Paediatric CSF shunt complications

Introduction

• 60% of shunts require revising at some stage
• Complications may present with subtle, non-specific symptoms/signs
• Infection most common in first 6 months after insertion/revision
• Types
  • All have proximal tube that takes CSF to outer surface of skull
  • Subcutaneous one-way valve at this point and sometimes a pump +- anti-siphoning device
  • Distal tubing tunneled under skin to drainage site (often have valves to prevent back-flow)

Clinical presentation

• Bulging fontanelle (undershunting)
• Sunken fontanelle (overshunting)
• Increased head circumference (undershunting)
• Signs and symptoms that on their own warrant referral to neurosurgical service
  • Bulging fontanelle
  • Decreased LOC
  • Fluid tracking around shunt tubing
  • Loss of upward gaze (sunset eyes)
  • Signs of local infection – Erythema, erosion/ulceration, CSF leak, purulent drainage
  • Meningismus
  • Peritonitis
• Absence of above does not rule OUT shunt complications
  • This is where Ix may be required

History

• Most commonly vomiting, headache, drowsiness
• Seizure alone has poor correlation (as lots of children with shunts also have epilepsy
• Abdominal pain and distension if distal complication
• Fever, lethargy, irritability or meningism suggest infection

Examination

• Examine course of shunt
  • Look for inflammation along route
  • Shunt-pump test
    • Most silicone pump bulbs can be compressed easily and refill in seconds
    • If incompressible, usually distal occlusion
    • If compresses easily but does not refill, proximal occlusion (most common site of occlusion)
    • Can be difficult to perform
    • Only perform once or twice as can lead to debris into catheter and low-pressure headache
  • CSF tracking around proximal catheter may cause fluctuant swelling
• Check for peritonism/pleurisy (distal drainage)

Investigations

• Needle drainage
  • Neurosurgeons can insert needle into pump chamber
  • If moribund, can relieve raised ICP by inserting 25G butterfly needle into pump chamber at 45 degrees to skin with strict aseptic technique
  • Can measure with manometer and remove CSF until pressure 10cmH20
• If stable:
  • X-ray of course of shunt may show disconnection or kink
  • CT is preferred method  but need to keep child still
    • Enlarged ventricles may indicate undershunting but need to compare to old images
    • Obliteration of perimesencephalic cistern mandates urgent neurosurgical consult
    • May show ventriculitis (ventricular enhancement with contrast) or site of blockage
    • Small ventricles may indicate overshunting, which leads to sharp fluctuations in ICP

Shunt infection

• 80% in first 9 months after any manipulation
• 1/3 of shunt malfunction are due to infection
• ¼ of fever cases are due to infection
• ¼ of localised wound or shunt tract inflammation are due to infection
• 20% of abdominal pain presentations are due to shunt infection
• CSF WCC elevated in 70% of cases
  • Blood WCC elevated in only 30%
• S. epidermidis is most common, then other coagulase-negative staph, S. aureus
• Antibiotic cover in concert with neurosurgeons – Flucloxacillin +- gram-negative cover

Trauma in children with shunts

• Was there a direct impact on hardware?
  • May cause breakage and malfunction even in minor trauma
  • May manifest weeks later
• Shunt penetration of abdominal viscera is a possibility
• Is there an open wound that may communicate with the shunt or CSF?
  • Scalp wound near entry point of tubing into cranial cavity may cause pneumocephalus and meningitis
• Risk of subdural haematoma from rupture of bridging veins that have been stretched by brain shrinkage after shunt placement

Last Updated on November 10, 2021 by Andrew Crofton