Normal Pressure Hydrocephalus (NPH)

Normal pressure hydrocephalus is one of the few reversible causes of dementia — and it is often missed for years. If an older adult has gait problems, incontinence and cognitive slowing together, NPH should always be on the diagnostic list, because a well-placed shunt can genuinely give a person their life back.

What Is Normal Pressure Hydrocephalus?

Normal pressure hydrocephalus (NPH) is a syndrome of enlarged brain ventricles, normal CSF pressure on lumbar puncture, and the classic triad of symptoms. It most commonly affects adults over 60. The mechanism is thought to involve impaired CSF reabsorption, leading to ventricular enlargement that stretches the fibers connecting the frontal lobes to the legs and bladder.

NPH is underdiagnosed. Population estimates suggest it affects ~5-6% of adults over 65 with dementia-like symptoms. Correct diagnosis and shunting in the right patient can produce dramatic improvement.

At a Glance

Normal pressure hydrocephalus (NPH) is one of the few reversible causes of dementia-like symptoms in older adults
Classic triad: gait disturbance (magnetic gait) + urinary urgency/incontinence + cognitive slowing
The shunt tap test — draining 30-50 mL of CSF and watching gait improve — is the most predictive test for shunt response
VP shunt implantation produces meaningful improvement in ~60-80% of correctly selected patients
Gait responds best and fastest; cognition responds more slowly and incompletely

Symptoms

The classic triad (Hakim's triad)

1. Gait disturbance (the most prominent and first-appearing symptom)

'Magnetic gait' — feet feel stuck to the floor, shuffling, small steps
Wide-based, unsteady, frequent falls
Difficulty initiating walking or turning

2. Urinary incontinence

Urgency — sudden urge with inability to delay
Eventually frank incontinence

3. Cognitive impairment

Slowed processing, difficulty concentrating, memory for recent events
Generally milder than Alzheimer's; executive function more impaired than memory

Diagnosis

MRI of brain — ventriculomegaly out of proportion to sulcal atrophy; Evans' index >0.3; disproportionately enlarged subarachnoid spaces (DESH pattern)
Lumbar puncture (LP opening pressure) — normal or low-normal (<20 cm H₂O) — important to exclude high-pressure hydrocephalus
CSF tap test (high-volume LP) — drain 30-50 mL; measure gait before and after with objective tests (Timed Up and Go, 10-meter walk, step count); improvement within 1-4 hours predicts shunt response with ~70-90% positive predictive value
Extended lumbar drainage (3-5 days) — gold standard for predicting shunt response; more invasive but ~90% PPV

Types

Treatment

Ventriculoperitoneal (VP) shunt — the standard treatment
A programmable pressure valve is implanted; catheter runs from the lateral ventricle to the peritoneal cavity. The valve can be adjusted non-invasively with a magnet. Most patients are in the hospital 2-3 days; some go home same day.

Programmable valve adjustment
Post-implant, valve opening pressure is adjusted based on CT scan and clinical response to optimize drainage without over-draining (which causes headaches, hygroma or subdural hematoma).

Lumboperitoneal shunt — alternative
Simpler to place; CSF drained from lumbar spine instead of brain. Associated with higher complication rates including valve malfunction and retroflexion of lumbar spine.

Outcomes

Outcome	Rate	Notes
Gait (walking) improvement after shunting	~70-90%	The most consistent response; improvement is often dramatic and rapid
Urinary incontinence improvement	~50-70%	Typically improves later than walking symptoms
Cognitive improvement	~30-50%	The slowest and most incomplete area of recovery
Overall meaningful improvement	~60-80%	Achieved in well-selected patients who have a positive tap test
Complication rate	~10-15%	Includes risks like overdrainage or infection; our use of programmable valves helps minimize these risks

References

Relkin N, et al. Diagnosing idiopathic normal-pressure hydrocephalus. Neurosurgery. 2005;57:S4-16. PMID: 16160426
Mori E, et al. Guideline for management of idiopathic normal pressure hydrocephalus. Neurol Med Chir (Tokyo). 2012;52:775-809. PMID: 23235160
Andrén K, et al. Long-term outcome of treatment for idiopathic normal pressure hydrocephalus. J Neurol. 2014;261:1549-1555. PMID: 24906933

Our Specialists

Arthur DiPatri, MD

Pediatric Neurosurgery

Paramita Das, MD, MS

Neurosurgery

Martin Herman, MD, PhD

Neurosurgery

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