Infectious Disease
[BRAIN INFLAMMATION]
Presentation and Differential Any brain inflammation will present with a backbone of fever + a headache. This is nonspecific for a particular diagnosis but antennae should go up for “problem in the brain.” Other signs and symptoms symptoms that help (photophobia, N/V, and seizures ) may be present but but are likewise likewise nonspecific. nonspecific. There There are 3 categories categories of of disease - each with their own unique findings. 1) Meningitis will have a stiff neck (Kernig and Brudzinski’s Signs). 2) Abscesses will present with Focal Neurological Deficits. 3) Encephalitis will present with encephalopathy (aka confusion).
Fever and a Headache + FND
Abscess or Cancer
Fever and
Fever and a Headache
Meningitis
a Headache + Stiff Neck
Fever and a Headache +Confusion
Eastern Equine Western Equine St Louis HSV Many Others
Encephalitis Meningitis Meningitis is inflammation of the meninges caused by any # of etiologies. The challenge is to identify which organism is most likely, confirm it, then treat it. The definitive test is the Lumbar Puncture. It gives a wealth of information (glucose, protein, cells) of the CSF as well as a body fluid for Gram Stain and Culture. It should be done before treatment is started. However, if the patient presents with signs and symptoms of ↑ICP a CT scan must be done 1st. That is: 1) Papilledema, 2) Focal Neurological Deficits , or 3) Confusion . If a CT scan is required empiric antibiotics should be given before the LP. This is the ONE time where you’ll treat before a culture (this decreases the sensitivity of the culture but it saves l ives). Once the LP/Tap is done CSF is analyzed. Glucose / Protein / # cells are useful but are Ø sensitive enough for treatment. One value can tell bacterial (1000s of PMNs ) or not. If bacterial, treat empirically while cultures grow. For immunocompetent patients give ceftriaxone. If immunosuppressed, add Ampicillin for Listeria. This will be the elderly neonate on steroids for the organ transplant with HIV. No matter their state, all patients get IV steroids for bacterial meningitis. If the tap comes comes back “Ø bacterial” we’re forced with a dilemma. The disease it is easy to diagnose if you know it’s there. To know it’s there look at history and risk factors. 1) HIV/AIDS point towards a potential Cryptococcus infection. Though India Ink is specific it’s not sensitive. Get a Cryptococcus Cryptococcus Antigen. 2) A targetoid rash on a hiker from the North East points towards Lyme disease. Get the Lyme Antibody and treat with ceftriaxone (not the doxycycline used for arthralgias). 3) A peripheral rash that develops proximally from the hands indicates Rocky Mountain Spotted Fever. Look for the RMSF Antibody and treat with ceftriaxone. 4) A history of homelessness or prison with fever/night sweats/weight loss/hemoptysis looks like TB. Get an and treat with 5) AFB RIPE. o STDs /Chancre /2 Rash/DCMLS point towards towards syphilis. Get an RPR on the CSF. They get 14 days of penicillin. 6) Viral is a diagnosis of exclusion and nothing can be done for it.
Bacterial Crypto TB Lyme Rocky Mountain Syphilis Listeria
Fever and a headache + Stiff Neck s/s of ↑ICP
Unsafe LP CT Scan
Safe LP
Normal
Abnormal
Lumbar Puncture
Anything
Mass
Else
Ø Bacterial
Bacterial
HIV ?
Yes
1000s of Polys
Immuno Im munocom com rom romise ise
No
Toxo
Abscess
Bx
No
Abx + Drain Cancer
Tx x6 wks Rescan
Chemo/Rads
Yes
Ceftriaxone Steroids
Ceftriaxone Steroids Ampicillin
Hx + Clx guides test
TB RIPE
Toxo
Crypto
Lyme
RMSF
Pyrimethamine
Amphotericin + Fluconazole CD>350
Ceftriaxone
Ceftriaxone
Bug Bacterial Viral Fungal TB Bug RMSF Lyme Crypto TB Syphilis Listeria Viral
Lumbar Puncture Puncture Findings Findings Cell Count Glucose Protein WBC PMNs ↑↑↑ ↓↓ ↑ Lymph ↑ ↑ Lymph ↑ ↓ ↑ Lymph ↑ ↓ ↑ Suspicious Hx Rash on hands, Spread Proximal Targetoid Rash, Hiker, Ticks HIV/AIDS Pulmonary TB STD, Palmar Rash, DCMLS Elderly Neonate on Steroids Diagnosis of Exclusion
Test Antibody Antibody Antigen AFB RPR -
© OnlineMedEd. http://www.onlinemeded.org
Tx Ceftriaxone
RIPE Tx Ceftriaxone Ceftriaxone Amphotericin RIPE Penicillin Ampicillin -
Infectious Disease
[BRAIN INFLAMMATION]
Encephalitis Encephalitis presents as a fever and a headache with confusion. Because there is confusion a CT scan is performed 1 st (usually with a dose of ceftriaxone). The CT will be normal. A Lumbar puncture will follow. Unless some bizarre travel has occurred or the person was bit by a fox (rabies), the only thing to be concerned with is Herpes Simplex Virus. The tap will have both WBC (“it is”, separating it from a SAH or traumatic tap) and RBC. When normal CT + WBC/RBC is seen in LP, do HSV PCR to confirm the diagnosis while treating with acyclovir . The diagnosis of HSV may be suspected if there’s any information about “temporal lobe” or “anosmia. ” Abscess vs Cancer (Mass Lesions) Since mass lesions present as a fever and a headache with Focal Neurological Deficits , this will also require a CT scan before the LP - usually with a dose of ceftriaxone. The CT will come back for a ring enhancing lesion; it’ll be contraindicating with the lumbar puncture. Instead, additional investigation of the mass must take place (i.e. a Biopsy). This will tell us if there’s an abscess requiring drainage and investigation of a primary source, ( organisms) or if it’s a cancer requiring radiation and chemo. Antibiotics won’t work for a cancer and chemo/radiation won’t work for an abscess.
Fever and a headache + Confusion CT Scan
Normal Encephalitis vs Meningitis Lumbar Puncture
Polys
Lymphs
Meningitis
Encephalitis
HSV PCR
HSV Acyclovir
You can’t do anything anyway
Fever and a headache + Confusion CT Scan
Normal Mass
There’s one exception to jumping to a biopsy - an HIV/AIDS patient. In a patient with a CD4 count < 200, the mass is Toxoplasmosis 90% of the time. For this patient treat empirically with pyrimethamine for 6 weeks . If there’s improvement keep it going. If not, go to biopsy. If “treat empirically” isn’t an option look for Toxoplasmosis-Ab.
Yes
HIV CD4 <200
Pyrimethamine Sulfadiazine
No
Biopsy
Presumed Toxo
Ø Improve Cancer
Abscess
Cancer
I&D Antibiotics
Chemo/Rads
CT scan
Improve Toxo Pyrimethamine Sulfadiazine
© OnlineMedEd. http://www.onlinemeded.org
