A 68-year-old man presents with a magnetic gait, urinary urgency, and progressive slowing of cognition over 8 months. CT head shows ventriculomegaly out of proportion to sulcal atrophy. Lumbar puncture reveals an opening pressure of 13 cmH2O with normal CSF composition. The most likely diagnosis is:
- A Alzheimer disease
- B Parkinson disease
- C Normal pressure hydrocephalus ✓
- D Multi-infarct dementia
Correct answer: C. Normal pressure hydrocephalus
Explanation
The classic triad of gait apraxia, urinary incontinence, and dementia with ventriculomegaly but a normal opening pressure defines normal pressure hydrocephalus, thought to reflect impaired CSF absorption despite preserved production. Gait disturbance typically appears first, distinguishing it from Alzheimer disease, where memory loss precedes any gait problem. Parkinson disease features rigidity and tremor rather than a wide-based magnetic gait with ventriculomegaly.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.