Normal pressure hydrocephalus
Impaired CSF absorption → ventriculomegaly at normal pressure
Overview
A potentially REVERSIBLE cause of dementia: the classic triad of gait apraxia, urinary incontinence and cognitive impairment ("wet, wacky, wobbly") with ventriculomegaly but a normal CSF pressure. CSF shunting can improve it — so it must not be missed among the dementias.
Recognise
- Triad: GAIT apraxia (magnetic, shuffling — usually first) + urinary INCONTINENCE + cognitive (dementia) decline
- Ventricular enlargement out of proportion to sulcal atrophy on imaging
- Older adults; gait often improves after CSF removal
Red flags
- A reversible dementia mimic — worth identifying because shunting can help
Differentials & how to tell them apart
Investigations
CT/MRI (ventriculomegaly disproportionate to atrophy); large-volume LP ("tap test") — gait improvement after CSF removal predicts shunt response; normal opening pressure.
Management
Ventriculoperitoneal shunt (after a positive CSF tap test)
- 1Imaging (disproportionate ventriculomegaly) + a high-volume LP tap test; gait improvement after CSF removal predicts shunt benefit.Gate: The opening pressure is NORMAL (hence "normal pressure") — diagnosis rests on the triad + imaging + tap-test response, not a raised pressure
- 2Ventriculoperitoneal shunt for responders; monitor for shunt complications.
Key points
"Wet, wacky, wobbly" with big ventricles at normal pressure = NPH — the dementia you can sometimes reverse with a shunt. Gait is usually the first and most shunt-responsive feature.
Monitor & prognosis
Gait, cognition, continence; shunt function/complications.
Variable; earlier shunting (gait-predominant) does better.
Source: Neurology/neurosurgical guidance