,

etc. The message carried by an action potential depends on the rate of firing of the action potentials. The higher the frequency of action potential firing, the more intense will be the strength of muscle contraction or intensity of sensation and the shorter the intervals between action potentials the weaker the contraction or the sensation. This is often referred to as frequency modulation (Deutsch and Deutsch, 1992). When generating action potentials artificially by electrical stimulation, the desired effect depends on the frequency of the stimulus. At higher frequency the effects are limited to those nerves with a low threshold of stimulation, i.e. sensory nerves. For the motor nerve to be stimulated effectively, due to its

8


higher threshold, the frequency of stimulation must be low and strong enough to produce muscle contraction.2 Every action potential is characterized by a specific active one hundred millivolt signal that does not decrease in amplitude over time (Kendal et al, 1991). Each of the fifteen sensory receptors of the body sends its message through a different path in the body. This is how one sensory message is differentiated from the other. The action potentials generated by motor nerves are similar in nature and can spread its effect to the neighbouring muscles throught he process of excitation. 3 Points to Ponder

• Creation of an action potential at one segment of the cell membrane triggers depolarisation of the neighbouring segments of the cell membrane. • This wave of depolarisation moves along the surface of the nerve or muscle cell, by local circuit conduction, until the entire cell has been covered. The nature and rate of conduction of the action potential varies according to the type of the tissue. • In non-myelinated nerve and muscle fibres the action potential spreads via successive depolarisation of the neighbouring sites of the cell membrane in local circuit conduction. The speed of such conduction is inversely proportional to the diameter of the cell fibre. • In myelinated nerves, the ion exchange takes place at the nodes of Ranvier, which are breaks in the myelin sheath of the nerve. Conduction of an action potential takes place from one node of Ranvier to the next. This type of jumping conduction is called staltatory conduction. The speed of such conduction is much faster than local circuit conduction.

• An action potential generated in a nerve may propagate along the axon of the nerve in either direction. • Action potentials travelling proximally towards the CNS are known as antidromic conduction and those travelling distally towards the neuromuscular junction are known as orthodromic conduction • The orthodromic propagation of action potential produces the desired effect in its target end organ where as the antidromic conduction is believed to be blocked at the next node of Ranvier from its point of origin. • The effect of an action potential depends on the rate of firing or the frequency of the action potentials, the amplitude being constant for a given type of nerve producing the action potential. WHAT IS THE SIGNIFICANCE OF THIS BIOELECTRICAL DRAMA TO THE PHYSIOTHERAPIST?

• In the preceding chapter we have seen that the living cell generates and maintains detectable electrical potentials. This electrical potential existing in the living cell is subject to change, with every physiological activity of the cell. The cellular electrical potentials are so essential for the survival of the cell, that any disturbance in the balance of electrical potentials in the cellular environment can make the cell sick. Conversely, restoring normal electrical potential of a sick cell can cure the disorder of the cell. Since a living cell, like the storage battery, is basically an electrical entity, it can be charged to an optimum potential by exposure to an external electrical energy source, either directly or indirectly through an electrical field generated by electrostatic or electromagnetic induction.


• Understanding the electrical characteristics of excitable cells like nerve and muscle helps the physiotherapist • To identify external electrical energy sources that can effectively influence the electrophysiological function of these cells and derive a therapeutic benefit out if such exposure. Different methods treatments for different malfunction in bodily tissues have been devised based on the bioelectrical properties of the cell and their response to various forms of electrical energy. Thus the foundation of all electrotherapy modalities is based on the bioelectrical drama being enacted in the living cell throughout its lifetime. • Apart from the therapeutic application, bioelectricity also serves an important diagnostic implication. Sensitive electrodes are used to pick up the electrical potentials generated by the cell. These tiny electrical potentials are amplified and modulated to produce discreet waveforms, which project reproducible information regarding the electrical functioning of the tissue. The waveforms are then projected on to a cathode ray tube for visual analysis. Any malfunction in the tissue is reflected in the waveform generated by the tissue. For example, ECG, EEG and EMG are bioelectrical tests that provide relevant information regarding the electrical functioning of the heart, brain and the skeletal muscles respectively, indicating the state of health of these organs. Nerve conduction velocity (NCV) study indicates the rate of conduction in a nerve. Results of these tests, when compared to normal values, may help in diagnosis of any disorder in these organs or tissues.

• Physiotherapist may use this information to assess, prognosticate and treat specific disorders pertaining to the musculoskeletal system. EMG biofeedback is a form of treatment that uses the electrical potentials generated by the skeletal muscles. The patient can be shown the pattern generated by maximal effort by a normal muscle, which acts as a target. The patient is then asked to focus his effort in the effected muscles to reproduce the pattern generated by the normal muscle. Such feedback reinforces the activity in affected muscles helping in re-education of function, which is useful in treatment of upper motor neuron lesions. • To summarise, for the physiotherapist, the knowledge of bioelectrical principals and its effects on the physiology of the living tissue serves as the corner stone for selection of appropriate electrotherapy modality and application of the same for different disorders. Further, this knowledge is also essential to under take various tests and interpret the results and protocols for electrodiagnosis. Therefore, an exhaustive knowledge of bioelectricity and electrophysiology is the key to turn the physiotherapist from a technician to a fully fledged clinician REFERENCES 1. Alberts B, Bray D, Lewis J, Ra HM, Roberts K, Watson JD. Molecular Biology of the Cell. Garland Publishing Inc: New York, 1983. 2. Walsh JC. Electrophysiology. In Electrophysical Agents in Physiotherapy: Therapeutic and Diagnostic Use (Wadsworth H, Chanmugan APP, Eds) Science Press: Marrickville, NSW Australia, 1988. 3. Charmen RA. Bioelectricity and electrotherapyTowards a new paradigm? Part 1-4. Physiotherapy 1990;76(9,10,11):503-730.

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2 Introduction to Electrotherapy Definition

Application of electrical energy to the living tissue for remedial purposes is known as electrotherapy. Such therapeutic application of electrical energy can be done: • Directly, through amplitude or frequency modulation of electric current to stimulate excitable tissues like nerves and muscles, commonly known as low or medium frequency stimulation. • Indirectly, using the capacitance or inductance properties of living tissue, subjected to high frequency electrical field, to generate heat in the tissues, commonly known as short wave or microwave diathermy. • By converting high frequency electric current into high frequency sound energy, to produce mechanical micro-massage, heat generation and protein synthesis, commonly known as ultrasound therapy. The first-ever recorded attempt at application of electrotherapy is credited to the ancient Greek, who used live electric eel placed in a shallow tub of water to soak the feet in, as a treatment for gouty arthritis.

Benjamin Franklin, philosopher, scientist and one of the authors of the Constitution of United States of America was probably the first person to deliberately apply electrical charge to a paralysed limb, with shocking results. The experiment however had to be prematurely discontinued due to extreme reluctance on the part of the patient to be subjected to such torture. Even today, most patients turn pale or even miraculously recover, whenever low frequency electrical stimulation is discussed as a therapeutic option. I have often found many seasoned therapists to be reluctant to test the electrical stimulators on themselves, and choose to ignore an essential safety checklist, just because of its close association to an electric shock. • The situation however reverses and the patient becomes readily compliant, if the same electrotherapy involves application of high frequency current to generate heat, as in SWD or ultrasound therapy. • Safety considerations in electrotherapy ELECTRICAL SAFETY

Dear reader, please pay close attention to the following passage and really think about the

Introduction to Electrotherapy 11

points to ponder, as this may save a life some day. Under the oath of Hippocrates, health care professionals are debarred from, knowingly or unknowingly, harming their patients. This stricture holds good for the physiotherapists, particularly when using a lethal energy source like electricity. Every possible precaution must be taken to prevent accidental injury to the patient while applying electrotherapy You must remember that electricity is a potentially lethal energy source that can kill or injure the careless. Safety in application and maintenance of all electrotherapy equipments should be given first priority, particularly if they are used in close physical contact of the patient, with the body being arranged as a part of the circuit. The Environment of the Electrotherapy Unit

Electrical energy, in spite of its uses, is potentially lethal in nature. Safety-first should be the primary concern behind the design of any electrotherapy unit. The common sense dictates that if you are playing with a potentially lethal energy, your primary concern should be to avoid risks that could endanger your and your patient’s life and well being. Points to Ponder

• The environment of the electrotherapy unit must be dry and damp free, with insulated flooring having vinyl tiles or linoleum. • The therapist and patient must use insulated footwear (rubber or plastic) in absence of insulated flooring. • Always use wooden plinths and insulated equipment trolley (metal frame with sun

mica/glass top) in an electrotherapy department. • Engage a qualified electrician to check your electric supply lines periodically, paying maximum attention to the affectivity of the earth line and proper calibration of the mains fuse. • All electrotherapy equipments must be isolated electrically from each other and the patient, to minimize the risk of accidents, signal interference and malfunction. Equipment Safety in the Electrotherapy Unit

Any machine has the freedom to malfunction and the electrotherapy equipments are no exception. Moreover since the nature of electrical energy is potentially lethal, its use on living human beings calls for extreme caution. • Electrotherapy equipments are electronic devices that usually operate on the domestic AC power supply. Some of these equipments may be battery operated. • As a safety feature, all electrotherapy equipments use earth free DC current. The primary current is obtained from domestic AC current supply. A suitable voltage is then obtained by subjecting the AC current to a step down Trans former. From the secondary coil of a step-down transformer, an earth free AC current is obtained. This earth free AC current is then routed through a full wave rectification circuit to obtain an earth-free DC current (Fig. 2.1). • Earth-free current used in electrotherapy equipments eliminate the risk of earth shock. It is therefore essential to periodically check the earth-free nature of the secondary current supply in all electro-

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Fig. 2.1: Converting AC current to earth-free DC current: Alternating current from the domestic outlet is subjected to full wave rectification and smoothing to obtain monophasic earth-free DC current which is utilised to operate electrotherapy equipments

therapy equipments by a qualified technician. • Any electricity that leaks from the circuit between the live and the neutral terminal from the primary circuit is diverted to the earth through the earth terminal. Hence a qualified electrician should check the proper functioning of the earth terminal provided with the domestic supply outlet. If the earth line is defective the equipment body. Points to Ponder

• The electrotherapy equipments must be stored in damp proof wooden cabinets. • The electrotherapy equipments must have matched internal fuses. Fuses of less or larger calibre may damage the equipment. • All leads and cables must be checked frequently for any crack or damage. Always store leads and cables in a loose coil and avoid trailing them on the floor, kinking or bending them.

• Always make a visual check before using any electrotherapy equipment and test the machines periodically on yourself. Any defective equipment must be taken out of circulation immediately and sent for repair. • The service engineer must certify repaired equipments in writing, before being put to use on patients. This will save you from legal action in case of an accident involving repaired equipment. • Preventive maintenance includes yearly checkups by qualified service engineer. • Do not handle equipments with wet hands. Safe Application Procedure of Electrotherapy Modalities

This should be clearly understood that the electrotherapy modalities are applied on the surface of the skin. Hence, the energy derived from these modalities are have to travel through the skin to the under lying tissues to produce the desired effects. The skin is the largest organ in the body, covering the entire surface of the body, which has largely a protective role to play. As such the skin has five layers of cell, four of the top layers being composed of dead cells and only the lower most layers having living cells. This arrangement of cellular layers is useful in making the skin impervious to heat, cold, water, corrosive chemicals, friction and electrical charge. The electrical resistance offered by dry skin is in the region of 5000 Ohms. For applying electrical stimulation, a large volume of electrical energy will be needed to over come this resistance and reach the underlying muscles and nerves. The sensory receptors of the patient may not be able to tolerate such high intensities of

Introduction to Electrotherapy 13

electrical current. Hence, prior to application of electrical charge, in the form of electrical stimulation to the body tissues, the skin resistance must be brought down to at least 1000 Ohms. This procedure of lowering the skin resistance is applicable to any form of electrotherapy or electrodiagnosis that utilises direct application/transducing of electrical charge to or from the body. It is not relevant for other applications of electrotherapy like thermotherapy, insonation or actinotherapy. Points to Ponder

• Ensure the body surface of the patient is dry before giving high frequency current, particularly in humid conditions, because of the risk of scald due to concentration of current over moist areas. • Moisten the part carefully before low or medium frequency current therapy, to lower the skin resistance or the patient is likely to feel intense burning sensation. • Make sure the patient does not have a pace maker while entering an electrotherapy section, because the electrical field generated by the electrotherapy equipments are likely to interfere with the function of the pace maker within a range of 3 meters. • Switch off and remove any mobile phones and hearing aids, while applying high frequency modalities. • Warn the patient not to move unnecessarily or touch the equipment body while being treated. • Be careful not to keep any lead or cable in contact with the body of the patient. • Explain to the patient in detail, the expected reaction or sensation produced by a specific modality, before application. • Stay close by while the patient is under going electrotherapy. You may be needed

if the patient feels any unexpected sensation like too much heat, prickling or burning. • Keep an alarm bell near the patient in case you are needed to be called. • In case of the very old or very young or mentally retarded patients, avoid the use of deep heat or prolonged cooling. The reaction threshold of these patients may be inappropriate and you may be informed of any discomfort too late to prevent damage. • In pregnant or menstruating patients avoid exposure of the pelvic region to deep heat modalities like short wave or microwave diathermy. In case of a male avoid exposure to testes. • Do not give any electrotherapy over eyes and heart. • Always use protective goggles while applying any light modality like infrared, ultraviolet or laser. • Keep a detailed record of any adverse reaction, like allergy or rash or burn that may occur in spite of precautions and seek medical advice if the reaction is severe. • Management of electrical accidents Accidents may still occur in spite of your best efforts to avoid them. In case of an unfortunate incident when someone suffers an electric shock follow the following points carefully. Points to Ponder

• Disconnect the mains supply to the equipment. • Disconnect the patient from the machine circuit. • Lay down the patient if in shock and turn the head to one side if the patient is unconscious; this will do to prevent the tongue from falling back (and so prevent

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any blockade of the airways). To position the tongue away from the windpipe, it must be tied to the lower jaw with a handkerchief, to prevent it from falling over the entrance of the airway. Start cardiopulmonary resuscitation (CPR) if breathing has stopped. Send for medical assistance while you try to stabilize the patient.

• Do not leave the patient alone. • In case of a scald or burn, apply cold water to the site. Do not spill water on the equipment. • Prescribe a topical antibiotic cream like silver sulphadiazine (silverex) in case of blister formation. • Keep your professional indemnity insurance paid up to date.

3 Therapeutic Electrical Stimulation Definition

Electrical stimulation involves application of suitably modified electric current to stimulate excitable tissues like nerves and muscles, with the aim of producing physiological reactions that have clear therapeutic benefits. The application of electrical stimulation, as an integral part of electrotherapy, has come a long way since the times of Benjamin Franklin. With the advent of computerized stimulators, with idiot proof features, it has now become an effective modality in the arsenal of the therapists, with carefully modulated impulses that cause minimum irritation and discomfort to the patient, while getting maximum response from nerves and muscles. However, to be able to use this therapeutic hardware, one must be well conversant with the characteristics of electrical stimulation, necessary to initiate depolarisation in excitable tissues like nerves and muscles. HOW DOES ELECTRIC STIMULATION WORK?

Nerves and muscles are excitable tissues that respond to any sharp and sudden stimulus that can cause depolarisation in these cells.

Nature of Such stimulus may be mechanical, like a sharp tap on the nerve or the tendon; chemical, like the discharge of neurotransmitters taking place at the neuromuscular junction or an electrical impulse. Once the depolarisation of theses cells reach a critical level the chain reaction takes over till an action potential is created. Since nerves have a lower threshold they are stimulated faster than the muscles. The required intensity of the stimulus is lower in the nerves than in the muscles (Fig. 3.1). Points to Ponder

• Intensity of each stimulus or pulse amplitude must be strong enough to cause the resting membrane potential to be lowered sufficiently to achieve the critical threshold, which is the point of no return for the nerve/muscle to depolarise completely. However, once the cell depolarises, repetition of the stimulus of same or greater intensity will not provoke any response till the cell has re-polarized. Nerve cells work on the principles of all or none law. • The duration of each stimulus or pulse duration must be long enough to produce

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Fig. 3.1: Nature of electrical stimulus: Electrical stimulation is an artificial electrical stimulus of specific pulse duration, intensity and shape, applied to an excitable tissue to generate a response. It is first given at low intensity, which is then gradually increased till the critical threshold of the excitable is crossed, to produce a response in the target tissue, i.e. nerve or muscle

•

•

•

•

depolarisation of the cell membrane. In case of nerve, pulse duration between 0.01 to 1 msec is adequate to produce a response but for a muscle this is too short a duration. A muscle cell devoid of nerve supply needs 100 to 300 msec pulse duration to provoke a contraction. The rate of rise of the stimulating current from zero to peak must be adequately matched to the response threshold of the target tissue to produce a satisfactory response (Fig. 3.2) To stimulate a nerve the rate of rise must be fast enough to prevent accommodation. Accommodation is the rapid adjustment of the nerve to changing electrical environment to prevent depolarisation. To stimulate a muscle devoid of nerve supply a slow-rising current is most suitable. The rate of rise of a stimulus is usually reflected in pulse shape.

Fig. 3.2: Types of electrical impulses: Types of electrical impulses commonly used in electrical stimulation are fast-rising or slow-rising in nature. In a fast-rising impulse the intensity rises from zero to peak within a very short period of time. This rapid rise does not allow the nerve to be accommodated, causing depolarization. Fast-rising impulses can be square, rectangular or spike-shaped. Slow-rising impulses, as the name suggests, rise from zero to peak intensity with sufficient time lag which allows the nerves to be accommodated to the changing electrical environment. Hence, with such slow-rising impulses, higher intensity stimulus can be used to stimulate denervated muscles, which have much higher threshold than the nerves

• A fast-rising impulse have square, rectangular or spike-shaped. • Slow-rising impulses are trapezoidal, triangular or saw-tooth in shape. Slowrising impulses are also called selective impulses. Frequency or rate of repetition of a stimulus is the third most important parameter in the biophysics of a stimulating current. • Lesser the frequency of a stimulus the greater will be its effect on nerves and muscles and vice versa. • Frequency of a stimulating current is inversely proportional to pulse duration. • The greater the frequency, smaller the pulse duration

Therapeutic Electrical Stimulation 17

Fig. 3.3: Motor unit— A motor unit is the fundamental building block of the neuromuscular complex. A motor unit consists of one motor nerve cell, its axon and muscle fibres supplied by the axon filaments. Many such motor units combine together to make an innervated muscle. The response threshold of such a muscle is equal to that of the motor nerve supplying it

• Motor nerve or a motor unit has a frequency threshold between 1 to 150 Hz with optimum pulse duration of 0.01 to 1 msec. WHAT IS A MOTOR UNIT?

• A motor unit is composed of one neuron, its axon, dendrites and the muscle fibres supplied by the axon (Fig. 3.3) • It forms the building block of the neuromuscular complex. The entire motor unit shares the response threshold of the motor neuron. Sensory nerves have a response threshold up to 4000 Hz, with very small pulse duration, because their response threshold is much lower than motor nerves. • Muscle tissue, without a nerve supply; have a very high response threshold requiring a large amount of current to be stimulated. It needs a pulse frequency from 1 to 3 Hz, with optimum pulse duration of 100 to 300 msec. .

RELATIONSHIP BETWEEN STRENGTH AND DURATION OF AN ELECTRICAL STIMULUS: THE SD CURVE

The SD curve, a graph in which the X-axis refers to the intensity and the Y-axis refers to the duration of the stimulus with which the nerve/muscle is stimulated, determines the close relationship between the intensity and the duration of an impulse (Fig. 3.4). The nerve/muscle is first stimulated at the longest duration, i.e. 300 msec and the intensity required in mAmp/mVolts to produce the minimal perceptible contraction is recorded. This is known as the rheobase value. The duration is then progressively lowered to 100, 30, 10, 3, 1, 0.3, 0.1, 0.03, 0.01 ms and the minimum intensity needed to produce a response is recorded. The values of intensity are then plotted against respective pulse durations on a standard graph paper. The resultant plotting is known as the SD curve. The first recording of the SD curve should be done at least three weeks after the suspected nerve injury. A series of recordings are

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then taken, preferably on the same graph paper, at an interval of one week each. The shifting of the curve will indicate the status of nerve recovery (Fig. 3.5). Points to Ponder

Fig. 3.4: Strength duration curve indicates the relationship between the intensity/strength of an electrical stimulus and the duration of the stimulating electrical impulse • Electrical response of any excitable tissue, like an innervated muscle, depends on the intensity, the duration and the rate of rise of the stimulus applied to it. • While plotting a SD curve the target muscle or nerve is stimulated with a rectangular interrupted galvanic stimulus with pulse duration of 300 msec. • The intensity required to produce a minimum perceptible response at maximum duration is recorded, which is known as the rheobase. • The duration is then progressively shortened to 100, 30, 10, 3, 1, 0.3, 0.1, 0.03, 0.01 msec respectively. • The intensity required eliciting response at each of these pulse durations are recorded. • The pulse duration that is needed to elicit a response at intensity double the rheobase is known as the chronaxie. • In the above example, at the maximum pulse duration of 300 msec, the minimum intensity required is 5 mv. • This remains constant even though the pulse duration is progressively shortened up to the pulse duration of 1 msec. • The required intensity then rises sharply as the pulse duration is further shortened to 3, 0.1, 0.03 and 0.01 msec. Such SD curve is typical of a normally innervated muscle

• Rheobase is the intensity of current required to produce a minimal perceptible response in a nerve/muscle with a stimulus of infinite duration, i.e. 300 msec. • Chronaxie is the shortest pulse duration required to produce a minimal perceptible response in a muscle, at twice the intensity of Rheobase. Normal chronaxie for innervated muscle is less than 1 msec. • A strength-duration curve (SD curve) is plotted to determine whether a muscle is innervated, denervated or partially denervated/innervated. TYPES OF THERAPEUTIC CURRENT

Therapeutic currents can broadly categorised as stimulating and ionising currents. Stimulating currents are classified on the basis of Frequency, duration and shape of the stimulating impulse They may be either low frequency or medium frequency currents, which have stimulating effects on nerves and muscles. The ionising currents usually have a high frequency range and have mostly heating effects on the body tissues. .

Low Frequency Currents

Electrical current impulses having pulse frequency between 1 and 250 Hz, used for stimulation of nerve or muscles, are known as low frequency currents (Fig. 3.6).


Fig. 3.5: Relationship between strength and duration of an electrical stimulus to predict improvement or worsening of nerve supply to a muscle • Strength duration curve, when plotted repeatedly, at intervals of one week, can give a picture of progressive innervations or denervations taking place in a muscle. • The graph at extreme right shows a picture of complete denervation in the muscle, with the required intensity rising sharply as the pulse duration is shortened beyond 100 msec. • When the graph is plotted subsequently after some time, the required intensity rises sharply till up to 10 msec and then levels off creating a kink at 10 msec. • Thereafter the required intensity remains same as the pulse duration is progressively shortened to 3 msec. • This kink is indicative of partial innervations of the muscle. Subsequent graph plotted at an appropriate interval indicates normal nerve supply. • In case of progressive denervation the kink shifts towards the right upper corner of the graph, till a full deneravtion pattern emerges. In case of progressive innervations, the kink shifts towards the lower left hand corner of the graph, till a normal pattern emerges. • Thus the SD curve can be used to predict the rate and the potential for recovery of muscle function, as a convenient tool of electrodiagnosis for the physiotherapist. • Site of lesion extent of denervation not detected by SD curve

Fig. 3.6: Low frequency current forms Low frequency currents are basically of two types, interrupted galvanic current and faradic current. • Monophasic rectangular pulses, with durations ranging from 10.01 to 300 msec are called interrupted galvanic current. • Ultrashort duration interrupted galvanic impulses, shaped like a spike, available in trains of impulses, are known as faradic type current. • Such train of impulses can be modulated to produce a wave-like pattern, is known as surged faradic current. • Biphasic impulses, with a shallow positive phase and a sharp negative phase is called pure faradic current. Such currents are produced by the SmartBristow coil and are not used nowadays

Subtypes of Low Frequency Stimulating Currents

a. Interrupted galvanic current Interrupted galvanic current is a monophasic direct or galvanic current, broken at preset intervals and allowed to flow for a preset pulse duration with a frequency between 1 and 6 Hz, and a pulse duration between 1 and 300 msec. These are also known as long duration currents, specifically used for stimulation of de-nervated muscles or

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b.

c.

d.

e.


motor point detection in innervated muscles. Faradic type of current Faradic type of current is very short duration monophasic interrupted galvanic current, with frequency between 50 and 100 Hz and Pulse duration between 0.01 and 1 msec. These are also known as short duration current, specifically used as surged faradic current for stimulation of innervated muscles. Pure faradic current Pure faradic current is a biphasic current with a sharp negative spike of 1 msec, followed by a gentle positive trough of 4 msec; with a frequency of 50 Hz. Traditionally it was produced by the Smart-Bristow coil, though not used any more. Transcutaneous electrical nerve stimulation (TENS) Transcutaneous electrical stimulation uses ultrashort duration (50 to 300 micro second) impulses at a frequency of 1 to 300 Hz, used mainly for relief of pain through stimulation of sensory nerves. The impulses may be asymmetrical biphasic or monophasic (Fig. 3.7). Iontophoresis Continuous direct current, used at low voltage and intensity, with the aim of transferring therapeutically useful ions, through the skin or mucous membrane to the body.

MEDIUM FREQUENCY CURRENT

Fig. 3.7: Current forms used in TENS: • Conventional TENS current consists of biphasic very short duration impulses at very high frequency, with intensity just at the level of sensory threshold. This type of TENS is called HI-TENS, used for relief of acute pain. • Selectively TENS may also be applied through acupuncture points, with longer duration impulses at low frequency, with high intensity almost to the level of pain threshold. Such TENS is called LOTENS, used for relief of chronic pain. • Burst mode TENS combines the characteristics of both HI and LO TENS, using train of impulses of HI-TENS repeated at a preset discrete interval

are available in two-pole or four-pole format (Fig. 3.8). Subtypes of Interferential Currents

These types of currents are commonly called a. Two-pole medium frequency current interferential currents and are in the frequency (2000-4000 Hz) range of 2000 to 4000 Hz. These types of 1. Russian current (2000 Hz) currents have a strong sensory effect and are 2. Medium frequency surge current used for stimulation of deep muscle through (4000 Hz) an interference pattern producing low fre- b. Four-pole medium frequency/interference quency stimulation at a very high intensity, current (4000-4100 Hz) bypassing the sensory barrier of the skin Such 1. Classical interferential current treatment modality is broadly referred to as 2. Isoplaner vector current 3. Dipole vector current interferential therapy. The interferential currents .


c. Microwave diathermy (Frequency 1-10 GHz, wavelength 3-300 cm). Points to Ponder

Fig. 3.8: Current forms used in medium frequency stimulation or IFT: • Medium frequency currents produce significantly less irritation than low frequency currents and therefore can be used at much higher intensities, with deeper effect. • M os t co mm on ly t wo i nd ep en de nt m ed iu m frequency currents are used, at frequencies slight out of phase. • Such current when crossed with each other’s field produces a beat frequency deep within the body tissue. • The beat frequency thus achieved has all features and effects similar to low frequency stimulation.

HIGH FREQUENCY CURRENTS

These are used mainly for deep heating and do not have any direct stimulating effect on nerves or muscle due to extremely high frequency in the range of 10,000 Hz to 3 MHz. With proportionately small pulse duration, that does not cause depolarisation but creates oscillation of ions and molecules of the cell releasing energy as heat. Subtypes of High Frequency Currents

a. Long wave (Frequency 1 MHz, wavelength 3 Km) b. Short wave (Frequency 27.12 MHz, wavelength 11.3 m)

• Stimulating currents are those that can generate response in excitable tissues like nerves and muscles. • Low frequency and medium frequency currents are capable of generating such response in nerves and muscles. This is because the pulse duration in low frequency and medium frequency currents are large enough to cause depolarisation in excitable tissues. • High frequency currents cannot generate such response because their pulse duration is too small. They are used primarily for heating tissues. Energy from high frequency current is transferred to the tissue through molecular agitation as heat. • Nerves are more sensitive than muscles. Nerves need smaller pulse duration than the muscle to produce a response. PRODUCTION OF LOW FREQUENCY STIMULATING CURRENT

Basic circuit used to produce stimulating current is based on the multivibrator circuit, which can interrupt a smooth monophasic DC current to produce interrupted galvanic current. Most modern electrical stimulators use a dual circuit with separated +ve and –ve terminals colored red and black respectively. The equipment also offers interrupted galvanic current with pulse durations of 300, 100, 30, 10, 3, 1, 0.3, 0.1, 0.03 and 0.01 msec available through a rotary step selector, as well as faradic type of current with adjustable surge duration and interval, through individual rotary selectors. The intensity controls are separate for either type of current (Fig. 3.9).

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alternating current used in surged faradic or asymmetrical alternating current, used in high voltage galvanic stimulation. • Polyphasic pulses Biphasic current producing three or more phases in a single phase, used in Russian or interferential current. ,

MODULATION OF STIMULATING CURRENTS Fig. 3.9: Production of stimulating currents using a multivibrator circuit: A multivibrator circuit is an oscillating circuit that is used to break smooth monophasic DC current into discrete impulses of different pre-selected pulse durations with different pre-selected repetition rates

WAVE PATTERNS OF STIMULATING CURRENTS

The shape, polarity and the arrangement of the electrical impulse used in therapeutic stimulation is critical to the response it produces and is called its wave pattern. Response of excitable tissue to the stimulating current varies according to the shape of the stimulating current. Specific types of current impulses are needed to produce desired response in specific type of tissues. Points to Ponder

• Monophasic pulses Unidirectional flow of electrons, interrupted at preset duration and repetition rate, producing square, rectangular, trapezoidal, triangular, used in Interrupted Galvanic Current or spike shaped pulses used in Faradic Type of Current. • Biphasic pulses Bidirectional flow of electrons, with one half of the cycle in + direction and the other in – direction of the isoelectric line, producing symmetrical

Modulation of a stimulating current is the changes in the characteristics of the stimulating current, which occurs at a preset rate and limit, to avoid accommodation of nerves during stimulation. Nerves have the ability to rapidly adapt to any changed electrical environment. This makes a stimulating electrical impulse ineffective, if applied for a long duration. As such, the type of the impulses are altered or modulated automatically by present generation equipments, to suit the response threshold of a nerve and the clinical result desired. Different forms of therapeutic stimulating low frequency currents are listed below along with their usual application in therapy. Points to Ponder

• Continuous direct current Smooth unvarying flow of electrons, used in Iontophoresis. • Interrupted direct/galvanic current Sharp interruption of current flow at preset intervals after a preset duration of flow, used in stimulation of denervated muscle. • Surged faradic current Wave-like gradual increase and decrease over a preset duration and interval, used in stimulation of innervated muscles. • Ramped current Sloping rise in intensity to a preset peak, within preset pulse


duration, followed by a gradual or sudden drop to zero, may be used in TENS, FES etc. THE MOTOR POINT

The motor point is that point on the surface of the body, where if applied, electrical stimulation can produce maximum response in the underlying muscle. Once the type of current has been selected it is important to identify the most suitable spot on the body, to apply it. The skin over entire muscle does not have equal sensitivity. The electrical stimulation should be applied through only those spots that produce maximum response with minimum intensity of current, i.e. the motor point (Fig. 3.10). Points to Ponder

• Electrophysiologically, the motor point can be defined as the area of greatest excita bility on the skin overlying any superficial muscle that can produce maximum muscle contraction with minimum amount of current.

Fig. 3.10: Motor point: • Anatomically, the motor point may be defined as the spot where the motor nerve axon enters the muscle. • Electrophysiologically, it may be defined as the spot on the skin surface over the muscle belly, where strongest muscle twitch can be obtained with minimum current intensity

• Anatomically, it is defined as the point where the motor nerve enters an innervated muscle. • When the nerve supply has been destroyed, the motor point is located slightly distal to its original spot, towards the insertion of the muscle. • A motor point is usually found on a muscle, at the junction of the proximal 1/3rd and the distal 2/3rd of the belly or the fleshy part of the muscle. • To trace a motor point, it’s most convenient to use interrupted galvanic current, at pulse duration of 1 msec in case of innervated muscles and 100 msec in case of deneravted muscles. • Once the skin has been prepared and the electrodes have been positioned in appropriate surface location over a given muscle, the intensity of the stimulus should be increased just enough to elicit a minimal perceptible twitch contraction in the muscle. The active electrode is moved over the approximate area of the motor point till the maximum response for a given stimulus is observed. This is the motor point, which should be marked with indelible pencil for future reference. • Tracing of a motor point is essential for: 1. Plotting of a SD curve of a muscle. 2. Giving interrupted galvanic stimulation to denervated muscles. 3. Locating the general area for electrode placement for surged faradic stimulation of innervated muscles. The main advantage of stimulating a muscle through its motor point is that, the current intensity required to produce muscle contraction is minimum, compared to any other area on the muscle belly, thus causing mild sensory irritation.

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4 Low Frequency Stimulation of Nerves and Muscles (NMES) INTRODUCTION

Electrical stimulation has been widely used for many years for a variety of therapeutic purpose on different types of excitable tissues. • In case of normal skeletal muscles, electric stimulation provides artificial exercise by producing sustained contraction, particularly when the muscle is unable to contract actively due to pain, weakness or restrictions like a plaster cast. For getting best results, the muscle must be contracted voluntarily, along with electrical stimulation. • In case of denervated muscles, electric stimulation is used to slow down the process of disuse atrophy and shorten the recovery time. Apart from gaining strength or maintaining the physiological properties in the muscle, neuromuscular electrical stimulation (NMES) also helps to accelerate blood supply and drainage of metabolic wastes from the muscles through pumping action it induces during muscle contractions. Such pumping action helps relieve swelling of soft tissue, reduce muscle spasm and hypertonus. • Electric stimulation is also widely used on the sensory nerves for management of

acute and chronic pain, because its effective and cheap, without any of the adverse side effects of the pain killing drugs. HOW DOES NMES WORK IN BUILDING MUSCLE STRENGTH AND PREVENTING DISUSE ATROPHY?

• High-intensity electrical stimulation is a proven way to maintain size, and even function in muscles, which may temporarily be rendered inactive due to injury or immobilisation. The idea may sound a little shocking, but a number of scientific studies have confirmed that the right type of electrical stimulation can keep muscles relatively sound, even when they are not being stimulated by the nervous system or engaging in any real activity. 1 In one of the earliest published studies on the effects of electrical stimulation, on the maintenance of size and strength in immobilised muscles, researchers electrically stimulated the quadriceps and hamstrings muscles in the leg of an athlete daily, who was immobilised in a lower-extremity cast for 3 weeks, because of Grade-II medial-collateral and anteriorcruciate ligament sprains in his knee. On the day the cast was removed, the girth of the

Low Frequency Stimulation of Nerves and Muscles (NMES) 25

athlete’s thigh had actually increased, suggesting that hypertrophy had occurred in the target muscles, instead of the usual immobilisation—associated atrophy. In addition, single-leg, vertical-leap height was 92% as great in the immobilised leg following cast removal, compared with the uninjured leg, and the athlete was able to immediately return to competition. 2 Research has shown that NMES is effective in preventing decreases in muscle strength, muscle size, and even the oxygen-consumption capabilities of thigh muscles after knee immobilisation. There is a fair amount of scientific evidence that NMES can enhance functional performance in a number of different strength-related tasks, in skeletal muscles and produce effects similar to those associated with physical training? • One theory is simply that NMES produces high-intensity muscle contractions which are similar to those occurring during standard, low-repetetion, high-resistance strength training, and that as a result muscles respond to NMES in ways which are similar to the adaptations which occur during normal training. NMES imposes specific patterns of muscle recruitment and a particular “metabolic solicitation” which forces muscle cells to respond in a significant way.1 However, there may be other factors at work. • It is known, for example, that NMES produces what is called a “reversal of voluntary recruitment order.” At the beginning of many volitional sporting activities, the central nervous system ordinarily first activates the smallest

“alpha motor neurons”. These nerve cells originate in the spinal cord and have relatively thin branches, which run out to muscle cells, which can stimulate muscle fibres to become active. As exercise continues and more force production by muscles is required, increasingly larger diameter alpha motor neurons become active. This order of activation from smaller to larger motor-nerve cells has been termed the ‘size principle’ of musclecell recruitment. 4 The size of the alpha motor neuron is closely related to the type of muscle cell it innervates. • Slow-oxidative (Type-I) muscle fibres are usually recruited first, by the small alpha motoneurons, whereas fast-glycolytic (Type-II) muscle cells are ordinarily much more difficult to recruit and generally depend on the biggest alpha motor neurons. This helps to explain why someone who is exhausted during prolonged endurance exercise, will suddenly feel capable of further effort, if he/she actually forces himself/herself to exercise much more intensely. In such cases, non-recruited, non-fatigued, fast-glycolytic muscle cells can be brought into the action, providing a big boost to exercise tolerance. During NEMS of muscles, the order of muscle-fibre recruitment is often reversed, with the fast-glycolytic muscle fibres stimulated first rather than last and the slowoxidative muscle fibres recruited later. Because Type-II muscle fibres have a higher specific force than Type-I muscle cells, selective augmentation of Type-II fibres through strong electrical stimulation may actually increase the overall strength of a muscle or group of muscles.

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Understandably, there has been a keen interest in whether NMES might work for healthy athletes or average person. The early work of Y. Kots in the former Soviet Union suggested that in certain cases NMES could be significantly more effective than exercise training itself in strengthening the muscles of elite athletes. 3 If Kots’ findings were valid, athletes could improve their power while sleeping, simply by placing the right electrodes over the key muscles involved in their sport! Subsequently, devices for electrical stimulation have been marketed to athletes and the general public, with the devices claiming that they can improve muscle strength; decrease body weight and body fat, and upgrade muscle firmness and overall tone. Sales of the NMES contraptions appear to be red-hot, with a large number of people buying the concept that they can build rock-hard buttocks and flat stomach while watching TV or relaxing at home. Recent, well-controlled scientific research carried out at the University of Wisconsin, scientists assigned 27 college-age volunteers into either a NMES group (16 subjects) or a control group (11 individuals). The NMES group were stimulated three times a week, following manufacturer’s recommendations, while the control group underwent concurrent placebostimulation sessions. 4 The muscles stimulated included the biceps femoris, quadriceps femoris, biceps brachii, triceps brachii, and abdominals (rectus abdominis and obliques). The study showed that NMES had no significant effect on body weight, body fatness, fat weight, lean body weight, arm girths, waist girths, thigh girths, isometric

strength, isokinetic strength, or even the appearances of the subjects, compared with the placebotreatments. Why such disappointing results?

In order for muscles to improve their strength, they must be stimulated beyond a critical threshold. This threshold probably needs to be as high as 60% of max-voluntary-contraction strength in case of well-trained athletes and 30% in case of sedentary persons. 6 In addition, NEMS should be utilised at the minimum threshold of at least 60% of maxvoluntary-contraction strength.7 Unfortunately, the over-the-counter device tested in this Wisconsin study produced a force equal to less than 20% of max-voluntary contraction. Importantly, too, the over-the-counter machine produced current frequencies of 90 to 151 pulses per second; whereas 50 to 75 pulses are considered optimal (overly high frequencies may induce too-early muscle fatigue). In addition, the ‘on-off ratio” (the ratio of time stimulated to recovery time) was only 1:3.5, even though about 1:5 is considered optimal because considerable recovery is needed between bouts of electrical stimulation to allow muscle cells to overcome fatigue. HOW DOES TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION RELIEVE PAIN?

TENS is a method of electrical stimulation, which provides a degree of relief symptomatic pain by specifically exciting sensory nerves. It can be used in several different ways, each being best suited to different mechanisms of pain production. Extent of pain relief would be in the region of 60%+ for acute pains and 40%+ for more chronic pains.


The technique is non-invasive and has few so doing; activate specific natural pain relief side effects when compared with drug mechanisms. There are two primary relief therapy. The most common complaint is an mechanisms that can be activated: the spinal allergic type skin reaction (about 2% of gate control mechanism and the endogenous patients) and this is almost always due to the opiate system. Pain relief by means of the spinal gate material of the electrodes, the conductive gel or the tape employed to hold the electrodes mechanism involves excitation of the A-beta sensory fibres, and by doing so, reduces the in place. The current intensity in the range of 0 to transmission of the noxious stimulus from the 80 mA is used, though some machines may ‘c’ fibres, through the spinal cord and hence on provide outputs up to 100 mA, which is easily to the higher centres. The A-beta fibres appear to appreciate being stimulated at a relatively tolerated by the patient. The machine delivers ‘pulses’ of electrical high rate (in the order of 90-130 Hz or pps). To activate the indigenous opiate mechaenergy, and the rate of delivery of these pulses (the pulse frequency) will normally be nisms, the A-delta fibres must be stimulated. variable from about 1 or 2 pulses per second These neurons respond preferentially to a (pps) up to 200 or 250 pps. In addition to the much lower rate of stimulation (in the order stimulation rate, the duration (or width) of of 2 - 5 Hz), which will, and provide pain relief by causing the releas e of an endogenous each pulse may be varied from about 40 to opiate (encephalin) in the brain, which will 250 microseconds (A microsecond is a reduce the feeling of pain. millionth of a second). The reason that such short duration pulses Points to Ponder can be used to achieve these effects is that the targets are the sensory nerves that tend to Therapeutic electric stimulation is used to: have relatively low thresholds, i.e. they are a. Reduce pain— using T.E.N.S, causing • Activation of the spinal gate control quite easy to excite and that they will respond mechanism of pain modulation as per to a rapid change of electrical state. There is Malzack and Wall. generally no need to apply a prolonged pulse • Release of indigenous opiates of the in order to force the nerve to depolarise, body at pain receptors of the brain. therefore stimulation for less than a milli b. Reduce muscle spasm—using faradic stimusecond is sufficient. lation, by The pulses delivered tend to be asym• inducing muscle fatigue, through metrical biphasic modified square wave titanic contraction for several minutes, pulses. The biphasic nature of the pulse means produced by continuous faradic that there is usually no net DC component, current stimulation. thus minimising any skin reactions due to the • pumping of muscles, increasing the build up of electrolytes under the electrodes. metabolic turnover, temperature, blood circulation and drainage of metabolic Mechanism of Action of TENS waste, through cyclic contraction and relaxation, produced by surged faradic This type of stimulation excites different current stimulation. elements of the sensory nerve system, and by

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c. Increase or maintain joint range of motion— using surged faradic stimulation, sometimes under tension, causing: • stretching of tightened soft tissue around a stiff joint, caused due to weak muscle action. • release spastic muscle by induced fatigue or by reciprocal inhibition. • reduction of pain inhibition, to permit muscle contraction and allow joint movement. d. Re-education of muscle action—using surged faradic stimulation, by actively assisting muscle action to complete a movement. • providing visual and proprioceptive feedback to the brain, to re-educate forgotten pattern of movement. • improving co-ordination of voluntary movements. e. Prevent disuse atrophy —using surged faradic stimulation to exercise a muscle, with intact nerve and blood supply, but unable to contract due to inhibition or immobilisation. This can be done even if a muscle is enclosed in plaster cast. Using interrupted galvanic stimulation to give contractions to a denervated muscle, to maintain its physiological properties, retard disuse atrophy and promote early repair of the damaged nerve. f. Reduce swelling of extremities—using surged faradic current under compression and elevation. g. Promote repair of soft tissue/wound— by increasing supply of blood carrying O 2 and nutrients, produced by pumping action in muscles due to surged faradic stimulation. WHEN NOT TO USE ELECTRICAL STIMULATION?

Though it’s a versatile modality, certain precautions must be taken while applying

electrical stimulation and in some conditions its application is strictly contraindicated. Points to Ponder

• Do not apply electrical stimulation over • Healing fractures —may lead to displacement of fractured bone ends. However, if the fracture is stabilized internally or in a plaster cast, stimulation may be applied through windows cut into the cast, to prevent disuse atrophy of muscles. • Recent haemorrhages —may lead to further bleeding. • Malignant tumours— may lead to spread of cancer cells. • Acute infective focus/carbuncle/cellulites— may lead to spread of infection to the blood stream. • Deep vein thrombosis— m ay lead to embolism of clot. • Superficial metal implants, as in ORIF of superficial bones— may cause concentration of charge and cause burn of the neighbouring tissue. • Muscle of pharynx or voice box— may lead to problem in swallowing, cause choking or impair speech. • Pregnant uterus—may cause spontaneous abortion. • Electrical stimulation is absolutely prohi bi te d in pa ti en ts wi th de ma nd ty pe pacemakers or diseases of hearts muscles like myocardial infarction. • Be careful while giving electrical stimulation over: • Loss of superficial skin sensation— stimulation may cause burn or itching of the skin due to overdose, which the patient will not be able to tell you. In such cases, look for strength of muscle contraction to guide you. It’s useless to


apply TENS for relief of pain, in a case of sensory loss, like in diabetic neuropathy or any other sensory nerve involvement, since the sensory pathways are not working and no relief of pain will be obtained. • Massive swelling —may lead to breakdown of skin, which is devitalised due to poor blood circulation. This is particularly important in chronic oedema following radical mastectomy or chronic circulatory failure of lower limbs in varicose veins or burger’s disease. Always use effleurage massage to reduce the superficial oedema substantially before applying faradism

under pressure, keeping the limb in elevation. REFERENCES 1. Muscle electric stimulation in sports medicine. Rev Med Liege 2001;56(5):391-95. 2. High intensity electric stimulation—Effect on thigh musculature during immobilisation for knee sprain. A case report physical therapy 1987;67(2):219-22. 3. Neuromuscular electric stimulation—An overview and its application in the treatment of sports injuries. Sports Medicine 1992;13(5): 320-36. 4. Effects of electric stimulation on body composition, muscle strength, and physical appearance. Journal of Strength and Conditioning Research 2002;16(2):165-72.

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5 Getting Started with Low Frequency Electrical Stimulation Know your stimulator , because it is very easy for a fresh graduate to be lost in the hype, created by the equipment manufacturers; keen to sell their equipments in a cutthroat market. Most often people end up buying equipments with useless features for a ridiculous price. To avoid such pitfalls, here are some tips on how to select the right machine for your need. Points to Ponder

• Electrical stimulators are used for stimulation of excitable tissues like nerves and muscles, for therapeutic benefits. • Depending upon the nature of application, an electrical stimulator may be called electrical muscle stimulator (EMS), neuromuscular stimulator (NMS), TENS (for pain control), functional electrical stimulator (FES), high voltage galvanic stimulator or interferential therapy unit, though its basic function remains same, i.e. to apply electric charge to excitable tissues of the body, through neural pathways.

• For routine work, low frequency stimulators offering surged faradic and interrupted galvanic current are used. • All modern low frequency stimulators use a basic circuit to produce interrupted galvanic current, with a wide range of pulse duration and frequency modulation. The latest models have microprocessor for accuracy of the pulse and frequency modulation • Modern low frequency electrical stimulators are marketed in two basic models, therapeutic and diagnostic. • Therapeutic model is cheaper than diagnostic model, but it does not have full range of pulse durations of IG current and a digital or analog meter to show the intensity of the current. These two parameters are essential to plot SD curve. My suggestion would be to buy the diagnostic model because it gives the equipment a wide range of clinical application. • A diagnostic stimulator must have separate colour coded output for interrupted galvanic and faradic type current. The

Getting Started with Low Frequency Electrical Stimulation 31

Fig. 5.1: A diagnostic electrical stimulator. The set of controls on the top row are for interrupted galvanic current. On the extreme left is a voltmeter indicating the intensity of the stimulating current (this being a constant current stimulator). To its right are the control knobs for pulse duration, pulse repetition rate and current intensity respectively. To the extreme right are LED indicators and two output terminals for galvanic current. The controls on the bottom row are dedicated for faradic current. From left to right are the main switch with integrated pilot lamp, toggle switch to determine the sensitivity of the voltmeter (30/120 volts), control knobs for surge duration, surge interval and intensity respectively. On the extreme right are LED indicators and two outlets for faradic current

pulse durations for IG current should be in the range of 0.01, 0.03, 0.1, 0.3, 1, 3, 10, 30, 100, 300 ms as well as continuous DC current. The faradic circuit should offer both continuous and surged currents with separate controls to modulate surge duration and intensity (Fig. 5.1). • While selecting the stimulator it is important to pay close attention to the following ten points: 1. Always opt for a model with fibre or powder coated metal body shell, to minimize the risk of body shock. Check the body for signs of crack or rust. 2. The face plate of the equipment must be made of polypropylene sheet or other non-conductive materials. The

display must be clearly and accurately printed under each control knob and output terminals. 3. The switches and knobs must not have any extra play and be of good quality. The leads and cables must have adequate conductors, insulation and be pliable. The electrodes must have no rough edges. Good quality accessories and exteriors with careful finish may indicate reasonable quality of the inner components. 4. Always check the make, model, and serial number is printed at the rear plate of the equipment casing. 5. Check the fuse type, calibration and the site of the fuse socket. Unusual fuses and awkward location of fuse sockets may leave you needlessly dependant on the service engineer. 6. Always test the machine on your self before the decision to buy it, looking for quality of the output current regarding smoothness and consistency, at each duration setting and surge duration. Any sharpness and burning sensation felt, means poor quality of modulation of the stimulating current and automatic disqualification of the equipment. 7. Shop extensively for the best deal. Ask for the trade price as well as the MRP from the supplier. For equipments made in India, negotiate directly with the Manufacturer. Manufacturers often quote a price with the dealer commission discounted. 8. Remember that small scale local manufacturers can often give you custom designed equipment, with maximum number of useful features at a reason-

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able cost, rather than established manufacturers, because their overhead cost is much less. 9. For imported equipments, contact the main importer rather than sub-dealers, because the importers can give you a better deal, as well as, provide quality spares and service, due to their tie-up with the foreign principals. Insist on complete installation and training at the cost of the supplier. 10. After sales service is the most important consideration for any equipment purchased. Most equipments carry oneyear warranty period. Negotiate for post-warranty annual maintenance contract, before concluding the deal for purchase. The supplier should preferably have a local service centre manned by qualified service engineer and off the shelf spares should be available. The response time in any case should not be more than 48 hours. Always withhold 50% of the AMC amount till the completion of the contract period. Renew the contract only on getting satisfactory service. Approach the consumer forum for redressal in case of any default by the supplier. MACHINE PREPARATIONS

Electrical stimulators are compact electronic devices that can be operated with 220 volts domestic AC electric supply. Some stimulators have dual mode of operation, i.e. they can work with mains, as well as, 9 volts battery power supply. Before commencing the treatment the therapist must be familiar with the controls and test the apparatus on him/her. This is essential to avoid any nasty surprises for the patient during treatment.

Points to Ponder

• Read the operating manual carefully to familiarize you with new equipment. Perform a visual check in case of old equipments. • All electrotherapy equipment has two functional components, the machine circuit and the patient circuit. • After checking the leads and mains cable for breaks or cuts, connect two carbon rubber electrodes of 5 sq cm size, with red and black leads each, to the output terminal of the IG/Faradic current. The red lead should be connected to the + terminal and the black-lead to the –terminal. • Connect the equipment to the domestic three pin wall socket, turn all knobs to zero, and keep the electrodes side by side on a wooden surface away from each other and switch on the power switch of the equipment. See the pilot lamp is glowing. This confirms the OK working of the machine circuit. Switch off the equipment from the power switch. • Wet your left hand and place it on the electrodes so that part of the hand connects with each of the electrodes, while the electrodes do not touch each other. This way your left hand becomes a part of the patient circuit. Make sure that your right hand is dry. Select 100 ms duration of IG at one pulse per second or middle level surge duration through the selectors on the equipment. Turn on the equipment power and slowly increase the intensity till you feel electric impulses flow through your hand. Twitch contraction will be produced in case of IG current and a titanic contraction will be felt in case of faradic current. • Please let the current flow for one minute and ensure the current out put flows in


uniform pulses and cause no burning sensation, then turn the intensity to zero and switch off the equipment. • Test the machine on yourself, preferably in front of the patient. It will not only confirm the OK status of the equipment, but also will also give confidence to the patient to undertake the treatment. PATIENT PREPARATIONS

Low frequency electrical stimulation is potentially painful procedure and can adversely affect the compliance of the patient. This is particularly important with young children and nervous patients. Start with an explanation to the patient as to why is it important for him/her to undergo the procedure and what are the nature and intensity of sensation he/she is likely to feel. If the patient is still apprehensive you may do the equipment testing on yourself in front of the patient. This is likely to remove any lingering apprehension in the mind of the patient. Points to Ponder

• Counselling the patient before the treatment session is essential. • Question the patient to rule out any absolute contraindication and identify any precaution that you must take. Assess the feasibility of electrical stimulation yourself even if it has already been prescribed. • Explain to the patient why it is necessary to give stimulation and type of sensation that will be felt during the treatment, best described as tapping/tingling/ant bite etc. • The treatment should be carried out in an area with optimum privacy, having good tangential light, which will make it easy for you to see contraction of muscles.

• In case of upper limb stimulation, place the patient in high sitting on a wooden chair with the limb resting in front of the patient on a wooden plinth. • In case of lower limbs and back, place the patient on supine/prone on a wooden plinth. • Expose the part to be treated and cover the rest of the body with a sheet. • Therapeutic electrical stimulation is usually applied transcutaneous or through the skin, to the nerves and muscles underneath. Skin resistance can be a major problem in application of electrical stimulation • Dry skin has a resistance of 5000 ohms, since the epidermis is made up of five layers of dead cells soaked in oily sebaceous fluid, all of which resist flow of electric current. • High skin resistance will need a large intensity of electric charge to reach the tissues below, which may be very painful to the patient. • Preparation of the skin over the area to be stimulated must be done to lower the skin resistance to approx 1000 ohms. • The skin should be washed with soap/ savlon to remove oil and dirt, rubbed vigorously with moist lint to remove dead skin cells and lower the skin resistance and then soaked in saline to provide ions that will help in carrying the current to the subcutaneous layers. • If there is a break in the skin, sterile petroleum jelly should be applied over the broken portion to avoid concentration of the electric charge. SELECTION AND PREPARATION OF STIMULATING ELECTRODES Points to Ponder

• Nature of stimulating electrodes: Electrodes used for therapeutic stimulation are

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strips of conductive material of sizes and shapes may vary from discs to rectangular or square plates depending on the site of placement and type of use. • Types of stimulating electrodes (Fig. 5.2): – May be shaped as pads or discs or pin points. – Made of conducting material such as lead, steel, zinc or carbonised rubber. Sizes range from pin-point, 1 sq cm to 10 sq cm discs or pads. • To avoid direct contact of the metal on the skin the metallic conductive material should be covered by at least 8 layers of absorbent lint or a 1/2 cm thick envelope of sponge.

Fig. 5.2: Different types of electrodes used in low frequency electrical stimulation: • At the top is a disc electrode mounted on a penholder. • Below that, clock-wise from the top left are stainless steel ball electrode, point electrode, disc electrode, steel plate electrodes and black carbon rubber plate electrodes of different sizes. • The ball, point and disc electrodes are used for detecting and stimulating motor points of muscles of different sizes. • The steel electrodes must always be covered with cotton and lint layer and must be soaked in water before use. Rubber electrode can be applied directly to the skin over a thin film of electrode gel.

• The covering of lint/sponge should be soaked in tap water and squeezed to remove excess water. The conductive plate is then introduced in to the layer of moist lint or sponge, which helps to absorb corrosive ions produced by electrolysis due to passage of electric current through the electrodes. • Polarities and types of electrode placement: The stimulating electrodes must have two polarities, + and - to complete the circuit, so that pulse of electrical current may flow between them. Any excitable tissue interposed between the two polarities will then be affected by the electrical stimulus. 1. Monopolar placement—Two electrodes of different sizes are needed to complete the patient circuit, usually during stimulation through the motor point. The larger one of the two is called the passive electrode and the smaller one is called the active electrode. The difference in size between passive and active electrode must be 3:1. 2. Bipolar placement—Sometimes two electrodes of same size may be used, usually while applying surged faradic stimulation to a group of muscles (Fig. 5.3, Plate 1). 3. Colour coding—The active electrode is connected to the + terminal colour coded red and the passive electrode to the – terminal colour coded black. 4. Shape of electrodes—In monopolar stimulation the passive electrode is usually a carbon rubber pad and the active electrode is a metal disc or point, attached to a pen holder. In Bipolar stimulation of muscle groups, two pads of equal sizes may be used.


ferably over the proximal attachment of a muscle or muscle group being stimulated. For example, to stimulate the wrist and finger flexor muscles, the passive electrode should be placed over the medial epicondyle of humerus, covering the common flexor origin. If such a spot is not easy to reach in other muscles, + electrode may be placed on the point where the motor nerve supplying the target muscle is most superficial or at the spinal root level of the motor nerve e.g. passive electrode may be placed over the lumbosacral junction to stimulate the muscles Fig. 5.4: Top—Vaginal electrode; Bottom—Rectal supplied by the sciatic nerve. If the above electrode: These are specialized electrodes used for three options are not convenient, the stimulation of the muscles of the vaginal and anal sphincters. Surged faradic current or two pole medium + electrode may be placed at any spot on the frequency current may used for such stimulation body, close to the site of stimulation, e.g. for stimulation of facial muscles, the most Special Type of Electrodes appropriate location of the passive electrode Specific areas like the vaginal and the anal is underneath the neck of the patient, in sphincter muscles may need to be stimulated supine position. The active electrode, commonly having the negative polarity, is used in case of bladder and bowel incontinence. to deliver the electrical charge to the excitable Special types of electrodes that incorporate tissues, preferably through the motor point, both positive and the negative polarities in since maximum stimulation can be obtained one cylindrical body is used for this purpose with minimum current intensity can be (Fig. 5.4). obtained. However in case of a denervated muscle the motor point may not be at the THUMB RULES FOR ELECTRODE original location and may have shifted PLACEMENT proximally on the muscle belly. When stimulating a muscle or a group of In low frequency stimulation, the electrical impulses are applied from the surface, muscles, the active electrode should be placed through the skin, to the nerves and muscles at the junction of proximal 1/3rd and the underneath. Optimum effect of electrical distal 2/3 of the fleshy belly of the muscle. stimulation can only be obtained when the stimulating electrodes are placed at appro- Points to Ponder priate spots on the skin surface. A few thumb • Low frequency stimulation is given on the rules must be remembered, in the following surface of the skin. order of preferences, to obtain best result. The • Excitable tissues underneath the skin are stimulated through the transcutaneous passive or + electrode is used to complete the route. patient circuit and it should be placed pre-

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• Stimulating current is delivered to the excitable tissues through a pair of electrodes. • The electrode connected to the positive terminal of the stimulator is commonly known as the passive/dispersive/collecting electrode. • The electrode connected to the negative terminal of the stimulator is commonly known as the active/stimulating/directing electrode. • The passive electrode is either larger than or of the same size as that of the active electrode. • The passive electrode may be placed on the origin or insertion of a muscle or muscle group, over the motor nerve supplying the muscle—at its most superficial spot, over the spinal segment of the motor nerve or any other location close to the point of stimulation. • The active electrode is placed over the motor point of the muscle, usually located over the junction of the proximal 1/3 and the distal 2/3 of the fleshy belly of the muscle. The Checklist to follow in Application of Electrical Stimulation

• Counsel the patient, explaining in details why the stimulation is needed, how it will be given and what sort of sensation to expect. • Follow the checklist of contraindications and cautions. • Make the patient comfortable on a wooden plinth, in a well-lit room with privacy to undress or expose the part to be treated. • Prepare the skin of the target area to minimize skin resistance and therefore the discomfort.

• Test the equipment on yourself before the patient. This helps in building confidence. • Select and prepare appropriate electrodes, check the connecting leads and jacks of any damage. • The passive electrode is secured to appropriate spot on the body with an elastic strap or Velcro fastener. • The active electrode is placed on the general location of the motor point of a superficial muscle in case of monopolar stimulation or junction of the proximal 1/3 and distal 2/3 of the muscle group in case of bipolar stimulation (Figs 5.5 and 5.6, Plate 1). • In case of deep muscles, the motor point may not be at the designated spot. The stimulus will spread to the overlying superficial muscles, with little benefit to the target deep muscle. In such case, the active electrode should be placed at a spot where any portion of the deep muscle which is at the surface, e.g. the tendon. • Set appropriate frequency, waveform and modulation rate of the stimulating current depending on the desired effect and the nature of target tissue. • Gradually increase intensity till the desired effect is felt, i.e. contraction of muscles for motor stimulation or tingling sensation for sensory stimulation. The level of stimulation should never be too uncomfortable or the patient may not comply with the treatment. At end of treatment, gradually decrease the intensity to zero before lifting the active electrode from the skin. Disconnect the electrodes from the patient and inspect the skin for any adverse reaction. Make a record of the treatment. Allow the patient go after a few minutes of stabilizing time.


CLINICAL APPLICATIONS OF LOW FREQUENCY STIMULATION

Low frequency electrical stimulation is the modality of choice in any paralytic conditions. The visual impact of a flail part, that was so far useless and lifeless, suddenly being rejuvenated at the touch of the electrode, is tremendous. The electrical stimulation can do to the morale of the patient, what words of counselling from the therapist fail to achieve. Hence there is always a temptation among the therapist to use this modality more frequently than warranted clinically. A clear understanding of the principles of clinical application of electrical stimulation is essential to prevent this modality from becoming a gimmick. Points to Ponder

• Low frequency stimulation, using IG current can be applied in all major peripheral nerve injuries, • The aim of preserving the physiological properties of the muscles supplied by the dysfunctional nerve. • The rationale is to provide exercise to the muscle through artificially-induced contractions, to promote exchange of blood. • Fresh blood carries nutrient and oxygen to the paralysed muscle, to keep its properties of contractility, excitability and extensibility intact, till the nerve re-grows to take over the function of muscle contraction. • Once the muscle has started contracting actively, stimulating current may be changed to surged faradic, should be applied simultaneously with voluntary contraction.

• This helps in better recruitment of motor units of weak muscles, thereby producing stronger contractions and quicker gain in power. • Further, since faradic stimulation produces titanic contraction similar to voluntary contraction, it is very useful in re-education of movements, in lesion of upper motor neuron. • Through biofeedback the patient regains normal function of the muscle. • Some patients cannot initiate muscle contraction voluntarily to produce movement, due to inhibition or hysterical paralysis, though there is nothing wrong with their muscles. • In such cases faradic stimulation may be used to facilitate muscle contraction and movement of the body part, to break the inhibition. • This principle is also used in re-education of new muscle action, in cases where a muscle or tendon has been transferred from its original location to different spot, to perform a different function. • In presence of swelling in the extremities, application of faradic stimulation assists in drainage of fluids. TECHNIQUES OF LOW FREQUENCY STIMULATION IN SOME COMMON CLINICAL CONDITIONS

In the following pages I have dealt with some common clinical conditions that need low frequency electrical stimulation. The students are likely to face such cases during the course of their supervised clinical practice. Details of the technique of application, as well as, outline of the specific pathophysiology of the

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disorder, along with tips on suitable adjunctive therapy, have been covered for easy reference. 1. Techniques of Low Frequency Stimulation in Bell’s Palsy

Clinical condition : Bell’s palsy. Nerve involved: Facial nerve or VIIth cranial nerve. Muscles involved : Facial muscles—Frontalis, corrugators, orbicularis oculi and oris, levator labi superioris and inferioris, nasalis, risorius and mentalis. Nature of impairment : Flaccid paralysis of muscles of one side of the face due to compression of the facial nerve, trapped the under zygomatic arch, where it emerges from the bone.

Fig. 5.7: Stimulation of facial muscles in Bell’s palsy• Note the stainless steel point active electrode being used, since the muscle involved is small in size, to stimulate the motor point of Risorius or the smile muscle. • The positive passive electrode with eight layers of lint cover placed under the neck.

Functional problems: Loss of facial expressions and symmetry, drooling, conjunctivitis.

Duration of treatment: Thirty to sixty contractions to each muscle.

Type of current used: Interrupted galvanic current, rectangular pulses at 100 ms duration at1 pulse per second. As the condition improves, the pulse duration can be progressively reduced to 30, 10, 3, 1 ms and the rate of repetition can be increased to 3 pulses per second.

Special precautions: Facial skin is delicate and subject to rashes and itching on prolonged stimulation. Use Betamethasone and zinc oxide based cream in case of rashes or itching. All facial must be shaved. Use a moisturizing lotion after treatment.

Type of technique: Monopolar technique, with passive electrode of 5 sq cm carbon rubber plate, active electrode with 1 sq cm disc on holder.

Contraindications : Do not stimulate in presence of severe acne or skin rashes.

Patient position: Supine on a wooden plinth. Placement of electrodes : With the patient in supine position positive electrode placed under the neck, negative electrode placed on the motor points of individual muscles (Figs 5.7; 5.8, Plate 2; 5.9).

Remarks: Easiest of cases to stimulate, but counsel the patient before the treatment. Facial massage and exercise to the facial muscles are essential for faster recovery and should be demonstrated to the patient to be practiced at home. Chewing gum or sipping water through straw is also effective form of home exercise.


Patient position: Sitting on a wooden chair Placement of electrodes: + ve electrode at the nape of the neck – ve electrode on the muscle belly on affected side of the neck (Fig. 5.10). Duration of treatment: 5-10 min. Special precautions: The skin preparation must, to minimize skin resistance, since treatment time is prolonged. Should use adequate water in the electrode cover.

Fig. 5.9: Position of the patient and the therapist during facial stimulation • The stimulator should be within easy reach of the therapist so that the controls can be operated comfortably. • The ambient light should be tangential to detect slightest contraction of the smallest muscle

2. Technique of Low Frequency Stimulation in Wryneck (Paracervical Muscle Spasm)

Clinical condition : Wryneck—muscle spasm of neck and upper back muscles.

Contraindications : The blood pressure of the patient with neck stiffness must be checked before treatment. Neck stiffness may be due to high blood pressure, where electrical stimulation should not to be given because it may increase blood pressure. Remarks: Moist hot packs and gentle manual mobilization of the neck, with mild traction component in the pain free range of the neck may be given as an adjunct to electrical stimulation. The patient must be asked to avoid exposure to cold for at least one hour after the treatment.

Nerve involved: Spinal accessory nerve (root value—C1-C4) Muscles involved: Trapezius upper fibres Nature of impairment: Muscle spasm and pain inhibition of neck movement due to postural stress or cervical spondylosis. No primary nerve involvement. Functional deficit : Pain and stiffness of neck and scapular movements. Type of current used: Surged faradic current, with surge duration of 10 sec and surge interval of 30 sec. Type of technique : Bi-polar technique, both electrodes 5-8 sq cm carbon rubber plates.

Fig. 5.10: Placement of electrodes for surged faradic stimulation to relieve spasm of muscle of the neckCarbon rubber plate electrodes of equal size are placed on either side over the posterior-lateral muscles of the cervical column

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3. Technique of Low Frequency Stimulation in Fibromyositis of Trapezius Muscle

Clinical condition : Fibromyalgia of parascapular muscles or T4 syndrome. Nerve involved : Dorsal scapular, suprascapular and thoraco-dorsal nerve (C4-8). Muscles involved : Rhomboids, supra and infraspinati, teres major, subscapularis. Nature of impairment: Muscle spasm resulting in ischemia producing fibromyalgia. Functional deficit : Inhibition of scapular and shoulder movements, often misdiagnosed as periarthritis of the shoulder joint. Type of current used: Surged faradic current Type of technique: Bi-polar stimulation. Patient position: Sitting on a wooden chair, with head and the upper girdle resting on a plinth. Placement of electrodes: Positive electrode at the nape of the neck. Negative electrode at the medial border of scapula on the affected side (Fig. 5.11). Duration of treatment: Surged faradic at 10 sec duration and 50 sec interval for 5 min Special precautions: Nothing specific Contraindications: Nothing specific Remarks : Manually-guided scapular movements must be given after faradic stimulation to obtain quick gain in power. Moist hot packs and local ultrasound therapy to fibromyalgic nodules are useful as adjunctive modalities for relief of pain. Deep friction massage applied with the tip of the thumb is also very effective in reducing fibromyalgic nodules. Type of current used: Surged faradic current, with surge duration of 10 sec and surge interval of 30 sec.

Fig. 5.11: Placement of electrodes for surged faradic stimulation to relieve spasm of suprascapular muscles. Carbon rubber plate electrodes of equal size are placed on the affected side, covering the upper fibres of trapezius muscles at its proximal and distal ends

Type of technique : Bi-polar technique, both electrodes 5-8 sq cm carbon rubber plates. Patient position: Sitting on a wooden chair Placement of electrodes: + ve electrode at the nape of the neck – ve electrode on the muscle belly on affected side of the neck. Duration of treatment: 5-10 min. Special precautions: The skin preparation must, to minimize skin resistance, since treatment time is prolonged. Should use adequate water in the electrode cover. Contraindications: The blood pressure of the patient with neck stiffness must be checked before treatment. Neck stiffness may be due to high blood pressure, where electrical stimulation should not to be given because it may increase blood pressure. Remarks: Moist hot packs and gentle manual mobilization of the neck, with mild traction


component in the pain free range of the neck may be given as an adjunct to electrical stimulation. The patient must be asked to avoid exposure to cold for at least one hour after the treatment. 4. Technique of Low Frequency Stimulation in Crutch Palsy

Remarks: As long as the deltoid is devoid of nerve supply, shoulder joint needs to be protected from subluxation with a sling or Bobath cuff. Axial suspension can be given when the power is between Gr.I – II. Once the re-innervation starts, manually-guided exercises or pendular suspension must be given simultaneous with faradic stimulation to obtain quick gain in power.

Nerve involved: Axillary nerve (root value-C5). Muscles involved : Deltoid muscle (Ant, mid and post. fibres)

5. Technique of Low Frequency Stimulation in Erb’s/Klumpke’s Palsy

Nature of impairment : Flaccid paralysis of deltoid muscle due to compression of axillary nerve.

Clinical condition : Brachial plexus injury 1. Erb’s palsy 2. Klumpke’s palsy

Functional deficit : Loss of shoulder abduction, flexion and extension.

Nerves involved: • Erb’s palsy—Lesion of C5 root, sometimes C6 root, caused due to traction injury between head and shoulder girdle, mainly during forceps delivery. • Klumpke’s palsy—Lesion of C8-T1 roots, caused due to traction injury between arm and trunk, caused by sudden pull of the body weight on the arm, when a person grabs something to prevent falling from a height or trying to get up on a moving bus or train.

Type of current used: Interrupted galvanic current, rectangular pulses at 100 ms pulse duration at 1 pulse per second. After re-innervations, surged faradic current may be used to build strength. Type of technique : Monopolar for IG and bi-polar for surged faradic stimulation. Patient position: Sitting on a wooden chair, arm resting on wooden plinth. Placement of electrodes : +ve electrode at the nape of the neck, -ve electrode at the common motor point of deltoid, 2 cm above the deltoid tubercle (Fig. 5.12, Plate 2). Duration of treatment: 60-90 contractions in one sitting for IG stimulation. Surged faradic stimulation at 10 sec duration and 50 sec interval for 5 min Special precautions: Nothing specific. Contraindications: Presence of superficial metal implant in case of #.

Muscles involved • In Erb’s palsy—Deltoid, rhomboids, supraspinatus, infraspinatus, teres minor, biceps brachi, brachialis. • In Klumpke’s palsy—Long flexor muscles of the wrist and fingers and intrinsic muscles of the hand. Nature of impairment: Flaccid paralysis of the muscles with significant sensory loss. Functional deficit : • In Erb’s palsy, (C5)—Loss of shoulder abduction, external rotation, elbow flexion

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and forearm supination and with (C6)wrist extension; typical deformity- Policeman’s tip. • In Klumpke’s palsy – Loss of grip (C8) and fine movements of hand; with (T1) typical deformity—Claw hand or ape hand. Type of current used: Interrupted galvanic current, rectangular pulses at 100-300 ms pulse duration, or selective trapezoidal pulses for prolonged stimulation, at 1 pulse per second. After re-innervations, surged faradic current may be used to build strength or reeducate muscle action following muscle transfer surgery. Type of technique: Monopolar for both I.G. and surged faradic stimulation. Patient position: Sitting on a wooden chair with the affected extremity resting on a plinth in front of the patient.

essential when the plexus has been repaired surgically. Axial suspension is the method of choice for exercising the affected limb. Once the re-innervation starts, manually-guided active exercises must be given simultaneous with faradic stimulation to obtain quick gain in power. • In Klumpke’s palsy, early splinting of the affected hand must be done to prevent irreversible clawing of fingers. • It’s wise to repeat SD curve at the beginning of electrical stimulation and then repeat at weekly intervals. It may create a reference point of prognosis, to decide for surgical intervention if the progress is not as expected and it’s so much cheaper than EMG/NCV tests.

Placement of electrodes : +ve electrode at the para-cervical area on the affected side, -ve electrode at the motor point of each affected muscle (Figs 5.13, Plate 2, 5.14, Plate 3; Figs 5.15 and 5.16). Duration of treatment: 60 contractions in one sitting for each muscle or group with I.G. Surged faradic—10 sec duration and 50 sec interval for 5 min. Special precautions : No traction should be applied to the affected limb while handling because it may cause further injury to the plexus. Contraindications: Presence of superficial metal implant within the field of stimulation, in case of # of the shoulder girdle bones. Remarks: • In Erb’s palsy, as long as the girdle muscles are devoid of nerve supply, shoulder girdle needs to be supported with a sling or airplane splint, to protect the plexus from traction. Such support is particularly

Fig. 5.15: Placement of electrodes for interrupted galvanic stimulation of forearm flexor muscle group– • A stainless steel plate covered with eight layers of lint is used as the passive (positive) electrode. • The passive electrode is placed on the affected side over the medial epicondyle of elbow, covering the common flexor origin and the proximal portions of wrist and finger flexor muscles. • The active (negative) electrode is a lint padded metal disc electrode mounted on a penholder. It is placed on the belly of individual muscles of the flexor compartment of the forearm, one after the other, to give each muscle the required number of contractions.


fibular neck due to crossed leg sitting, sleeping on side lying on a hard surface, tight leg cuff of orthosis or BK plaster cast, applied with knee in hyperextension or a ganglionic growth on the proximal tibiofibular ligament. 2. Anterior tibial nerve may be damaged during insertion of tibial pin during application of skeletal traction.

Fig. 5.16: Placement of electrodes for interrupted galvanic stimulation of intrinsic muscles of the hand• A stainless steel plate covered with eight layers of lint is used as the passive electrode. • The passive (+) electrode is placed on the affected side over the lower 1/3rd of the forearm on the flexor aspect, covering the median and ulnar nerves at its superficial most point. • The active (-) electrode, stainless steel point electrode mounted on a penholder. It is placed on the belly of individual intrinsic muscle of the hand, one after the other, to give each muscle the required number of contractions.

6. Techniques of Low Frequency Stimulation in Foot Drop/Flail Foot

Clinical condition : Foot drop. Nerve involved: 1. Lateral popliteal (common peroneal) nerve, most commonly involved. 2. Anterior tibial nerve Muscles involved: 1. Lat popliteal nerve—Muscles of the anterior-lateral compartment of the leg (Tib.ant, EHL, EDL, EDB, Peronei). 2. Anterior tibial nerve—As above except Peronei. Nature of impairment: 1. Flaccid paralysis of muscles and loss of sensation over the dorsum of foot, usually due to compression of the nerve against

Functional problems : Dropped foot compensated with high stepping gait. Type of current used: Interrupted galvanic current, rectangular pulses at 100 ms pulse duration, 1 pulse per second. Type of technique : Monopolar technique, passive 5 sq cm carbon rubber plate, active 1 sq cm disc on pen holder. Patient position: Supine on a wooden plinth, a roll under the knee to keep the knee in 10-15 degrees in flexion. Placement of electrodes: +ve electrode over the neck of the fibula. • -ve electrode on the motor points of individual muscles (Figs 5.17, Plate 3; 5.18 to 5.20). Duration of treatment: Thirty to sixty contractions to each muscle. Special precautions : Rashes and etching on prolonged stimulation are common. Use Betamethasone and zinc oxide based cream in case of rashes or etching. The leg must be shaved before treatment to minimize skin resistance. Use a moisturizing lotion after treatment. Contraindications : Do not stimulate in presence of open wound or skin rashes. Remarks: Easiest of cases to stimulate, but counsel the patient before the treatment.

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Fig. 5.18: Placement of electrodes for surged faradic stimulation of dorsiflexor and evertor muscle groups– • Two stainless steel plate covered with eight layers of lint of equal sizes are used as the passive (positive) and active (negative) electrode electrodes. • The passive electrode is placed on the affected side over the neck of the fibula, covering the common peronial nerve at its superficial most point. • The active (negative) electrode is placed on the junction of proximal 2/3rd and the distal 1/3rd of the belly of muscles on the anteriolateral compartment of the leg, to give all the muscle the required number of contractions.

SPECIALISED TECHNIQUES USED IN LOW FREQUENCY STIMULATION 1. Faradic Footbath

Indication : Flat feet or pes planus, due to weakness of intrinsic muscles of the feet, resulting in dropped medial longitudinal arches of the feet. Points to Ponder

• Primary cause is usually congenital, due to cramped space for the foetus within the pelvis of the mother. Parents usually detect it as the child begins to walk. • Secondary causes may be childhood obesity, paralysis of foot muscles or derangement of the bones of the foot due to injury.

Fig. 5.19: Placement of electrodes for interrupted galvanic stimulation of planter flexor muscle groups– • A stainless steel plate covered with eight layers of lint is used as the passive (positive) electrode. • The passive electrode is placed on the affected side over the popliteal fossa, covering the posterior tibal nerve at its superficial most point. • The active (negative) electrode is a lint padded metal disc electrode mounted on a penholder. It is placed on the belly of individual muscles of the posterior compartment of the leg, one after the other, to give each muscle the required number of contractions.

Functional Problem

• Pain in the feet and legs on prolonged standing and walking. • Secondary knock-knee may appear as the child begins to walk for longer durations. • It may be a cause for disqualification for defence services. Plan of Management

• The primary management in the case of flat feet depends on the age of detection. • If the case is detected as early as 12 months the defect can be corrected reasonably by giving the child corrective foot wears with medial arch support and exercises like sand walking, tip toeing, to develop the intrinsic muscles of the feet, etc.


particularly when there is correctible bony derangement of the feet. Equipment and Type of Current Used

• Standard low frequency stimulator, offering surged faradic current with separate controls for surge duration and intervals. Type of Electrodes

Fig. 5.20: Placement of electrodes for surged stimulation of planter flexor muscle groups – • Two stainless steel plate covered with eight layers of lint of equal sizes are used as the passive (positive) and active (negative) electrode electrodes. • The passive electrode is placed on the affected side over the popliteal area, covering the posterior tibial nerve at its superficial most point. • The active (negative) electrode is placed on the junction of proximal 1/3rd and the distal 2/3rd of the belly of muscles on the posterior compartment of the leg, to give all the muscle the required number of contractions.

• When the child is little older, say 3-5 years, this therapy may be complimented with faradic footbath, with a little coaxing to create acceptance of the electrical stimulation. • In cases with milder presentation or with late detection, like in the teen age, faradic footbath forms the first choice of therapeutic management, along with medial arch support shoes and exercise like toe curling. The Rationale Behind Faradic Footbath

• The intrinsic muscles of the foot form the dynamic support system for the arches of the feet. Building up the strength of these muscles with surged faradic stimulation helps to stabilize the arches of the feet,

• Bipolar metal or carbon rubber electrodes, rectangular plates of 3 × 7 cm. • The passive and active electrodes are of the same size. • No lint or sponge electrode cover is needed since the treatment is done under water, which allows free conduction of current while washing off any electrolyte produced under the electrodes. Placement of Electrodes

• The electrodes are placed in a shallow bath of water, the positive under the heel and the negative under the ball of toes. • The level of water should be up to the junction of the dorsal and planter skin of the foot. This will ensure that the current passes easily through the intrinsic muscles in the sole of the foot and does not spread to the dorsum. Application of Current

• Surged faradic current, with surge duration of 10 sec and interval of 30 sec is applied. • The intensity should be enough to produce visible contraction of intrinsic muscles of the foot creating clenching of toes . Patient should be asked to curl toes simultaneously along with the current flow and relax during surge interval. • The treatment should be given for 15-30 min.

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Precaution: Do not allow the patient to touch

mities.

• Collection of fluid in tissue interstitial space also interferes with supply of nutrition and oxygen to the tissue through blood stream. This may lead to further complications like skin breakdown and tissue necroses.

Points to Ponder

Plan of Management

• Such oedema develops in the distal end of limbs due to collection of fluid in the tissue interstitial space. • Common pathological causes are soft tissue injury like sprain and strain, inadequate lymph or blood drainage due damage to the vessels like deep vein thrombosis or following radical mastectomy or systemic disorders like congestive heart or kidney failure etc. Therapy is indicated for such pathological oedema • Physiological or gravitational oedema may develop in the legs if the limbs hang down for long periods without any movement, e.g. as in long bus or air journey. The gravitational force pulls fluid down in to the lower extremities, which is not pumped out due to lack of muscle contraction. Elevation of the limb and frequent movements are enough for physiological oedema.

• The primary goal in the management of pathological oedema is to remove the fluid from the site of oedema as quickly as possible. • This can be achieved by the combination of elevation, compression and isometric muscle contraction. • Elevation of extremities utilizes the gravity to drain the fluid to the systemic circulation, provided the limb is elevated above the level of the heart. • Compression applied with crepe bandage or pressure stockings and isometric muscle contraction helps to push the fluid from the tissue interstitial space in to the blood or lymphatic vessels.

the equipment or the wall during treatment. 2. Faradism Under Pressure Indication: Oedema or swelling of extre-

Functional Problem

• The girth of the limb increases and it becomes heavy, creating problems in joint movements and locomotion. • If allowed to remain undisturbed for long, oedema, which is initially soft and pitting under finger pressure, may consolidate or harden. If this happens around a joint, the movement of the joint may be permanently lost.

Rationale Behind Faradism Under Pressure

• The process of fluid drainage can be made more effective by application of surged faradic current to major muscle groups to generate stronger contractions that creates a pumping action on the muscles and the blood vessels. • When the limb is maintained under pressure during such induced contraction, the recoil force of the muscle contraction acting against the force of compression makes the drainage more effective, further assisted by gravity if the limb is kept in elevation.


Equipment and Type of Current Used

Application of Current

• Standard low frequency stimulator, offering surged faradic current with separate controls for surge duration and intervals

• Surged faradic current, with surge duration of 30 sec and interval of 90 sec is applied. • The intensity should be enough to produce visible contraction of muscles of the creating clenching of toes/fingers. • Patient should be asked to do active movement simultaneously with the current flow and relax during surge interval. The treatment should be given for 30 min.

Type of Electrodes

• Bipolar carbon rubber electrodes, rectangular plates of 3 × 5 cm with sponge electrode cover. The passive and active electrodes are of the same size. Placement of Electrodes

The skin must be cleaned and moistened adequately before treatment. Placement of electrodes varies from site to site: • For oedema of the leg, ankle and foot, the active electrode is placed on the calf, approximately at the centre of the fleshy belly of the muscles. The passive electrode is placed on the sole of the foot. • For oedema of hands and forearm the active electrode is placed on the flexor aspect of the forearm, approximately at the junction o the proximal 1/3rd and the distal 2/3rd of the muscle belly. The passive electrodes may be placed on the palm or on the cubital fossa. • The electrodes are fixed to the skin with straps or adhesive tapes.

Special Precautions

• Skin rashes are common on prolonged stimulation. • Use Betamethasone and zinc oxide based cream in case of rashes. • The body hair must be shaved before treatment to minimize skin resistance. • Use a moisturizing lotion after treatment. Contraindications: Do not stimulate in pre-

sence of open wound or skin rashes. 3. Faradism Under Tension

Indication: Shortening of Contractile soft tissue like muscles and some type of connective tissues in and around joints. Points to Ponder

Application of Pressure

Plan of Management

• With the patient in supine position on a wooden plinth, the limb is elevated above the level of the heart, using pillows. • The pressure bandage or garment is applied over the electrodes, keeping maximum pressure at the distal most end of the limb, becoming progressively less proximally.

• Such contractures develop in major muscle groups of the extremities, like the quadriceps or elbow flexor group leading to restriction of knee flexion or elbow extension, mostly after prolonged immobilisation following fractures. • Conventionally, such tightened muscles and soft tissue are mobilized by forced

48


passive movements, which is an extremely painful procedure. Rationale Behind Faradism Under Tension

• Titanic contraction induced by surged faradic stimulation generates intrinsic tension in the myofibril, which is made to contract against external traction force trying to stretch them apart. • The interplay of opposing forces pulls apart the shortened myofibrils, gradually increasing their length, with much less pain than would be felt with forced passive movement. • The patient is asked to try and contract the tightened muscle as hard as possible in time with the surge of faradic stimulation. This adds to the intrinsic contractile force of the myofibrils, leading to quicker releases of contracture, as well as power gain.

and active over distal 1/3rd over front of the thigh. • In contracture of the elbow flexors, passive electrode is placed over proximal 1/3rd and active over distal 1/3rd over front of the arm Application of Tension

• In case restriction of knee flexion due to contracture of quadriceps muscle group the patient is positioned on wooden plinth, with the legs hanging down. A roll of towel is placed below the knee to prevent posterior translation of the tibia over femur. The thigh is strapped to the plinth

Equipment and Type of Current Used

• Standard low frequency stimulator, offering surged faradic current with separate controls for surge duration and intervals. Type of Electrodes

• Bipolar carbon rubber electrodes, rectangular plates of 5 × 10 cm with sponge electrode cover. • The passive and active electrodes are of the same size. The skin must be shaved, cleaned and moistened adequately before placement of electrodes, which varies from site to site. Placement of Electrodes (Fig. 5.21)

• In contracture of the quadriceps, passive electrode is placed over proximal 1/3rd

Fig. 5.21: Placement of electrodes for surged stimulation under tension to the quadriceps muscle groups – • Two stainless steel plate covered with eight layers of lint of equal sizes are used as the passive (positive) and active (negative) electrode electrodes. • The passive electrode is placed on the affected side over the proximal 1/3rd of the quadriceps. • The active (negative) electrode is placed on the junction of proximal 2/3rd and the distal 1/3rd of the belly of the muscle. • The limb is kept at its limit of flexion to give the muscle the required degree of stretch and then the required number of titanic contractions is given to the muscle under tension.


with a 6”wide canvas strap. Tension to the affected knee joint is applied with a sand bag or weighted belt (1/2-3kg) attached to the front of the ankle. • In case restriction of elbow due to contracture of elbow flexor muscle group, the patient is positioned supine on a wooden plinth. A roll is placed under the elbow, just proximal to the joint. The arm is stabilized with a sand bag placed on the lower end of the arm, keeping the elbow free to move. Tension to the muscle is applied with a sand bag or weighted belt (1/2-1 kg) strapped to the anterior aspect of the wrist. Application of Current

• Surged faradic current, with surge duration of 30 sec and interval of 90 sec is applied.

• The intensity should be enough to produce visible contraction of the muscles. • Patient should be asked to do active movement simultaneously with the current flow and relax during surge interval. • The treatment should be given for 30 min. Special Precautions

• Skin rashes are common on prolonged stimulation. • Use Betamethasone and zinc oxide-based cream in case of rashes. • The body hair must be shaved before treatment to minimize skin resistance. • Use a moisturizing lotion after treatment. Contraindications: Do not stimulate in pre-

sence of open wound or skin rashes.

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6 Pain Modulation— Transcutaneous Electrical Nerve Stimulation (TENS) It is a modern, non-invasive, drug-free pain management modality, designed to provide afferent stimulation, used for relief of acute or chronic pain. TENS is frequently used to relieve muscle pain in the neck, back or joint pain of knee, shoulder, etc, arising from work or sport related injuries, e.g. carpal tunnel syndrome, RSI (repetitive strain injuries), as well as, postural musculo-skeletal problems related to faulty working environment. PHYSIOLOGICAL EFFECT OF TENS

Two theories are used to justify the relief of pain achieved by TENS. Points to Ponder

A. The Gate Control theory by Malzack and Wall in 1972 postulated that: • Activation of A-beta fibres simulates the inhibitory interneuron in substantia gelatinosa located in the dorsal horn of the spinal cord. • The activated interneuron produces inhibition of transmission through pain carrying A-delta and C fibres.

• This pre-synaptic inhibition of the T cells closes the spinal pain gate to prevent the painful impulses from reaching the sensory cortex, where the pain is felt. • Pain modulation is thus achieved by activation of central inhibition of pain transmission B. The Endorphin Release theory states that: • Noxious stimulus causes production of endorphins in the pituitary gland. • Endogenous opiates are also synthesized in periaquductal grey matter, midbrain and thalamus. • Painful stimulus causes release of these opiates in the pain receptor sites in the brain. • Pain modulation can thus be achieved through the descending pathways generating body’s own pain killing chemicals or endogenous opiates. 1 EQUIPMENT AND THE NATURE OF TENS CURRENT Points to Ponder

• Externally applied electrical potential from TENS must produce evolved potentials in

Pain Modulation—Transcutaneous Electrical Nerve Stimulation (TENS) 51

underlying peripheral sensory nerve(s) or receptors on the skin. • To do this, there must be an adequate stimulus to cause depolarisation of the nerve cell membrane. • Relief of pain by selectively stimulating the nerve fibres of choice, either large diameter A-Beta fibres or small diameter A-Delta fibres by adjusting the parameters of the machine. Characteristics of A-Beta Fibres

• Large diameter, densely myelinated, with rapid conduction velocity • Low capacitance—does not maintain depolarised state for long • Fibres remain excitable to pulse widths as short as two microseconds • To excite A-beta fibres, high-frequency impulses with short pulse widths is used. Characteristics of A-Delta Fibres

is rapid but transient, i.e. no pain is felt as long as the current is on. Points to Ponder

• Rate: 50-100 Hz • Pulse width: 50-100 microseconds • Pulse shape: Bipolar asymmetric spike potentials. • Duration of treatment: 20-60 min in one sitting may be given continuously for 8 hrs if required. • Intensity: Between the first threshold of tingling and less than an intensity at which slight discomfort/muscle contraction is felt. • Frequency of treatment: Relief only as long as current applied, hence repeated application, particularly while working, is recommended. • Uses: Relief of acute and postoperative pain, and in areas of hypersensitivity or increased muscle tone.

• Light myelination, slower conduction velocity • High capacitance—longer latency • Fibres are unexcitable with pulse widths below 10 microseconds • To excite A-delta fibres, low-frequency stimulation, with longer pulse width is used.

2. Low Rate TENS

DIFFERENT TYPES OF TENS USED IN CLINICAL APPLICATION

Points to Ponder

1. High Rate TENS

Most common mode of TENS, used in acute or chronic stage of pain syndrome. Modulation of pain takes place by activation of the gate control mechanism by inhibition of pain carrying fibres by large diameter fibres. Effect

This is acupuncture like strong low-frequency stimulus, useful in relief of chronic pain. Modulation of pain takes place through release of endogenous opiates, which suppress the pain receptors in the cerebral cortex. Effect is relatively slow but lasts longer, i.e. more than hours after treatment. 2

• • • •

Rate: 1-5 Hz Pulse width: 150-300 microseconds Pulse shape: Monophasic pulses Intensity: Sufficient to cause visible muscle twitches within comfortable tolerance level of the patient. • Duration of treatment: 20-30 minutes per sitting.

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• Frequency of treatment: Once or twice a day, depending on duration of pain relief • Uses: Relief of chronic pain, effective over area of tissue or skin disturbance where destruction of large fibres means that a long pulse width is needed to achieve the effect, e.g. diabetic Neuropathy, neuralgia. 3. Brief Intense TENS

Potentially painful, intense stimulation used to provide rapid short-term pain relief during painful procedures like tooth extraction, wound debridement and dressing of wounds, deep friction massage, forced passive movements of joints or passive stretching of soft tissue contractures. Relief of pain is temporary.

• Pulse width: 50-200 microseconds • Pulse shape: Asymmetrical biphasic • Intensity: Comfortable with intermittent tingling sensation • Duration of treatment: 20-30 minutes • Uses : Suitable for relief of chronic muscle spasm or a combination of musculoskeletal and neurogenic pain of chronic nature, e.g. sciatic syndrome. WAVEFORMS OF TENS Points to Ponder

Rate: 80-150 Hz Pulse width: 50-250 microseconds Pulse shape: Monophasic pulses Intensity: Strong to the level of pain threshold • Duration of treatment: 15 minutes • Frequency of treatment: S.O.S. • Uses: To suppress pain during potentially painful procedures.

• There is no definitive work or publication to support the claim that one waveform is better than the others. • Both basic waveforms, asymmetrical biphasic or monophasic pulses, are used in TENS stimulation. • The spike and the square waveforms are most effective, having a sharp rate of rise, which sufficiently depolarizes the target sensory nerve. • Most popular waveforms used are biphasic and are balanced so that there is a net zero DC component, to prevent buildup of ion concentrations beneath the electrodes.

4. Burst Mode TENS

MODULATION OF TENS

This form combines the characteristics of high and low TENS, leading to release of endogenous opiates. The stimulation is welltolerated by patients, even on prolonged application, with slower onset of pain relief as compared to low TENS.

Points to Ponder

Points to Ponder

• • • •

Points to Ponder

• Rate: 50-100 Hz, delivered in bursts, of 1–4 pulses per second.

• Modulation of electrical parameters (pulse rate, pulse width) is offered on some TENS machines in order to prevent accommodation of the nerve and receptors to the stimulus. • Its clinical value remains to be assessed, apart from a pulsation, which some patients find more comfortable.

Pain Modulation—Transcutaneous Electrical Nerve Stimulation (TENS) 53

PARAMETERS FOR OPTIMAL STIMULATION

An optimal stimulation/site should be: • Strong enough to stimulate the CNS. • Suitable for proper placement of electrodes, free of bony or hairy area. • Segmentally-related to the source, as well as, the site of pain. • Anatomically-distinct, like specific spinal segment or the nerves. ELECTRODE PLACEMENT

Since the modality of TENS is still under exploration, placement of electrodes in TENS is controversial. A basic thumb rule is that the negative electrodes should be placed distal to the positive electrodes. The positive electrodes may be located as close to the representative spinal segment as possible (Fig. 6.1). The negative electrodes may be located at: • Acupuncture sites • Dermatome of the involved nerves • Over the painful spot • Proximal and distal to the pain site • Segmentally-related myotomes • Trigger points The exception to the rule is pain due to surgical incisions, where the electrodes must be placed parallel to each other on either sides of the suture line. Placements rules have to be adapted with multiple channel application to ensure maximum coverage of large affected area (Figs 6.2 and 6.3).3

CONTRAINDICATIONS FOR TENS

TENS is an inexpensive patient friendly modality having a wide range of application with superb safety record. However in some types of cases the application of the modality should be withheld. • Patients with demand type pace makers • Over the chest wall of cardiac patients • Over the eyes, larynx, pharynx over mucosal membrane • Over the head or neck of a patient with recent history of stroke or epilepsy. PRECAUTIONS FOR HOME PRESCRIPTION

Being a patient friendly device, due to its easy battery operation, compact size and negligible weight, TENS units may be used by patient constantly, like a hearing aid, to have effective pain control while working or at home. High TENS is the current of choice in such situations. Before prescribing the therapist should ensure the following: • Patient can understand and follow operating instructions perfectly. Do not prescribe it for very old or young. • The desired pulse width and rate must be set by the therapist and then locked in, so that these parameters cannot be changed by accident. The patient should only have access to the intensity control and be able to adjust the strength of the stimulation to his level of tolerance. • The therapist must coach the patient on basi c ma inte na nc e of th e eq uipmen t, which is similar to a mobile phones. 4

54


Fig. 6.1: General rules for placements of electrodes for application of TENS: • Carbo Carbon n rubber rubber plate plate electr electrodes odes of equal equal sizes sizes (2 cm × 3 cm) cm) are commo commonly nly used. used. • The electrod electrodes es may have two two or four four pole arrang arrangement ement,, depending depending upon upon the exten extentt of area area to be covere covered d and the type of equipment available. • As a thumb thumb rule, rule, the positi positive ve electrod electrode e is placed placed proxima proximally lly over over the spinal spinal segmen segmentt representi representing ng the neural supply of the target area. • The active active electro electrodes des may may be placed placed over over the distal distal most point point of the target target nerve nerve or over over the the dermatome dermatome of the target segment.

Pain Modulation—Transcutaneous Modulation—Transcutaneous Electrical Nerve Stimulation (TENS) 55

Fig. 6.2: Specific placement of electrodes for application of TENS for various painful conditions on the posterior surface of the body

Fig. 6.3: Specific placement of electrodes for application of TENS for various painful conditions on the anterior surface of the body

56


APPLICATIONS OF TENS IN COMMON DISORDERS Disease conditions

Type of current

Current parameters

Electrode placement

Tension Headache

Bu B urst

Pulse duration—50 microsecond Pulse fr frequency—100 Hz Burst frequency—10 Hz Dose—15 Minutes

Crossed 4 pole, 2 each over the origin an and in insertion of of bi bilateral Trapezius muscle upper fibres, strong tingling felt.

Frozen Shoulder (chronic Stage)

Burst

Pulse duration—40 microsecond Pulse frequency—100 Hz Burst frequency—2 Hz Dose—15 Minutes

Cross 4 pole around the shoulder joint

Postherpetic Neuralgia

Burst

Pulse duration—50 microsecond Pulse frequency—100 Hz Burst frequency—10 Hz Dose—15 Minutes

4 Pole method: 2 over the affected area and 2 above and below the exit nerve root.

Neuralgia

Cont Co ntin inuo uous us

Pulsee dur Puls durat atio ion— n—42 42 mi micr cros osec econ ond d Pulse frequency—100 Hz Dose—10-15 Minutes

2 or or 4 Po Pole le me meth thod od ov over er th thee affected area.

Reflex Sympathetic Dystrophy


Pulsee du Puls dura rati tion on—4 —422 mi micr cros osec econ ond d Pulse frequency—160 Hz Dose—10-15 Minutes

4 Po Pole le me meth thod od:: a) U/ U/L: L: 2 Electrodes at paravertebral region of C-8 to T-9 and 2 electrodes over levator scapulae and lateral part of spine of scapula. b) L/L: 2 Electrodes over paravertebral region of T-10 to L-2 and 2 electrodes over the iliac crest and lateral part of buttock.

Postoperative Pain


Pulsee du Puls dura rati tion on—4 —400 mi micr cros osec econ ond d Pulse frequency—100 Hz Dose—10-15 Minutes

4 Po Pole le me meth thod od:: 2 pr prox oxim imal al and 2 distal to operated area.

Menstruation Pain


Pulsee dura Puls durati tion on—1 —100 00 mic micro rose seco cond nd 2 Pole Pole met metho hod: d: ove overr the the Pulse frequency—80 Hz sacrum bilaterally. Dose—15 Minutes

Stress Incontinence

Surge

Pulse duration—100 microsecond 2 Pole method Pulse frequency—60 Hz Dose—15 Minutes

REFERENCES 1. Walsh D. TENS: TENS: Clinical Clinical Applica Applications tions and Related Theory. Churchill Livingstone, 1997. 2. Ellis B. A retrospec retrospective tive study study of long-t long-term erm users users of TNS. British Journal of Therapy and Rehabilitation 1996;3(2):88-93.

3. Walsh Walsh D, Baxter Baxter D. Transcut Transcutaneo aneous us electric electrical al nerve stimulation—A review of experimental studies. European Journal of Medical Rehab 1996;6(2):42-50. 4. Roch Rochee P, Wright Wright A. An investi investigat gation ion into into the value of TENS for arthritic pain. Physiotherapy. Theory and Practice 1990;6:25-33.

Advanced Applications of Low Frequency Electrical Stimulation 57

7 Advanced Applications of Low Frequency Electrical Stimulation Ongoing research and the constant quest among professional working in the field, for effective modalities to achieve quick results have yielded different applications of low frequency currents. Some of theses applications like the high voltage pulsed galvanic stimulation and functional electrical stimulation are results of such quests. Advent of microprocessor technology has been at the root of designing sate of the art stimulators at affordable prices that has helped to popularise these applications. Few applications, like the iontophoresis had been in use in the past decades but had fallen out of favour due to lack of suitable water soluble ionic mediums in those times. Nowadays, due to the progress made in pharmacy sciences many therapeutically useful active ions are available in watersoluble gel form, which are easily absorbed by the body through the skin and are suitable for use in iontophoresis. Due to this there is resurgence in interest among therapists towards this time-tested modality.

HIGH VOLTAGE PULSED GALVANIC STIMULATION (HVPGS)

HVPGS is relatively uncommon form of stimulating current modulation, used primarily to achieve stimulation of deeper tissues, useful for sensory stimulation for pain relief and to assist in wound healing. Parameters of HVPGS Current

• HVPGS current consists of monophasic, twin peak pulses of 7 to 200 microseconds duration, delivered at 300 to 500 volts. • The twin peak pulse are spike-shaped, rising and falling rapidly • As pulses rise and fall rapidly, the second spike cancels out the irritation produced by the first spike. • The modulation may be continuous, pulsed at 80 to 100 pulses per second or surged. • The passage of HVGS is relatively easy because it is offered little resistance by the skin due to higher frequency.

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• The specific duration and voltage requirements vary depending upon the condition being treated. Effects and Uses of HVPGS

• Application of HVPGS tends to produce comfortable tingling sensation and parasthesia that closely resembles high frequency TENS. • It is used for relief of neurogenic pain through stimulation of trigger points, relaxation of deep muscle spasm and wound healing. Instrumentation of HVPGS

• HVPGS therapy is applied through high voltage direct current generators, capable of producing extremely short duration pulses (microseconds), generally in the range of 300 to 500 volts. • Standard electrodes used for low voltage low frequency stimulation, is used for HVGPS. • The protocol for electrode placement and treatment is similar to low frequency or TENS for relief of muscle spasm and trigger point pain. • It is more specifically used for wound healing. Application of HVPGS in Wound Healing

• The patient is positioned comfortably on a plinth. The wound is exposed with the rest of the body covered. • Inspect the wound closely for any slough. • The wound must be cleaned and debrided before application of HVPGS, since infection may interfere with the beneficial effect of HVPGS.

• Cover the clean wound with several layers of sterile gauze soaked in saline. • Place the active electrode over the gauze. • If the wound has chronic infection, to get antibiotic effect, the active electrode should have negative polarity. • If the wound is free of infection, to promote healing, the active electrode should have positive polarity. • The passive electrode must be three times the size of active electrode and placed proximal to the active electrode. • The intensity must be gradually increased to a comfortable level. • The duration of treatment should be 30 to 60 minutes, for one sitting, on alternate days. FUNCTIONAL ELECTRICAL STIMULATION (FES)

Functional electrical stimulation, also known as functional neuromuscular stimulation, is an adapted version of motor stimulating current modulation, similar in physiological characteristics to the surged faradic stimulation, used for activation of innervated muscles. Parameters of FES Current

The current used is asymmetrical bi-phasic with high amplitude negative phase followed by low amplitude positive phase. • The pulse frequency is in the range of 12 to 100 Hz, with continuous modulation. • Intensity of current: 90 to 200 milli ampere. • Pulse duration: 20 to 300 microsecond. • Voltage: 50 to 120 volts. Effects and Uses of FES

• This type of current is suitable for producing controlled titanic contraction of muscles,


which generates adequate torque to produce functional movements, in the absence of adequate voluntary contraction. • It is widely used to: 1. Prevent or correct disuse atrophy, 2. Improve ROM in stiff joints, reduce muscle spasm or spasticity, 3. Re-education of new muscle action in case of muscle or tendon transfers 4. Most commonly used for trial, supplementation or substitution of orthosis. Instrumentation of FES

1. Stimulator: Specialized FES stimulators are rechargeable battery operated compact devices, providing option for continuous modulation of pulse amplitude, duration and frequency, which can be carried by the patient like a hearing aid. The slandered surged faradic stimulator may be used for treating of localized complaints that involve no mobility. 2. Leads: Flexible and thin, such leads are 0.5 to 1.5 meters in length and have a high degree of resistance to torsion and strain. 3. Electrodes: a. Self-adhesive pre-gelled electrodes. b. Carbon rubber electrodes. Application of FES in Hemiplegic’s Shoulder

• Hemiplegic patients with one-sided paralysis of the body may have flaccid paralysis of deltoid and supraspinatus muscle, resulting in subluxation of the glenohumeral joint. • The force of gravity tends to pull the unsupported upper extremity downwards causing stretching of the rotator cuff, resulting in ischemia, that produces severe

•

•

•

•

•

pain and inhibition of movement in the upper extremity. Conservative management of such painful shoulder involves a supportive cuff (Bobath cuff) to relive the stretch on the rotator cuff tendons and ligaments. FES is used as supplement to the Bobath cuff, in such subluxated shoulder to increase the supportive action of the key muscles of the rotator cuff and relieve the painful structures of constant painful stretch. Current parameters—Asymmetrical, biphasic, square wave pulses with continuous modulation may be used, applied from a standard faradic stimulator or rechargeable battery operated portable stimulator. Electrode placement—Bipolar surface electrodes, carbon rubber type may be used. One electrode is placed on the supraspinatus muscle belly just above the spine the scapula and the other should be placed on the posterior fibres of deltoid muscle. Treatment procedure 1. The patient is placed in high sitting on a wooden chair, with the arm supported in front, on a wooden plinth. 2. The arm and the shoulder girdle are exposed. The procedure and its poten– tial benefits are explained to remove any anxiety felt by the patient. 3. The skin is prepared, the equipment is tested and the electrodes are fixed to the skin with straps or adhesive tapes. 4. The intensity should be adequate to produce tetanic contraction of target muscle, within the limit of patient’s tolerance. Patients with CVA may be hypertensive. Therefore special care

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should be taken not to cause any distress to patient. 5. The pulse rate is adjusted to 12 to 25 pulses per second. 6. The on-off ratio between surge duration and surge interval should start with 1:3, i.e. 2 seconds on and 6 seconds off. The patient must be encouraged to contract the muscle voluntarily with the current surge. The ratio is gradually progressed to 12:1, i.e. 24 seconds on and 2 seconds off as the muscles gain power. 7. The duration of treatment should be for 15 to 30 minutes in one sitting and should be repeated twice initially. Later the treatment may be given daily for up to 6 to 8 hours. Application of FES in Idiopathic Scoliosis

• Idiopathic scoliosis is the gradual sideways curving (Lateral curve) of the vertebral column, commonly seen in growing children. • Teenage girls are the commonest victims of this disorder, which can result in severe spinal deformity. • Before the bony maturity has taken place, such disorder can be rectified with CTLSO spinal brace. • CTLSO spinal brace or Milwaukee brace works on the principal of a static brace with dynamic correction. • FES can be used in cooperative candidates, to supplement the corrective function of the brace, by encouraging the contraction of posterior spinal muscles, in a progressive deformity, when the spinal curvature (Cobb’s angle) is between 20 and 45°. • Current parameters—Interrupted monophasic rectangular pulses with pulse

duration of 225 microseconds are used, applied from a rechargeable battery operated portable stimulator. • Electrode placement—Bipolar surface electrodes, carbon rubber type may be used. 1. In case of single curve—Place two electrodes from a single channel machine 2” lateral to the spine, on the convex side of the curve, placed above and below the ribs attached to the vertebra at the apex of the curvature. 2. In case of a ‘S’ curve—Place four electrodes from a two channel machine, placed convexity, on either side, placed above and below the ribs attached to the vertebra at the apex of the curvature. Treatment Procedure

1. FES in scoliosis should be applied, with the brace on, with a portable stimulator, which the patient can continue to use while performing normal activities. 2. The electrodes are positioned as detailed above under the straps of the brace and then the straps are tightened to give optimum tension on the curvature and maximum contact to skin. 3. The intensity is increased within the limit of tolerance, to produce titanic contraction of paravertebral muscles. 4. The pulse rate is adjusted to 25 pulses per second. 5. The surge duration/interval ratio should be 1:1, i.e. 6 seconds on and 6 seconds off. 6. The duration of the treatment may be up to 8 hours. The patient must be encouraged to perform the self-stretch exercise with braces on, while undergoing FES, to get best results.


Application of FES in Foot Drop

xion of the ankle as preparation to heel strike. 6. As soon as the heel comes in contact with the ground, pressure sensitive feet switch cuts off the flow of the current, allowing the foot-flat to take place during the stance phase. 7. The duration of the treatment may be up to 8 hours, during walking. The patient must be encouraged to perform the exercises for dorsiflexon with braces on, while undergoing FES, to get best results.

• Inability to dorsiflex the ankle voluntarily results in foot drop. • During the heel strike of the gait cycle, foot drop is the most important cause of gait deviation i.e. circumduction gait, in hemiplegic patients. • FES, if applied to the affected leg during walking, can be used to control foot drop by stimulating the action of dorsiflexors of the ankle and evertors of the foot, at the swing phase of gait. • Current parameters—Asymmetrical biphasic or square wave pulses with pulse IONTOPHORESIS: ION TRANSFER duration of 20 to 250 microseconds, app- WITH DIRECT CURRENT lied from a rechargeable battery operated It a specialized technique of electrical stimuportable stimulator. lation that uses electrical polarity of continuous • Electrode placement—Bipolar surface direct current to ionize medicinal agents placed electrodes, self-adhesive pre-gelled type beneath surface electrodes and transfers them may be used. One electrode placed on the into the body through the skin or mucous peroneal nerve at the neck of fibula and membrane. the other should be placed on the muscles of anterior-lateral compartment of the leg. How does Iontophoresis Work? • Treatment procedure: • With iontophoresis, weak electric current 1. FES in foot drop can be applied, with a is used to introduce medication through portable stimulator, with the brace/ the intact skin to the underlying tissue. AFO on, which the patient can continue • The medication is supplied directly in to to use while performing normal actithe area that will be treated—a form of vities. pharmacological sharp-shooting. 2. The electrodes are positioned as de- • Systematic affect is reduced to a minimum tailed above under the straps of the and no adverse effects have been reported. brace and then the straps are tightened Iontophoresis is an effective and pain-free to give maximum contact to skin. treatment method. 3. The intensity is increased within the • It is based on the principle that, electrical limit of tolerance, to produce titanic stimulation affects the ions in a solution contraction of target muscles. so they may move, depending on their 4. The pulse rate is adjusted to 30 to 300 charge. pulses per second. • With iontophoresis the polarity that corresponds with the charge of the medica5. The flow of current is turned on during tion’s ion is connected to electrode. the swing phase to produce dorsifle-

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• This entails the repelling of the active pharmaceutical ion, which results in the medication being introduced down through the skin. Biophysics of Iontophoresis

• Transfer of ions depends on the principle of “Like poles repel and opposite poles attract each other”. • Dissolved acids, bases, salts or alkaloids in a watery solution break down into charged particle or ions. • Ions are charged particles, with positive or negative charge, that can be pushed through the skin by a similar charge applied to the electrode placed over it or pulled through the skin by a oppositelycharged electrode placed away from it • These ions, on entering through the skin, combines with other ions and radicals present in the blood stream to form new compounds that are therapeutically valuable in specific disease conditions. • Selection of suitable ionic compounds and placing them under appropriately charged electrode is the key to the success of iontophoresis. • Low voltage (<100V) monophasic continuous direct current, applied at lo w intensity (<5 mA), applied over low ionic concentration (1-5%) in the iontophoresis medium is most effective in producing desired result. • Direct current applied is not the treatment, but only the means of ion transfer. • Efficacy of the treatment will depend on selection of specific ionic medium , aimed at producing a specific reaction, to treat a specific disorder.

Dosimetry of Iontophoresis

The number of ions transferred through the skin depends on: 1. Duration of treatment 2. Current density or current intensity per square cms area of the electrodes. 3. Concentration of ions in the medium used in iontophoresis. Based on the above the formula to calculate quantity of substances introduced through iontophoresis is: I × T × ECE = grams of substances introduced through skin, where, • I—stands for intensity of direct current in amperes • T—stands for duration of application in hours • ECE—stands for standardized ionic transfer coefficient with fixed current and time factors. • The dosimetry of iontophoresis is fairly controversial, due to conflicting reports. • It has been reported that low ampere current has a better effect in ion transfer because of less resistance offered by the than high intensity current. • It has also been suggested that lower concentration of active-charged ions in the iontophoresis medium is far more effective because of less repelling going on between the like-charged ions themselves, which allows better penetration. • By and large, for effective ion transfer it is recommended to use maximum 5 m. amp current applied over a medium with active ion concentration of 1-5%. Indications for Iontophoresis

There are three main areas of treatment for iontophoresis: • Cortisone treatment of superficial local inflammations.


• Quick and effective surface anaesthesia with a local aesthetic. • To treat hyperhydrosis or excessive sweating in the palm of the hands, soles of the feet or axilla. Application of Iontophoresis in Local Inflammation

• Iontophoresis has shown good results in treatment of acute and sub-acute superficial local inflammations, such as tendonitis, bursitis, and fasciitis . • Administration of cortisone using iontophoresis is a pleasant alternative to cortisone injections. • The anti-inflammatory effect is achieved while avoiding the adverse effects for systemic or injected cortisone. • Effective alternative to treatment with antiinflammatory tablets or NSAIDs. • With iontophoresis a higher concentration of the medication is obtained locally in the tissue while systemic effect is avoided. • Commonest sites of application are medial and lateral epicondylitis, Achilles tendonitis, inflamed ligaments of knee, bicepital tendonitis, shoulder rotator cuff tendonitis/tenosynovitis, carpal tunnel syndrome etc. Application of Iontophoresis in Local Anaesthesia

• With iontophoresis, superficial local anaesthesia can be achieved quickly and effectively by supplying the drug, without needles and without pain. • The method is faster and penetrates deeper than local anaesthesia and is excellent alternative for anaesthetizing before injections, wound dressing or taking blood/ tissue samples.

• The skin is as anaesthetized within 10 minutes of iontophoresis, as compared to 60 minutes with local anaesthetic cream. Application of Iontophoresis in Hyperhydrosis

• Tap water iontophoresis is considered by many dermatologists to be the first line of treatment for hyperhidrosis of the palms and soles. • Although more cumbersome, iontophoresis can be used to treat axillary hyperhidrosis as well. • In addition to simple tap water, anticholinergics and other drugs can be introduced to areas affected by hyperhidrosis. Which Medications may be Used as Ionising Agents?

Medications or mediums that are used with iontophoretic treatment must be watersoluble and ionisable. Local Inflammation

Hydrocortisone in a water-soluble base or gel at 1-10% concentration by volume may be used. This medium has a negative charge, so the negative pole (black) must be connected to the medication electrode. Local Anaesthesia

Xylocaine hydrochloride solution or gel used for local anaesthesia, at 1% concentration is recommended medium. Xylocaine has a positive charge, so the positive pole (red) must be connected to the medication electrode. Electrodes for Iontophoresis

The electrodes used in iotophoresis have to be specifically tailor made for a specific site and patient.

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• Use aluminium foil, cut in square or round shape, large enough to cover the entire skin surface of the target area. • The active electrode should be bigger than the passive, to provide for low current density, which helps in better penetration of ions. • The aluminium foil electrodes are covered with 8 to 10 layer of tissue paper, which can be discarded after single use. • The active electrode is soaked in the active ingredient solution made of distilled water. • The passive electrode is soaked in tap water. In case of hyperhydrosis both electrodes are soaked in tap water. Technique of Application Iontophoresis

• Clean and soak the skin to reduce the skin resistance. If there are cuts or break in the skin, apply a thin layer of sterile petroleum jelly on the spot. • Position the patient on a wooden plinth. Support the area to be treated with pillows. • Rub the medium containing the active ingredient on the skin over the spot to be treated. • Active electrode having the same polarity as the active ion is placed on the area to be treated. Special medicated active electrodes are available readymade in the market,

• • •

• •

• • •

though these are much more expensive than aluminium foil electrodes. The passive electrode is placed at a site away from the site of stimulation. Electrodes are secured with straps or adhesive tapes (Figs 7.1A and B, Plate 4) Calculate the dosage as per the guidelines given above. Remember that the safe limit for positive active electrode is 1.0 mA/sq cm and negative active electrode is 0.5 mA/sq cm. Turn the intensity gradually to the safe limit. Keep close watch over the treatment area. Inspect the site after every 5 mins. If there is itching or burning stop treatment immediately. After 20 to 30 min of treatment slowly turn the intensity to zero. Remove the electrodes; inspect the area for rash or reddening. Slight reddening is expected. Wash the area thoroughly with water and allow the patient to leave.

Contraindications of Iontophoresis

• • • • •

Impaired skin sensation Allergy or rashes Recent scar Broken skin Metal in the treatment area.

Ions commonly Used in Iontophoresis and Their Clinical Indications Ions

Polarity

Source

Indications

Lidocaine/Xylocaine Salicylate Acetate Zinc Copper Calcium Magnesium Dexamethasone

+ – – + + + + +

Lidocaine/Xylocaine gel Sodium salicylate gel Acetic acid Zinc oxide solution Copper sulphate solution Calcium chloride Magnesium sulphate Dexamethasone 1% gel

Local anaesthesia Relief of pain and inflammation Dissolve calcification of soft tissue Skin ulcers Fungal infection Muscle spasm do Soft tissue inflammation

Medium Frequency Currents 65

8 Medium Frequency Currents • Sine wave current, in the frequency range of 2000 to 5000 Hz, modulated to produce physiological response in nerves are called the medium frequency currents. • The basic advantage of medium frequency stimulation over conventional surged faradic current, is its ability to produce the strong physiological effects of low frequency electrical stimulation, in much deeper muscle and nerve tissues, without the associated painful and unpleasant sensation of low frequency stimulation. • To produce low frequency effects at sufficient intensity at depth, most patients experience considerable discomfort in the superficial tissues (i.e. the skin). • This is due to the resistance (impedance) of the skin being inversely proportional to the frequency of the stimulation. In other words, the lower the stimulation frequency, the greater the resistance to the passage of the current and so, more discomfort is experienced. • The skin impedance at 50 Hz is approximately 3200 ohms whilst at 4000 Hz it is reduced to approximately 40 ohms.

• The result of applying such medium frequency current is that it will pass more easily through the skin, requiring less electrical energy to reach the deeper tissues, therefore producing less discomfort. TYPES OF MEDIUM FREQUENCY CURRENT

Medium frequency current can be broadly categorized in to two forms: 1. Medium frequency surge current 2. Interferential current Medium frequency surge current is a twopole interference current, which increases and decreases in intensity over a set duration and interval, like the surged faradic current. It is far well-tolerated by the patient than faradic stimulation and the etching effect of IG stimulation are not seen It is available in two formats; 1. Russian current with carrier frequency of 2500 Hz 2. MF surge current with carrier frequency of 4000 Hz.

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Russian Current

• It is a polyphasic sine wave continuous current having a basic or carrier frequency of 2500 Hz. • The current is frequency modulated to produce a train of pulses with a pulse duration of 10 ms and a pulse interval of 10 to 50 ms. • Such frequency modulation produces 50 to 10 pulses in one second, each pulse lasting for 10 ms. • It is applied in bi-polar mode, usually with carbon rubber or vacuum electrodes. • It is effective in muscle strengthening and for relief of muscle spasm.

• It is more useful for relief of pain and improving circulation in muscles. • Though it causes significant muscle contraction, it is less powerful than produced with Russian current. INTERFERENTIAL CURRENT

Interferential current utilizes two amplitude modulated medium frequency sinusoidal currents; in the frequency range of 4000 to 5000 Hz. These are called the carrier currents.The carrier current in both channels has the same amplitude but the frequencies of are kept slightly out of synchronization.The carrier currents are passed through the tissues Method of Application simultaneously, so that their paths cross and For muscles strengthening, the intensity is interfere with each other’s field deep within adjusted to produce strong titanic muscle the tissues.This interference gives rise to contraction, using a pulse rate of 50 to 70 amplitude modulated frequency, like the pulses per second with pulse duration of 150 strings of a sitar, to produce a pulsing effect to 200 microseconds. The current is applied or beat; wherever they cross each other. When during volitional activities like isometric the two carrier waves are in phase, construccontractions in different ROM, slow speed tive interference takes place. The resultant isokinetic and short arc isotonic movements. beat frequency has an amplitude (intensity) Primary effects are to build up muscle power that is the sum total of the amplitudes of the delivery in different range of motion or carrier currents when the carrier waves are mobilize stiff joints. The stimulation is applied to produce contraction for 15 seconds and 180 degree out of phase, destructive interference cancels out the carrier amplitudes. The relaxation for 50 seconds. For relief of muscle spasm, titanic contrac- resultant beat frequency has amplitude (intensity) of zero. The beat frequency current tion is produced to the limit of tolerance a pulse rate of 50 to 70 pulses per second, with has the characteristics of low frequency pulse duration of 50 to 170 microseconds. The stimulation (Fig. 8.1). stimulation is applied to provide brief • The exact frequency of the beat frequency isometric contractions for 5 to 12 seconds and can be controlled by the input frequencies 8 to 15 seconds of relaxation. • If one carrier current is at 4000 Hz and its companion current at 3900 Hz, the resulMEDIUM FREQUENCY SURGE CURRENT tant beat frequency would be the difference of the two carrier frequencies i.e. 100 • It is a polyphasic sine wave continuous Hz, spreading in a typical clover leaf current having a basic or carrier frequency pattern (Fig. 8.2B). of 4000 Hz.


• Modern machines usually offer frequencies of 1 to 150 Hz, though some offer a choice of up to 250 Hz or more. • To a greater extent, the therapist does not have to concern themselves with the input frequencies, but simply with the appropriate beat frequency, which is selected directly from the machine. • In 2 pole interferential stimulation, where there is clearly no interference within the body, is made possible by electronic manipulation of the currents, i.e. the interference occurs within the machine. This is suitable for small areas like sinus, temporo-mandibular joints etc. Fig. 8.1: Principle of interference using two channels of medium frequency currents

• The amplitude modulated beat frequency may be constant or variable. • Constant beat current is obtained when both the carrier frequencies remain fixed. • Variable beat current is obtained when one carrier remains fixed and the other keeps on changing in frequency at regular intervals from a lower to a higher level and back, known as sweep. • This produces a spectrum of frequencies in the beat current at regular sweep. • Such sweep prevents accommodation of nerves. • By careful manipulation of the input currents it is possible to achieve any beat frequency to use clinically. • Classical interferential (static) field is generated when the beat current remains constant. • Vector current (dynamic) field is produced when the interferential field rotates by 45 in clockwise or anticlockwise direction within the tissue, constantly changing the stimulation zone.

Physiological Effects of Interferential Current

• Excitable tissues can be stimulated by low frequency alternating currents. • All tissues in this category will be affected by a broad range of stimulations • Savage in 1984 postulated that different tissues will have an optimal stimulation band, which can be estimated by the conduction velocity of the tissue, its latency and refractory period. • These are detailed below: Sympathetic nerve: 1 to 5 Hz Parasympathetic nerve: 10 to 150 Hz Motor nerve: 10 to 50 Hz Sensory nerve: 90 to 100 Hz Nociceptive fibres: 90 to 150 Hz Smooth muscle: 0 to 10 Hz. Therapeutic Effects of Interferential Current

• The clinical application of IFT therapy is based on response thresh old and the physiological behaviour of stimulated tissues.

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• Select Selection ion of a wide wide trea treatme tment nt band band can be be considered less efficient than a smaller selective band because by treating with a frequency range of say 1 to 100 Hz, the appropriate treatment frequencies can be covered, but only for a relatively small percentage of the total treatment time. • Add Additi itiona onally lly,, some some part partss of the the rang rangee might be counterproductive for the primary aims of the treatment. • Mai Main n clini clinical cal app applic licati ations ons of of IFT IFT are: are: 1. Pa Pain in rel eliief 2. Mu Musc scle le st stim imul ulat atio ion n 3. In Incr crea ease sed d blo blood od fl flow ow 4. Re Redu duct ctio ion n of of oed oedem emaa 5. Tis Tissue sue hea healin ling g and and rep repair air.. • Sin Since ce IFT IFT acts acts primar primarily ily on the the excita excitable ble tissues like nerves and muscles, the strongest effects are likely to be those produced by such stimulation, i.e. pain relief and muscle contraction. • The othe otherr effect effectss like like drain drainage age of of fluid fluid and and reduction in muscle spasm are secondary consequences of the primary effects. Instrumentation of IFT

Most modern IFT units (Figs 8.2A and 8.3) allow the therapist to get tailor made current, suitable to treat a specific disorder, which may be built in to the memo memory ry of the soft software ware ba se d eq ui p me n ts o r by ad ju st me n t o f following machine parameters: • Amp Amplit litude ude modu modulat lation ion para paramet meter er (AMF) (AMF),, to choose the basic value of the low frequency modulation that is desired. • Spectrum parameter, to set the range of variation in the AMF value that is desired; setting the AMF at 100 Hz and spectrum at 50 Hz will give an AMF variation from 100 Hz upto150 Hz and back to 100 Hz.The spectrum is useful in preventing accommodation in nerves (Fig. 8.2B).

Fig. 8.2A: Advanaced Interferential equipment: The Phyaction 787 stimulator with microprocessor controlled circuits is a later generation equipment that offers a wide range of stimulating current selection in low and medium frequency range, with ultrasonic therapy module which can be used for combination therapy or as an independent modality (courtesy M/ S Hintek Electronics, New Delhi). Note four channel conventional carbon rubber plate electrodes connected to the machine through colour-coded leads. On the left of the plate electrodes are four sockets for vacuum suction electrodes. Unlike the plate electrodes, the vacuum suction electrodes do not need straps to hold them in place, hence are easy to apply over irregular surfaces.

Fig. 8.2B: Advanaced interferential equipment: The LCD display of Phyaction 787 in classical interference current mode, showing amplitude modulated frequency at 100 Hz, nil spectrum or sweep frequency, sweep time of 1sec and a rise or fall rate of surge at 67 per cent. The clover leaf pattern of the classical interference current is also shown along with intensity of each channel and the treatment timer


Fig. 8.3: Overall arrangement of the interferential therapy instrumentation (equipment and electrodes) in a clinical setting

• Sweep time parameter sets the time period for the AMF to change from base to peak frequency. Faster the sweep less painful is the stimulation. However, if strong muscle contraction or sensory input is desired, then the sweep must be slow, to ensure aggressive stimulation. • Contour parameter sets the rate of change of the AMF from base to peak frequency. This is expressed in percentage of time taken to reach from base to peak of AMF. Greater the percentage, the gentler is the stimulation. • Rotation parameter is applicable in case of vector currents only and sets the rate of rotation and the direction of change of the AMF field within the tissues. Treatment Parameters to Achieve Pain Relief with IFT

• Electr Electrica icall stimul stimulati ation on for pain pain reli relief ef has widespread clinical use. • Dir Direct ect res resear earch ch evide evidence nce for for the the use of IFT IFT in pain relief is limited. • One coul could d use the the highe higherr frequ frequenc encie iess (90-150 Hz) to stimulate the pain gate

mechanisms and thereby mask the pain symptoms for the duration of application. • Alt Altern ernati ativel vely, y, stimul stimulati ation on with with lower lower frequencies (1-5 Hz) can be used to activate the release of indigenous opiates, providing long-term relief of pain. • The These se two two diff differe erent nt mode modess of act action ion can be exp explai lained ned phys physiolo iologica gically. lly. Eac Each h has different latent periods and varying duration of effect. • Rel Relief ief of pain pain may may be be achiev achieved ed by by stimu stimu-lation of the reticular formation at frequencies of 10 to 25 Hz or by blocking C fibre transmission at frequencies greater than 50 Hz. Treatment Parameters to Achieve Muscle Stimulation with IFT

• Stimul Stimulati ation on of of the the moto motorr nerve nervess can can be be achieved with a wide range of frequencies. • Sti Stimul mulati ation on at at low low frequ frequency ency (e.g (e.g.. 1 Hz) Hz) will result in a series of twitches: • Sti Stimul mulati ation on at 50 50 Hz will will resul resultt in a titan titanic ic contraction. • The choice of treatment parameters will depend on the desired effect. • To co mbine muscle stimulation with an increase in blood flow and a possible reduction in oedema, selecting a frequency range which does not produce strong sustained titanic muscle contraction. • In suc such h cas cases es,, a sweep of 10 to 25 Hz is often used, to produce pumpi pumping ng effect on the target muscles, which will help in drainage of fluid from the interstitial space. • The There re is is no pri primar mary y nervo nervous us contr control ol of oedema re-absorption and the direct electrical stimulation of blood flow is limited in its effectiveness. • It is is sugges suggested ted the theref refore ore,, that that in ord order er to to achieve these effects, suitable combina-

70


tions of muscle stimulation should be made. Treatment Techniques

• Preparation of the patient and the machine is done, as before any low frequency electrical stimulation • The same same loca locall precau precauti tions ons,, genera generall contraindications, environment and the safety considerations apply for IFT, as in case of low frequency stimulation. • The IFT is usua usually lly app applie lied d thro through ugh four carbon rubber electrode plates between 5 and 15 sqcm in size. These are applied on the prepared skin, with a coating of conductive electrode gel and fixed with elastic strap. • Som Somee IFT mac machin hines es have have buil built-i t-in n or optional vacuum suction pumps, for application of vacuum cup electrodes, with moist sponge fillers to maintain electrical contact with the skin. Fixing such electrodes is easy, particularly over odd-shaped areas like the shoulder joint. • Ele Electro ctrode de posi positio tionin ning g should should ensu ensure re adequate coverage of the area for stimulation (Fig. 8.4, Plate 5) • In some some circ circums umstan tances ces,, a bipol bipolar ar meth method od is preferable if a longitudinal zone requires stimulation rather than an isolated tissue area. • Plac Placemen ementt of of the the electr electrodes odes shou should ld be such such that a crossover effect is achieved in the desired area. • If the the elec electro trodes des are not pla placed ced so that that a crossover is achieved, the physiological effects of I/F cannot be achieved. • Ner Nerves ves wil willl accom accommod modate ate to a con consta stant nt signal and, • A sweep sweep (or (or grad gradual ually ly chan changi ging ng frefrequency) is often used to overcome this

•

• •

•

•

•

•

•

•

problem (as well as generating a range of effects). The swee sweep p (rang (range) e) shou should ld be be appro appropri priate ate to the desired physiological effects, though again it is suggested that an excessive range may minimise the clinical effect. The mod modee of del delive ivery ry of of the the selec selected ted swee sweep p varies with machines. The mos mostt commo common n appli applicat cation ion is the the 6 second rise and fall between the pre-set frequencies. Forr exam Fo exampl ple, e, if if a 10 to 25 25 Hz rang rangee has has been selected, the machine will deliver a changing frequency, starting at 10 Hz, rising to 25 Hz over a 6 second period. Once this upper limit has been achieved, the frequency will once again fall, over a 6 second period to its starting point at 10 Hz. This pattern is repeated throughout the treatment session Treatm Tre atment ent time timess vary vary widely widely acco accordi rding ng to the usual clinical parameters of acute/ chronic conditions and the type of physiological effect desired. In acut acutee condit condition ions, s, short shorter er trea treatme tment nt times of 5 to 10 minutes may be sufficient to achieve the effect. In other circumstances, it may be necessary to stimulate the tissues for 20 to 30 minutes. It is is sugges suggested ted that that shor shortt treatm treatment ent time timess are initially adopted especially with the acute case in case of symptom exacer bation. These The se can can be pro progre gresse ssed d if the aim has not been be en ac achi hiev eved ed an and d no un unto towa ward rd si side de effects have been produced. There The re is is no resea research rch evi eviden dence ce to to suppor supportt the continuous progression of a treatment dose in order to increase or maintain its effect.


TYPES OF INTERFERENTIAL CURRENTS (FOUR POLE APPLICATION) Classical Interference Current

• Interference occurs between two unmodulated currents, crossing each other’s path within the target tissue (Fig. 8.5, Plate 5) • In this classical form of interference current, modulation depth is 0 per cent at the axis of two electrodes of pole. In this direction no stimulation takes place. • 100 per cent modulation takes place only at a diagonal, creating a field of stimulation perpendicular to the lines of forces between two electrodes of a single pole. • Since the lines of forces of two poles are crossed within the tissues, a four armed (chatuevuj) field is generated. This type of pattern is called the Clover Leaf Pattern (Fig. 8.6) • The effect of this type of field produced by four pole application is very dependant on the direction of electrode placement and the resultant field. • It is vital to position the crossing area of the currents at the correct location to ensure the accurate alignment of the field of 100 per cent stimulation, with the target tissue. • Since the stimulation is optimal only in two directions, the position of the four electrodes must be done with great care. • Fine tuning of the spread of stimulation can be done with the balance control. It works like the balance knob of a stereophonic sound system. The Clover Leaf Pattern Isoplaner Vector Field

• Applied through four electrodes like classical interference current (Fig. 8.7).

Fig. 8.6: Clover leaf pattern of electrical field in IFT

Fig. 8.7: Isoplaner vector field application to the knee joint

• Gives a stimulus, which is equal in all directions instead of clover leaf pattern. • The depth of modulation is 100 per cent and the current is same in all directions, making sure that all tissue between the four electrodes will receive effective treatment.

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• Suitable for large joints like the knee, particularly when swollen and when the complaint is diffuse and hard to localize. • Because of the mildness of isoplaner field stimulation, it is best suited for acute conditions like sciatica (Fig. 8.10). Dipole Vector Field

• Though applied through four electrodes, the distribution of current in one direction is 100 per cent and the other is 0 per cent. • This enables the current to be applied selectively to a specific area through static vector mode or rotate the field like the lights of a lighthouse, stimulating tissues cyclically in all directions between the four electrodes, in a dynamic vector mode. • The static vector mode is most useful in case of longitudinal structures, e.g. brachioradialis or rectus femoris muscles. A band of maximum intensity may be set up between the poles of the electrodes to target a specific structure along its entire length, avoiding unnecessary stimulation of adjacent structures. • The dynamic vector has deionising effect on acute muscle spasm of large muscular areas because of the massaging effect it creates and its soothing nature of stimulation. • Cyclic contraction and relaxation creates pumping in muscles, increasing venous drainage, reducing oedema, and improving blood circulation. • This type of current is most suitable for the treatment of muscle spasm of heavily

Fig. 8.10: Placement of electrodes for application of IFT to the sciatic root

muscled areas like painful shoulder, low back pain and, pain of the thighs etc (Figs 8.8A and B and 8.9, Plate 5). Two pole Medium Frequency Current

• This type of current gives the same type of stimulation as compared to four pole interferential method • Current modulation depth is 100 per cent in all direction. Maximum stimulation is produced in the tissues lying between the electrodes, along the lines of forces connecticting the electrodes and 0 per cent perpendicular to the lines of forces. • Application is simpler due to less number of electrodes, though in depth effect is comparable to the four-pole method. • Suitable for localized smaller areas like the temporomandibular joints, muscles of the hand, paracervical muscles, etc. It is specifically used to achieve relief of pain in sciatic neuralgia.


Clinical Applications of Interferential Current Disease condition

Type of current

Current parameter

Electrode placement

Tension headache

Dipole vector field

AMF-100 Hz, Autosweep-3 sec Contour-40%, Dose-15 minutes

Crossed 4 pole, 2 each over the origin and insertion of bilateral Trapezius muscle upper fibres, strong tingling felt

Periarthritis of shoulder, with generalized pain and spasm around the joint and restriction of ROM at end range

Dipole vector field

AMF-100 Hz Spectrum-50 Hz, Manual sweep Contour-40%, Dose-15 minutes

Crossed 4 pole method Channel A Anteriorposterior of shoulder, Channel B over deltoid tubercle and acromion arch, light rhythmic contraction seen (Fig. 8.8A, Plate 5)

Periarthritis of shoulder, with localized tenderness and no significant restriction of ROM

2 Pole medium Frequency field

AMF-100 Hz Spectrum-50 Hz, Manual sweep-3 sec Contour-40%, Dose-15 minutes

2 Poles of a single channel, AP placement across the shoulder covering the tender spot, light rhythmic contraction seen

Frozen shoulder or adhesive capsulitis, with gross restriction of ROM and night pain, especially in diabetics

a. Isoplaner vector field b. Dipole vector field

a. AMF-100 Hz; 1 min. b. AMF-100 Hz, Autosweep-3 sec Contour-40%, Dose-12 minutes

Crossed 4 pole method Channel A Anteriorposterior of shoulder, Channel B over deltoid tubercle and acromion arch, light rhythmic contraction seen (Fig. 8.8A, Plate 5)

Peripheral oedema of transudate type

Isoplaner vector field

AMF-50 Hz Spectrum-50 Hz, Manual sweep-1 sec Contour-01%, Dose-10 minutes

Crossed 4 pole method Cover the entire oedema, elevate the limb, strong vibration felt

Lumbago

a. Isoplaner vector field b. Dipole vector field

a. AMF-200 Hz; 2 min. b. AMF-100 Hz, Autosweep-3 sec Contour-40%, Dose-12 minutes

Crossed 4 pole method Electrodes placed on either side of the vertebral column covering the muscle painful region, light rhythmic contraction seen (Fig. 8.4, Plate 5)

Muscle contusion

Dipole vector field


Crossed 4 pole method Cover the entire lesion support the limb, light rhythmic contraction seen (Fig. 8.9, Plate 5) Contd....

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Contd... Disease condition

Type of current

Current parameter

Electrode placement

OA hip joint


AMF-50 Hz Spectrum-50 Hz, Sweep-6 sec Contour-67%, Dose-15 minutes

Crossed 4 pole method Channel A Anteriorposterior of the hip, Channel B dorsal to greater trochanter and the groin, light rhythmic contraction seen

Tennis elbow or Golfer’s elbow

2 Pole medium Frequency field

AMF-80 Hz Spectrum-40 Hz, Manual sw sweep-3 se sec Contour-75%, Dose-10 minutes

2 Poles of a single channel, mediolateral placement ac across th the elbow covering the tender spot, light rhythmic contraction seen

Weakness of abdominal muscles

Dipole vector field


Crossed 4 pole method Electrodes placed on either side of the midline covering the muscles, light rhythmic contraction seen

Post immobilization contractures of large joints



Crossed 4 pole method Electrodes placed on either side covering the joint, light rhythmic contraction felt (Fig. 8.7)

Post immobilization contractures of small joints

2 Pole medium frequency field


Trans-arthral 2 pole method Electrodes placed on either side covering the joint, deep stimulation felt

Atonic bladder

Classical interferential current

AMF- 1 Hz Spectrum-99 Hz, Sweep-3 sec Contour-50%, Dose-10 minutes

Crossed 4 pole, 2 large electrodes over the buttock just lateral to the SI joint and 2 smaller electrodes on either side just above the symphysis pubis, strong tingling felt.

Myalgia of large muscle groups

Dipole vector field


Crossed 4 pole, electrodes covering the whole muscle group, along with the antagonists (Fig. 8.5, Plate 5)

Myalgia of small muscle groups

Medium frequency surge currents

AMF-100 Hz, Surge duration -3 sec

2 Electrodes over the muscle belly. Contd....

Medium Frequency Currents 75 Contd... Disease condition

Type of current

Current parameter

Electrode placement

Surge in interval-3 se sec Contour 30% Dose- 10 minutes

Minimum perceptible contraction.

Haemoarthrosis of knee joint (up to grade-II)



Crossed 4 pole method Channel A Anteriorposterior of the joint, Channel B Medio-lateral to the joint, light rhythmic contraction seen (Fig. 8.5, Plate 5)

Tenosinovitis

Medium frequency current


2 Pole: One over the muscle belly and one over the tendon. Definite alternating sensations felt.

Cellulites

Dipole vector

AMF- 50 Hz Sweep- 3 sec Dose- 15 minutes

Rheumatoid arthritis

Isoplanar vector field

AMF- 100 Hz Spectrum- 50 Hz Sweep time- 3 Sec Contour- 67 % Dose- 10 minutes

4 Pole placement over the affected area. Clear rhythmical contractions felt. 4 Pole placement around the affected joint (Fig. 8.7)

Chronic constipation

Classical interferential current

AMF- 20 Hz Spectrum- 20 Hz Sweep time- 4 sec Contour- 33% Dose- 30 minutes

Crossed 4 pole method: 2 electrodes placed on the abdominal wall, over the iliac fossa on either side: other two placed under the SI region.

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9 Therapeutic Heat Human body seeks warmth, particularly at the time of distress or while in pain. Since time immemorial, the humankind has used heat for various useful purposes, especially for the treatment of aches and pains. Before the discovery of fire, the primary natural source of heat was the sun. The heat of the sun still remains a favourite among the elderly population for giving relief to their aching bones. This is the first ever application of therapeutic heat. With the discovery of fire, mankind found a new tool for their survival. Apart from keeping predators away heat from the fire helped cook food and keep them warm. Ancient healers used rocks, sand and salt packs heated on fire for treating many types of painful disorders. Heated water also provided an important source of therapeutic heat. The ancient Romans first introduced the concept of heated mud packs, hot bath and steam bath or sauna to treat muscular and skeletal rheumatism. With the progress of science, newer methods of generating heat has been identified, many of which have been adapted for application to the human body to derive therapeutic benefits.

NATURE OF THERAPEUTIC HEAT

Therapeutic heat can be used in two forms, superficial heat and deep heat. The classification is done on the basis of depth of penetration of the thermal effect in to the body tissue. In either kind of application the intensity of the heat is first perceived by the thermal receptors present on the surface of the skin. Therefore the level of the heat should never exceed a feeling of comfortable warmth, whether the mode of application is superficial or deep. SUPERFICIAL HEAT THERAPY

Superficial heat has a maximum depth of penetration of 5 mm from the surface of the skin. The effect is therefore restricted to the skin and superficial subcutaneous tissues. Transmission of Superficial Heat

Heating depends on transfer of heat energy from a point of higher concentration to a point of lower concentration. Such transmission of heat energy can occur by three methods. 1. Conduction of heat: Heat energy transferred from a warmer object to a cooler object by direct transmission of molecular agitation through physical contact, e.g. salt packs, moist packs, and paraffin wax bath.

Therapeutic Heat 77

2. Convection of heat: Heat energy transferred by movement movement from a warmer warmer zone of fluid fluid or air to a cooler area by convection current, resulting in indirect transmission of molecular agitation through physical movement of the molecules over the cooler body bod y par part, t, e.g e.g.. whi whirl rl poo pooll bat bath, h, war warm m saline bath, hydrotherapy. 3. Radiation of heat: Heat energy transferred from a warmer object to a cooler object by electromagnetic radiation, without any heating of the medium of heat transfer, e.g. infrared radiation (Fig. 9.1). Physiological Effect of Superficial Heat

Superficial heat has different kinds of effects depending on the nature of application. A. Generalized heating of large areas of the body surface surface,, like the entire upper or lower limbs, whole back or whole body, with whirlpool bath, Hubbard’s tank or heated hydrotherapy pool, produces following effects: • Inc Increa reased sed phys physiol iologi ogical cal reac reactio tions: ns: Raised cardiac output, metabolic rate, pulse rate, respiratory rate and superficial blood circulation due to dilatation of capillary network. • Dec Decrea reased sed phys physiol iologi ogical cal reac reactio tions: ns: Lowered blood pressure, muscle spasm, blood supply to internal organs and muscles and stroke volume of the heart. B. Local heat application to small areas of the body, like the knee or shoulder joint, neck, low back region, with infrared lamp, Paraffin wax bath, moist hot packs, electric heating pads or hot water bags, produces following effects. a. Increased physiological reactions: 1. Incr Increased eased loca locall blood blood flow due to vasodilatation.

Fig. 9.1: 9.1: Position of the patient and the relative position of the infrared lamp for application of superficial heat to the nape of the neck.

2. Increa Increased sed inters interstit titial ial fluid fluidss turn over and better drainage due to higher capillary permeability. 3. Incre Increased ased flexi flexibili bility ty of capsu capsules, les, ligaments and tendons due to greater elasticity of collagen fibres. 4. Incr Increase eased d metab metabolic olic rate due to increase in cellular oxidation. b. Decreased physiological reactions : 1. Decre Decreased ased join jointt stiffn stiffness ess due due to to greater flexibility of collagen tissue. 2. Decr Decreased eased musc muscle le torq torque ue due to suppression of glycol breakdown. 3. Dec Decrea reased sed musc muscle le spas spasm m due due to diminished neural activity. 4. Dec Decrea reased sed pain pain due due to prepre-syn synapt aptic ic inhibition of pain transmission. Indications for Superficial Heat

Superficial heat is the modality of choice, to raise the general or local temperature of the body tissues, as a preparatory step before application of active movements, passive mobilisation, massage or electrical stimulation to

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the musculoskeletal system, particularly in presence of: • Joint stiffness and pain • Muscle spasm and pain • Painful chronic lesions—Posttraumatic, degenerative or inflammatory • Rheumatism of the skeletal and soft tissue. Contraindications for Superficial Heat

• Acute traumatic and inflammatory lesions of the musculoskeletal system • Infections—local or general • Circulatory deficiency • Diminished thermal sensation • Deep vein thrombosis • Malignancy • Bleeding disorder • Severe swelling • Impaired cognition or inability to assess the degree of heat being felt. • Very young and very old patients. PREPARATION OF PATIENT BEFORE APPLICATION OF HEAT OR COLD THERAPY

Application of thermal energy to the body carries the risk of thermal injury, usually to the skin, sometimes affecting the deeper tissues. The nature of injury varies with the intensity and duration of heat applied, the colour and sensitivity of the skin, presence of skin rashes or allergies on the area being treated, sensory acuity or cognitive ability of the patient etc therefore, before application of any kind of thermal energy, heat or cold , adequate preparations must be done. • Thermotherapy must be done personally or under direct supervision of a qualified therapist.

• Position the patient comfortably so that he/she can sustain the position for at least ½ hour. • Expose the part to be treated; rest of the body should be covered with a sheet. • Check for rashes, cuts, bruises and discoloration of the skin. • Test the thermal sensation of the skin. Take two test tubes and fill either with hot or cold water, beyond the sight of the patient. Place the test tubes by turn against the skin and ask the patient to identify the type sensation felt. • Test the awareness level of the patient prior to application of thermotherapy. Heat therapy should be avoided in patients with cognitive dysfunction, e.g. Alzheimer’s disease, multiple infarct dementia or mental retardation. • Make sure the patient understands the nature and the extent of heat that should be felt during the treatment. Explain the possible adverse reactions of overheating, because some patients may believe that more heat means quicker relief. A call bell should be placed near the patient, to summon the therapist in case of overheating or burning sensation during the treatment. • Inspect then part closely for any rashes, blister formation or excessive reddening after the treatment. Calamine lotion may be applied over the reddened area or heat rash and the subsequent sittings deferred till the skin becomes normal. Preparation of patient, delivery of treatment and precautions to be observed in thermotherapy are same for most forms of superficial heat or deep heat or cold modalities. Specific modalities have few specific concerns that need attention, covered under the heading of ‘ special points’.

Therapeutic Heat 79

TYPES OF SUPERFICIAL HEAT MODALITIES

A number of superficial heat modalities are available for the therapist to use. These are hydrocollator, hydrotherapy, paraffin wax bath and infrared therapy, which have been detailed below. Infrared can be obtained from luminous (visible light) or non-luminous sources, though its biophysics and effects are essentially the same. Thus for convenience of the reader, only the non-luminous variety has been considered along with the basic biophysics, under the section of superficial heat, with the luminous variety detailed under the section of therapeutic light in this volume. Moist Hot Packs—Hydrocollator Points to Ponder

2. For large-sized packs—Fold two large Turkish towels breadth wise in to eight folds. Place one-folded towel over the area to be treated, usually covering the whole back and place the heated pack on it. Cover the pack with the other folded towel to prevent heat loss and place a small sand bag on top to keep the pack in position. Extra towel layers may be used if the heat is too much for comfort. • Duration of treatment—20 to 30 minutes in a sitting may be repeated twice a day in acute conditions. • Effective in—Superficial muscle spasm and pain, inhibition and restriction of joint movement. • Special points: Moist packs and towels are a potential source for fungal growth. They must be dried thoroughly before reuse. Wash all linen and packs in weak disinfectant solution once a week.

• Packs used are made of canvas, filled with silica gel, which has the capacity to retain heat for long period of time. • The packs are available ready made in large, medium, small sizes, as well as for specialized HYDROTHERAPY FOR SUPERFICIAL application of cervical region . HEATING—WHIRLPOOL BATH/ • The packs are placed in a double-walled HUBBARD’S TANK/SAUNA stainless steel tank, containing hot water at 50 to 60° C, heated electrically and regula- History ted by a thermostat. The origin of hydrotherapy can be traced back • Method of heating— C onduction of heat to ancient times, when soaking in natural hot from hot water to silica gel. springs were favoured by traditional healers • Method of application— for treatment of all forms of joint disorders. 1. For small and medium-sized packs —Fold Ayurvedas and Charka Samhita has number of a large Turkish towel lengthwise into references to the therapeutic application of four folds. Wrap the folded towel whole body submersion in hot springs, as well around the heated pack so that both as, cold water baths. Ancient Chinese and side of the pack has eight layers of Arabs also used hydrotherapy as a method towel cover. Place the pack over the of treatment in the years B.C. Ancient Roman area to be treated, e.g. knee, elbow, and Turkish physicians popularized the wrist or shoulder joint and secure it in concept of public bath houses, with pools position with a strap. having variety of water temperatures, with

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add on services like massage, steam bath or sauna, for treatment of stress and musculoskeletal disorders. These bath houses soon became popular meeting ground for the common man and the ruling elite. In medieval Europe painful joint disorders were clubbed together as rheumatism. These were referred for treatment to health centres known as ‘Spa’ located close to natural hot springs. Over time these places developed into tourist attractions. Treatment in such ‘Spas’ were outrageously expensive and could be afforded by only the elite of the society. Many such ‘Spas’ are still to be found in countries like Germany, Austria, Italy, Russia, as well as, in India. The mode of treatment followed in such naturopathy centres are based on regular soaking of the entire body of the patient in the mineral rich water of the hot springs, supplemented by a natural diet, massage and exercises. They are still as expensive. With the western medical science becoming more cosmopolitan and oriented to the service of common man, methods were devised to provide the beneficial effects of the ‘Spa’ in a general hospital setting, with proportionate reduction in cost of treatment. This is how modern hydrotherapy was born in mid 19th century in England, soon to be adopted by the entire Europe and the World. Points to Ponder

• Definition: Hydrotherapy can be defined as partial or total submersion of the body in water baths or pools, where the water may be ag it at ed or mi xed wi th ai r, to be directed as jets, against or around the part to be treated. • The buoyancy of water, an upward thrust equal to the weight of water displaced by

submersion of a body in water (Archimedes principle), renders the limb or body weightless making it easy for the patient to move a weak limb actively or allow him to stand and walk on weakened legs. • The capacity of water to absorb heat is known as specific heat, which the amount of heat needed to raise the temperature of 1 gram of water by 1°C. The heat from the water is transferred to the body by means of convection giving relief from pain, muscle spasm and stiffness. • Modern hydrotherapy utilizes three modes of superficial heat application: Whirlpool bath, Hubbard’s tank and steam bath or sauna. Method of Application of Whirlpool Bath

A. Whirlpool bath is immersion of an extremity in a pool of circulating heated water, suitable for treatment of the extremities only. It is widely used for heating of soft tissue around joints prior to mobilisation or debridement and disinfection of burn wounds. B. Whirlpool bath consists of a oblong-shaped stainless steel tank, usually 3’deep x 3’long x 2’wide in size, mounted on four castor wheels, fitted with a thermostatcontrolled, immersion type electric heating coil and an air-jet pump with nozzle. C. The tank is filled with water, leaving a gap of 6’ to 8’ from the top. The water is heated to 35° to 40°C. A disposable plastic liner may be used and any common disinfectants like sodium hypochlorite at dilution of 200 parts per million (ppm), povidoneiodine at 4 ppm or savlon at 100 ppm may be added while treating burn injuries and infected wounds.

Therapeutic Heat 81

D. The patient is assisted to immerse the body part in the tank, after sitting down comfortably on a height-adjustable stool placed beside the tank. E. Adjust the direction and force of the air jet to get the desired effect, which may be to offer resistance or assistance to active movement or debridement (peeling off) of dead tissues from the surface of a wound. Most patients, including those with severe bu rn s, fin d th e wh ir lp oo l ba th ve ry soothing. F. The duration of treatment is usually 20 to 30 min. After the treatment the part should be dried and inspected closely for any adverse reaction from heat.

D.

E.

F.

Method of Application of Hubbard’s Tank

A. Hubbard’s tank is immersion of the whole body in a pool of circulating heated water, suitable for the treatment of acute or subacute rheumatoid arthritis presenting with multiple joint pains, whole body burn injury and paraplegia. It is ideal for treatment of very ill-patients in unstable condition, with severe pain or serious infections, as in extensive burn, since the patient can be treated with whole body immersion, in an isolated environment. B. Hubbard’s tank consists of a butterflyshaped steel tank having a depth of 3’ and large enough to accommodate the entire bo dy of th e pa ti en t, fit te d wit h tw o thermostat-controlled, immersion type electric heating coils and two air-jet pump with nozzles at either end of the tank. C. The tank is filled with water to the desired level (see whirlpool), which is then heated to the desired temperature. A disposable

G.

liner may be used and disinfectants be added if a burn patient is to be treated. The patient, if ambulatory, may be helped to climb in the tank, using a metal step stool. Mostly they are transferred into the tank using a nylon sling and bed side hoist. The patient should be lowered gradually into the tank to allow him to get accustomed to the water temperature. Care should be taken to keep the head of the patient out of water. This may be done using an inflatable neck ring and a head support. The rest of the body may be allowed to float free in the circulating water of the tank. Adjust the direction and force of the air jet to get the desired effect, which may be to induce relief of pain or relaxation in spastic muscle prior to exercises or debridement (peeling off) of dead tissues from the surface of a wound. Most patients, including those with severe burns, find tanking very soothing. The duration of treatment is usually 20 to 30 min. After the treatment the part should be dried and inspected closely for any adverse reaction from heat.

Special Points to Ponder

• Since immersion type heating elements are used, electrical safety of the patient must be ensured at all times, because in case of any leakage of current, it is likely to flow through the body of the patient, to the ground. • All electrical components like the heating element; thermostat, turbine etc must be checked weekly to prevent any leakage of current and earth fault. • All circuits must have properly calibrated circuit breakers.

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Method of Application of Steam Bath or Sauna

Traditional sauna, used in Scandinavian countries, Turkey and Russia, as a public utility service, consists of a sealed room, lined with wood panels for insulation, with a coal burning stove with a metal jacket, in the centre of the room. Water is poured on the heated metal jacket to generate steam. Clients sit around on wooden benches surrounding the stove and enjoy the effects of steam. • The steam bath as used in modern hydrotherapy consists of an insulated chamber made of laminated waterproof ply wood or man made fibres, large enough accommodate a person in sitting position. • The patient is asked to strip and a towel used for preserving the modesty. Total privacy is essential for this form of treatment, so that the patient can relax during the treatment. A female therapist or a female attendant must treat female patients. • The chamber is sealed air-tight, leaving the head of the patient seated inside, through a head port. • Steam is fed into the chamber from a boiler situated outside the chamber. • Approximate temperature within the chamber is maintained at 40° to 45°C. • The patient is instructed to call the therapist in case of any discomfort. A call bell may be provided for this purpose. • Treatment sessions can be for 20 to 30 minutes. • Physiological effects are same as that produced by generalized heating. • Therapeutic benefits are relief of stress, muscle spasm, pains and aches. Claims of reduction in body weight, as a major effect of sauna, is mostly temporary due to loss of water from the body due to sweating, which is made up with few glasses of

water the patient drinks after the treatment. Special Points to Ponder

• Dehydration is a major risk in steam bath. Patients with chronic dehydration, like the elderly, must be given sauna with caution. All patients must be encouraged to drink electrolyte-balanced drinks before and after the therapy. • Patients with hypertension and heart diseases must not be given sauna because of adverse physiological responses produced by prolonged exposure to heat and excessive sweating. PARAFFIN WAX BATH

• Paraffin wax bath is the therapeutic application of molten mixture of paraffin wax and mineral oils, for relief of pain and joint stiffness, suitable for peripheral joints like small joints of hands and feet, ankle, knee and elbow joints • The paraffin wax bath consists of a double walled insulated stainless steel bath, 24”× 12”× 8”in size, heated indirectly by heating coil. • The mixture of paraffin wax, liquid paraffin and petroleum jelly, in a ratio of 3:1:1, melts at 42 to 45°C and is self-sterilizing in nature. The temperature is sustained by thermostat-controlled heating. • Molten wax mixture solidifies on contact with the skin, giving up latent heat of solidification, which is transferred to the body by conduction. Method of Application

• All jewellery and metal object must be removed from the part to be treated. • The part should be washed and checked for any infection, rash or bruises.

Therapeutic Heat 83

• The part is repeatedly dipped in the molten wax mixture, as for hands and feet or the molten mixture is poured over the part, as for wrist, ankle, knee and elbow, to form ten successive layer of wax coating. • The coated part is then wrapped with a polyethylene sheet, followed by few layers of towel to retain the heat. • The part is then placed in a comfortable position till the feeling of heat ceases. The solid mixture peels off after cooling and can be reused again in the wax bath. • Physiological effects are same as that produced by localized heating. • Therapeutic benefits are relief of reduction of pain and joint stiffness, which can be used prior to passive movements RADIANT HEAT–INFRARED RAYS

• Radiant heat is the therapeutic application of radiant electromagnetic energy, obtained either as invisible infrared from any heat source or in combination with visible light and ultraviolet rays from an incandescent electric bulb or sunlight. • In this section only the non-luminous infrared has been considered since it is a superficial heat modality. The luminous infrared has been covered under the section of therapeutic light. • Non-luminous infrared contains far infrared electromagnetic rays in the frequency range of 1500 to 12000 Angstrom units, having a penetration of 2 mm in the epidermis. • Heat transmission with infrared radiation is governed by following physical principles: a. Lambert’s cosine law, which states that the angle incidence of radiation is

directly proportional to the extent of radiation absorbed. Optimal absorption is possible only when the source of radiation is perpendicular to skin. b. Inverse square law, which states that the intensity of radiation varies inversely with the square of the distance between the source of radiation and the skin. Intensity of the radiation is reduced if the distance between the source and the target is increased and vice versa. Method of Application

• The non-luminous lamp is turned on approximately 5-10 minutes before application to ensure maximum output. • Expose and support the part to be treated and examine the skin as detailed in general preparatory methods. • Give the patient a glass of water before and after the treatment. • After positioning the patient comfortably, cover the eyes and avert the face from the source of infrared. • Commence the treatment with the I.R source placed at a distance of 30” to 36”from the surface being treated (Fig. 9.2). • The dosage can be adjusted by shifting the source closer or away from the treatment surface, depending on the feeling of warmth by the patient. The feedback of the patient is absolutely essential to adjust the dose, hence the patient must explained in detail about the expected heat sensation. This is done by asking the patient to blow on the back of his hand, holding it close to the mouth. The amount of heat felt on the dorsum will be the optimum limit of warmth to be felt on the skin, with any form of heat therapy. • Duration of treatment should be 15 to 20 minutes once or twice a day.

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Fig. 9.2: The arrangement of the lamp and the position of the patient should be such that the incident rays are perpendicular to the skin. The intensity of the superficial heat can be increased or decreased by moving the lamp closer or away from the skin. The minimum distance between the source of infrared and the skin should be 50 cm

COMPARATIVE PROFILE OF SUPERFICIAL HEAT MODALITIES Modality

Most commonly used for

Advantages

Disadvantages

Moist heat

Muscle spasm, pain and stiffness of major joints of the extremities, neck and trunk

• Reusable and cost effective • Safe for delicate skin, • Prolonged analgesia, • Circumferential heating.

Infrared

Superficial muscle spasm and localized pain of neck and trunk

• Easy to apply • Risk of burn if source • Better localization of heat. is too close to the skin • Cost effective for home • Risk of eye injury in management luminous I.R • Effect is transient

Paraffin wax bath

Stiffness of joints and pain • Circumferential heating, due to degenerative disorders, • Improves the texture of Soft tissues contractures the skin following immobilisation • Increases pliability of soft tissue • Prolonged analgesia. • Reusable and cost effective

• Initially expensive, • Risk of scalds • Risk of fungal infections

• Messy application procedure, • Regulation of temperature difficult and may cause burn, • Highly inflammable composition, hence fire hazard

Whirl pool/ Multiple joint stiffness and • Applicable for whole or • Expensive to install Hubbard’s tank pain, disuse atrophy, wound part of the body and run debridement in burn, paralytic • Induces relaxation, relief • Needs more space conditions of pain and spasm • Extensive preparation • Exercise can be done and constant supereasily due to buoyancy vision needed • Messy operation • Risk of electrical accidents

10 Deep Heat Therapy Heat can be generated deep inside living tissues by conversion of non-thermal energy like electromagnetic radiations and sound absorbed by the body tissue, in to thermal energy. This conversion of non-thermal energy into heat energy is achieved using the interaction between the non-thermal energy fields and the physical properties of the body tissues, namely capacitance, inductance and acoustic impedance. Different modalities using such energy conversion are shortwave—diathermy, microwave diathermy and therapeutic ultrasound. SHORT-WAVE DIATHERMY (SWD) Definition

• Short-wave diathermy is the commonest deep heat modality used in physiotherapy departments in India. It utilises high frequency alternating sinusoidal current at frequency of 27.12 MHz to produce electromagnetic (Radiowaves) with wavelength of 11.3 meters. This wavelength and the frequency are reserved for therapeutic purpose by International agreement, to avoid interference with other radiofrequencies and communication network. • When subjected to the electromagnetic field generated by the SWD, heat is produced in

living tissues , with clear physiological effects and therapeutic benefits. Biophysics of Deep Heating Using Short-Wave Diathermy

Heating with SWD is achieved by two methods: a. Capacitor or condenser field method b. Inductance or magnetic field method. Capacitor or Condenser Field Method of Application

• Two electrodes, consisting of flexible metal plates encased in heat resistant rubber or air-spaced drums, are connected to the output terminals of the high frequency current generator. The metal plates act as the plates of a condenser, bearing + and – charge. • The charge of the electrodes keeps oscillating at a high frequency of 27.12 MHz, producing a powerful electromagnetic field between the two electrodes. • This field of energy is conventionally described as the lines of forces, which are imaginary lines connecting the opposing faces of the electrode plates. • Body tissues placed between the two electrodes, become a part of the condenser

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circuit, as a di-electric medium, and are subjected to these lines of forces. High frequency oscillating current produces rapid oscillation of the ions, rotation of the dipoles and distortion of insulators present at the molecular level of the living tissues. This activity at the molecular level of the living tissue produces displacement current in tissues with high electrical resistance and conduction current in tissues with low electrical resistance. Resistance to the passage of current deep within the tissues produces heat. Dense tissues with closely-packed molecules like the skin, fat, fascia, ligament etc offer greater resistance to the passage of the electrical field and become warmer, than loosely-packed tissues like muscles and blood. Subcutaneous fat is an insulator and therefore the layer of fat absorbs much of the lines of forces. Though technically the condenser field method should be effective for through and through heating, in reality little heat reaches to layer deeper than the subcutaneous fat. This type of application is therefore most effective when the target tissues do not have a thick layer of fat covering. Intensity of heating and depth of penetration are determined by the shape and the distance between the electrodes.

Inductance or Magnetic Field Method of Application

• An insulated monoaxial cable or hinged plastic drums each containing a coil of conductor, is connected to the output

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terminals of the high frequency current generator. High frequency oscillating current produces an electromagnetic field around the conductor. The cable is coiled around the body part to be treated. The hinged drum is placed over the body part, without actually being in contact with the body surface. Through electromagnetic induction, secondary Eddy current is induced in the body tissue placed within the electromagnetic field, though it is not a part of the circuit. Resistance to the passage of Eddy current produces maximum heat in deep tissues with high electrolyte concentration, particularly in tissues with high conductivity like blood, nerves and muscles. Dissipation of heat is much slower and the effect of heating tends to be prolonged.

Production of High Frequency Current The machine circuit –Consists primarily of the

high frequency current generator, with three controls on the faceplate of the device. The intensity knob is a rotary step switch that controls the amplitude of the high frequency current and is a part of the machine circuit, the tuning knob is a constantly variable rotary switch attached to a variable condenser and is a part of the patient circuit and auto cut-off timer to set the duration of treatment and stop the flow of high frequency current to the patient circuit on completion of the treatment duration. It may be either a digital or analogue stopwatch (Figs. 10.1 and 10.2). • The patient circuit – The variable condenser, electrode connecting cables, electrodes

Deep Heat Therapy 87

Fig. 10.1: Short-wave diathermy unit

Fig. 10.2: The circuit configuration of the highfrequency AC link DC-DC converter using secondary phase-shifted PWM control scheme (below called “proposed control scheme”) is shown in Fig.1. This circuit is composed of the high-frequency inverter, the high-frequency transformer, the diode rectifier circuit and the LC filter. A difference between conventional DC-DC converter and proposed DC-DC converter is two power devices are newly connected inside the diode rectifier circuit. Fig.2 shows its switching pattern, inverter output voltage waveform and output current waveform. In conventional control scheme, the converter output voltage was controlled by giving phase-difference between the right and left arms of the full-bridge inverter on the primary side. In proposed control scheme, the converter output voltage is controlled by giving phase-difference between the primary side and the secondary side, which is synchronized with the primary side. From this reason, between the right and left arms of the fullbridge inverter does not have phase-difference. Namely, it operates as a square-wave generator like a symmetrical drive with 50% duty including dead time. By using proposed control scheme, secondary switches S5 and S6 are both off during the circulation interval (t1 < t < t2) in which the power is not supplied form the primary side. At this point, the circulating current will flow only the secondary circuits via the high-frequency transformer. Therefore, the circulating current cannot flow on the primary side (this state is called “the self circulation interval”). As a result, almost conduction losses are eliminated because circulating current can be removed. This is the distinctive feature of proposed control scheme. In addition to this, all power devices can operate under soft-switching condition, independent of changing load resistance. From these reasons, the conversion efficiency become high compared with conventional DC-DC converter because proposed control scheme can effectively solve the problems mentioned above

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and the body part which act as the dielectric of the variable condenser. Transfer of energy— Maximum transfer of energy from the machine circuit to the patient circuit takes place when the product of the capacitance and the inductance in both the machine and patient circuits match perfectly or said to Resonate. This is resonance of two circuits, is called tuning and it is conventionally achieved by rotating the tuning knob of the variable condenser, like tuning an old-fashioned radio. The patient’s body acts as a part of the variable condenser setup, till the product of the capacitance and the inductance in both circuits match. Most modern SWD machines have automatic tuning, where the machine circuit automatically searches for and finds resonance with the patient circuit, like the push button car radio. The tuning may be indicated by a neon tube tuning lamp, which glows brightest at the point of maximum resonance between the two circuits. It may also be an ammeter, the needle of which shows maximum deflection on tuning of the circuit.

PHYSIOLOGICAL EFFECTS OF SHORT-WAVE DIATHERMY

Deep heating produces physiological effects that are similar to those produced by superficial heat, but its effects are spread much wider and deeper in the body tissue. General physiological changes produced by deep heating with SWD. Adequate heating of the blood pool is produced on exposure to SWD for 15 to 30 minutes, which produces significant

generalized change in the body. These changes are as follows: • Increased physiological reactions: Raised Cardiac output, metabolic rate, pulse rate, respiratory rate, and generalized vasodilatation. • Decreased physiological reactions: Lowered blood pressure, stroke volume and blood supply to internal organs. Local Physiological Effects and Therapeutic Benefits of Deep Heating with SWD

SWD application to specific areas of the body like the knee joint, shoulder joint, neck, lumbosacral region produces following local effects, which have significant therapeutic value. Increased reactions 1. Increased local blood flow due to vasodilatation, leads to tissue healing, relief of muscle spasm and pain. 2. Increased interstitial fluids turn over and better drainage due to higher capillary permeability, leads to reduction of swelling. 3. Increased flexibility of capsules, ligaments and tendons due to greater elasticity of collagen fibres lead to greater mobility of joints. 4. Increased metabolic rate leads to activation of dormant tissue. 5. Increased pain threshold due to sedation of the pain carrying nerve fibres resulting in pain relief. Decreased reactions 1. Decreased joint stiffness due to greater flexibility of collagen tissue. 2. Decreased muscle torque due to suppression of glycol breakdown.


3. Decreased muscle spasm due to diminished neural activity. 4. Decreased pain due to pre-synaptic inhibition of pain transmission. INDICATIONS FOR SHORT-WAVE DIATHERMY

SWD is effective in management of pain and inflammation associated with the following disorders: • Musculoskeletal system disorders, e.g. spondylosis, osteoarthritis, rheumatoid arthritis, degenerative joint diseases and postural or posttraumatic muscle spasm and pain. • Pelvic inflammatory disorders, e.g. pelvic endometriosis. • Inflammation of body cavities, e.g. Sinusitis. • Using non-thermal effect of pulsed SWD for healing of wounds. CONTRAINDICATIONS OF SHORT-WAVE DIATHERMY

SWD should not be applied in following conditions: • Presence of metal implants or ornaments within the field of the lines of forces. • Patients with pace-maker • Pregnant women should not be given SWD in the region of low-back or lower abdomen. • Acute traumatic and inflammatory lesions of the musculoskeletal system • Infections—local or general • Circulatory deficiency • Diminished thermal sensation • Deep vein thrombosis • Malignancy

• Bleeding disorder • Severe swelling • Impaired cognition or inability to assess the degree of heat being felt. • Very young and very old patients. METHODS OF APPLICATION OF SHORT-WAVE DIATHERMY Preparation of the Equipment

• The equipment is connected to the mains • The electrodes/cable are attached to the output terminal of the machine. • The equipment is turned on and warmed up for at least 2 minutes. • The therapist places one hand between the electrode plates/over the coil of the cable electrode, increases the intensity at least two steps from the minimum. The machine is then tuned by turning the tuning knob in one direction till maximum deflection shows on the tuning meter. A comfortable warmth should be felt after a minute or so, indicating that the machine output is adequate for treatment and it’s safe for patient application. • After testing the machine output the intensity is returned to zero level and hand removed from the electrodes. Application of Treatment with Short-Wave Diathermy

• The patient is positioned in a comfortable position on a wooden plinth, part exposed and the rest of the body draped with a sheet. • The part may be wrapped double layer of Turkish towel to absorb sweat produced during the treatment and acts as spacer with air-space.

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What are Spacers?

or induction field method, as well as the area to be treated and the effect desired from deep heat therapy.

• Spacers are insulating material containing airspaces, like perforated felt pads or Turkish towels applied in two or more layers between the pad electrodes and the skin CONDENSER FIELD METHOD surface. The spacers increase the distance SHORT-WAVE DIATHERMY between the electrode surface and the skin to The condenser type electrodes may be, either ensure an even distribution of the lines of pads made of flexible metal plates covered forces and therefore the effect of the with a layer of heat resistant rubber or airheating. For optimum heating, the sum spaced drums electrodes. These are available total of the thickness of the spacers must in different sizes, from 4”× 6” up to 10” × 12” be less than the distance between the pad and may be round, square, rectangular or electrodes, if kept side by side bu tt er fl y-s hap ed fo r ap pl ic at io n to th e • Drum or disk electrodes used in condenser maxillary and frontal sinuses. The electrodes field method of application have a hard are connected to the output terminal of the plastic shell covering the metal disk high frequency current generator through conductor. The air-space within the plastic shell is used as spacer , which can be varied, insulated co-axial cables. SWD Machines by sliding the metal disk mounted on a usually have separate output sockets for telescoping stalk, within the plastic shell. drum/pad/cable type electrodes. Perforated felt pad spacers are placed on either side of (Fig. 10.3). the pad electrodes and the whole complex is enclosed in a cotton cloth envelope. ExtraELECTRODE PLACEMENT spacing, if required, may be provided by SHORT-WAVE DIATHERMY using several layers of Turkish towel or extraThe electrodes placement varies depending felt pad spacers. Before application of electon the type of application, i.e. condenser field rodes, all clothing must be removed and the part must be wrapped in at least one layer of clean Turkish towel. This towel layer is recommended for hygienic purpose, as well as, to absorb any sweat that form while heating the part (Figs 10.4 and 10.5, Plate 6). a. Contraplaner placement: This is the preferred method for treating joints like the knee or elbow or shoulder joints using SWD. The electrodes are placed on either sides of the joint, on opposite planes, preferable on a regular surface, without any bony Fig. 10.3: Disc electrodes used in SWD. The outer prominence underneath the electrodes. plastic shell has been removed to show the metal Bony prominences create concentration of discs within


lines of forces, which may lead to burn. The electrodes are held in position with a Velcro strap (Fig. 10.6, Plate 6). b. Coplaner placement: This is the method of choice for treating large, flat areas like the ba ck, us ing SWD. Th e elec trodes are placed side by side on the same plane, covering the entire treatment area (Figs 10.7, Plate 6, and 10.8, Plate 7). c. Cross-fire placement: This method of electrode placement combines the effect of two contraplaner placements, to heat a large joint like the knee, from all directions. The electrodes are first placed on the medial and lateral aspects of the joint and heat applied for half of the total treatment time. Then the electrodes are shifted to superior and inferior aspect of the joint and heat applied for the remaining duration. This way the joint is heated thoroughly from all directions. This is the method of choice for treatment of chronic synovitis, when the entire joint must be heated uniformly. d. Asymmetrical placement: These are specialized technique of application of SWD for preferential heating of heavily-muscled areas like the calf or deep-seated joints like the hip. • For calf muscles: Patient is placed in high sitting on a wooden plinth, with the feet placed on a wooden stool. One pad electrode is placed under the sole of the foot and the other on the top of the flexed knee. With this method, the lines of forces pass parallel through the calf and leg muscles, producing maximum beneficial effect of electromagnetic field in the muscles themselves, which is most useful in anterior-lateral compartment syndrome or chronic spasm of calf muscles or as a preparatory step before stretching of the calf muscles.

• For hip joint: (Figs 10.9 and 10.10, Plate 7). CABLE METHOD SHORT-WAVE DIATHERMY

• The cable electrode consists of flexible co-axial conductor, enclosed in a sheath of heat resistant rubber. • The length of a cable electrode is 1.5 meter. • Two metal jacks are attached to either ends of the cable, which are inserted in to the output sockets of the machine, specifically earmarked for cable diathermy • The arrangement of the cable in relation to the body part depends on the relative density of high or low impedance tissues present in the part to be treated. • The cable can be applied either by wrapping it around the part to be treated like the extremities or in the form of a concentric coil placed over flat areas like the back or abdomen. • The ends of the cable have greater concentration of electrostatic forces which produces more heat in high impedance tissues like skin, fat, fascia, tendon, ligaments, joint capsules etc. For treatment of parts like hand, wrist and distal forearm or foot, ankle and lower leg or joints like the knee or elbow, the outer 1/3 of the cable on either side is used. • The middle 1/3 of the cable generates a strong electromagnetic induction field, which have greater effect on the low impedance tissues like muscles and blood vessels. Hence the segment can be used heavilymuscled and highly vascular areas like the calf, thigh, upper arm etc. APPLICATION OF TREATMENT WITH SHORT-WAVE DIATHERMY

• After the machine circuit has been warmed up for at least 2 minutes, the intensity knob

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is turned up one step and the machine temperature during the treatment and it circuit is manually tuned to the patient circuit must be stabilized before being allowed to by rotating the tuning the tuning knob in be exposed out side temperature, especially clockwise or anticlock wise direction till in winter. the needle of the tuning indicator shows maximum deflection. This function may be Technique of Application of Short-Wave Diathermy in Few Specific Disease automatic in a modern machine. This indicates that two circuits are now in Conditions tune and maximum transfer of energy is Short-wave diathermy is a versatile modality taking place between the machine circuit that can be used in many disorders. Its and the patient circuit. application, as a deep heat modality, to gain The intensity knob is now turned up therapeutic benefit in suitable target tissue, gradually step by step up to 1/3rd to 1/2 mark depends on the ingenuity of the therapist. from the maximum limit till the should Methods of application for few conditions feels a comfortable sense of warmth in the part listed in Table 10.1 should serve as a guide being treated. for the therapist to explore further possiThe treatment timer is then set for the bilities. desired period, i.e. 10 to 30 minutes. The patient is reminded to use the call bell to MICROWAVE DIATHERMY (MWD) summon the therapist in case of any over or Definition: Microwave diathermy (MWD) under heating or any discomfort. After the treatment time is over, most can be defined as a deep heat modality that equipments cut-off the power automati- is similar in concept, but differs widely in its cally. Turn the intensity knob to zero, bio-physics and application from the shortremove the electrodes from the body and wave diathermy . inspect the part closely for any reddening. Biophysics Ask the patient to rest on the plinth for 5 minutes after the treatment is over, before • Microwave diathermy utilizes electromagnetic energy with a frequency of 2450 Hz and being allowed to get up. SWD creates wavelength range of 10 to 12 cm. pooling of blood in the treated area, lowering the blood pressure and depriving the brain of • A composite oscillator known as a magnetron produces MWD. The magnetron conadequate blood supply. This may lead to sists of ring-like perforated iron core, with positional vertigo if the patient is allowed to get up suddenly after the treatment. multiple holes drilled in such a way that, This precaution is particularly relevant in flow of electrons over theses holes create pelvic diathermy or cable method where large a electromagnetic frequency, response that volume of blood is heated. vary in proportion to the velocity and the The patient is then allowed to dress and electromotive force moving the electrons. asked to wait indoor for another 5 to 10 In the frequency of 2450 Hz it is called the minutes before stepping out. This premedical microwave energy. caution is essential to avoid sudden exposure, • The electromagnetic energy thus produced since there is significant rise in the body is directed through a co-axial cable to an


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antenna, mounted inside a hard plastic shell, known as an applicator. The electromagnetic wave released from the applicator is directed to the target tissue. There is no need for tuning in MWD, since the target tissue, unlike in SWD, is not a part of the circuit. The intensity levels are constant for individual applicators and are printed on the directors for reference during treatment. The dosage of MWD is governed by the inverse square law, which implies that greater the distance from the source of the radiant energy lesser will be its intensity. Clinically, the patient should experience a sensation of comfortable warmth. The penetration of MWD, like any electromagnetic energy, is directly proportional to its frequency, though clinically for the therapist; heat production is more a result of absorption of energy, than of linear penetration. Hence its absorption of MWD is far more relevant to study. Absorption of microwave energy, like that of the shortwave, depends on the relative densities of the tissues and the clinical effect depends on the type of tissue involved. It is believed that MWD is absorbed better by fat than most other tissues. Since fat is very superficial, the direct thermal effect of MWD is restricted to relatively superficial area. Any effect on deeper tissues is mainly due to heat transfer from the heated superficial fat layer.

Indications for Microwave Diathermy

• Broad clinical indication of MWD is similar to SWD. • It is preferred in cases where more concentrated and localized heating is required in

superficial targets like trigger points, fibromyositis, epicondylitis etc. Contraindications for Microwave Diathermy

• MWD is strictly contraindicated in presence of pacemakers or deficit in thermal. • Avoid exposure over genitals, eyes or gravid uterus. Technique of Application of Microwave Diathermy Patient Preparation

• Patient is positioned suitably on wooden plinth or chair to ensure adequate and easy access to the target area. • Part to be treated is exposed and rest of the body is draped with a sheet. • Clean the skin of the target area and inspect for cuts, skin lesions or bruises. Selection of Treatment Applicator

• Shape of the treatment applicator may be small circular, large circular or rectangular, each offering field of radiation in the shape of the applicator. • Selection of treatment applicator therefore depends on the shape of the target area. • Since the microwave energy is emitted in a divergent field, the extent of its divergence and focusing of the field, like the focusing of a light, depends upon distance between the applicator and the skin. • A compact fluorescent tube (CFL) may used by the therapist to detect the concentrated area of focus as well as the periphery of the field. The lamp will glow the brightest in the concentrated field and gradually fade as the CFL is moved to the periphery of the field.


Selection of Appropriate Power Level and Application of Treatment

• The equipment should be turned on at least five minutes before the treatment to allow the magnetron to develop enough charge to produce adequate emission of electromagnetic energy. • As per inverse square law, the distance of the target from the applicator determines the dosage of microwave. • The distance from the applicator to target is critical for optimum distribution of the field, which must be measured with a built in distance regulator on the treatment head. • Closer the head to the target lesser the power level and vice versa. • It is recommended to set the power level

at medium and then adjust the distance of the applicator from the skin depending upon the heatfelt by the patient. • The distribution of the field may be checked using the CFL tube to ensure adequate distribution and correct focus of the microwave energy. • The patient feed back should be a sensation localized heat, the intensity of which can be adjusted simply be moving the applicator closer or away from the skin. Alternatively a lower or higher power setting, if the equipment offers the option of different intensity levels. • The optimum duration of treatment is in the range of 10 to 20 minutes for smaller areas like elbow, wrist or ankle and 25 to 30 minute for large areas like the low back, knee or shoulder.

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11 Therapeutic Ultrasound (US Therapy) Sound can be defined as a periodic mechanical oscillation of an elastic medium such as air or water. Sound energy can be produced from an oscillating source and needs a medium to transmit. Sound travels through the transmitting medium in the form of waves created by alternate bands of compression (pressing together) and rarefaction (pulling apart) of the molecules of the medium (Fig. 11.1). The frequency of the sound wave can be defined the rate at which such bands of compression and rarefaction occur in the medium per second and the wavelength as the distance between two successive band of compression or rarefaction. The velocity at which the sound energy propagates through the medium depends upon the physical properties of the medium such as density, specific gravity etc. The velocity of sound is 0 in vacuum, 344 m/sec in air, 1410 m/sec in water and 1540 m/sec in muscles. The resistance offered by the medium to the passage of sound is inversely proportional to the velocity and is known as acoustic impedance. Therefore vacuum has the highest

Fig. 11.1: Wave patterns of ultrasound energy

and the muscle has the lowest acoustic impedance. • Human ear can hear sound with frequency of 20 kHz, i.e. 20000 cycles/sec, whereas dogs have hearing range of 50 kHz. • Any sound having frequency greater than 80 to 100 kHz is classified as ultrasound.

Therapeutic Ultrasound (US Therapy) 99

It has extensive uses in industrial, medical diagnostic and therapeutic purposes. DEFINITION

Ultrasound is a form of mechanical vibration. Therapeutic ultrasound can be defined as, high frequency acoustic energy, available in longitudinal waveforms in the frequency range of 0.8 to 3.5 MHz. The frequencies used in ultrasound therapy are typically between 0.75 and 3.0 MHz (1 MHz = 1 million cycles per second). Since sound waves consists of longitudinal waves consisting of areas of compression and rarefaction, molecules of any material exposed to a sound wave will oscillate about a fixed point rather than move with the wave itself. As the energy within the sound wave is passed to the material, it will cause oscillation of the molecules in that material. Clearly any increase in the molecular vibration in the tissue will result in heat generation, and ultrasound (US) can be used to produce thermal changes in the tissues, though current usage in therapy does not focus on this phenomenon. In addition to thermal changes, the vibration of the tissues appears to have effects which are generally considered to be nonthermal in nature, though, as with other modalities (e.g. pulsed short wave) there must be a thermal component however small. As the US wave passes through a material (the tissues), the energy levels within the wave will diminish as energy is transferred to the material. The energy absorption and attenuation characteristics of US waves have been documented for several types of tissue. • The ultrasound energy is non-electromagnetic in nature and it creates successive bands of compression and rarefaction in

the conducting medium, producing heat and mechanical deformation of the medium. When applied to body tissue ultrasound energy is converted to heat energy and mechanical micro-massage within tissues, to produce definite physiological reactions, with definable therapeutic benefits. Biophysics of Therapeutic Ultrasound

• Therapeutic ultrasound is produced by the high frequency cyclic deformation of a piezoelectric crystal of natural quartz or synthetic composite materials like BariumTitanate and Lead Zirconate Titanate, of specific thickness, bonded to the metal face plate of a hand held transducer (Figs 11.2 and 11.3). • High frequency electric current is applied through a co-axial cable to the piezoelectric

Fig. 11.2: Ultrasonic transducers of different types – (top) with fixed head, (bottom) with swivel head. Modern machines have transducers with contact indicator. Optimum contact with the skin is essential for adequate transfer of ultrasonic energy to the body tissue. Whenever the contact is inadequate, the contact indicator lamp glows red and the flow of ultrasonic energy stops. The treatment timer also stops automatically and is not resumed till the contact has been re-established

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• Fig. 11.3: Different sizes of ultrasonic transducer head–(top) 3 sq cm size head is used for very localized treatment area (9 sq cm), usually used with 1 MHz frequency, (bottom) 5 sq cm size head is indicated for larger areas (max 15 sq cm), commonly used with 3 MHz frequency

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• crystal to produce mechanical deformation of the crystal through reverse piezoelectric effect. The rate of deformation or resonance of the crystal depends on the frequency of the applied oscillating current. • This cyclic resonance of the piezoelectric crystal to the applied current frequency sets up a vibration in the metal face plate of the transducer, to which the crystal is bonded. • Air, with acoustic impedance of 1, reflects ultrasound waves. Hence a conducting medium like ultrasound gel, degassed water, glycerine or liquid paraffin, in the above order of preference, may be used to eliminate air-space between the metal face plate of the transducer and the body surface. These mediums are called coupling mediums, which apart from transmission of U.S., also reduces friction between the transducer head and the body surface. • These vibrations, when transmitted through a conducting medium, produce a

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beam of ultrasound waves, with little or no dispersion of energy. The ultrasound energy produces mechanical pressure waves in the tissue fluid medium through which it passes, with resultant release of heat, micromassage and acceleration of protein synthesis. The ultrasound energy has a maximum penetration of 3 to 5 cm in the living tissue; however the depth of penetration varies inversely to the frequency. Commonly used frequencies of therapeutic ultrasound are 3 MHz and 1 MHz. At 3 MHz, the depth of penetration is relatively shallow, with maximum absorption of energy and therefore greater effect, in the superficial tissues like the capsule of the ankle, knee or shoulder joint. At 1 MHz, the depth of penetration is deeper, with maximum absorption of energy and therefore greater effect, in the deep tissues like muscles of the back or gluteus region. Therapeutic ultrasound may be applied in continuous or pulsed mode. In continuous mode the thermal effect is more pronounced and in pulsed mode the non-thermal effects are more prominent. Mark-space ratio—The ratio between the flow time and off time of ultrasound energy in pulsed mode application. Commonly the “on time” is 2 msec and the “off time” varies from 2 to 8 msec.

Points to Ponder

• The beam of ultrasound energy is cylindrical in shape, at least in the near field. The diameter is nearly the same as the diameter of the transducer. • The concentration of the energy is very irregular in the near field, which becomes more uniform in the far field.


• The near zone of the ultrasound (Fresnel zone) is therapeutically relevant and it varies in direct proportion to the square of the radius of the transducer head and inversely to the wavelength. Physiological Effects of Therapeutic Ultrasound and its Applications

The Thermal Effect

Therapeutic ultrasound, when applied in continuous mode, at an intensity of 0.5-3 W/cm2, through following mechanisms, produces heat, due to: 1. Absorption of the sound energy in body tissues, resulting in increased tissue temperature. If the tissue temperature can be raised to 40-45°C for at least 5 minutes, it produces therapeutic benefits such as increased pain threshold, increased collagen extensibility, increased enzyme activity, increased tissue perfusion and decreased nerve conduction velocity. 2. The extent of energy absorption depends on the protein content, blood supply and the depth of the tissue, as well as the frequency of the ultrasound used. Tissues with high protein content like muscles, ligaments, tendons and blood, tend to absorb more energy as compared to fat. This deferential heating of tissues with highly localized effect is the unique advantage of ultrasound therapy. 3. Depth of heating or penetration, produced by ultrasound , depends on the half value distance for a given frequency. The half value distance is the depth of tissue at which the intensity of the ultrasound energy reduces by half. Ultrasound therapy given at 3 MHz has an average half value distance of 3 to 5 mm and at 1 MHz it is 11 mm.

4. The ultrasound beam refracts when travelling from one tissue to another, due to difference in acoustic impedances of tissues. 5. Reflection of a part of the ultrasound energy (30%) takes place at tissue interfaces, resulting in release of heat. Tissue interfaces are adjoining surfaces between two types of issues, e.g. the bone/peritoneum, fascia/ muscle, muscle/periosteum, bone/ligament or bone/capsule, which become the sites of heat concentration. 6. Maximum reflection of ultrasound takes place between the bone/periosteum interface, causing intense heating, which may be felt as a sudden sharp ache at the site of application. This is commonly felt over areas with minimum soft tissue cover, like the epicondyles of the elbow, joint line of the knee and ankle, acromial arch etc. This can heat the tissues to dangerous levels, particularly if the tissue has poor blood supply, e.g. tendons. The intensity of ultrasound must be reduced immediately if such pain occurs and bony prominences must be avoided all together. 7. Hot spots may also be created under the transducers, if inadequate coupling medium is used, resulting in uneven distri bution of the sound energy or if the head is kept stationary, creating standing waves. The Non-thermal Effect

Ultrasound energy can produce significant effect in the tissues, without its heat component being used, as in pulsed mode application. Such reactions are due to non-thermal effect of ultrasound, which can be described as follows: 1. Mechanical effects : The high frequency vibrations created by ultrasound energy

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produce deformation of the molecular structures of loosely-bonded substances like the soft tissues. This produces micromassage of soft tissues which has sclerolytic effect, i.e. it can break down calcification or adhesions in soft tissue, resulting in relief of muscle spasm, softening of scars tissues, release of contractures and adhesions. 2. Cavitations : Kinetic energy of the ultrasound beam is absorbed by tissue fluid, releasing gas bubbles, due to molecular agitation. These bubbles resonate with the ultrasound frequency within and outside the cell membrane, creating faster transmigration of ions at cellular level, having beneficial effects on the cell. This is known as stable cavitations. However, if the gas bubbles pick up too much energy from the ultrasound beam, they tend to expand and form unstable cavitations, accumulating a lot of heat. After limited degree of expansion, the gas bubbles may burst releasing a lot of heat deep within the tissues causing serious damage. 3. Acou st ic st re aming : Intracellular fluid moves in the direction of the ultrasound beam, like rain drops blowing in the direction of strong wind. Fluid tends to be stream towards the cell membrane, creating high-pressure areas along the cell membrane altering the permeability of the cell membrane temporarily during ultrasound exposure. Free radicals and other waste products of cell metabolism are expelled and protein synthesis and repair process of the cell is activated. 4. Formation of standing waves: A percentage of the ultrasound energy is reflected when the beam crosses from one tissue to another at the interface. The reflected energy resonates with the incedent energy

to set up a standing wave. The standing waves have points of maximum and minimum pressure, known as antinodes and nodes, at the distance of half a wavelength. The tissue exposed to the nodes are benefited by microstreaming and stable cavitations effects but those exposed to the antinodes may be seriously damaged due to excessive microstreaming and unstable cavitations. To achieve safe insonation, the therapist must avoid creating standing waves by moving the transducer continuously while giving ultrasound and use minimum intensity required. Points to Ponder

• Attenuation of ultrasound takes place due to absorption, reflection and refraction of ultrasonic energy. • Absorption depends on protein and water content of individual tissue, as well as, the wavelength and frequency of the ultrasound. • Reflection and refraction takes place at the tissue interface and depends on the relative density of the tissues forming the interface. • Continuous ultrasound produces mainly thermal effect on tissues. • Pulsed ultrasound produces non-thermal effects such as cavitations, acoustic streaming, standing waves and micro massage. Indications for Ultrasound Therapy

Ultrasound therapy may be used for following conditions: • Ac ut e sof t ti ss ue in ju ri es — I t has now become a stan dard practice in sports


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physiotherapy to use of ultrasound therapy in acute soft tissue injuries, even in the sports filed. The reasons are as follows: 1. Mechanical effect of ultrasound helps to remove post-traumatic exudates and reduce the risk of adhesion formation. 2. Mild thermal effect of ultrasound helps to induce relief of pain and allows early movement of the injured part. 3. Protein synthesis accelerated by biological effect of ultrasound helps in rapid healing of the damaged tissue. Inflammation of joint capsules, tendons, ligaments, bursa associated with acute exacerbation of chronic degenerative like osteoarthritis or inflammatory disorders like rheumatoid arthritis, gout, R.S.I. (repetitive stress injuries). Mechanical effect of ultrasound helps to remove postinflammatory exudates, thermal effect of ultrasound helps to induce relief of pain, sclerolytic action of ultrasound helps to break down unwanted calcification of soft tissue, helping to restore function. Scar tissue: Sclerolytic action of ultrasound helps to soften scar tissue, which makes the contracted scar more pliable and easy to stretch. Mechanical effect of ultrasound helps to create micro massage of adherent scar and free it from the underlying tissue. Chronic indurate oedema: Mechanical effect of ultrasound creates micro massage in tissue with chronic oedema, helping to breakdown adhesions between tissue layers and allows free circulation of blood and lymph that accelerates the drainage of chronic oedema. Wound healing: Micro-streaming effect of ultrasound promotes ionic exchange at the cellular level, creating a favourable environment for healing of injured tissues

to begin. Protein synthesis effect of ultrasound also helps in growth of granulation tissue, provided the wound is free of infection. It further promotes the plasticity of the newly formed granulation, to mould it in such a way, that the healed tissue regains near normal texture. Points to Ponder

• The main therapeutic application of ultrasound are healing of chronic ulcers, acute soft tissue lesions, pain relief and softening of scars and contracture. • Therapeutic ultrasound may be used for diagnosis of stress fractures by the sharp pain it will produce immediately from the site of the fracture. This may prove useful when radiological findings are inconclusive. Contraindications for Ultrasound Therapy

Ultrasound therapy must not be used in following conditions: • Vascular conditions (Thrombophlebitis or Phlebothrombosis): A clot may break off within the blood vessel due to the mechanical effect of ultrasound to create an embolus. • Poor blood supply : (Burger’s disease/ arteries/atherosclerosis/varicose veins): Burn injury in the deep tissue may arise due to poor dissipation of heat, generated by ultrasound energy in tissues with deficiency of blood supply. Use pulsed mode U.S. to avoid heating the tissue but still get its beneficial effect. • Infected lesion : (Carbuncles/cellulites/ abscess): Infected particles may break loose due to the mechanical effect of ultrasound and enter the blood stream to spread to other areas or create septicaemia.

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• Suspected neoplasia: (Benign/malignant): Cancerous cells may break loose and spread to other areas creating metastasis due to the mechanical effect of ultrasound. The biological effect of US therapy may initiate growth or change benign tumours to in to malignancy. • Tissues exposed to radiation: (Deep X-ray therapy/cobalt therapy) Tissues devitalised by radiation may breakdown when exposed to the combined effect of heat, mechanical and biological effect of ultrasound therapy. • Pregnant uterus: Mechanical effect of therapeutic ultrasound may damage the foetus. The ultrasound scanning utilizes different frequency, which is harmless to the foetus. • Heart diseases : Patients with demand type pacemaker should not be exposed to therapeutic ultrasound because the high frequency electrical field associated with ultrasound may interfere with the function of the pacemaker. In those cases without a pacemaker, ultrasound exposure to cervical region must not be given as it may cause stimulation of vagus nerve, leading to arrhythmia of the heart.

connected to the mains by the mains cable (Fig. 11.4). The transducer jack is fitted and secured tightly to the output socket. Keeping all the controls at zero position, the apparatus is turned on through the power switch. Timer is set for two minutes, few drops of water is placed on the transducer head holding it horizontal facing up wards and the power is gradually increased by turning the intensity knob clockwise, till ripple is observed in the water drops. This is known as the fountain test , which indicates that the machine is giving satisfactory output of ultrasound energy (Fig. 11.5, Plate 8). The intensity is then reduced to zero by turning the intensity knob in anticlockwise direction. The duration of fountain testing must be limited to few seconds only;

Points to Ponder

Ultrasound is strictly contraindicated in the presence of: • Neoplasia and malignancy • Pregnant uterus, ovary and testes • Haemorrhage or ischemia • Acute infection • The eyes, ear and exposed nerve. Technique of Application of Ultrasound Therapy

a. Setting up and testing of the ultrasound therapy equipment is the first step in application of treatment. The apparatus is

Fig. 11.4: Digital ultrasonic machine—on the extreme left is the digital treatment timer indicating treatment time in minutes. Below are the timer control switches for setting and resetting the treatment time. To its right is the selector switch for continuous and pulsed mode of ultrasonic application. Next to it is the rotary switch for intensity control. At extreme right is the digital display for intensity in W/cm2. Below it is the output socket to which the jack of a coaxial cable is connected. The other end of the coaxial cable is connected to the transducer seen on the top of the machine


otherwise the quartz crystal may be damaged due to reflection of ultrasound from air. After testing, the power may be turned off or the timer may be reset for the duration of treatment, if a patient is available and ready for treatment. b. Preparation of the patient: The patient is positioned in a comfortable position, either sitting on a wooden chair or lying down on a plinth, depending upon the part to be tr eat ed . Th e pa rt to be tr eat ed is exposed, well-supported, with the rest of the body carefully draped with a sheet for sake of modesty of the patient. While treating tightened soft tissue or shortened tendons, ligaments or muscles, the tissue must be partially-stretched when being treated. The treatment must be carried out in a screened off area with good light and no cross draught of breeze. c. Technique of application of therapeutic ultrasound varies depending on the site, depth of target tissue, underlying pathology and the desired clinical effect. The commonest method of application is with direct contact of the transducer on the skin surface over the target tissue (Fig. 11.6, Plate 8). Indirect application of ultrasound is done by the water bath and the water bag method, which are used for specifically for irregular areas with bony prominences and thin soft tissue cover. Specialized applications of ultrasound are phonophoresis and combined ultrasound and iontophoresis, which are used for administration of therapeutically useful substances transcontinuously to the target tissue. Direct Contact Method

This is the commonest method of ultrasonic application, suitable for relatively flat surfaces, free of irregularities and bony promi-

nences, with adequate soft tissue cover, like the back, chest wall, fleshy portions of the extremities and around various large and medium-sized joints (Fig. 11.7, Plate 8). • Adequate quantity of coupling medium is squeezed on to the faceplate of the transducer and on the skin surface over the target area. • The coupling medium is a fluid or gel that is used to eliminate air-space between the transducer and the skin to ensure effective transmission of ultrasound energy. Coupling mediums may be liquid paraffin, glycerine, aqua-based gel or degassed water. Different mediums have different rate of transmission of ultrasound energy. Liquid paraffin has the lowest rate of transmission at 19%, degassed water at 59%, glycerine at 67%, while the aqua based sonic gel has the highest rate of transmission at 72.6% • The transducer is then placed on the skin surface over the target site, holding the face plate parallel to the skin surface firmly. • The transducer is then moved gently over the skin to apply a thin film of coupling medium over the skin on the target area. • The timer is then set for the duration of the treatment and the intensity is gradually increased to the desired level, while moving the transducer slowly in concentric circles over the skin. • The speed of movement of the transducer should not exceed 2 to 3 cm/sec, to ensure adequate insonation of the target tissue. • Treatment intensity generally used is 0.3 to 3.0 W/cm sq depending on the treatment goal. • For acute conditions or arrears with thin soft tissue cover, like the hand or wrist, lower intensities in the range of 0.3 to 0.8

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W/cm sq is used. Alternatively pulsed dose of sound energy, which may cause mode of ultrasound may be preferred if irreversible damage to the tissues heating effect is not desired. (Figs 11.8 to 11.15). • For chronic conditions or areas with thick • Presence of DVT, acute sepsis or inflamtissue cover, like the back, higher intenmation, healing fracture or osteoporosis, sities in the range of 1 to 3 W/cm sq in metal or plastic implant in the treatment continuous mode may be used. field is strict contraindication to ultra• Duration of treatment may be set for 3 to sound therapy. 10 minutes, depending on the area being • Care should be taken against overdose covered. For effective treatment the area while treating primary repair of tendons, covered should never exceed three times ligaments and over-grafted skin. the surface area of the transducer head, i.e. 5 sq cm × 3 = 15 sq cm, for every five Water Bag Method minutes of application. Large areas may This is the method of choice for indirect be divided in to grids of 15 sq cm each with application of ultrasound over irregular bony a marker pen and then treated. area like the dorsum of the hands, feet, ankle • Specific indications for this method of joint, epicondyles and olecranon of the elbow. application are bursitis, tendonitis, liga- It is also an alternative method of indirect ment strain or sprain, musculofascial application to proximal portions of the body trigger point (fibromyositis nodules), scars which cannot be treated by full immersion in and keloids, neuromas at the end of stump a water bath, e.g. the temporomandibular of amputed limb and margin of open wounds. Precautions to be Observed in Direct Contact Method

The patient must be instructed carefully about the sensation being felt during ultrasonic therapy. • With continuous mode of ultrasonic energy, the patient should feel mild warmth, whereas with pulsed ultrasound there should never be any feeling of warmth. • If the transducer is kept stationary momentarily, particularly over a bony prominences, the patient may feel intense heat sensation at a point. This is due to periosteal pain caused by concentration of ultrasound energy reflected by the bone in the periosteum. The therapist must be alerted immediately if any such feeling occurs, as this indicates dangerous over-

Fig. 11.8: Application of ultrasonic therapy over the medial epicondyle of the elbow for the treatment of medial epicondylitis (golfers elbow). Ultrasonic therapy is the modality of choice for golfers elbow. Since the area is bony the ultrasonic should be in pulsed mode. Care should be taken not to keep the transducer stationary, because that may create standing waves, which may produce periosteal irritation and pain. For best results, ultrasonic application must be followed up with deep friction massage and stretching of the common attachment of the flexor tendons


Fig. 11.9: Application of ultrasound to the palmar fascia for treatment of Dupuytren’s contracture. Ultrasonic therapy in pulsed or continuous mode may be opted for depending up on whether the condition is acute or chronic respectively. For best results, ultrasonic application must be followed up with deep friction massage and stretching of the soft tissue contracture

Fig. 11.10: Application of ultrasound to the supraspinatus tendon and subacromial bursa for treatment of rotator cuff impingement syndrome. Ultrasonic therapy in pulsed or continuous mode may be opted for depending up on whether the condition is acute or chronic respectively. For best results, ultrasonic application must be followed up with deep friction massage and stretching of the contracted soft tissue

Fig. 11.11: Application of ultrasound to the temporomandibular joint. Since the area is bony the ultrasonic therapy should be in pulsed mode. Care should be taken not to keep the transducer stationary, because that may create standing waves, which may produce periosteal irritation and pain

Fig. 11.12: Application of ultrasound to the sternocostal joint for the treatment of costochondritis. Since the area is bony the ultrasonic therapy should be in pulsed mode. Care should be taken not to keep the transducer stationary, because that may create standing waves, which may produce periosteal irritation and pain. For best results, ultrasonic application must be followed up with deep friction massage and stretching of the contracted pectoral aponeurosis

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Fig. 11.13: Application of ultrasonic therapy over the lateral epicondyle of the elbow for the treatment of lateral epicondylitis (Tennis elbow). Ultrasonic therapy is the modality of choice for tennis elbow. Since the area is bony the ultrasonic therapy should be in pulsed mode. Care should be taken not to keep the transducer stationary, because that may create standing waves, which may produce periosteal irritation and pain. For best results, ultrasonic application must be followed up with deep friction massage and stretching of the common attachment of extensor tendons

Fig. 11.15: Application of ultrasonic therapy over the carpal tunnel on the ventral aspect of the wrist for the treatment of carpal tunnel syndrome. Ultrasonic therapy is the modality of choice for carpal tunnel syndrome. Since the area is bony the ultrasonic therapy should be in pulsed mode. Care should be taken not to keep the transducer stationary, because that may create standing waves, which may produce periosteal irritation and pain

Fig. 11.14: Application of ultrasonic therapy over the tendon of abductor policis longus, extensor policis brevis and extensor policis longus on the lateral aspect of the wrist for the treatment of tenosynovitis (de Quervain’s disease). Ultrasonic therapy is the modality of choice for de Quervain’s disease. Since the area is bony the ultrasonic therapy should be in pulsed mode. Care should be taken not to keep the transducer stationary, because that may create standing waves, which may produce periosteal irritation and pain

joint, acromioclavicular arch, sternocostal junctions, etc. • A latex rubber surgical glove is filled with degassed water. • Water is degassed by boiling it for few minutes which removes all the dissolved gas bubbles, which otherwise may reflect ultrasound energy during treatment. • The opening of the gloves closed with a rubber band. • A thin film of coupling gel is applied over the part to be treated, as well as, on either surfaces of the palm portion of the gloves filled with degassed water. The film of coupling medium eliminates air-space between the transducer head and the surfaces through which the ultrasound has to pass to reach the body tissue. • The bag is then placed over the target area and may be fixed in place on the skin with


sticky paper tape at its edges. The water bag evens out the bony irregularities, thus avoiding concentration of ultrasound energy over bony prominences. • Ultrasound is applied by directly on the outer surface of the water bag. The ultrasound energy passes through two layers of latex and the degassed water to reach the target tissue. • Since a significant amount of energy is absorbed by the layers of latex and water the intensity of ultrasound used as well as the duration of the treatment must be 30 to 50 percent more than that used in case of direct contact method over similar areas. Precautions to be Observed in Water Bag Method

• Position of the bag must be accurate in relation to the target tissue and the ultrasound head keeping the head as perpendicular to the skin surface as possible. • Ultrasound beam refracts while travelling from one medium to the next. In water bag method the ultrasound beam has to travel through first layer of latex, then the layer of degassed water and then the second layer of latex before it reaches the skin. So many layers in the path of the ultrasound beam cause significant divergence. Allowance should be made for this divergence of the ultrasound beam by selecting a target area not larger than the size of the transducer, i.e. 5 cm sq and the bag has a tendency to slip over the skin making it difficult to focus the beam perpendicular to the skin. Hence the bag must be held in position with sticky tape.

Water Bath Method

This method is most suitable for indirect application of ultrasound over bony areas with irregular surface or with sensitive or delicate skin, e.g. skin grafts or newly-healed wound, where direct contact or water bag method may be unsuitable due to the friction involved. • A plastic wash tub is filled with degassed water. Plastic is used because it reflects minimum amount of ultrasound energy. • The part to be treated is immersed completely in the degassed water. • The transducer head is placed under the water and held 1 mm away from and parallel to the skin surface. • As the intensity is increased the head is moved in small concentric circles at a speed of 3 cm/sec, covering the entire surface of the target area as the intensity is increased to the desired level. • Periodically air bubbles must be wiped off the body part and the transducer. Precautions to be Observed in Water Bath Method

It will be wise to remember that in this method a high frequency electrical device is being used in an environment full of water. Hence to avoid the electric shock to the patient and the therapist following points must be checked. • The power supply must have proper earth connection and the equipment must not have any leakage of current to the body of the machine. The fuses must be properly calibrated and installed. The transducer should be completely waterproof. The floor of the treatment area should have a rubber or coir floor mat to stand or rest the feet.

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• Prolonged soaking in water can devitalise and damage delicate or grafted skin. This point must be kept in mind while using the water bath method. Hence the duration of the immersion of the part should be limited to only for the period of the treatment. After the treatment a thin layer of petroleum jelly or lanolin based skin cream may be applied on the part. Phonophoresis

It is the use of ultrasound energy to introduce molecules of medication through the skin into the subcutaneous capillary network, from where these molecules can be carried by the blood stream to deeper tissues. The molecules thus introduced dissociate into elements and radicals within the tissue, which then combine with the free-radicals existing in the blood stream, to produce the desired clinical effect. The available clinical evidence suggests that the depth of penetration of such molecules is in the range of 1 to 2 mm.

Fig. 11.16: Application of ultrasound to the clavicular fossa for treatment of brachial neuralgia. Ultrasonic therapy in pulsed or continuous mode may be opted for depending upon whether the condition is acute or chronic respectively. For best results, ultrasonic application must be followed up with adverse neural tension stretching of the brachial roots

Technique of Application

• A small quantity of the medication in gel or cream or ointment form is rubbed in to the skin over the target area. Gel form responds well to the passage of ultrasound, whereas cream and ointment may inhibit the process of insonation. It is therefore important to use gel form wherever possible. Wherever cream or ointment-based medications are the only option, be sure to massage the medication thoroughly into the skin before applying ultrasound (Fig. 11.16). • Same gel or ointment mixed with standard ultrasound gel is placed over the transducer head as coupling medium. • Ultrasound is then applied to the target area by the direct contact method (Fig. 11.17).

Fig. 11.17: Application of ultrasonic therapy over the medial collateral ligament of the knee for the treatment of strain, sprain or osteoarthritis of the knee. Ultrasonic therapy is the modality of choice for medial joint-line tenderness of the knee. Since the area is bony the ultrasonic therapy should be in pulsed mode. Care should be taken not to keep the transducer stationary, because that may create standing waves, which may produce periosteal irritation and pain. For best results, ultrasonic application must be followed up with deep friction massage over the ligament


• Standard treatment intensity used for phonophoresis may be 1 to 2 w/cm sq. • Standard treatment duration may be 5 to 10 min. • Treatment done with low intensities over long periods is more effective in introducing the medication through the skin (Fig. 11.18). • Selection of the medication depends on the pathophysiology of the disorder being treated and the desired effect. Phonophoretic Agents: Indications, Possible Adverse Reactions and Contraindications

• Hydrocortisone gel or ointment 1-10%— It may be used for strong anti-inflammatory action in acute inflammation of soft tissue. In rare cases skin rashes may be seen which is best treated by antihistaminic (cetrizine) drugss (Figs 11.19 and 11.20). • Lidocaine 4-5% gel (xylocaine) —It is very effective for analgesia and relief of acute pain with no adverse reactions (Fig. 11.21). • Methyl salicylate 4.8% ointment (Iodex) or salicylate 10% ointment (Myoflex) —As a basic anti-inflammatory agent salicylate may be considered for chronic painful disorders of the musculoskeletal system. Patients sensitive to aspirin should not be treated with salicylate (Fig. 11.22). • Iodine 4.7% ointment (Iodex)—It is useful as a vasodilating, anti-inflammatory and sclrolytic agent in softening of scar tissue, soft tissue adhesions, calcification of ligaments and tendons and adhesive capsulitis of joints. Patients that are allergic to sea food should not be treated with iodine. In case of skin irritation and itching give antihistaminic drugs (Fig. 11.23). • Zinc oxide creams 20% (Siloderm)—Zinc is a healing agent and can be useful in treatment of open wounds. It can be used

Fig. 11.18: Application of ultrasonic therapy over the lateral collateral ligament of the ankle for the treatment of strain or sprain. Ultrasonic therapy is the modality of choice for ligament strains of the ankle. Since the area is bony the ultrasonic therapy should be in pulsed mode. Care should be taken not to keep the transducer stationary, because that may create standing waves, which may produce periosteal irritation and pain. For best results, ultrasonic application must be followed up with deep friction massage over the ligament

Fig. 11.19: Application of ultrasound to fibromyositic nodule in rhomboids muscle. Since the area is fleshy, continuous mode of ultrasonic therapy may be used. For best results, Ultrasonic application must be followed up with deep friction massage

as a medium for phonophoresis to the edges of the indolent wounds to promote healing. Patients who cannot wear metal wrist watch bands or jewellery due to

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Fig. 11.20: Application of hydrocortisone phonophoresis therapy over the retro-calcaneal bursa of the ankle for the treatment of bursitis with effusion and acute pain. For best results, ultrasonic application must be followed up with ice massage over the bursa

Fig. 11.21: Application of Lidocaine phonophoresis therapy over the lumbo-sacral junction for the treatment of acute low back pain. For best results, Ultrasonic application must be preceded by infrared radiation to the painful spot for 10-15 min

Fig. 11.22: Application of Iodex phonophoresis therapy over the popliteal bursa of the ankle for the treatment of chronic bursitis with indurate effusion and dull pain. For best results, Ultrasonic application must be preceded with deep heat like SWD over the bursa

Fig. 11.23: Application of ultrasound to the calcaneal spur. Since the area is fleshy, continuous mode of ultrasonic therapy may be used. For best results, Ultrasonic application must be followed up with deep friction massage

allergic skin reaction are sensitive to metals and they should not be treated with zinc. Consult a skin specialist if adverse reaction does take place. The agents of phonophoresis discussed above are the fruit of the cumulative know-

ledge gained by many practioners in their clinical practice and should act as a guide to the future generations of physiotherapists. Pharmaceutical companies almost on daily ba sis ar e ma kin g ne w dr ugs , in ge l or ointment form, available. It is recommended


that the therapists should experiment with the application of theses drugs through phonophoresis in suitable disease conditions and contributes to the data-base of clinical knowledge. Combination Therapy Using Ultrasound and Electrical Stimulation

In general terms, combination therapy involves the simultaneous treatment with ultrasound and electrical stimulation. In Europe, the trend is towards using diadynamic currents with ultrasound, but in the UK, it is most often combined with two-pole medium frequency current. Important Considerations

• There is a significant lack of published material in this area. And much of the information herein is anecdotal or based on the experience of those who use the modality frequently. • Broadly, the effects of the combined treatment are those of the individual modalities. There is no evidence at present for any additional effects, which can only be achieved when the modalities are used in this particular way. • By combining US with MF 2 pole current, the effects of each treatment modality can be realised, but lower intensities of both are used to achieve this effect. • The accommodation effects on sensory nerves that accompany MF treatment are reduced (or even eliminated) The therapeutic advantages of combination therapy are said to be in localising lesions (especially chronic) i.e. for diagnostic purpose. Ensuring accurate localisation of the lesion for application of ultrasound therapy provides

increased accuracy and effectiveness in treating deeper lesions, especially while treating trigger points. Biophysics of Combination Therapy

Ultrasound exposure to a peripheral nerve reduces its resting membrane potential by increasing its permeability to various ions, especially sodium (Na +) and calcium (Ca++). Due to this altered permeability, the nerve membrane is taken closer to its response threshold, though it does not usually make the nerve fire. The simultaneous application of MF2 pole current through the nerve induces the depolarisation, with a much less current intensity than usual, due to the sensitization created by ultrasound exposure. This can easily be demonstrated. If both the US and MF are being applied and during the treatment if the intensity of the US is turned down to zero, the sensation produced by the MF will diminish even though the MF intensity has not been changed. The intensity of sensation produced by the MF intensify as the intensity of the US is turned up (Fig. 11.24).

Fig. 11.24: Biophysics of combination therapy

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In summary, it would appear that by combining the two treatment modalities, none of the individual effects of the treatments are lost, but the benefit is that lower treatment intensities can be used to achieve the same results, and there are additional benefits in terms of diagnosis and treatment times. Technique of Application of Combination Therapy

Combination therapy is a relatively new form of treatment. The guidelines for application, as presented below, are derived from experiences and findings of different workers in the field. Lot of work is still in progress for fine-tuning the procedure and the parameters given here are by no means absolute. • It is suggested that a continuous US output of 0.5W/cm 2 should be used for this procedure. • A frequency of 1MHz is preferable if available as it gives more effective penetration into the tissues. • The MF output is most commonly set to 100 Hz using a bipolar output. a. As a diagnostic tool • Place one of the MF pad electrodes in a position on the body surface so that the current can pass through the tissue in question. As the passive electrode it can be placed on the same aspect of the limb for superficial lesions or on the opposite side of the limb for deeper lesions. • The other terminal of the MF is connected any metal part of the ultrasound transducer with the help of an alligator clip, turning the transducer into an active electrode. May modern units offer special sockets built into the ultrasound machine to connect one output terminal of the MF two pole current for combined therapy.

• The ultrasound is turned on, the duration is set and the treatment head placed along with a liberal coat of conducting coupling media on the skin. Intensity is then increased to the desired level. • The MF is then turned on and the intensity increased to minimum perceptible level. • Starting with ultrasound the head distant from the lesion, gradually increase the MF output intensity until the patient encounters the ‘normal’ tingling. • Move the ultrasound transducer towards the site of the lesion, noting any areas of increased sensitivity, local or referred pain. • The point of maximal sensitivity to MF stimulation is assumed to be the focal point of the lesion, though it will not provide information as to the precise tissue in question, nor to depth (Fig. 11.25) • This test provides only a ‘geographical’ location of the trigger point. This posi-

Fig. 11.25: Localisation of trigger point using combination therapy


tion is usually consistent and reproducible. • Once the focal point of a lesion has been detected further treatment may be done with only ultrasound therapy or combined therapy. b. As a treatment protocol : • Diagnostic and therapeutic uses of Combination Therapy need not be used together. • As a treatment, combination therapy is appropriate when the therapeutic effects of US and those of MF current are both justified. • The individual doses for the US and IF should be those which are appropriate for the lesion and the therapeutic effects desired. There is no evidence that ‘special’ treatment doses are required. However, the intensity of the MF current required to produce desired effect is likely to be lower than usual. • Manufacturers claim that it is not necessary to incorporate a sweep frequency in the MF current as the effect of accommodation is minimised. However appropriate MF frequency sweep can be used if it is appropriate to the produce the desired effect in the target tissues. • If the treatment times are dissimilar, there is a potential problem in that the US component will usually finish first, leaving the IF element to continue in isolation. The therapist should therefore try to match the treatment time for both modalities by selecting an optimum duration of treatment wherever possible. • If treatment times are similar, the combination of the modalities can save time and effort (even without addi-

tional effect). When they are dissimilar, it may be more effective to apply as two separate treatments. • It is important to observe the usual precautions applicable for both modalities during combination therapy, i.e. always using a moving treatment head, maintain effective contact, the perpendicular relationship between the treatment head and the patient’s skin whenever possible. c. Clinical example : • For a patient with an acute lesion of the lateral ligament of the ankle joint, pulsed ultrasound is justified because it will promote the repair process and interferential may be used for its effect in reducing acute pain. • Recommended US dose (based on normal dose calculations) should be 3 MHz, 0.2 W/cm 2 , Pulse 1:4, 10 minutes. • Recommended interferential dose (for acute pain) should be 90 to 130Hz, bipolar, 10 minutes. • Interferential pad as the passive electrode should be placed on the medial aspect of the ankle joint. • US treatment head should be applied over the injured component(s) of the lateral ligament. • The effect of such combined treatment could be more effective, than either one modality in isolation, though there is no evidence to prove that by using them simultaneously, there is any advantage over using them sequentially one after the other. d. Contraindications for combination therapy : There do not appear to be any specific contraindications for combination therapy other than those for the individual modalities.

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DOSIMETRY OF ULTRASOUND THERAPY

Appropriate dosage in ultrasonic therapy has been a subject of controversy ever since the inception of this modality in therapeutic practice. Theories abound regarding the propriety of space-averaged or time-averaged intensities, the effectiveness of pulsed or continuous mode of application and the halfvalue distances. For the want of concrete scientific evidence, the dosing parameters have for long been based on the clinical experience of individual therapists. Majority of established authors have documented only the general principles and guidelines for dose calculation in ultrasound therapy, leaving the actual dosing to the imagination and experience of the individual practioner. In this section I have made a humble attempt to simplify this ambiguous picture for the beginner.

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Points to Ponder

• The space-averaged intensity of ultrasound is the net output of ultrasound energy per square centimetre area of the transducer, expressed as Watts/cm sq. This is the most commonly used dosing format of ultrasound therapy, displayed on the analogue or digital metre available on the ultrasound therapy equipment. • The time-averaged intensity of ultrasound is the total output of ultrasound energy over a specific period of exposure. This is calculated by multiplying the spaceaveraged intensity with the total surface area of the transducer and the duration of exposure in seconds. • The intensity of the ultrasound beam is reduced by half at a certain depth below

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the body surface, known as the half-value distance. This attenuation takes place due to reflection, absorption and refraction of the ultrasound energy, as it travels from the transducer, through different mediums, to the target tissue. To calculate the appropriate dosage the first thing that must be taken into consideration is the location or depth of the target tissue, i.e. the number of tissue layers or interfaces the beam of ultrasound must cross before it can reach the target. Thick tissue cover will mean more attenuation of the ultrasound energy and vice versa. Hence, for superficial targets lower intensity and for deeper targets higher intensities of ultrasound will be needed. The intensity of the ultrasound can be further modulated to suit the clinical condition being treated by using continuous or pulsed beam of ultrasound energy. For acute conditions the mechanical and the biological effects are preferred, hence pulsed mode of ultrasound given for shorter periods will be most suitable. For chronic disorders the heating effect is desirable, hence continuous mode of ultrasound applied over longer durations will be appropriate. Dosage of ultrasound depends on: 1. Mode—Pulsed mode delivers less energy than continuous. 2. Frequency—Lower frequency has greater penetration than higher. 3. Intensity—Usually used space-averaged intensity measured in Watts/sq cm.


4. Duration—Duration of treatment is calculated in minutes and varies in direct proportion to the size of the area bein g tr ea te d. Al wa ys re st ri ct th e maximum area covered to three times the surface area of the transducer head, i.e. if the transducer head is 5 sq cm. in area then maximum area covered for adequate insonation in one sitting should not exceed 15 sq cm. Larger areas may be divided into grids; each of 15 sq cm and then treated one after the other. 5. Treatment should be repeated once or twice daily for acute lesions and less frequently for chronic lesions.

Dosage for Ultrasound Therapy

For the young practitioner Table 11.1 may act as a guideline, till such time he/she can build up his/her own clinical repertoire. Points to Ponder

• Therapeutic ultrasound is commonly applied through direct contact method using a coupling medium to eliminate air space between the treatment head and the skin surface. • In direct contact method, as far as possible, the patient should be positioned in such a way that the transducer head is applied vertically downwards on the body surface

Table 11.1: Dosage for ultrasound therapy

Condition

Dosage in Watts/cm sq

Mode

Duration in minutes

Abscess of soft tissue Bursitis Cellulitis Myalgia Neuralgia Periarthritis of shoulder Radiculitis (root pain) Intermittent claudication Lumbago Lymph-oedema Muscular rheumatism Sciatica Stump neuroma Ulcer Coxydanea Myositis ossificance Polyarthritis Sudecks osteodystrophy Tenosynovitis

0.5–2 0.6–1.5 1–2 2–3 1–3 0.5–3 1–2 1–3 1–3 0.5–2 0.8–3 1–2 2–3 1–3 1–3 1–2 1–2 1–3 1–2

Pulsed Continuous Continuous Continuous Continuous Pulsed/Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous

8–10 8–10 10–15 10–15 10–15 10–15 10–15 5–20 10–15 10–15 10–15 10–15 10–15 10–15 10–15 10–15 5–15 10–15 10–15

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being treated. The weight of the treatment head will contribute to the pressure applied by the therapist, holding the treatment head firmly against the body surface. This position will also make sure that the coupling medium does not trickle down the surface of the skin.

• Other infrequently used methods of applications are water bag and water bath methods. • New methods of application of ultrasonic therapy, such as phonophoresis and combination therapy is gaining acceptance.

Therapeutic Cold 119

12 Therapeutic Cold DEFINITION

BIOPHYSICS

Localised cooling of the body surface to extract body heat from the underlying tissues, by evaporation or conduction, in order to lower local tissue temperature and thereby provoke therapeutically useful physiologic thermoregulatory reaction is known as cold therapy or cryotherapy. 1

• Therapeutic cold can be applied to the skin through evaporating or conducting modalities • Volatile liquids, when brought in contact with warm objects, extract heat of vaporisation from the underlying tissue. Most common evaporative cold modality used in the sports field is Furio-Methane sprays • Cold substances, when brought in physical contact with warm body tissues, extract heat through direct molecular energy transfer or conduction. Ice is the conductive cold modality most commonly used for therapeutic purpose. Ice can be applied to the body in the form of crushed ice packs, cold water bath or ice massage. Commercially available reusable cold packs can also be used, after cooling it to the appropriate degree in a freezer • On application of such cold source, heat is drawn @ 333 joules/gram of ice, by conduction from the subcutaneous tissues through the skin, to convert the ice to water. This causes drastic drop in the tissue temperature • The drop in tissue temperature, i.e. the degree of cooling achieved in the tissues

DISCUSSION

Generalised cooling of the body , commonly known as hypothermia , is used to lower the temperature of the whole body. As a result of hypothermia the basic metabolic rate, pulse rate, respiratory rate, venous blood pressure and therefore the oxygen demand in the tissues fall to a minimum. There is a rise in blood flow to internal organs, cardiac output, stroke volume and arterial blood pressure. Hypothermia is used during major surgical interventions to lower the oxygen demand in tissues and give more operating time to the surgeons during open-heart surgeries. Localised cooling of tissues , commonly known as cryotherapy is used in physiotherapy as an anti-inflammatory and analgesic agent, effective in musculo-skeletal disorders.

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depends on the rate and duration of energy extraction, which in turn depends on the following factors. 1. The difference in temperature between the coolant and the tissue. Greater the temperature gradient, faster the cooling. 2. The heat conduction property of individual tissues. Cooling is greater in tissues with large water content, i.e. muscles or blood and relatively less in tissues like skin or subcutaneous fat which act as insulators. 3. Temperature of tissue subjected to localised cooling will continue to drop till the heat generated in the tissue equals the heat extracted from. 4. The total surface area of the body subjected to cooling is directly proportional to the extent of heat loss. 5. The skin temperature can be lowered significantly with short period of cooling, though it takes much longer to lower the temperature of the deeper tissues like muscles or joints. 2 Physiological Effects of Localised Cooling

The therapeutic benefits of cold post-acute injury, postoperatively, and during rehabilitation are well documented. The physiological effects of cold include a decrease in tissue temperature and metabolism. Circulation is also decreased as a result of vasoconstriction and increased blood viscosity. Increased tissue and synovial fluid viscosity will create muscle stiffness and slightly impair muscular efficiency. Pain and muscle spasms are reduced as a result of cryotherapy’s effect on the nervous system. Cold reduces the rate of firing in nerves to the point that sensory nerve conduction is blocked and thermal anaesthe-

sia or numbness is experienced. In addition to decreasing sensory and motor nerve conduction velocity, cryotherapy decreases pain through the stimulation of endorphin release, reduction in metabolism, and counter irritation. Furthermore, the decrease in sensory input inhibits the stretch reflex and aids in reducing muscle spasms. Reduction in metabolism to healthy tissues surrounding the injured area is beneficial in order to prevent secondary hypoxia. 1 Following acute injury, the build-up of fluid and proteins and increased interstitial pressure create oedema, which compromises circulatory integrity, placing the surrounding tissues at risk for hypoxia. Slowing tissue metabolism reduces energy and, therefore, oxygen requirements of the surrounding tissues, enabling them to survive without hypoxic damage. In terms of motor performance, sensory changes will result in a decrement in manual dexterity and fine motor activity. However, most skilled or gross motor tasks performed immediately following cold application will not be impaired. • Different body tissues respond differently to localised application of cold • Skin cools the fastest with maximum drop in temperature • Subcutaneous tissue cools more slowly than the skin and shows moderate drop in temperature • Muscles and bones show minimal changes in temperature, even on prolonged exposure to cold • Dramatic vasoconstriction of skin capillaries creates blanching (white colour) of the skin at the point of contact with the cold source. The skin over the surrounding area turns red (hyperaemic) due to histamine mediated rebound vasodilatation


• If the exposure to cold is prolonged, Lewis hunting reaction sets in. Lewis hunting reaction is alternate cyclic vasodilatation and vasoconstriction, while the body searches for the mean volume of blood flow to the cold area to maintain minimum sustainable circulation to meet the meta bolic demand of the tissues • Application of local cooling of the body tissues trigger following set of negative physiological responses . 1. Reduced blood flow —Due to vasoconstriction of arteries, arterioles and venules resulting from sympathetic adrenergic activity. 2. Reduced capillary permeability —Due to less fluid in the interstitial tissue. 3. Reduced elasticity of non-elastic soft tissue—Due to decreased elasticity of collagen. 4. Reduced metabolic rate —Due to inhi bition of cellular oxidation. 5. Reduced muscle spasm—Due to inhi bition of tonic extrafusal activity. 6. Reduced strength of muscle contraction— due to inhibition of blood flow to the muscle and increased muscle protein viscosity, on application time > 5 to 10 min 7. Reduced spasticity —Due to reduce muscle spindle and gamma motor activity • Application of local cooling of the body tissues trigger following set of positive physiological responses 1. Increased joint stiffness—Due to decreased extensibility of collagen. 2. Increased pain threshold—Due to inhi bition of A-delta and C fibres (spinal gate control mechanism). Breaks the pain spasm vicious cycle through

inhibition of sympathetic, sensory and motor conduction. 3. Increased blood viscosity—Due to increased adherence of RBC to each other and walls of blood vessels. 4. Increased strength of muscle contraction— Due to facilitation of alpha neuron activity, application time < 1-5 min. Adverse Physiological Effects of Localised Therapeutic Cooling

• Hypersensitivity to cold is mostly related to release of histamine leading to 1. Cold Urticaria- red wheals on the skin associated with sever itching. 2. Flushed face. 3. Puffy eyelids. 4. Respiratory distress. 5. Anaphylactic shock and syncope. TECHNIQUES OF THERAPEUTIC COOLING

There are many cryo-therapy modalities available. These include the ice pack, cold pack, ice massage, cold whirlpool, cryo-cuff, cold spray, cryo-stretch, and cryo-kinetics Different Methods of Therapeutic Cooling

Ice Packs

• It is the most cost effective method of therapeutic cooling for joints and smaller body segments like the hands, feet, knee, elbow, shoulder etc. • This method of cooling can be practiced at the clinic or at home, with minimum inputs in terms of infrastructure, equipment and recurrent expenditure. • A standard refrigerator, ice tray, polythene bags, hand towel and water are all that is needed to give effective ice packs.

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Ice cubes are placed in the clear polythene bag, wrapped in moist towel to form a pack. The pack should be large enough to cover the target area. The pack is applied to the body and then covered with a dry towel to prevent rapid melting of ice. Heat transfer takes place by conduction of heat from the body tissue to the ice packs to supply the latent heat of melting to the ice. The part to be treated is exposed and checked for any cuts, bruises, discoloration, loss of sensation and skin diseases. Average treatment time with ice packs is 10 to 20 minutes. The melted ice is retained by the sealed polythene bag and does not cause a mess.

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Ice Towels

• This is the method of choice for cooling of large, flat, predominantly muscular areas like the back, thigh and calf. • In this method the equipments needed are the same as in case of ice packs. Water is added to crushed ice in a tub to form slush. • Two towels, large enough to cover the target segment are soaked in this slush. One towel is wrung out and placed in two folds on the part to be treated. • The towels should be exchanged after every 1 to 2 minute, till 15 to 20 minutes. • The part to be treated is exposed and the skin should be checked for any cuts, bruises, discoloration, and loss of sensation and skin diseases. Ice Massage

• This is the method of choice for cooling much-localised spots like a trigger point. • A cone of ice is frozen keeping water in a paper cup in the freezer. An ice cream stick

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or wooden spatula is placed in the cup of water prior to freezing to provide a convenient handle for the ice cone. The ice cone is applied directly to the skin over the trigger point and massaged with firm pressure, in a concentric circle just like an ultrasound transducer. The maximum area suitable for ice massage in one sitting should not exceed 4” × 6”. The rate of movement of the ice cone over the skin should not exceed 2”/second. The part to be treated is exposed and the skin should be checked for any cuts, bruises, discoloration, and loss of sensation and skin diseases. During the application of ice massage the patient will initially feel cold sensation followed by burning, aching and finally numbness of the part being treated. Treatment should be continued till the part becomes numb. The duration of treatment is 5 to 10 minutes. Massaging ice over superficial nerves like the ulnar nerve at the medial epicondyle of elbow or common peronial nerve at the neck of the fibula is contraindicated as it may interfere with the nerve function.

Commercial Cold Packs

• This is the most hassle free form of cold therapy, since there is no need to make ice packs, slush or cones, as well as, no mess created by melting ice. • Commercial cold packs are made of vinyl casing filled with silica gel, available in different sizes ranging from 6” × 8” to 10”× 14” and are quite expensive as compared to ice packs described above and therefore are suitable for hospital settings only.


• Before application, the packs are cooled to freezing point or below in a deep freezer. • The part to be treated is exposed and the skin should be checked for any cuts, bruises, discoloration, loss of sensation, etc. and for skin diseases. • One towel, folded width wise, is soaked in warm water and then wrung out to remove excess water. The moist towel is then placed over the part to be treated and the pack is placed on the moist towel. A dry towel folded width wise is placed on top of the pack to slow down warming and the whole thing secured with a Velcro strap. • The treatment time is 10 to 20 minutes. Coolant Spray

• It is the cooling modality of choice for use in the sporting arena, where rapid cooling is needed in a very short time to provide temporary relief of pain and spasm, to allow the athlete to continue to perform. • A non-toxic, non-inflammable, volatile liquid in form of aerosol spray is used for this purpose. • The coolant is sprayed on the skin to reduce muscle spasm and for desensitisation of injured soft tissues or trigger points. • Heat is extracted from the body tissue for the evaporation of the volatile liquid. • To apply the coolant, the spray can is first shaken hard and then inverted, holding the nozzle 18” away from the skin. • A thin layer of coolant is sprayed at an angle of 20 to 30° in sweeping strokes to cover the skin over the affected area. • The speed of the strokes should be 3-4”/ second. The liquid should be allowed to dry completely before applying any subsequent strokes.

• Number of strokes should not exceed 3-5 only, to avoid cold injury to the skin. • In case of muscle spasm, the target muscle should be stretched to the limit of pain free range, during and in between each application of spray. The patient must be encouraged to perform active exercises of the affected muscle immediately after the coolant spray. • When a crucial soft tissue like the ligament or tendon has been injured, the painful site should be sprayed 2 to 3 times and the stabilised with elastic tape/bandage/strap to prevent aggravation of the trauma during further activity. • It must be realised that coolant spray is only a temporary pain relieving measure that allows the athlete to complete the sporting event. It is essential for the therapist to examine the injured part thoroughly after the event to identify any serious and lasting damage to the involved tissues and take appropriate remedial measures. Contrast Bath

Definition: It is alternating immersion of body segments, like hands and feet, in warm and cold water, to produce alternating vasodilatation and vasoconstriction in the peripheral blood vessels to provide vascular exercise to the part. For the patient exhibiting psychological intolerance to cryo- kinetics, contrast baths combined with active exercise may be a treatment alternative. Traditionally, contrast baths consists of alternating immersion of the injured body part in hot (106°F) and cold (50°F) water over a period of 20 to 30 minutes. Immersion time is typically 4 minutes of hot followed by 1 minute of cold. The comforting sensation of

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the warm water, combined with the limited exposure to the cold water, may enable coldintolerant patients to initiate active exercises earlier in their rehabilitation program. Active movement can be incorporated into contrast baths by adding active exercises as a third step, immediately after the 1-minute cold immersion, just before re-immersing the part into the hot water. This three-step cycle would then be repeated over a series of four to five times, ending the treatment with cold water immersion. Controversy does exist, however, regarding the universally accepted, but never demonstrated theory, that oedema reduction during contrast baths occurs as a result of the “pumping mechanism” induced from the alternation of vasodilatation and vasoconstriction. The contrast bath serves as an appropriate treatment alternative, more in the sub-acute, rather than acute, phase of soft tissue inflammation. Two-way heat transfer takes place in this method, i.e. by conduction of heat from the body tissue to the cold water and from the hot water to the body tissue. • Two plastic containers or washtubs, large enough to hold the body part, are filled with warm and cold water. • The temperature of the hot water should be 40 to 45°C and cold water around 5 to 10°C. While instructing the patient for home programme, explain for the ease of understanding that the hot water should be as ho t as ca n be to le ra te d on th e immersed part and the cold water should feel ice cold to the skin, without any discomfort on prolonged immersion.

• The treatment commences with hot water. The part to be treated is first immersed in hot water for 6 to 10 minutes at a stretch. If the water feels too hot, some tap water may be added to the hot tub or if it is not warm enough, some more hot water may be added to the tub. • After soaking in warm water the part is transferred to the cold tub and allowed to soak for 1 minute. If the water does not feel cold enough, some more ice cubes may be added to the tub. • The part is then transferred to warm water and allowed to soak for 4 minutes. • The cyclic immersion in hot and cold water in the ratio of 4:1 is continued for 30 minutes. • The treatment cycle ratio of 4:1 is variable, depending upon the underlying disorder. In acute conditions, the ratio may be changed to 2: 1. • In chronic conditions with indurate oedema, the contrast bath treatment should commence and end with hot-water soak. In acute conditions with significant effusion, treatment should be terminated with cold-water soak. • Contrast bath is indicated for any condition that needs stimulation of peripheral circulation. It is a modality of choice for acute and chronic musculo-skeletal injuries, like sprain, strain, post fracture stiffness and in peripheral vascular disorders like lymph-oedema, vasculitis, varicose veins and Burger’s disease. • Losses of thermal sensation and arteriosclerosis in advanced stage with chronic insufficiency of blood supply are strict contraindication to contrast bath.


APPLIED COLD THERAPY: CRYO-KINETICS

The combination of therapeutic cold and exercises, to restore pain-free function, is known as cryo-kinetics.3 Indications and Advantages of Cryo-kinetics

the application of therapeutic heat. Furthermore, tissue gliding during early mobilization minimizes the risk of adhesions while concurrently facilitating scar tissue remodelling. Finally, active motion helps the patient overcome the neural inhibition that frequently accompanies post injury pain and inflammation. Cryo-kinetics is relatively inexpensive and easy to implement. Therefore, it is practical for almost every rehabilitation setting. Depending on the mode of cryotherapy chosen, equipment needs may include: buckets, basins or whirlpools, ice that is preferably crushed, cold packs, ice bags or frozen ice cups, towels, a rubber mat or no slip surface, and toe or finger caps if needed. Therapeutic equipment needed vary depending on the individualized exercise programmes.5,6

Cryo-kinetics consist of numbing an injured body part to allow the patient to tolerate progressive, active exercise. This active exercise is subsequently followed by reapplication of cold and the series is repeated a number of times. Cryo-kinetics dates back to the 1960s when rehabilitation specialists at Brooks Army Medical Hospital reported an 80 per cent success rate in returning soldiers to unrestricted duty within 3 days of implementing an aggressive cryo-kinetic program. Perhaps the most appropriate use of cryokinetics is treating patients with acute joint Treatment Guidelines for Cryo-kinetics sprains in which range of motion (ROM), weight-bearing tolerance, and functional Step One activity tolerance are limited by pain and Prior to initiating treatment, the patient must oedema. Following an acute injury, pain often be give n a th or ou gh ex pl an at io n of th e restricts motion, which prevents patients from purpose and expectations from the treatment. returning to their work or sport. Cryo-kinetics Patients must be forewarned about the speeds the recovery process by enabling discomfort associated with cryotherapy while patients to participate in pain-free controlled emphasizing the necessity of the temporary mobilization sooner than would normally be pain in order to achieve the desired outcome. tolerated. Cryo-therapy decreases pain to The thermal sensation of the patient must be allow the patient to receive the benefits of checked for normalcy before application of active motion that may otherwise not be cold. tolerated. The muscle-pumping action of active motion aids in removal of dead tissue, Step Two pain-inducing substances, and excess fluid Patients must be instructed on how to lingering at the injured site. Knight reports differentiate among the different types of pain this active pump is aided by exercise-induced and discomfort that they may experience vasodilatation brought about that actually during the treatment. They need to be able to surpasses circulatory increases stimulated by choose from pre-existing pain, due to their

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injury or pathology, from cold-induced pain, as a result of the sensory changes due to the cold application. The numbing process, which begins with sensation of cold, followed by tingling, burning and aching, finally leading to anaesthesia. On the other hand , exerciseinduced pain, of an anaesthetized foot may mean the exercise is inducing additional tissue damage. Pain-free motions are crucial during the exercise component of cryo-kinetics. Exercise-induced pain is a signal to the rehabilitation specialist that the particular exercise is too strenuous and needs to be modified if possible or discontinued. The patient must be able to differentiate between the return of pre-numbing discomfort and exercise-induced pain. Step Three

Treatment is initiated by numbing the body part with a chosen method of cryotherapy. Ice immersion, ice water bath or whirlpools, ice massage, and cold packs are all considered acceptable means for cryo-kinetics. The length of time for the cold application varies depending on the modality chosen and the body part being treated. The patient reporting numbness of the part, determined by a loss of tactile sensation, serves as the guide for the duration of treatment. The initial numbing takes anywhere from 10 to 20 minutes during the first cold application before exercise. Cooling the part after exercise takes less than 5 minutes in most cases. Step Four

Once numbness is established, active exercise within the pain free range may commence. Each exercise set should last approximately 2 to 3 minutes, until the numbness begins to

wear off and sensation returns to the part. Patients should attempt to perform five to six sets of active exercise, separated by periods of cold application to restore numbness. Exercise progressions in cryo-kinetics are similar to those in more traditional therapeutic exercise programs. Exercise-Specific Guidelines

• Non-weight-bearing, pain-free, active ROM should start with single plane and progress to multi-planar motions. Postural repositioning and active-assisted stretching may also be introduced for the patient with low back pain • The weight-bearing exercises include a progressive shifting from partial weight bearing to full weight bearing, unilaterally on the involved lower extremity (LE). Weight-bearing activities can also be introduced into upper extremity (UE) by having the patient lean on a table or wall. • ROM exercises in weight bearing, including closed kinetic chain exercises (CKC), wall push-ups; biomechanical ankle platform board (wobble board) exercises are introduced progressively. If the patient has not achieved full ROM in the ankle, weight-bearing stretches such as a standing TA stretch may be incorporated into this phase of rehabilitation • Progression is made to ambulation, static cycling, stair climbing and climbing stairs or ramps. Training should proceed cautiously, with a strong emphasis on proper form. If the patient is not able to tolerate full weight bearing, additional tissue damage may occur if the exercises are progressed too quickly or performed incorrectly. Lower extremity activities should be performed with both shoes off,


as a self-imposed leg length discrepancy may contribute to faulty biomechanics and induce additional damage. Furthermore, caution must be taken during LE cryokinetics to ensure that the limb is adequately dried before exercises are performed. Exercise and gait training must be performed on a no slip surface such as a rubber mat. Increasing the speed or resistance to the movements makes progressions in the exercises • Resistive exercises restore muscular strength and power and may consist of progressive resistive exercises (PREs) using weights, bands, or other available equipment. Pain-free heel walking and toe walking utilize the patient’s body weight as resistance to movements, in a safe and controlled manner • For Progression into functional activities of daily living or sports, specific activities should be introduced into the cryo-kinetic program at safe intensities, before attempting them at pre-injury intensities. For a sedentary person, high speed walking may progress to jogging and then to slow running. For athletes, the running speed can be increased progressively until they can tolerate short sprints. Step Five

• As numbness wears off, patient’s sensation of the pain will return. This is the signal to reapply the cold and re-numb the affected area. Re-numbing generally takes between 3 and 5 minutes. Step Six

• The focus of cryo-kinetic documentation should be on the description and the amount of time spent on the individual

exercises Progression can be objectively recorded as an increase in demonstrated ROM, weight- bearing tolerance, or movement speed. Functional progress is demonstrated through the documented advancement from basic functional skills such as ambulating, to the more complicated, sport-specific skills like sprinting and jumping.4 Step Seven

• The final phase of cryo-kinetics involves allowing the numbness to wear off while functional activity continues. This enables the therapist to assess the patient’s exercise tolerance. At this stage, sport or work specific activities can be performed in more realistic settings such as the work places or the practice field. During this phase of rehabilitation, braces, taping, protective shoes may be utilized to increase safety and support. Follow-up

• Ideally, cryo-kinetics should be performed two to three times a day for the patient whose main goal is to return to sport or work, as soon and as safely as possible. The therapist should teach the patients how to carry out the cryo-kinetic program at home. An adequate quantity of ice is needed. The patient can use own body weight through CKC for the resistive exercise for the home program. In the sports setting, the athletic trainer can readily carry out the treatments. Likewise, for a therapist working in an inpatient hospital facility treating postoperative patients or running an outpatient work hardening program, cryo-kinetic treat-

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ments, done twice to three times daily are realistic and strongly encouraged. The suitability of cryo-kinetics for a given patient depends on the location and extent of the injury. For example, following a minor ankle sprain, cryo-kinetics can be initiated within the first 24 to 48 hours. However, severe joint sprains may be unsafe for the cryo-kinetics. Points to Ponder

The physiological effects of local cooling are: • Perception of cold, tingling, burning and pain due to stimulation of thermal and pain receptors • Localised vasoconstriction followed by rebound vasodilatation, which continues in a cyclic manner due to Lewis hunting reaction, creating a vascular pumping action. Reduction of blood flow in the soft tissue is the long-term result • Lowered metabolic rate as per Van’t Hoff’s law, resulting in reduced oxygen consumption, production of metabolites, cellular activity and rate of healing • Inhibition of peripheral nerves due to reduced NCV, resulting in reduction of pain sensation, tone and spasm of skeletal muscles and the dexterity and speed of fine motor activity. The therapeutic uses of local cooling are: • When applied to recent trauma, therapeutic cold limits blood loss due to vasoconstriction and increased viscosity of the blood, controls formation of soft tissue oedema or effusion in joints, reduces pain by inhibition of conduction in pain carrying nerve fibres, reduces metabolic rate of injured tissue and thereby restricts tissue necrosis.

• When applied in chronic pain, therapeutic cold helps activate the gate control mechanism of pain relief through sensory stimulation. The intense cold sensation also stimulates the release the indigenous opiates like beta-endorphins in the brain, which modulates the pain receptors at the cortical level. • Reduces muscle spasm and spasticity through stimulation of cutaneous receptors and muscle spindles, which inhibits stretch reflexes of the spasmodic/spastic muscle. Techniques of Local Cooling

• Preparation of patients: Explain the reason for, intensity desired and the nature of cold application to the patient. This will some fear and misconception towards application of cold. The patient is told what sensation to expect and to inform the therapist if there is any increase in pain. The patient should be interviewed briefly to rule out any general contraindication like hypertension or cardiac problems and the area to be treated is examined for any local contraindication to application to cold. • Preparation of the part: The part to be treated should be exposed and positioned with adequate support. The skin should be examined for abrasions, skin disease, loss of sensation etc. Sensitive skin may be coated with liquid paraffin, before immersion in ice water bath. In acute trauma with swelling, the part should be arranged in elevation before applying cold packs. • Preparation of the cold source: The temperature of the cold source must be carefully monitored before and during treatment.


This is particularly important while using ice-bath. The condensation from the cold source must be mopped up from plinth or working surface with an absorbent cloth or paper towel. Application of Therapeutic Cold

1. The cold packs should be held firmly against the skin for optimum heat transfer. Every 2-3 minutes the packs should be moved slightly on the skin the avoid formation of ice layer on the skin, which may cause frostbite. 2. The desirable temperature of cold therapy should not be less than 4 to 6°C. To lower the intensity of cold, keep the pack loosely on the skin. Loosely held packs retain air pockets between the cold pack and the skin which act as insulator and therefore restrict the intensity of cooling. 3. While giving ice water bath treatment ask the patient to move the part periodically in the bath. This movement will dissipate the heat faster and result in uniform cooling. 4. Cold compression technique is very effective in reducing swelling. This type of cooling is applied through an intermittent compression machine with cold fluid instead of air in the compression sleeve. The part must be kept in elevation during such treatment for getting best results.

Alternatively faradism under pressure may be applied for 15 to 30 minutes to mobilise the tissue fluid just before application of cold therapy. 5. The condition of the skin must be checked periodically (every 2-3 minutes) during the treatment, to monitor the onset of vasoconstriction and vasodilatation. If hyper reaction occurs the treatment should be terminated immediately. 6. After completion of the treatment the patient should be advised to avoid heat exposure or hot bath for at least two hours. 7. The patient should be asked to monitor the skin condition closely for the next 24 hours and to report any adverse changes before the next sitting. REFERENCES 1. Knight KL. Cryo-therapy in Sport Injury Management. Champaign, Ill: Human Kinetics; 1995:3-18,59-71, 77, 107-130, 175-177, 217-32. 2. Barnes L. Putting injuries on ice. Physicians Sports Med 1979;7(6):130-36. 3. Denegar CR. Therapeutic Modalities for Athletic Training. Champaign, Ill: Human Kinetics; 2000;104-11. 4. Gaydos HF, Dusek ER. Effects of localized hand cooling versus total body cooling on manual performance. Journal of Applied Physiology 1958;12:376-80. 5. Hayden CA. Cryo-kinetics in an early treatment program. Physical Therapy. 1964;44:990-93. 6. Prentice WE. Therapeutic Modalities in Sports Medicine. Boston: WCB/McGraw-Hill 1999; 187-89.

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13 Therapeutic Light (Actinotherapy/Heliotherapy) And God said, “Let there be light”.

The light in the Bible means both visual and non-visual light. Of all the electromagnetic radiations striking the earth, approximately 50 per cent is visible light, having wavelengths between 400 and 700 nanometres. (A nanometre (nm) is the standard measurement used to express wavelength of electromagnetic radiation. It is equivalent to one billionth of a meter in length). Electromagnetic radiation comes in many forms. The most familiar among them is visible light. Other forms include X-rays, ultraviolet (UVR), infrared, microwave and radio waves. Daylight consists of direct solar radiation, diffused radiation from the sky (sky shine) and wavelengths reflected from surroundings, such as buildings, etc. Generally the moisture in the atmosphere absorbs a great deal of ultraviolet radiation and even more so by smoke and dust particles. Visible light has seven colours, violet, indigo, blue, green, yellow, orange and red, which are only a fraction of all wavelengths known to mankind. Colour combinations and blends of hue in this visual range can exceed 100 million.

In physiotherapy, light energy in the form of ultraviolet, infrared and laser are used for therapeutic purpose. Since all types of light originate from the sun, this form of therapy is called Heliotherapy (Helios means sun in Greek) or Actinotherapy (Actinos means light in Latin). HISTORICAL PERSPECTIVE

Helios is the god of sun in Greek mythology. Heliopolis, an ancient Greek city was famous for its temples of sunlight healing. This is where Heliotherapy or science of therapeutic sunlight was born. Herodotus, the father of heliotherapy wrote that exposure to the sun is essential for a sick persons who needs to restore his health. In winter, spring and autumn, the patient should permit the rays of the sun to fall upon him; but in summer, because of the excessive heat, this method should be used in moderation. In 1877, Downs and Blunt discovered the dramatic ability of sunlight to destroy and provide for an effective means of treating bacterial infections. Another famous practitioner of heliotherapy was Auguste Rollier MD, whose clinic was at 5,000 feet above sea

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level. Dr. Rollier stated that his patients would get the best results if they received the highest amount of ultraviolet light at this altitude. Ultraviolet intensity increases 4% to 5% every 1000 feet ascended. He apparently substantiated incredible results, which were published in his book La Cure de Soleil, i.e. Curing with the Sunlight. Dr. John Otto , the father of modern photobiology noted that sensible exposure to sunlight is not only safe but is desirable for good health. Life on Earth evolved under natural sunlight and has existed for billions of years under the full spectrum of light (visual and non-visual) that it contains. Many prehistoric tribes and even entire civilizations like the Mayans and the Persians worshiped the sun for its healing powers, using its light to treat physical and mental illnesses. Though exposure to UV light in large amounts is harmful; in trace amounts, as in moderate amounts of natural sunlight, it acts, as a lifesupporting nutrient that is highly beneficial. WHAT DOES SUNLIGHT THERAPY ACTUALLY DO?

Sunlight Therapy can have the following effects on the human body: 1. Increase circulation by formation of new capillaries to replace damaged ones to speed up the healing process by carrying more oxygen as well as more nutrients needed for healing and carry waste products away. 2. Stimulate the production of collagen , the most common protein found in the body essential for repair of damaged tissue and to replace old tissue. By increasing collagen production less scar tissues are formed at the wounds.

3. Increase RNA and DNA synthesis helping damaged cells to be replaced more promptly. 4. Stimulate fibroblastic activity , which aids in the repair process. Fibroblasts are present in connective tissue and are capable of forming collagen fibres. 5. Stimulate tissue granulation and connective tissue projections, which are part of the healing process of wounds, ulcers or inflammation. 6. Stimulate the release of adenosine triphos phate (ATP). ATP is the major carrier of energy to all cells. Increases in ATP allow cells to accept nutrients and get rid of waste products faster by increasing the energy level in the cell. 7. Increase lymphatic drainage. Research has shown that the lymph vessel diameter and the flow of the lymph can be doubled and the venous diameter and the arterial diameters can also be increased with the use of light therapy. This means that both liquid and protein components of oedema can be evacuated at a much faster rate to relieve swelling. 8. Relieve pain. Light therapy is successfully used in pain management, dermatology and rheumatology with excellent therapeutic effects. 9. Stimulate acetylcholine release and other parasympathetic effects. 10. Increase phagocytosis, as an important part of the infection fighting process. Destruction of the infection and clean up must occur before the healing process can take place. 11. Induce thermal effect , which raises the temperature of the tissue being treated, to kill or disable bacteria and viruses.

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Discussion

Modern scientific research claims that sunlight; especially ultraviolet rays can be hazardous to our body. Controversy exists over potentially-harmful effects of the invisible ultraviolet frequencies (wavelength 100 to 400 nm), which equal 10 per cent, and infrared frequencies (wavelength over 700 nm), which are 40 per cent of all radiation reaching earth. Of course, the fact remains that without ultraviolet and infrared our world would not be the same. Infrared provides us with the required heat that keeps us warm. Ultraviolet provides us with the ability to fight off germs in the air (UVC), creates skin pigmentation as a natural protector (UVB) and helps in our vitamin and mineral absorption capabilities (UVA). UVC are the shortest ultraviolet rays and our atmosphere and the ozone layer absorb virtually all of these frequencies. The remaining UV light that reaches the ground is about 10 per cent UVB and 90 per cent UVA at midday. Overexposure to sunlight may cause varying degrees of sunstroke, heat stroke or sunburns and such symptoms as headache, undue fatigue or irritability. On the other hand, properly applied sunshine act as a powerful tonic, helpful in increasing general powers of resistance and promoting mental and physical development. For this reason the duration and extent of exposure to sunshine should be carefully graduated and those who do not pigment efficiently or easily should be warned to be especially careful.

emitted with a wavelength bandwidth of 180 to 12000 nm. These contain visible light as well as invisible radiations like UVR and Infrared. Such radiations are governed by following laws of physics. • Lamberts cosine law, which states that, “the angle of incidence of radiation determines the amount of radiant energy absorbed.” In terms of therapeutic application it means that optimal absorption the radiations should occur when the rays are perpendicular to the skin surface being treated. • Inverse square law, which states that, “ the intensity of radiation varies inversely with the square of the distance between the source of radiation and the surface it falls” In terms of therapeutic application it means that if the source of radiation is moved halfway closer to the skin it’s intensity will increase four times. Hence to increase or decrease the intensity of any type of therapeutic light the distance between the emitter of radiation and the skin should be increased or decreased. TYPES OF THERAPEUTIC LIGHT

Apart from natural sunlight, in physiotherapy, three types of light energy are used for treatment of different disorders. These are ultraviolet radiations, infrared radiations and LASER. Each of these light energy have specific effects on the physiology of the human body and is used to correct specific disorders.

PHYSICS OF THERAPEUTIC LIGHT

ULTRAVIOLET RADIATION THERAPY (UVR THERAPY)

Sunlight is the source of all types of light energy used for therapeutic purpose. Therapeutic lights are electromagnetic radiations

Ultraviolet light is part of the electromagnetic energy spectrum, which can be classified into three wavelength ranges:


UV-C : 100 nm - 280 nm; UV-B : 280 nm - 315 nm; UV-A : 315 nm - 400 nm. Points to Ponder

• Light is a form of electromagnetic energy that moves in measurable waves. • The human eye is capable of seeing only a small segment of the spectrum known as visible light; shorter and longer wavelengths are not visible. • Shorter length cosmic rays, gamma rays, X-rays and UV light and the longer length infrared and radio waves are all invisible to humans. • UV radiations are between 180 nm and 400 nm wavelengths in the narrow region between X-rays and the violet end of the visible light spectrum. Biophysics of UVR

Fluorescence

More than 3,000 natural and man-made substances can transform invisible radiated UV into longer, visible wavelengths that appear in a variety of colours. These substances react to UV because they are composed of easily excitable molecules. When UV light strikes one of these molecules, photons cause each molecule to oscillate violently to release longer, visible wavelengths that appear to the human eye as a glow, in the colour specific to activated substance. This phenomenon, called fluorescence is instantaneous and ceases the instant the UV light is removed. Fluorescence lets users detect otherwise invisible traces that indicate various quality defects, diseases and contamination.

Luminescence and Phosphorescence

Luminescence is the emission of light produced by means other than combustion such as the luminous glow of a watch dial. Ultraviolet radiation has particular physical characteristics, which affect such phenomena as Luminescence and Phosphorescence and can cause Fluorescence. Physiological Effects of UVR

1. Antibiotic properties of UVR like inactivation of toxins and destruction of bacteria or virus are produced by UVR-C, having wavelengths of 100 nm-280 nm. UVR-C is widely recognised for it’s bactericidal and antiviral properties, useful for sterilization of infected wounds, medical supplies, surgical instruments, drinking water and processed food. UVR-C has been used as a disinfectant for many years and is, in fact, still used for that purpose. In the late 1900’s, Niels Ryberg Finsen used this bactericidal and antiviral property for a new application and started using ultraviolet rays from external sources for the treatment of diseases of the skin and mucus membrane, for which he was awarded a Nobel Prize in 1903. By the mid-1930’s treatment with ultraviolet was well accepted for erysipelas and other skin infections, as well as for mumps. Other researchers Hancock and Knott (1942) have demonstrated the effectiveness of ultraviolet blood irradiation (UVR) in treating both bacterial and viral infections, having demonstrated that ultraviolet light could be used effectively in the treatment of bloodstream infections. However with the debut of antibiotics, it’s ease of

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treatment and its success in treating infections, it became the treatment of choice, and UVR therapy fell by the wayside. 2. Biotic properties of UVR are beneficial to the living tissue. Out of the entire spectrum of UVR, UV-B (280 nm - 315 nm) and UV-A (315 nm-400 nm) are known to have profound beneficial effects on the living tissues. • Enhancement of the immune system’s ability to fight infections. • Increase in oxygenation of the blood. • Activation of steroids. • Increased cell permeability. • Release of vasoactive agents in the subcutaneous capillary network resulting in vasodilatation and reddening of the skin, known as erythema reaction. • Increased desquamation i.e. peeling of the skin. • Promote granulation • Activation of cortisone-like molecules, called sterols, into vitamin D. Sensitivity to UVR

Individuals vary in their sensitivities to UVR. Persons with light skin shades are more affected through tanning, though it is the dark skinned that run the risk of developing basal cell carcinoma due to overexposure to UVR. Certain drugs such as tetracycline, sulphonamides, phenothiazine, quinine and gold may alter sensitivities of a person to UVR. Over-dosage with ultraviolet light may produce severe systemic reactions similar to allergic reactions and lower the resistance to bacterial infections. The level of exposure required for an overdose is not approached in proper clinical practice. Instrumentation of UVR therapy

Therapeutic UVR is availed from three types of sources, air-cooled mercury vapour lamps,

water-cooled kromayer lamps and theractin tubes. • Air-cooled mercury vapour lamps consist of a hot quartz tube, mounted on a movable stand like an operation theatre light. It has a hemispherical shutter to control the extent of exposure to the rays. The lamp produces bright bluish light, containing, predominantly UVB and UBA with a small proportion of UVC in the wavelength range of 240 to 400 nm, along with significant amount of infrared and visible light. Such lamps need to be warmed up for 5 minutes to ensure maximum output of UVR and are suitable for superficial wounds and pressure sores on the skin surface. Since significant heat is generated by this type of lamps. Hence the distance between the lamp and the skin surface should be 20 to 40 inches. • Water-cooled kromayer lamp contains a cold quartz mercury vapour tube, mounted in a hand held applicator unit, which produces invisible UVC in the wavelength range of 180 to 290 nm. This type of lamp needs no warm up time. The field covered by the lamp is just 5 sq cm and therefore, it’s suitable for small deeps sores or sinuses. Since this type of lamp generates virtually no heat, it is applied in direct contact with the skin surface. • Theractin tubes consist of specially coated fluorescent tubes, arranged in a battery of 6 to 8 tubes fitted with in a semicircular tunnel, which produces visible violet light, containing UVA in the wavelength of 400 nm. This type of lamp utilises biotic properties of UVR and is used for treatment of neonatal jaundice, vitamin D deficiency and as a sunlamp for tanning the skin. Since no heat is produced and the desired effect is largely generalised, the


distance of the tube form the skin should be such that the field covers the entire body. Points to Ponder

• Therapeutic ultraviolet is produced by excitation of mercury atoms. • The mercury vapour lamps may be of two types 1. Hot quartz type (Alpine Sunlamp), which produces heat and visible light along with UVR- A, B and C. 2. Cold quartz type (Kromayer Lamp), which produces mostly UVR-C. • Fluorescent tubes with phosphorescent coating, producing UVR-A along with visible light. Arranged in Tunnels, which is used for whole body exposure. Ultraviolet Applications

Methods of UVR applications and its dose depends upon: • The type of ultraviolet source being used. • The selection of the source depends upon the type of the clinical problem being treated. • The most critical element in dosimetry of UVR is the extent of erythema reaction produced by UVR exposure on the skin. Erythema Reaction

Definition

Reddening of the skin, which appears a few hours after the exposure to UVR, is called erythema reaction. The intensity of the reaction is directly proportional to the duration of exposure to UVR and varies according to types of skin tone and sensitivity of the individual. After appearing, the erythema

reaction increases in intensity for a few hours and may be associated with superficial oedema and peeling of the skin on strong exposure. The reddening of the skin fades spontaneously after few hours or days. Mechanism of Erythema Reaction

It is dependent on histamine-mediated dilatation of the subcutaneous capillaries. Several anti-inflammatory agents like histamines; kinins are released from the mast cells following exposure to UVR, which lead to permanent dilatation of capillary network at the site of the exposure, resulting in clearly demarcated area of uniform redness in the skin. The reddening caused by exposure to heat is often mottled and diffuse in nature. Dosimetry of UVR

The skin response to UVR depends on the quantity of ultraviolet energy applied to per square inch area of the skin, tone and the sensitivity of the skin being treated. Since the sensitivity of UVR varies from person to person, its optimum dosing parameters are determined on case-by-case basis, through trial and error of application. This is known as the test dose. Practical Points

• Take a 3” wide and 10” long strip of flexible but opaque cardboard. • Cut three holes in the cardboard ½” × ¾” of three different shapes, 3” apart. • Fix the cardboard strip with adhesive tape, on the flexor surface of the forearm, lower abdomen or chest of the patient, after washing and drying the part. Ensure the test strip is flat on the body surface to avoid shadows.

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• Cover the part, along with the test strip with a towel. The rest of the body of the patient should be draped with a sheet and the eyes protected with a UVR resistant goggles. • The Mercury vapour type UVR lamp should be placed 30”-36” away from and at right angles to the body surface, so that the incident rays are perpendicular to the skin. • The lamp should then be warmed up for 5 to 10 min. • Open the shutter of the lamp and expose the first cut out on the cardboard for 15 seconds, uncovering the second and the third cut outs successively at intervals of 15 seconds. • With this procedure the first cut out is exposed for 45 seconds, the second for 30 seconds and the third for 15 seconds respectively. • After the exposure is completed the shutter of the lamp is close and the unit should be switched off. • While using kromayer lamp preparation of the patient and the test dose cutouts remain the same. The distance of the lamp from the skin should be 1” or less. Three cutouts are exposed one after another for 15, 30 and 45 seconds respectively. Interpretation and Use of the Test Dose

• The patient is given a card with holes of similar shapes as that on the test dose card. • The patent is asked to record the time at which reddening appears on the exposed spots on the skin and the time at which it subsides, on the matching holes on the card. • Minimal erythemal dose, producing a faint reddening on the Indian skin within 4 to 6

hours, which subsides within 24 hours. Minimal erythemal doses are used for generalised applications, useful for vitamin D synthesis. • First-degree erythema produces mild reddening along with light peeling of the skin. It appears within 4 to 6 hours and lasts for 48 hours. First-degree erythemal doses are used to treat superficial skin conditions such as Acne and sub acute psoriasis • Second-degree erythema produces marked reddening along with marked peeling, oedema and pigmentation of the skin lasting for 72 hours. Second-degree erythemal doses are suitable for chronic psoriasis, where peeling or exfoliation is desired. • Third-degree erythema produces severe blistering, peeling and exudation along with pain. It should be applied only on open sores or wounds, to destroy infective organism through UVC component and promote the granulation through the UVB and A components. RED LIGHT THERAPY (INFRARED RAYS) Definition

It is the therapeutic application of radiant energy from a visible light source, commonly referred to as the red light, which emits both visible light in the wavelength from 400 to 700 nm and invisible wavelengths from the infrared portion of the electromagnetic spectrum, in the band width of 700-12000 nm. Biophysics

Wavelength dependent photo biochemical reactions occur throughout nature and are involved in such things as vision, photosyn-


thesis, tanning and vitamin D metabolism. Application of Red Light therapy has been shown in over 40 years of independent research worldwide to deliver powerful therapeutic benefits to living tissues and organisms. Such light contains both visible red (600-700 nm) as well as invisible infrared rays (700-12000 nm). Types of Infrared Energy

Infrared energy covers a bandwidth of 760-12000 nm with in the electromagnetic spectrum. • Near infrared rays or I.R.A have a wavelength range of 760 to 1500 nm and are emitted along with red visible light. This the commonest variety of infrared energy used in physiotherapy. These rays penetrate to the depth of 5 to 10 mm, reaching the dermis and the subcutaneous tissue and are emitted by the luminous infrared lamps. Such lamps produce visible light, which is passed through a red colour filter to eliminate undesirable wavelengths like the UVR from the visible light. • Far infrared rays or I.R.B. and I.R.C. is emitted by any non-luminous heat source, like an electric heating coil or a hot water bottle. These rays have a wavelength range of 1500-12000 nm and penetrate to a depth of 2 mm and its effect is restricted only to the superficial layers of the skin. Methods of Application of Infrared Ray

Two types of infrared sources are used in physiotherapy practice. 1. Non –luminous infrared lamps: These are large lamps, similar to operation theatre lights, mounted on a movable stand. They have a heating element mounted on a

ceramic cylinder like in an electric room heater and their working is similar in nature. The heating coil is mounted in the front of a parabolic reflector, which directs the radiations in a parallel beam towards the target area. • The lamp must be switched on at least 5 minutes before application of the treatment, to warm up the heating element and ensure maximum output of infrared energy. • The area to be treated is exposed and inspected for any break in the skin or any skin disease. The thermal sensation of the skin must also be checked before application of I.R. the rest of the body is then draped with a sheet and the eyes must be protected with a pair of sunglasses. • The lamp is then positioned 30-36” away from skin. The position of the reflector should be such that the radiant energy falls perpendicular to the skin, to ensure maximum absorption. • The duration of exposure should be 20 to 30 minutes in one sitting. During the exposure the therapist must be available within easy reach of the patient. If the patient feels less or more heat the lamp may be moved closer or away from the skin as the case may be. It is wise to remember that the feed back of the patient is the only guide you have to give appropriate dosing of I.R. Hence, ask the patient repeatedly regarding the extent of heat being felt and be ready to adjust to the dose to suit the comfort level of the patient. • After completion of the treatment the lamp may turned off or moved away from the skin. The lamp may be kept

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on if there are more patients to treat. nature. All biological systems have a unique Inspect the skin that has been treated absorption spectrum, which determines what for any undue reactions. Slight redden- wavelengths of radiation will be absorbed to ing of the skin over the exposed area is produce a given therapeutic effect. Lasers are to be expected and this should be focused beam single-wavelength (monochroexplained to the patient. matic) light that can be intense enough to • In case of irritation or severe reddening burn/cut tissue or mild enough to only have of the skin calamine lotion (lacto cala- photobilogical effects on the living tissues. 1 mine) may be applied over exposed Laser devices emit an intense, coherent and skin. It should be realised that fair skin highly directional beam of “light” which may reddens more readily as compared to be infrared, visible or ultraviolet , depending on dark skin. the type of the diode being used. 2. Luminous infrared lamps: These are devices The peak power output of lasers is meaconsisting of an incandescent bulb of 150 sured in watts. The primary reaction of laser watts mounted on parabolic reflector, on the living tissue is thermal i.e. production having portable or stand mounted set-up. of heat which. Such heat is due to the highly The incandescent lamp has a red filter intense nature of the beam and its ability to placed in front or painted on to the be focussed over small areas. The heat is suffifaceplate of the bulb. This filter helps to cient to coagulate or ablate tissue by evaporemove the UVR associated with the ration. However, even with low power visible light produced by the incandescent application of laser, significant benefits were bulb. These types of lamps are preferred observed in diseased tissue, without any by most clinics and for home use because: • No warm-up time needed. The lamp destruction of the cells. This led to the use and gives maximum output as soon as it is subsequent popularity of low power laser in physiotherapy and very low power laser in turned on. • It has deeper penetration and therefore dermatology. Effects of such laser exposure are mainly photo biological in nature. The greater effect on body tissues. • Face and the eyes need to be protected peak power output of laser is measured in strictly due to the presence of visible watts used frequently for endoscopic surgery 2 and UVR in the luminous I.R. output. for endometriosis, vascular surgery, etc. Other reactions of laser exposure are used • The distance from the lamp to the skin should be 18-24” and the duration of are photo biological in nature. In physiotherapy low powered lasers as used and in exposure should be 15 to 20 minutes. • Procedure of application, patient pre- ophthalmic treatments such as capsulotomy paration and precautions observed are photo acoustic effect is used.3 similar to non-luminous IR applicaPoints to Ponder tions. • LASER stands for “light amplification by THERAPEUTIC LASERS stimulated emission of radiation”. Lasers are devices for producing light at • Laser consists of a large number of identispecific wavelengths that is therapeutic in cal photons emitted from an energised


source called a diode on application of will protect the eye. Positioning lasers used electrical charge. for aligning patients for radiotherapy, X-rays • Laser radiations have the same wave- and scans are usually Class 2 length i.e. are mono chromatic in nature. Class 3a - Similar to Class 2, except that if the • Laser radiations are coherent in phase and beam is focussed onto the eye, e.g. through direction, i.e. has temporal and spatial magnifying glasses, beam could be hazarcoherence. dous. • Laser emitted from a source is collimated Class 3b – Potentially hazardous to the eyes in nature, i.e. parallel to each other. because either the blink reflex is not fast • Laser behaves like light i.e. they can be enough to prevent damage or the beam is reflected, refracted and absorbed. invisible and therefore the blink reflex cannot work. Lasers used in physiotherapy produce Different Types of Lasers invisible infrared beams (Galium-AlumiEmployed for Clinical Use (Table 13.1) nium-Arsenide Diode) at class 3B.These equipments also incorporate a visible orange i. Candela pumped dye laser: (Helium-Neon diode) as an aiming laser beam Dermatology at lower power, which should also be regarii. Neodymium: YAG laser: ded as hazardous. In scanning laser, the power Surgery density is considerably reduced by the iii. CO2 Laser: cylindrical lens, which spreads the beam from Obstetrics and Gynaecology a spot to a line. iv. Argon; iris diode lasers: Class 4 – High power devices capable of Ophthalmology causing immediate injury to the skin, eye or v. He-Ne; infrared diode lasers: living tissue - even diffuse reflections may be Physiotherapy hazardous. Most surgical lasers are in Class 4. Damage from Class 4 lasers can occur in a Hazards of Laser Therapy fraction of a second, far faster than the eye The principal hazard due to laser is damage can blink to shut out the beam. The hazard to the eye. Laser radiations in the visible and can arise from direct exposure to the laser near infrared wavelengths can penetrate the beam or accidental reflections of the beam eye and damage the retina permanently, from shiny objects. It must be stressed that eye where as radiation in the ultraviolet and far damage is the most likely and immediate infrared wavelengths can cause damage only injury - thus the operating rules must be to the surface of the eyes. Lasers are divided understood and adhered to by all staff into five hazard classes, depending on the involved. The likelihood of an accident is very output and the risk of damage from accidental small, but the consequences are often serious.4 exposure.The hazard classes of laser used in Other potential hazards are fire. Lasers can clinical practice are: ignite flammable materials. Laser may cause Class 1 - Intrinsically safe explosion of anaesthetic gases or ignite Class 2 – Low power devices emitting visible inflammable substances like surgical ether light - not completely safe, but the blink reflex causing skin burns.

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Procedures and Equipment

The Nominal Ocular Hazard Area (NOHA) is the region around a laser therapy unit, where eye protection is essential. For therapeutic laser this is the entire room, in which the laser is being used, but it may be less for specific lasers, e.g. NOHA is within one metre of any ophthalmic laser. It is important to avoid any unexpected entry into a laser area when the equipment is in use. A laser hazard sign must be displayed at eye level at all entrances to the room. The hazard sign must indicate the classification and type of laser being used. Ensure that all personnel working with the laser are adequately instructed on eye safety measures. Ensure that adequate supply of protective eyewear for the particular type of laser is available. Appropriate eye wear specific to the type of laser being used must be wo rn by all st af f pres en t du ring th e treatment procedure, and spare eye wear must be available for staff wanting to enter the area. Staff working with lasers, which have the ability to ignite flammable materials, must be aware of the location of a nearby fire

extinguisher. The supervisor, in a secure place when not in use, shall keep the master key for each laser and an authorised person should only energise the equipment frequently for endoscopic surgery for endometriosis, vascular surgery, etc. All lasers must be checked routinely for proper output and performance prior to each procedure. Faults should be notified immediately to the Biomedical Engineer in charge. REFERENCES 1. Lasers and Wound Healing, Albert J. Nemeth, MD; and Dermatology Centre, Clearwater FL, Dermatologic Clinics, Vol. 11 #4, 1993. 2. Wound management with Infrared Cold Laser Treatment, P Gogia; B Hurt and T Zim; AMIPark Plaza Hospital, Houston TX, Physical Therapy, Vol. 68, No. 8, August 1988. 3. Effects of Low-Level Lasers on the Healing of Full-Thickness Skin Defects, J Surinchak. MA; M Alago, BS, R Bellamy, MD; B Stuck, MS and M Belkin, MD; Lettennan Army Institute of Research. Presido of San Francisco, CA; Lasers in Surgery and Medicine, 1983;2:267-74. 4. Effect of Laser Rays on Wound Healing, E Mester, MD; T Spiry, MD; B Szende. MD and J Tola; Semmelweis Medical Univ. Budapest, the American Journal of Surgery 1971;122.

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14 Frequently Asked Questions in Practical: Viva Examination SECTION 1: DEEP THERMOTHERAPY

Q 1. What do you understand by SWD? A. It is a method of producing deep heat in the body tissues using high frequency current at the frequency of 27.12 MHz and wavelength of 11 meters. Q 2. What are the effects and uses of SWD? A. Primary effect of SWD is to generate heat in body tissues by subjecting it to an oscillating electrical field. Results of such heating are increased blood circulation, metabolic rate, protein synthesis and drainage of cellular waste. These effects are used for relief of pain, spasm of muscle, stiffness of joints, resolution of inflammation and tissue healing. Q 3. What are the types of SWD machines? A. SWD machines are available with valves or solid-state circuit. • The valve sets have the advantage of giving consistent outputs in the range of 400 to 500 watts over long periods of continuous operation without overheating and therefore, suitable for hospital or clinic use. The disadvantages of valve sets are that these units are larger, heavier, have delicate RT valves that need careful handling and

also are much more expensive than solidstate units. • SWD equipments with solid-state circuit have an output of 100 to 250 watts over short periods and are prone to overheating on continuous use. These units have lightweight, rugged-construction and are therefore, suitable for portable use. Q. 4. What are the important features of a modern SWD machine? A. Modern SWD machines have individual controls for input voltage, output intensity, tuning and autocut timers. Many models have auto-tuning facility for quick and accurate tuning of the machine circuits with the patient circuit. Most modern equipments have individual output sockets for cable and condenser electrodes. The equipments should also have provision for using cable, disc and pad electrodes, along with flexible disc electrode mounting arms as standard accessories. Q. 5. What type of input current is used in SWD? What is the output current frequency and wavelength? A. AC current from a domestic power outlet, with a voltage range of 220 to 240 volts is used

Frequently Asked Questions in Practical: Viva Examination

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to operate SWD machines. The output current is high frequency current with a frequency of 27.12 and wavelength of 11 meters.

Q. 11. How much thickness is appropriate for spacers? A. 2 to 4 cm.

Q. 6. What are the common methods of application of SWD? A. Condenser field and cable method.

Q. 12. What shoul d be the appr opriate distance between two condenser plate electrodes? A. The minimum distance between two condenser plates should be greater than the sum total of the thickness of the spacers being used.

Q. 7. What is condenser field method of SWD? A. Body tissue is interposed, as a dielectric medium, between two condenser electrodes, metal disks or plates, enclosed in nonconducting covers like plastic or rubber. Q. 8. Which tissue is heated most in condenser field method? A. Tissues with minimum water or electrolyte content, which offers maximum resistance to oscillating high frequency current, like the subcutaneous fat or skin, are heated most with condenser field application of SWD. Q. 9. What are different techniques of condenser plate electrode placement used in SWD? A. Coplaner, contraplaner and cross-fire placement. Q. 10. What are spacers? Name a few spacers. A. Spacers are layers of insulating material containing large air-spaces, which are interposed between the condenser electrodes and the skin surface. The spacers can be perforated felt pads, Turkish towel or air-space. The spacers increase the distance of the electrodes from the skin, eliminating irregularities of the body surface, for even distribution of the lines of forces. Concentration of the lines of forces on a specific spot may cause overheating and burn.

Q. 13. What is the method of heat production in cable SWD? A. Heat is produced by oscillation of ionic particles present in the tissue due to the effect of eddy current generated by electromagnetic induction. Cable method is also called inductothermy. Q. 14. Which tissues are best heated by cable method of SWD? A. Tissues with high ionic content like blood or muscles are best heated. Q. 15. What type of cable is used in cable method of SWD? A. Coaxial cable with a flexible conducting core coated with a layer of heat resistant rubber. Q. 16. What is the optimum length of the cable used in SWD? Why? A. Since the wavelength of SWD is 11 meters and resonance of such waves will be possible in either 1/2 or 1/4 of the wavelength, the optimum length of the inductothermy cable should be 2.25 meters or multiples thereof. Q. 17. When is pulsed SWD recommended? A. Pulsed SWD is recommended when heat component of the SWD is not desired but the

144


electromagnetic field is deemed to be beneficial for any condition like broken bones, wounds and acute inflammation.

mission of energy from the transducer to the body. This is essential, since air is a reflector of ultrasound energy.

Q. 18. How is the dose of SWD calculated? A. The dose of SWD is delivered based on the feedback of the patient. Hence, it is mandatory that the patient must have intact thermal sensation over the area being treated. The patient should be able to guide the therapist on the extent of heat being felt, based on which the output of the equipment is adjusted.

Q. 23. What effects does ultrasound energy produce in the body tissue? A. Mechanical effect, thermal effect and micro streaming effect.

SECTION 2: ULTRASONIC THERAPY

Q. 19. What do you understand by therapeutic ultrasound? A. Therapeutic ultrasound is sound energy beyond the range of human hearing at the frequency range of 0.8 to 3.8 MHz, applied to the body tissue through a transducer. Q. 20. What are the essential components of ultrasound therapy machine? A. Therapeutic ultrasound equipment consists of a high frequency current generator, a transducer with a quartz piezoelectric crystal and a coaxial cable that transmits the high frequency current from the generator to the crystal. Q. 21. What are coupling mediums? A. Coupling mediums are liquid or gel with minimum acoustic impedance that transmits ultrasound energy from the transducer to the skin, e.g. degassed water, glycerine, aqueous gel, etc. Q. 22. What is the role of coupling medium in application of US therapy? A. Coupling mediums eliminate air-space between the faceplate of the ultrasound transducer and the skin and allow trans-

Q. 24. What are the benefits of ultrasound application? A. a. The mechanical effect causes micro massage at the tissue level. This helps break down adhesions, soften scar tissue and release soft tissue contractures. b. The thermal effect raises tissue temperature that may help in resolution of inflammation and reduce pain. c. The micro-streaming effect promotes protein synthesis at the cellular level that is useful in the process of repair. Q. 25. What are the different modes of US application? How do they differ in character? A. a. Therapeutic ultrasound can be applied to the body in continuous or pulsed mode. b. In continuous mode the output of U.S. energy is uninterrupted and has a large thermal component. c. If the continuous flow of ultrasound is interrupted at specific intervals, the thermal component is reduced significantly, though the other effects like mechanical and micro streaming remains intact. This is known as pulsed U.S. Q. 26. What is the relevance of mark-space ratio? A. Mark-space ratio is relevant to pulsed U.S. It signifies the ratio between the duration in


milliseconds, of energy flow with the interval between successive pulses of energy. Usual mark space ratios used in therapeutic U.S. are 1:4, 1:8 or 1:16, the higher values indicating lesser thermal content. Q. 27. What are the dosing parameters of US therapy? A. • Mode of Ultrasonic- pulsed mode gives less power than continuous mode • Frequency of Ultrasonic- Lower the frequency of the US greater the penetration. • Intensity of US energy- measured as W/ cm2 • Duration of exposure. • Frequency of repetition of treatment- in acute, superficial lesions, low intensity at high frequency, in a pulsed mode for a short duration (<3 min) may be repeated twice a day for very short duration. For deep, chronic lesions- high intensity at low frequency, in a continuous mode for a long duration (>5 min) may be given on alternate days. Q. 28. What do you understand by half value distance of US? A. The distance at which, from the point of contact of the transducer on the skin, the value of the sound energy reduces by half is known as the half value distance. Q. 29. What are the factors that determine the absorption of US energy? A. Absorption of the US energy depends on the nature of protein and water content of the target tissue, frequency and the wavelength of the ultrasonic energy being used. Q. 30. What do you understand by attenuation of ultrasound? A. The loss of energy from the ultrasound be am in th e ti ssue s du e to ab sor pt io n,

145

reflection and refraction is called attenuation. The extent of energy loss due to absorption is 60%, due to refraction and reflection 25%. Q. 31. What are the principal therapeutic uses of ultrasonic therapy? A. Healing of acute soft tissue injury, relief of neurogenic and somatogenic pain, increase pliability of soft tissue contractures and scars and healing of chronic ulcers. Q. 32. What are the different methods of application of therapeutic ultrasound? A. Therapeutic ultrasonic can be applied: i. By direct contact method using coupling gel ii. In a bath of de-gassed water iii. Through a water bag iv. Through a solid sheet of coupling gel. Q. 33. What are absolute contraindications for application of ultrasonic therapy? A. Absolute contraindications for application of ultrasonic therapy are: • Tumours in precancerous stage or malignant. • Pregnant uterus • Testes and ovary • Acute infective focus like boils and carbuncles • Tissues that bleeds easily • Deep vein thrombosis • Over the eyes Q. 34. What is phonophoresis? A. Introduction of medicinal substances into and through the skin using ultrasound energy. Q. 35. What type of ultrasound energy is suitable for phonophoresis? A. Low intensity, low frequency ultrasound, applied over longer durations (>8 min) is most suited for phonophoresis.

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SECTION 3: THERAPEUTIC STIMULATING CURRENTS

Q. 36. What are the characteristics of therapeutic direct current? A. It is a unidirectional flow of electrons through the tissues that may be continuous (Galvanic) or interrupted (I.G.) at preset pulse duration, frequency and pulses intervals. Q. 37. What are the biophysical properties of continuous DC? A. Continuous DC sets up convection current in the tissues, causes electrolysis under the electrodes, which can produce transcutaneous penetration of therapeutically valuable ions into and through the skin to the subcutaneous circulation, by the force of ionic dissociation. Q. 38. What are the physiological effects of therapeutic DC? A. Physiological effects of DC are: • Stimulation of sensory nerve ending in the skin creating a tingling sensation. • Reflex vasodilatation of peripheral capillary network resulting in reddening of the skin. • Increase sensitivity of peripheral nerve ending. • Relief of pain by blocking of pain transmission. • Accelerate of tissue healing. • Introduction of drugs through the skinIontophoresis. Q. 39. What are uses of Iontophoresis? A. Iontophoresis can be used to introduce selected drugs through transcutaneous rout for: • Local anaesthesia by lignocaine/xylocaine iontophoresis. • Treat hyperhydrosis by water iontophoresis.

• Treat infections by copper sulphate iontophoresis. • Treat inflammation and pain by Methyl salicilate and iodine iontophoresis. Q. 40. What are the risk factors of iontophoresis? A. Potential risk of: • Chemical burns. • Electric shock. • Skin irritation and allergic dermatitis. • Anaphylactic shock due to drug allergy. Q. 41. What do you understand by an electric pulse? A. An electrical pulse is an isolated electrical incident, defined by a specific duration in millisecond, intensity in milliamperes/volts and rate of repetition/frequency in Hz. Q. 42. What are the bi ophysical ch aracteristics of a stimulating electrical pulse? A. The bio-physical properties of any stimulating electrical pulse depends on • Phase or direction of current flow- Monophasic or Biphasic. • Waveform or the shape of the pulse on a cathode ray tube. • Frequency or rate of repetition in PPS or Hz. • Ramping or progressive increase of intensity in each successive pulse, arriving in a train of impulses. • Rate of rise and fall from zero to peak intensity. Q. 43. How do you classify therapeutic currents on the basis of pulse frequency? A. Therapeutic currents can be classified on the basis of pulse frequency as: • Low frequency- 1 - 1000 Hz. • Medium frequency- 1000-10,000 Hz • High frequency – 10, 000- 100, 000, 000 Hz.


Q. 44. How do you classify low frequency stimulating currents? A. Low frequency stimulating currents are classified on the basis of pulse duration as: • Long duration currents- those with pulse duration > 1 m.sec, includes all types of muscle stimulating currents, such as rectangular, square, trapezoidal, triangular and trapezoidal pulses. • Short duration currents- those with pulse duration < 1 m.sec, , includes all types of nerve stimulating currents, such as faradic current, TENS, HVPGS, etc. Q. 45. What is the mechanism of action of low frequency stimulating currents? A. A single electrical impulse with appropriate pulse duration, strength and shape triggers an action potential in a nerve. This action potential spreads through out the nerve membrane to trigger momentary depolarisation of the nerve. In a motor nerve, this depolarisation spreads to the muscle, causing a muscle twitch and in a sensory nerve it creates a sensory impulse that is carried to the sensory receptors in the brain as a tingeing sensation. Q. 46. What are the requisite parameters to produce a response with a stimulating current? A. To produce a perceptible response in a nerve or muscle, the stimulating current must have: • Sufficient intensity, which must be equal to the rheobase value for long duration pulses and more than the rheobase value for short duration pulses. • Adequate rate of rise and fall from zero to peak intensity and back.

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Q. 47. What is the expected response to a series of stimulating current impulses applied to the skin? A. The reaction to such stimulation would be: • Stimulation of sensory nerve ending causing a tingling sensation at liminal intensity and pain at higher intensity. • Stimulation of motor nerves causing titanic muscle contraction. Q. 48. What are the expected responses to low frequency stimulation at commonly used rates of repetitions? A. Responses to low frequency stimulation at different rates of repetitions commonly used are: • 1Hz- Twitch muscle contraction along with sharp shock. • 10 Hz- Fast twitches of muscles along with tapping sensation. • 30 Hz – Rapid twitch contraction of muscles along with tingling sensation. • 100 Hz- Tetanic contractions of muscles along with strong tingling sensation. • > 100 Hz- Used as TENS for pain modulation. Q. 49. What are the therapeutic effects and uses of low frequency stimulation? A. Therapeutic low frequency stimulation are used for: • Strengthening of healthy muscles, even when immobilised. • Preventing atrophy in denervated or immobilised muscles and retaining functional capability of muscles at risk of disuse, through enhanced vascular turnover and metabolic activity. Other tissues in the vicinity are also benefited by increased drainage and supply of body fluids.

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• Building up or retaining voluntary muscle control. • Maintaining or increasing muscle joint range of motion. • As a functional aid, promoting voluntary muscle action, control hyper or hypo tonus and splint the limbs in functional position during activities of daily living. Q. 50. What are the mechanisms of action of electric charge, in producing therapeutic effects in the body? A. Therapeutic effects produced by application of electrical charge to the body are due to: • Direct current causes chemical changes, used in phonophoresis. • Low frequency currents cause stimulation of excitable tissues • High frequency currents cause heating • Low intensity D.C. and different types of pulsed currents can stimulate repair and growth in tissues. • Placebo effect

Q. 51. What are the primary considerations for application of therapeutic electricity? A. Following issues should be addressed satisfactorily for selection of any electrotherapy modality: • The effect desired i.e. pain relief, tissue healing or restoration of motor function. Modalities must be selected on the basis of the effect desired. • The extent of safety involved. All modalities have potential hazards. • The cost involved. The selection modality should be such that it achieves results in the shortest possible time. Q. 52. What are the primary mechanisms of pain modulation by TENS? A. Pain modulation by TENS is achieved by: • Activation of the spinal gate through sensory nerve stimulation • Release of indigenous opiates like Bendorphins, through stimulation of the nociceptors.

Index A

E

Absolute refractory phase 6 Actinotherapy 131 physics of 132 Action potential 5 propagation of 6,7

Electrical energy 11 Electrical field 2 behaviour of 2 Electrical impulses, types of 16 Electrical safety 10 Electrical stimulation 20,24, 36 Electrical stimulators 30-36 electrical muscle 30 functional electrical 30 high voltage galvanic 30 interferential therapy unit 30 neuromuscular stimulator 30 TENS 30 Electrical stimulus 16-19 nature of 16 strength duration curve 18 Electrophysiology 2 Electrotherapy unit, equipment safety in 11 Electrotherapy, safe application procedure of 12 Endorphin release theory, TENS 50

B

Bioelectrical drama, significance of 8 Bioelectricity 2 C

Combination therapy 113-115 biophysics of 113 contraindications for 115 important considerations 113 technique of application of 114 treatment protocol of 115 Conduction 6 antidromic 6 local circuit 7 orthodromic 6 Coupling mediums 100 Cryotherapy 119-129 application of therapeutic cold 129 biophysics of 119 cryo-kinetics 125 exercise-specific guidelines 126 physiological effects of 120 techniques of 121 commercial cold packs 122 contrast bath 123 coolant spray 123 ice massage 122 ice packs 121 ice towels 122 techniques of local cooling 128 D

Deep thermotherapy 142 Depolarisation 6

F

Fluorescence, phenominon 133 Functional electrical stimulation 58-61 application in 59-61 foot drop 61 hemiplegic’s shoulder 59 idiopathic scoliosis 60 effects and uses of 58 instrumentation of 59 parameters of current 58

High frequency currents 21 production of 86 subtypes of 21 High voltage pulsed galvanic stimulation 57 application of 58 effects and uses of 58 instrumentation of 58 parameters of current 57 Hyperpolarisation, phase of 6 I

IFT therapy 67-69 advanced interferential equipment 68 clinical application of 68 clover leaf pattern in 71 electrodes for application of 72 instrumentation of 68 isoplaner vector field application 71 treatment parameters to 69 treatment techniques to 70 Inverse square law, radiation 83 Iontophoresis 61-64 application in 63 hyperhydrosis 63 local anaesthesia 63 local inflammation 63 biophysics of 62 contraindications of 64 dosimetry of 62 electrodes for 63 indications for 62 ionising agents 63 ions commonly used in 64 technique of application 64

G

Gate control theory, TENS 50 H

Heliotherapy 130

L

Lambert’s cosine law, radiation 83 Low frequency currents 18 production of 21 subtypes of 19

150


M

Medium frequency current 20, 65-73 burst mode TENS 20 conventional TENS 20 current forms used in 21 interferential current 20, 65, 66 clinical applications of 73 clover leaf pattern 71 physiological effects of 67 therapeutic effects of 67 two pole medium frequency current 72 types of 71 medium frequency surge current 65,66 Russian current 65 selectively TENS 20 types of 65 Microwave diathermy 92-96 biophysics of 92 contraindications for 96 indications for 96 technique of application of 96 Modern low frequency electrical stimulators 30-47 clinical applications of 37 diagnostic electrical stimulator 31 diagnostic stimulator 30 electrode placement 35 machine preparations 32 patient preparations 33 rectal electrode 35 selection and preparation, electrodes 33 special type of electrodes 35 specialised techniques used in 44 faradic footbath 44 faradism under pressure 46 faradism under tension 47 techniques in, clinical conditions 37 in Bell’s palsy 38 in crutch palsy 41 in Erb’s/klumpke’s palsy 41 in fibromyositis of trapezius muscle 40

in foot drop/flail foot 43 in wryneck 39 therapeutic model 30 vaginal electrode 35 Motor point 23 Motor unit 17 N

Nernst potential 5 Nerve conduction velocity 9 Neuromuscular electrical stimulation 24 R

Red light therapy 136 biophysics of 136 methods of application of 137 types of 137 Relative refraction, phase of 6 Resting membrane potential 3,4 S

Short-wave diathermy 85-92 application of treatment with 91 biophysics of 85,87 cable method 91 condenser field method 90 contraindications of 89 disc electrodes used in 90 electrode placement 90 indications for 89 method of application 85, 86, 89 physiological effects of 88 technique, specific disease conditions 92 therapeutic benefits of 88 Static electricity 2 Stimulating current 19, 21 faradic type of current 20 interrupted galvanic current 19 iontophoresis 20 low frequency current forms 19 modulation of 22 production of low frequency 21 production using multivibrator circuit 22

wave patterns of 22 pure faradic current 20 transcutaneous electrical nerve stimulation 20 Superficial heat therapy 76-84 comparative profile of 84 contraindications for 78 indications for 77 physiological effect of 77 preparation of patient 78 transmission of 76 types of 79 Hubbard’s tank 81 hydrotherapy 79 moist hot packs—hydrocollator 79 paraffin wax bath 82 radiant heat–infrared rays 83 steam bath or sauna 82 whirlpool bath 80 T

Therapeutic current 18 types of 18 Therapeutic heat 76 Therapeutic lasers 138 different types of 139 hazards of 139 procedures and equipment of 141 Therapeutic light 132 types of 132 Therapeutic stimulating currents 146 Therapeutic ultrasound 99-111 biophysics of 99 contraindications for 103 digital ultrasonic machine 104 dosimetry of 116 indications for 102 phonophoresis 110 phonophoretic agents 111 physiological effects of 101 technique of application of 104 direct contact method 105 water bag method 106 water bath method 109 ultrasonic transducers 99

Handbook of Practical Electrotherapy

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