Idiopathic normal-pressure hydrocephalus presents a diagnostic challenge
Although the complete triad is not seen in all cases, idiopathic normal-pressure hydrocephalus is characterized by gait dysfunction, cognitive impairment and urinary incontinence. These symptoms, however, are frequently encountered in older adults without the condition.1 The onset of cognitive impairment in idiopathic normal-pressure hydrocephalus, which is often insidious with slow progression, may resemble Alzheimer disease,2 but is potentially reversable.3 The prevalence varies from 0.3% to 3% among patients older than 65 years, and increases with age.3
Gait dysfunction described as “freezing” and “magnetic” should trigger suspicion for the condition
Gait disturbance, typically the first symptom of idiopathic normal-pressure hydrocephalus, is characterized by a short-stepped gait and difficulty initiating movements, resulting in postural instability and falls.1,3 Some gait abnormalities in the condition may mimic Parkinson disease, but idiopathic normal-pressure hydrocephalus is associated with a wide gait and normal arm swing.3
Magnetic resonance imaging of the brain showing ventriculomegaly with no obstruction to the flow of cerebrospinal fluid supports the diagnosis
Ventriculomegaly seen on imaging may be a result of progressive cortical atrophy. However, ventriculomegaly in the absence of, or out of proportion to, sulcal enlargement and cortical atrophy increases suspicion for idiopathic normal-pressure hydrocephalus.1
A high-volume lumbar puncture can be used as a confirmatory test and to select patients for surgery
The opening pressure is normal (8–18 mm Hg) in idiopathic normal-pressure hydrocephalus. Cognitive testing and a timed gait assessment should be conducted before and 30–60 minutes after the procedure.2 Improved gait after a high-volume lumbar puncture (removal of 30–60 mL of cerebrospinal fluid) is a positive predictor of improvement with a ventriculoperitoneal shunt.2
A prompt referral to a neurosurgeon is recommended in selected patients
Ventriculoperitoneal shunts can improve symptoms, especially gait dysfunction, in up to 74% of patients.4,5 Early treatment within 3 months of diagnosis is associated with better outcomes.5
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Footnotes
Competing interests: None declared.
This article has been peer reviewed.
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- Idiopathic normal-pressure hydrocephalus presents a diagnostic challenge
- Gait dysfunction described as “freezing” and “magnetic” should trigger suspicion for the condition
- Magnetic resonance imaging of the brain showing ventriculomegaly with no obstruction to the flow of cerebrospinal fluid supports the diagnosis
- A high-volume lumbar puncture can be used as a confirmatory test and to select patients for surgery
- A prompt referral to a neurosurgeon is recommended in selected patients
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