Initial Management at Presentation
Management of shunt infection
- Evaluate for shunt malfunction: Determine if ICP is elevated due to failure of the infected shunt; this is probably the most imminent threat to the patient’s life.
- Remove infected hardware: Remove infected hardware and insert EVD catheter. Infected hardware represents a reservoir for microorganisms. If the patient has evidence of persistent hydrocephalus, a temporary CSF diversion to the exterior is mandatory.
- Evaluate for other infections and complications: Rule out potential associated infected shunt complications.
- Tailor antibiotic coverage to infective organism(s): Obtain microbiological samples of CSF and infected hardware for cultures. Once the strain is isolated and its antibiotic sensitivity determined, tailor antibiotic treatment accordingly.
Management of suspicion of shunt infection
Other presentations, which can be extremely challenging, may arise. Examples are as follows:
- Normal CSF profile but positive culture: The patient has a positive culture without evidence of CSF cytochemical abnormalities. Usually these cultures are obtained in a child who has been worked up for suspected shunt malfunction. If the patient has improved and there is no present evidence of shunt malfunction, a new tap should be performed to confirm if there is colonization of the shunt reservoir. If colonization is confirmed, the shunt can be removed and replaced in the same procedure. CSF from the ventricular insertion is always checked for final cultures.
- Normal CSF profile and abdominal pseudocyst: The patient has an abdominal pseudocyst with negative CSF findings on shunt tap examination. For this patient, the distal catheter should be exteriorized below the clavicle under local anesthesia, the catheter is cut, and the proximal end is connected to an EVD drainage system. The distal catheter is then aspirated in an attempt to decompress the cyst. If the aspiration is unsuccessful, the cyst can be punctured percutaneously with the aid of ultrasound guidance. Samples of fluid removed with these aspirations and fluid aspirated from the proximal shunt are sent for prolonged cultures in search of Actinomyces sp. or Staphylococcus sp.
- Normal CSF, negative cultures, but cellulitis: The patient with a cellulitis surrounding the distal catheter with a normal CSF and negative cultures can benefit from prompt shunt removal and replacement on the opposite side with concurrent systemic antibiotic therapy. This will lessen the risk for spread of the infection to the CNS.
- CSF profile suggests infection, EVD placed, but cultures yield no growth: This group of patients usually has received partial antibiotic treatment for other suspected illnesses. Therefore, they typically have CSF levels of antibiotic that are bacteriostatic but not bactericidal at the time of their initial evaluation for a shunt infection. The author routinely treats them for 21 days with antibiotics, and cultures will be held in the laboratory for up to 10 days in search of Propionibacterium acnes or other slow-growing organisms.
- Antibiotics: Antibiotic therapy, tailored to the isolated agent causing the infection, remains the mainstay for control and cure of CSF shunt infections.
- Anticonvulsants: Patients with associated seizures should receive adequate seizure control medication, which can be provided intravenously (midazolam, diazepam, phenobarbital, phosphenitoin, phenytoin) or orally once the patient has been stabilized.
- Fluid replacement therapy: Newborns and small children with a high CSF output may require adequate IV fluid replacement 1:1.
- Nutritional management: Patients under septic conditions and with high protein CSF output with long-term EVD therapy may require serial checks of total serum protein content with adequate albumin or enteric formulas.
- Hydrocephalus control: Infection in the CSF cranial and spinal spaces can modify the dynamics of CSF flow because the inflammation it triggers alters the compliance and elastance of ventricular walls and results in scarring with the formation of isolated cavities within the ventricles. Treatment can be complicated, with shunting requiring multiple catheters and endoscopy requiring thoughtful guidance. Serial CT follow-up is needed to determine if the hydrocephalus has been effectively treated.
- Wound integrity: An office visit is scheduled 10 days postoperatively to check the integrity of wounds and remove suture material if appropriate.
- Associated complications follow-up: Patients with evidence of brain abscess, empyemas, or retained shunt hardware should be screened with serial imaging to determine if the infection has been eradicated. Other complications such as seizures, cognitive impairment, or learning disabilities should be addressed by the appropriate health professional.