VP Shunt – Over-Drainage — SCE Neurology MCQ

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ModerateNeurodegenerative DiseaseVP Shunt – Over-DrainageSCE Neurology

A 60-year-old man with a diagnosis of normal pressure hydrocephalus undergoes VP shunt insertion. Post-operatively, he develops headache when sitting up that is relieved by lying flat. CT head shows slit-like ventricles. What has occurred?

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Correct answer: C — Shunt over-drainage (low-pressure syndrome) — the shunt is draining CSF faster than it is produced, causing intracranial hypotension

Over-drainage is a common VP shunt complication where CSF drains faster than production, causing intracranial hypotension. Symptoms include postural headache (worse upright, better supine), nausea, and slit-like ventricles on CT. It can lead to subdural collections (hygroma or haematoma) from bridging vein traction. Management includes adjusting the shunt valve pressure (programmable valves allow non-invasive pressure changes), adding an anti-siphon device, or lying flat temporarily. A: Infection causes fever, meningism, wound inflammation. C: Blockage causes recurrent hydrocephalus with enlarged ventricles. D: Subdural haematoma can result from over-drainage but slit ventricles are the primary finding. E: Postural headache with slit ventricles is pathological.

Reference: EAN NPH Guidelines; Neurosurgical Principles