Ventriculoperitoneal shunt problems

Background

• Also called a cerebral sinus fluid (CSF), VP, or cerebral shunt
• Highest incidence of postoperative complications of any neurosurgical procedure
  • Majority in the first 2 years (40% in the first year)
• May drain into peritoneal cavity or less commonly the right atrium, pleural cavity, ureter, gallbladder

Clinical Features

• Develop over several days

Adults

• Cephalgia, nausea and vomiting, lethargy, ataxia, altered mental status
• Paralysis of upward gaze ("sunset eyes"), dilated pupils, cranial nerve palsies

Infants

• Vomiting, irritability, bulging fontanelle
  • Often very subtle: a caregiver-reported change in behavior predicts malfunction

Differential Diagnosis

Ventriculoperitoneal shunt problems

• Ventriculoperitoneal shunt obstruction
• Ventriculoperitoneal shunt overdrainage (Slit Ventricle Syndrome)
• Ventriculoperitoneal shunt infection
• Ventriculoperitoneal shunt mechanical failure

Loculation of Ventricles

• Separate, noncommunicating CSF accumulations may develop within a ventricle
  • Shunt device unable to drain entire ventricular system leading to increased ICP

Abdominal Complications

• Pseudocyst may form around the peritoneal catheter
  • Can lead to occlusion and/or abdominal pain (depending on size)

Evaluation

• Physical Exam
  • Neither Sn nor Sp
  • Decreased level of consciousness, erythema along shunt tract, buldging fontanel, nausea/vomiting, irritability should raise suspicion
• Valve chamber abnormality
  • Gently compress chamber and observe for refill
  • Difficulty compressing chamber indicates distal flow obstruction
  • Slow refill (>3s) indicates proximal obstruction

Work Up

• CBC, Chem7, coags
• Blood cultures
• Shunt tap if concerned for infection (this is usually done by or in consultation with neurosurgery)
  • A normal lumbar puncture does not rule out ventriculitis (shunt infection)
• Imaging
  • Shunt series
    • AP and lateral skull, AP chest and abdomen
    • Identifies kinking, migration, or disconnection
  • CT
    • Needed to evaluate ventricular size (if larger, concerning for elevated ICP)
    • Very helpful to compare to previous study (many patients with shunts have abnormal baseline)
    • One-third of patients with shunt malfunction will have normal head CT^{[citation needed]}
  • US
    • If the baby has an open fontanelle, you may use US
    • Some literature for ultrasound of optic nerve diameter (if normal (3.3cm), lower chance of elevated ICP)^{[citation needed]}

Management

• Assume shunt malfunction in patients with suggestive features regardless of findings on imaging
• Revisions are extremely common, low threshold to contact Neurosurgery
• Ventriculoperitoneal shunt drainage

See Also

• CSF Studies

References

Authors

Ross Donaldson