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Difficulty: HardNeurocognitive Disorders

A 7575-year-old man is brought to the clinic by his daughter due to a progressive decline in his mobility and memory over the past 88 months. The daughter reports that he has become increasingly forgetful and struggles to manage his finances. Additionally, his walking has become remarkably slow and unsteady; he walks with his feet spread apart and appears as if his shoes are 'stuck to the floor.' In the past month, he has had several episodes of urinary incontinence, which he seems largely unconcerned about. His medical history includes hypertension and osteoarthritis. Neurological examination reveals a wide-based, magnetic gait with short steps. Muscle strength and deep tendon reflexes are normal, and there is no resting tremor or cogwheel rigidity. Montreal Cognitive Assessment score is 21/3021/30. Which of the following is the most appropriate next step in the diagnostic workup?

  1. A
    High-volume lumbar puncture
  2. Magnetic resonance imaging of the brainAnswer
  3. C
    Dopamine transporter (DaT) single-photon emission computed tomography (SPECT) scan
  4. D
    Cerebrospinal fluid analysis for amyloid-beta and tau proteins
  5. E
    Urodynamic testing

Answer

Magnetic resonance imaging of the brain
The correct answer is magnetic resonance imaging of the brain. This patient's presentation of cognitive impairment, a wide-based 'magnetic' gait, and urinary incontinence constitutes the classic triad of normal pressure hydrocephalus (NPH). The initial diagnostic step for suspected NPH is always structural neuroimaging (MRI or CT of the brain). This is essential to document ventriculomegaly out of proportion to cerebral atrophy and to rule out other structural etiologies before any invasive testing is attempted.

Step-by-Step Solution

1
Analyze the patient's clinical presentation.
The patient exhibits a progressive triad of cognitive impairment, wide-based magnetic gait, and urinary incontinence.
Identifying symptom clusters is essential for accurate syndromic diagnosis in geriatrics.
2
Formulate a primary differential diagnosis based on the triad.
The combination of 'wacky, wobbly, and wet' is the classic presentation of normal pressure hydrocephalus (NPH).
This specific combination distinguishes NPH from other dementias like Alzheimer disease or vascular dementia.
3
Determine the safest and most appropriate initial diagnostic step.
Structural neuroimaging must be performed first.
Imaging confirms ventriculomegaly and rules out structural lesions, which is a prerequisite before performing invasive testing like a high-volume lumbar puncture.

Key Concept

Diagnostic evaluation algorithm for Normal Pressure Hydrocephalus
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Topics

Neurocognitive Disorders

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