Examqo › Examqo library › Geriatric medicine › Cognition and dementia · IMLE
Normal pressure hydrocephalus
Normal pressure hydrocephalus is ventricular enlargement in an older adult with a triad of gait disturbance (appearing first and most prominent), urinary incontinence and cognitive impairment; it is one of the few causes of dementia that can be improved, mainly gait, by draining cerebrospinal fluid (a shunt).
Why it matters in the exam
The exam presents an older adult with a slow gait of "small, wide steps" — as if the feet were "stuck to the floor" — followed by urinary incontinence and decline in attention and memory. Candidates are asked what imaging will show (enlarged ventricles not explained by atrophy, a narrow callosal angle) and which test predicts response to surgery: a high-volume lumbar puncture (30–50 mL) with improvement in gait.
Recurring points: the opening pressure at puncture is normal or borderline; gait improves after a shunt more than cognition and incontinence; and the difference from Parkinson disease — in normal pressure hydrocephalus the arms are hardly involved, there is no rest tremor, and the response to levodopa is poor.
In clinical questions the patient usually presents because of falls or "a changed gait", and on examination limb strength is normal, but they struggle to lift their feet, to start walking and to turn. Candidates are also asked who is suitable for surgery: a patient with a typical picture, matching imaging and a response to the tap test, whose general condition allows an operation. The surgical risk includes subdural haematoma from over-drainage, infection and shunt obstruction, so the decision is shared between the neurosurgeon, the geriatrician and the patient and family.
It is important to remember that normal pressure hydrocephalus is a relatively uncommon diagnosis, so not every older adult with slightly wide ventricles and a slow gait is a candidate for surgery. Other diseases that mimic it are Parkinson disease, vascular white matter disease, spinal canal stenosis and vitamin B12 deficiency.
Key points
- Triad: gait (first), urinary incontinence, cognitive decline.
- Imaging: enlarged ventricles not explained by atrophy, Evans index above 0.3.
- Puncture of 30–50 mL — improvement in gait predicts response.
- Treatment: ventriculoperitoneal shunt.
- Gait improves more than cognition.
Summary table
| Issue | Finding | Exam point |
|---|---|---|
| Gait | Slow, short wide steps, difficulty starting and turning ("magnetic") | Appears first and improves most |
| Urine | Urgency and incontinence | Appears later |
| Cognition | Slowness, attention and executive function | Less memory loss than in Alzheimer disease |
| Imaging | Enlarged ventricles (Evans index above 0.3), callosal angle below 90 degrees, tight high-convexity sulci | Enlargement not explained by atrophy |
| Tap test | Puncture of 30–50 mL with gait measured before and after | Improvement predicts response to a shunt |
| Treatment | Ventriculoperitoneal shunt | Complications: subdural haematoma, infection, obstruction |
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
The full version is open to subscribers of: Geriatrics, Medical licensing exam (IMLE), Neurology, Neurosurgery, Internal medicine.
Subscriber? Read the full topic Plans and prices 25 free questions
Sources
- Japanese guidelines for management of idiopathic normal pressure hydrocephalus, 3rd edition (2021) — Diagnosis, tap test and shunt surgery
- Hazzard's Geriatric Medicine and Gerontology, 8th edition (2022) — Dementia — potentially reversible causes
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Dementia
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.