What are the signs of Normal Pressure Hydrocephalus (NPH)?

Signs of Normal Pressure Hydrocephalus

Normal Pressure Hydrocephalus presents with a classic triad: gait disturbance (the cardinal and often first sign), cognitive impairment, and urinary incontinence. 1, 2

Cardinal Clinical Sign: Gait Disturbance

• The hypokinetic gait disorder is the hallmark of NPH, occurring in approximately 70% of patients and typically the presenting symptom. 1
• The characteristic gait appears as if the feet are "glued to the floor" or "magnetic," representing a distinctive hypokinetic pattern. 1, 3
• Gait alterations occur early in the disease course, often preceding other symptoms by months to years. 2, 4
• Associated findings include posture and balance abnormalities. 3

Cognitive Impairment

• Cognitive dysfunction develops later in the disease course and manifests with frontal lobe symptoms rather than typical Alzheimer's-type memory loss. 2
• Specific cognitive deficits include:
  • Psychomotor slowing 2
  • Deficits in attention and working memory 2
  • Impaired verbal fluency 2
  • Executive function deficits 2
  • Memory lapses (though less prominent than in other dementias) 2
• The cognitive impairment is characterized as subcortical dementia. 5

Urinary Symptoms

• Urinary urgency and incontinence complete the classic triad. 2, 5
• Urinary symptoms include urgency, frequency, nocturia, and frank incontinence. 3
• These symptoms typically develop after gait disturbances but may precede cognitive decline. 2

Critical Imaging Findings

• MRI without IV contrast is the preferred imaging modality and reveals characteristic findings: 1, 2, 4
  • Ventriculomegaly (enlarged ventricles) 1, 4
  • Narrowed posterior callosal angle (<90°) 1, 4
  • Effaced sulci (flattened brain surface grooves) 1, 4
  • Widened sylvian fissures 1, 4
  • Periventricular white matter changes 1, 4
  • Cerebral aqueduct flow void on MRI 1, 4
  • Disproportionately enlarged subarachnoid-space hydrocephalus (DESH) pattern 4
  • Enlargement of temporal horns 1

Important Clinical Pitfalls

• Patients typically present late in the disease course due to the slow, gradual onset of symptoms, making early recognition challenging. 4
• Approximately 75% of NPH patients severe enough to require treatment have comorbid neurodegenerative disorders (such as Alzheimer's disease in 20-57% of cases), complicating diagnosis. 2, 4, 6
• An estimated 80% of NPH cases remain unrecognized and untreated, likely due to difficulty distinguishing it from other neurodegenerative disorders. 6
• The prevalence is 3.7% in patients over 65 years, making it a significant potentially reversible cause of dementia accounting for approximately 5-6% of all dementias. 4, 7