A 70-year-old man presents with a 3-month history of progressive gait difficulty described as 'magnetic gait', urinary incontinence, and cognitive decline. CT shows enlarged ventricles out of proportion to sulcal prominence with no obstructive lesion. Lumbar puncture opening pressure is normal, and CSF drainage produces transient gait improvement. What is the most likely diagnosis?

• A Normal pressure hydrocephalus (NPH) ✓
• B Alzheimer's disease
• C Parkinson's disease
• D Multi-infarct dementia

Explanation

The classic triad of gait apraxia (magnetic gait), urinary incontinence, and dementia with ventriculomegaly disproportionate to atrophy and normal CSF pressure defines idiopathic normal pressure hydrocephalus. B positive CSF tap test (gait improvement after removing 30-50 mL CSF) predicts shunt responsiveness. Alzheimer's has cortical atrophy without disproportionate ventriculomegaly. Parkinson's shows rigidity and tremor. Multi-infarct dementia shows stepwise decline with imaging evidence of infarcts (Adams and Victor, Principles of Neurology, 11th ed.).

Reference: Adams and Victor's Principles of Neurology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.