Normal pressure hydrocephalus vs Alzheimer disease
How to tell Normal pressure hydrocephalus and Alzheimer disease apart when a board question makes them look alike.
NPH is gait plus bladder plus cognition with big ventricles; Alzheimer is memory-first gradual neurodegeneration.
Side by side
Normal pressure hydrocephalus causes gait disturbance, urinary urgency/incontinence, and cognitive decline with ventriculomegaly out of proportion to cortical atrophy and often normal opening pressure.
Alzheimer disease causes gradual episodic memory loss and impaired new learning with cortical/hippocampal atrophy rather than the classic gait-first hydrocephalus triad.
Communicating hydrocephalus enlarges ventricles and disrupts periventricular frontal-subcortical gait and bladder circuits.
Amyloid and tau neurodegeneration injures hippocampal and association cortex memory networks.
Magnetic gait, urinary incontinence, dementia, ventriculomegaly disproportionate to sulcal atrophy, and improvement after CSF drainage support NPH.
Progressive amnestic syndrome with medial temporal atrophy and no ventriculomegaly-out-of-proportion pattern supports Alzheimer disease.
The trap
Both can cause dementia, but early gait/bladder symptoms and ventriculomegaly point to NPH.
The repair move
For dementia with gait symptoms, check whether ventricles are too large for the amount of atrophy.
Try a free question
CoreAn older adult develops magnetic gait, urinary incontinence, and cognitive slowing. MRI shows ventriculomegaly out of proportion to cortical atrophy. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Normal pressure hydrocephalus. Gait, urinary symptoms, cognitive decline, and ventriculomegaly out of proportion to atrophy point to NPH.
Why the other choices are tempting
- B. Alzheimer disease is gradual memory-first dementia without the classic hydrocephalus triad.
- C. Frontotemporal dementia is behavior or language-first.
- D. Huntington disease causes chorea with psychiatric and cognitive decline.
- E. Wernicke encephalopathy is acute confusion, ataxia, and ophthalmoplegia.
Flashcards
Tap a card to flip it.
What triad points to normal pressure hydrocephalus?
Gait disturbance, urinary incontinence, and cognitive decline point to NPH.
What imaging clue supports NPH over Alzheimer disease?
Ventriculomegaly out of proportion to cortical atrophy supports NPH.
Quick answers
What is the fastest way to tell Normal pressure hydrocephalus from Alzheimer disease?
NPH is gait plus bladder plus cognition with big ventricles; Alzheimer is memory-first gradual neurodegeneration.
What is the key clue for Normal pressure hydrocephalus?
Normal pressure hydrocephalus causes gait disturbance, urinary urgency/incontinence, and cognitive decline with ventriculomegaly out of proportion to cortical atrophy and often normal opening pressure.
What is the key clue for Alzheimer disease?
Alzheimer disease causes gradual episodic memory loss and impaired new learning with cortical/hippocampal atrophy rather than the classic gait-first hydrocephalus triad.
What is the common trap with Normal pressure hydrocephalus vs Alzheimer disease?
Both can cause dementia, but early gait/bladder symptoms and ventriculomegaly point to NPH.