Neurology · PANCE / PANRE

Normal Pressure Hydrocephalus

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

Communicating hydrocephalus with normal CSF pressure presenting as the triad of gait disturbance, urinary incontinence, and dementia.

Also known as: NPH, Hakim-Adams syndrome, idiopathic NPH, iNPH

Overview

A communicating hydrocephalus characterized by ventriculomegaly disproportionate to cortical atrophy, normal CSF opening pressure, and the clinical triad of gait disturbance, cognitive impairment, and urinary incontinence. May be idiopathic or secondary to prior subarachnoid hemorrhage, meningitis, head trauma, or radiation.

Epidemiology

Prevalence ~1.5-3% of adults >65; rises with age. Often underdiagnosed because triad mimics common comorbidities. Slight male predominance.

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Question 1NeurologyEasy
A 75-year-old male has a 3-month history of progressive gait difficulty described as magnetic (feet stuck to floor), urinary incontinence, and cognitive decline. He denies headaches or falls. MRI shows marked hydrocephalus with dilated ventricles disproportionate to cortical atrophy. Lumbar puncture (LP) shows opening pressure 12 cmH2O and removal of 50 mL CSF markedly improves his gait immediately. Which of the following is the most likely diagnosis?
  • AAlzheimer disease
  • BMeningitis with hydrocephalus
  • CNormal pressure hydrocephalus
  • DChronic subdural hematoma
Reveal answer & full explanation
Correct answer: C — Normal pressure hydrocephalus
  • AAlzheimer disease
  • BMeningitis with hydrocephalus
  • CNormal pressure hydrocephalus✓
  • DChronic subdural hematoma

Why Normal pressure hydrocephalus is correct

  • Normal pressure hydrocephalus (NPH) presents with the classic Hakim-Adams triad: gait apraxia (most prominent; magnetic gait with wide-based shuffling), urinary incontinence, and dementia (frontal-subcortical pattern).
  • Diagnosis is supported by hydrocephalus on MRI with an Evans ratio above 0.3 and disproportionately large ventricles relative to cortical atrophy.
  • Lumbar puncture (LP) opening pressure is normal (below 18 cmH2O) or low-normal despite dilated ventricles — hence the term normal pressure.
  • Large-volume tap test (removal of 30-50 mL CSF): immediate gait improvement after LP predicts ventriculoperitoneal (VP) shunt response (sensitivity 50-60%).

Why the others are wrong

  • Alzheimer disease — Alzheimer produces cortical atrophy and amnestic dementia, not magnetic gait with ventriculomegaly disproportionate to atrophy or tap-test gait improvement (anchoring on cognitive decline).
  • Meningitis with hydrocephalus — there is no fever, headache, or acute presentation, and the opening pressure is normal rather than elevated (confused-with infectious cause).
  • Chronic subdural hematoma — MRI shows hydrocephalus with dilated ventricles, not an extra-axial crescentic collection, and there is no trauma history (right-symptom-wrong-lesion).

Additional high-yield points

  • Definitive treatment is VP shunt, which improves gait in 70-80% of patients; cognitive symptoms respond less reliably.
  • Extended LP drainage trial is more predictive of shunt response than a single LP.
  • Gait responds best to shunting; dementia responds least well.
Question 2NeurologyEasy
A 72-year-old male has progressive gait difficulty described as magnetic (feet stuck to floor), urinary incontinence, and cognitive decline. MRI shows dilated ventricles with Evans ratio 0.35. Lumbar puncture (LP) shows opening pressure 12 cmH2O. Large-volume LP (50 mL removed) causes immediate gait improvement. Which of the following is the most appropriate definitive treatment?
  • AVentriculoperitoneal shunt placement
  • BLong-term oral corticosteroid therapy
  • CDonepezil and memantine
  • DNeurosurgical hematoma evacuation
Reveal answer & full explanation
Correct answer: A — Ventriculoperitoneal shunt placement
  • AVentriculoperitoneal shunt placement✓
  • BLong-term oral corticosteroid therapy
  • CDonepezil and memantine
  • DNeurosurgical hematoma evacuation

Why Ventriculoperitoneal shunt placement is correct

  • Normal pressure hydrocephalus (NPH) presents with the classic Hakim-Adams triad: gait apraxia (most prominent — magnetic gait with wide-based shuffling), urinary incontinence, and dementia (frontal-subcortical pattern)
  • Diagnostic MRI shows hydrocephalus with Evans ratio above 0.3 (maximum ventricular width/maximum brain width) with disproportionately large ventricles versus cortical atrophy
  • Lumbar puncture (LP) opening pressure is normal (below 18 cmH2O) or low-normal despite dilated ventricles; this patient's opening pressure is 12 cmH2O
  • Large-volume tap test (30-50 mL CSF removed): immediate gait improvement predicts ventriculoperitoneal (VP) shunt response — this patient had immediate improvement after 50 mL removed
  • Definitive treatment is VP shunt; improves gait in 70-80%; cognitive symptoms respond less reliably

Why the others are wrong

  • Long-term oral corticosteroid therapy — has no role in NPH; the problem is impaired CSF dynamics, not inflammation (wrong-mechanism)
  • Donepezil and memantine — treat Alzheimer dementia symptomatically but do not address the reversible CSF disorder responsible here (confused-with Alzheimer)
  • Neurosurgical hematoma evacuation — indicated for subdural or intracerebral hematoma; imaging shows hydrocephalus, not a hematoma (anchoring)

Additional high-yield points

  • Gait responds best to shunting; dementia responds least well
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Risk factors

  • Advancing age (>60)
  • History of subarachnoid hemorrhage, meningitis, or significant head trauma (secondary NPH)
  • Vascular comorbidities — hypertension, diabetes, white matter disease
  • Family history (rare familial forms)

Pathophysiology

Impaired CSF absorption at arachnoid granulations, possibly with altered CSF dynamics and reduced compliance, leads to ventricular enlargement. Stretched periventricular tracts, particularly the corona radiata and corpus callosum, impair frontal and motor function. Coexisting Alzheimer pathology is common and confounds outcomes.

Clinical presentation

Symptoms

  • Gait disturbance — the earliest and most characteristic feature; magnetic, shuffling, broad-based, with difficulty initiating ('feet stuck to floor')
  • Cognitive impairment — frontal-subcortical pattern: psychomotor slowing, executive dysfunction, apathy (memory relatively spared)
  • Urinary urgency progressing to incontinence (urge-pattern, frontal-type)
  • Falls
  • Triad is rarely all present at first; gait typically appears first, incontinence and cognitive change later

Signs / physical exam

  • Magnetic gait — small steps, reduced stride, en bloc turning, no festination
  • Postural instability without overt parkinsonian rigidity
  • Frontal release signs in some
  • Bedside cognition: bradyphrenia, impaired attention/executive function, set-shifting deficits

Classic findings

Older adult with 'wet, wobbly, wacky' — gait, incontinence, and cognitive change — and ventriculomegaly on imaging.

Differential diagnosis

  • Parkinson disease — Asymmetric tremor, bradykinesia, rigidity; responsive to levodopa; gait shuffling but normal stride width
  • Vascular dementia — Stepwise decline, focal deficits, extensive white matter disease on MRI
  • Alzheimer disease — Memory dominant, hippocampal atrophy disproportionate to ventricular size
  • Lumbar spinal stenosis — Gait worsens with walking, improves with sitting/forward flexion; lower extremity pain
  • B12 deficiency / subacute combined degeneration — Sensory ataxia, posterior column signs, low B12
  • Frontal lobe tumor / subdural hematoma — Focal lesion or extra-axial collection on imaging
  • Obstructive hydrocephalus — Ventriculomegaly with anatomic obstruction (aqueductal stenosis, tumor); elevated CSF pressure

Diagnostic workup

Diagnostic criteria

Probable iNPH (Relkin/Marmarou 2005): progressive gait disturbance + at least one additional triad feature + ventriculomegaly without obstruction + normal CSF opening pressure (5-18 cm H2O on LP).

Labs

  • CBC, BMP, TSH, B12, RPR (reversible dementia screen)
  • Urinalysis to exclude UTI as incontinence contributor

Imaging

  • MRI brain — ventriculomegaly (Evans index >0.3) disproportionate to cortical atrophy, with effaced cortical sulci over the convexity and dilated Sylvian fissures (DESH pattern: disproportionately enlarged subarachnoid space hydrocephalus)
  • No aqueductal obstruction (distinguishes from obstructive hydrocephalus)
  • CSF flow void through aqueduct on MRI
  • Large-volume lumbar puncture ('tap test') — remove 30-50 mL CSF; reassess gait and cognition before and ~1-24 h after
  • Extended lumbar drainage trial (3 days, 10 mL/h) — higher sensitivity than single tap

Treatment

First-line

  • Ventriculoperitoneal (VP) shunt — definitive therapy; programmable shunts allow pressure titration to reduce overdrainage
  • Patient selection driven by tap test or lumbar drain trial response, severity of triad, comorbidities, and surgical risk
  • Gait improvement is the most reliable post-shunt outcome; cognitive and continence response are less predictable
  • Multidisciplinary preoperative evaluation: neurology, neurosurgery, physical therapy, neuropsychology

Pre-shunt evaluation

  • Standardized gait assessment (timed up and go, 10-meter walk) before and after CSF removal
  • Cognitive testing (MoCA, frontal assessment battery)
  • Exclude or document comorbid Alzheimer pathology (CSF Aβ/tau, amyloid PET) — predicts more limited shunt response

Post-shunt management

  • Adjust programmable valve pressure for symptom control vs overdrainage (subdural collections)
  • Routine surveillance for shunt failure: recurrence of gait/cognitive symptoms
  • Physical therapy and gait training to consolidate gains

Second-line / adjunct

  • Acetazolamide and serial LPs — temporizing measures only; not durable
  • Cognitive rehabilitation and behavioral strategies for residual deficits

Complications

  • Shunt malfunction (mechanical or infectious) — re-presentation with declining gait
  • Subdural hematoma from overdrainage (more common with non-programmable valves)
  • Shunt infection (~5%, higher in early postoperative period)
  • Persistent cognitive impairment if AD pathology coexists
  • Falls, urinary tract infection, deconditioning

PANCE pearls

  • Gait disturbance is the symptom most likely to improve with shunting; isolated dementia rarely responds.
  • Evans index = maximal frontal horn width / maximal inner skull diameter on the same axial slice; >0.3 supports ventriculomegaly.
  • Disproportionately enlarged subarachnoid space hydrocephalus (DESH) on coronal MRI is a strong imaging predictor of shunt response.
  • Tap test high specificity but limited sensitivity — a negative tap test does not exclude shunt-responsive NPH.
  • Coexisting Alzheimer pathology is the most common reason for limited shunt response — counsel families accordingly.

References

  • Relkin 2005 — Relkin N et al. Diagnosing idiopathic normal-pressure hydrocephalus. Neurosurgery 2005;57(3 Suppl):S4-S16.
  • International iNPH Guidelines — Nakajima M et al. Guidelines for management of idiopathic normal pressure hydrocephalus (third edition). Neurol Med Chir (Tokyo) 2021;61:63-97.
  • AAN Practice Advisory — Halperin JJ et al. AAN practice guideline: Idiopathic normal pressure hydrocephalus: Response to shunting and predictors of response. Neurology 2015;85:2063-2071.

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Related Neurology diagnoses

Ischemic StrokeHemorrhagic (Intracerebral) StrokeTransient Ischemic Attack (TIA)Subarachnoid Hemorrhage (SAH)Subdural Hematoma (SDH)Epidural Hematoma (EDH)Concussion / Mild Traumatic Brain InjuryMigraineTension-Type HeadacheCluster HeadacheSeizures and EpilepsyStatus EpilepticusMultiple SclerosisGuillain-Barré Syndrome

Differentials & related conditions

Parkinson DiseaseVascular DementiaAlzheimer DiseaseLumbar Spinal Stenosis

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