A 72-year-old man develops a progressively widening, magnetic gait, urinary urgency, and slowing of cognition over 6 months. MRI shows ventricles enlarged out of proportion to cortical sulci, without a mass. Lumbar drainage of 30 mL of CSF improves his gait. What is the definitive treatment?

• A Endoscopic third ventriculostomy
• B Levodopa trial before any surgical decision
• C Acetazolamide and serial lumbar punctures lifelong
• D Ventriculoperitoneal shunt insertion ✓

Explanation

Idiopathic normal pressure hydrocephalus classically produces the triad of gait apraxia (the earliest and most responsive sign), urinary urgency, and cognitive slowing, with ventriculomegaly disproportionate to sulcal atrophy. Improvement after removal of CSF, the tap test, predicts a good response to a ventriculoperitoneal shunt, which is the definitive treatment. Endoscopic third ventriculostomy works for obstructive hydrocephalus but performs poorly in idiopathic NPH, and levodopa responsiveness would favour parkinsonism instead.

Reference: Greenberg Handbook of Neurosurgery, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.