Shunt Externalization

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Thieme eNeurosurgery ‑ procedures

PROCEDURES

Edison Patricio Valle, Cong J. Bui

Shunt Externalization

Introduction and Background

Operative Detail and Preparation

Outco Ou tcomes mes an and d Pos Posto tope perat rative ive Co Cour urse se

Referen Re ferences ces

Ventriculoperitoneal shunt placement is one of the most common procedures performed in neurosurgery and the most common procedure performed by pediatric neurosurgeons. The infection rate ranges from 8–15%, with 10% being generally accepted. The greatest risk for infection is within the first 6 months of the original implantation. Shunt infection is often treated with antibiotics and cerebrospinal fluid (CSF) diversion. Shunt externalization with systemic with or without intraventricular antibiotics is an effective option for CSF diversion in the setting of shunt infection. Temporary shunt externalization may also be needed for other abdominal pathologies in shunt-dependent patients.

Alternate Procedures Conservative treatment with antibiotics (systemic ± intraventricular) without externalization or removal of shunt hardware Patients with Staphylococcus aureus shunt infections should not be treated conservatively. Removal of entire shunt system External ventricular drainage af af ter ter removal of shunt system Repositioning of distal cat catheter in another location (pleura, (ple ura, gallbladder, atrium)

Goals To divert CSF in patients with hydrocephalus and active shunt/CSF infections To prevent the spread of an abdominal infection to the proximal portion of the shunt in patients with intraabdominal infections To allow intraabdominal pseudocysts to resolve while CSF is diverted

Advantages Allows for CSF diversion without removing the entire shunt Allows for CSF diversion without a new incision or catheter placement (external ventricular drain) https://eneurosurgery.thieme.com/app/procedures/view?startnum=150&id=978‑1‑60 https://eneurosurgery.thieme.com/app/procedures/view?startnum= 150&id=978‑1‑60406‑335‑6&q=cat… 406‑335‑6&q=cat…

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Minimally invasive procedure Allows for the possibility of internalization without cranial access Does not restrict activity as much as an external ventricular drain The presence of a valve allows for more-regulated CSF drainage

Indications Abdominal loculated pseudocyst Shunt infection Shunt infection in which the lateral ventricles are slit and difficult to cannulate with an external drainage catheter Peritonitis Major abdominal or pelvic surgery in which peritoneal contamination is likely and/or possible Abdominal wall infections Major abdominal trauma Meningitis Distal tubing erosion into the abdominal viscus To prevent tumor spread into the abdomen when there is tumor infiltration into the CSF

Contraindications Proximal catheter occlusion Valve breakage or malfunction Active infection (pus) within the valve or tubing

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PROCEDURES





Outcomes and Postoperative Course

References

Preoperative Planning and Special Equipment If a shunt infection is suspected, an infection workup should be performed (complete blood count (CBC) with differential, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), blood cultures, urinalysis (UA), and chest x-ray in conjunction with radiographic evaluation of the entire shunt system (head computed tomography [CT] and shunt series). If an abdominal pseudocyst is suspected, then an abdominal CT or ultrasound should be performed. If a pseudocyst is present, one must always consider the potential for infection. One should be able to identify the entire tract of the shunt system on x-ray to ensure that there are no disconnections. It is important to identify residual tubing from previous shunt systems to ensure that the correct tubing is externalized. An external drainage kit or CSF collection bag should be available. A connector should be available to ensure a tight connection between the externalized tubing and the drainage collection system. An 18-gauge blunt-tipped needle may be used if a connector is not available. One should be prepared to obtain CSF for culture once the shunt is externalized. One should be prepared to aspirate a pseudocyst through the externalized catheter (via the abdominal end of the tubing). One should be prepared to remove the entire shunt system and place an external ventricular drain if the externalized shunt is occluded or grossly infected.

Expert Suggestions / Comments Tapping the shunt prior to externalization not only collects CSF for analysis, but also establishes that there is proximal flow. https://eneurosurgery.thieme.com/app/procedures/view?startnum=150&id=978‑1‑60406‑335‑6&q=cat…

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The authors suggest externalizing the shunt catheter as distally as possible to allow for the option of internalization without reopening at the valve site. If the patient is obese or the tubing is difficult to find, one can palpate for the catheter at the level of the clavicle. Deep intravenous sedation or general anesthesia may be used when possible. This procedure can be done with local anesthetic only, but the potential for difficult dissection exists. Electrocautery is used on a low setting to dissect around the tubing. This is safer than dissection with sharp instruments. For young or uncooperative patients, enough tubing is externalized so that the external segment can reach behind the flank and be taped to the back. This minimizes the patient’s manual manipulation of the catheter and thus reduces the likelihood of breakage of the tubing.

Key Steps of the Procedure A standard operating room set-up is utilized for these procedures. The patient is positioned in a manner that allows for access to the entire shunt system if necessary. A meticulous and wide prep area allows for an alternative site of externalization should the primary site be problematic. The shunt tubing or tract in the area of planned externalization is palpated. Local anesthetic is given in a dose appropriate to the patient’s weight. A small transverse incision is made (usually 1–1.5 cm) over the tubing. The authors use a Colorado Bovie tip or an insulated Bovie set at a low setting (cutting: 6, coag: 15) to perform the soft tissue dissection down to the tubing. This allows for an aggressive dissection without prematurely cutting the tubing. Once the tubing is visualized, the cranial and caudal ends should be clearly identified. The tubing should be pulled out from the caudal end. If there is a pseudocyst, after ~5–6 cm of the catheter has been externalized, the tubing is cut and aspiration from the distal tubing is performed to decompress the pseudocyst and obtain culture specimens. All distal tubing is then removed from the abdomen. The exposed proximal tubing is then connected via a connector system or a blunt-tip needle to a closed disposable external drainage system (Fig. 1).

Fig 1 Steps involved in shunt externalization. ( A ) Location of the skin incisi on shown below the clavicle at the site of the shunt tubing. ( B ) Externalization of the catheter is shown using careful dissection. Ultrasound localization may be used to evaluate presence of a pseudocyst. ( C ) If a pseudocysts or pus pocket is present, it may be aspirated via the distal catheter remnant using a syringe attachment. ( D ) Once the proximal portion of the distal catheter is externalized, it may be connected to a draining chamber and set to drain passively under gravity. The distal portion of the distal catheter is removed and the wound is secured. The wound is then closed in layers and occlusive dressings are applied to keep the tubing and connector from being dislodged.

Avoidances / Hazards / Risks https://eneurosurgery.thieme.com/app/procedures/view?startnum=150&id=978‑1‑60406‑335‑6&q=cat…

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If using a scalpel to dissect down to the tubing, it should be used with great care as this may cause inadvertent damage to the tubing. If the tubing has been in place for a long time, a calcified tract often forms around the tubing. This often requires more extensive dissection. Multiple incisions may be needed to externalize and/or remove old tubing. An incision that is too small may make dissection more difficult. One should avoid performing the procedure with only local anesthetic in young children or infants. Reinternalizations should not be performed until the CSF clears and infectious markers normalize (the authors routinely wait for the patient to be afebrile for at least 72 hours, with three consecutively negative CSF cultures, and normalization of laboratory values). Leaving an externalized shunt in place for more than 2 weeks should be avoided when possible.

Salvage and Rescue If the shunt tubing cannot be palpated or localized, C-arm fluoroscopy can be useful. Fibrous or calcified sheets around the shunt tubing should not be mistaken for the tubing itself. This layer should be extensively removed to gain adequate exposure to the actual tubing. In the case of tubing breakage, straight connectors can be used to salvage an adequate length of externalized tubing. If the CSF does not clear despite adequate antibiotics, then removal of the entire shunt system must be considered. If there is any question about the functionality of the shunt or infection of the shunt hardware, then the shunt system can be replaced with an external ventricular drain.


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PROCEDURES






References

Postoperative Considerations Because CSF drainage is still rate-controlled by the valve, shunt externalization does not require the same leveling and activity restriction as external ventricular drains. Serial CSF sampling can aide in tracking the course of an infection. Antibiotic treatment should be tailored to specific infectious organisms. Systemic and intraventricular antibiotic(s) should be considered in patients with complicated or recurrent infection. The authors generally wait for three consecutive “clean CSF” samples before reinternalization. If the shunt is externalized for noninfectious reasons, prophylactic antibiotics are recommended; however, their use is not yet well established in the literature.

Complications Proximal catheter occlusion while the shunt is externalized Tubing breakage, damage, or inability to locate the tubing Reinfection. The reinfection rate varies with the type of organism (Staphylococcus epidermidis has one of the highest rates of reinfection). Prolonged infection. Removal of the entire shunt system and intraventricular antibiotics should be considered if an infection does not clear with the appropriate antibiotics.


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PROCEDURES

Edison Patricio Valle, Cong J. Bui Shunt Externalization




References

1. Arnell K , Enblad P , Wester T , Sjölin J . Treatment of cerebrospinal fluid shunt infections in children using systemic and intraventricular antibiotic therapy in combination with externalization of the ventricular catheter: efficacy in 34 consecutively treated infections. In: J Neurosurg . 2007 ; 107 ( 3 ): 213 - 219 2. Brown EM , Edwards RJ , Pople IK . Conservative management of patients with cerebrospinal fluid shunt infections. In: Neurosurgery . 2008 ; 62 ( ): 661 - 669 3. Brown JA , Medlock MD , Dahl DM . Ventriculoperitoneal shunt externalization during laparoscopic prostatectomy. In: Urology . 2004 ; 63 ( 6 ): 1183 - 1185 4. Dasic D , Hanna SJ , Bojanic S , Kerr RSC . External ventricular drain infection: the effect of a strict protocol on infection rates and a review of the literature. In: Br J Neurosurg . 2006 ; 20 ( 5 ): 296 - 300 5. de Oliveira RS , Barbosa A , Vicente YA , Machado HR . An alternative approach for management of abdominal cerebrospinal fluid pseudocysts in children. In: Childs Nerv Syst . 2007 ; 23 ( 1 ): 85 - 90 6. Donovan DJ , Prauner RD . Shunt-related abdominal metastases in a child with choroid plexus carcinoma: case report. In: Neurosurgery . 2005 ; 56 ( 2 ): E412 - , discussion E412 7. James HE , Bradley JS . Management of complicated shunt infections: a clinical report. In: J Neurosurg Pediatr . 2008 ; 1 ( 3 ): 223 - 228 8. Li G , Dutta S . Perioperative management of ventriculoperitoneal shunts during abdominal surgery. In: Surg Neurol . 2008 ; 70 ( 5 ): 492 - 495, discussion 495–497 9. Morissette I , Gourdeau M , Francoeur J . CSF shunt infections: a fifteen-year experience with emphasis on management and outcome. In: Can J Neurol Sci . 1993 ; 20 ( 2 ): 118 - 122 10. Muttaiyah S , Ritchie S , John S , Mee E , Roberts S . Efficacy of antibioticimpregnated external ventricular drain catheters. In: J Clin Neurosci . 2010 ; 17 ( 3 ): 296 - 298 11. Thomas DD, Kureshi SK, George TM. Infected ventriculoperitoneal shunts. In Goodrich JT, ed. Neurosurgical Operative Atlas. Pediatric Neurosurgery. 2nd ed. https://eneurosurgery.thieme.com/app/procedures/view?startnum=150&id=978‑1‑60406‑335‑6&q=cat…

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New York, NY: Thieme Medical Publishing; 2008:233–240


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Shunt Externalization

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