A 68-year-old man develops a wide-based gait over 6 months, followed by urinary urgency and slowing of thought. MRI shows ventricular enlargement out of proportion to cortical sulcal atrophy. Lumbar tap test improves his gait. What is the most likely diagnosis?

• A Progressive supranuclear palsy
• B Vascular parkinsonism
• C Alzheimer disease with coexisting lumbar canal stenosis
• D Normal pressure hydrocephalus ✓

Explanation

The classic triad of gait apraxia (usually the earliest sign), urinary incontinence, and subcortical dementia with disproportionately enlarged ventricles defines normal pressure hydrocephalus. Improvement after CSF removal (tap test) supports the diagnosis and predicts response to ventriculoperitoneal shunting. In PSP the gait problem is due to balance loss with vertical gaze palsy, not ventriculomegaly, and it would not improve with a tap test.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.