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Difficulty: MediumNeurocognitive Disorders

An 81-year-old retired teacher is accompanied to the outpatient geriatrics clinic by her daughter. The daughter reports that over the past six to nine months, the patient has become increasingly forgetful and struggles to plan her usual weekly garden club meetings. Furthermore, the patient has recently stopped visiting her friends because she is embarrassed by frequent episodes of urinary incontinence. When asked about her mobility, the patient states, 'My feet feel like they are stuck to the ground.' Medical history is significant for well-controlled type 2 diabetes mellitus and mild osteoarthritis. Vital signs are within normal limits. Neurologic examination reveals a wide-based, slow, shuffling gait, but there is no resting tremor, cogwheel rigidity, or bradykinesia of the upper extremities. Cognitive testing reveals prominent deficits in executive function and attention. Which of the following is the most likely diagnosis?

  1. Normal pressure hydrocephalusAnswer
  2. B
    Alzheimer disease
  3. C
    Parkinson disease dementia
  4. D
    Vascular neurocognitive disorder
  5. E
    Dementia with Lewy bodies

Answer

The most likely diagnosis is Normal pressure hydrocephalus.
The correct answer is Normal pressure hydrocephalus (NPH). NPH is a potentially reversible cause of dementia characterized by the classic clinical triad of abnormal gait (described as magnetic, wide-based, or shuffling), urinary incontinence, and cognitive decline (particularly prominent executive dysfunction and psychomotor slowing). The gait abnormality is typically the first symptom to appear. The underlying pathophysiology involves decreased absorption of cerebrospinal fluid at the arachnoid granulations, leading to ventriculomegaly. The enlarged ventricles stretch the descending cortical fibers of the corona radiata, particularly those controlling leg movement and bladder function, resulting in the characteristic symptoms.

Step-by-Step Solution

1
Analyze the patient's presenting clinical symptoms and their timeline.
The patient exhibits a triad of cognitive decline (executive dysfunction), urinary incontinence, and a 'glued to the ground' magnetic gait developing over several months.
Identifying the specific symptom cluster is crucial for distinguishing between various major neurocognitive disorders.
2
Evaluate the neurologic examination findings to rule out related differentials.
The absence of resting tremor, cogwheel rigidity, and upper extremity bradykinesia makes Parkinson disease dementia and Dementia with Lewy bodies highly unlikely.
Gait abnormalities can be seen in multiple disorders, but the specific pattern (magnetic gait without upper body parkinsonism) isolates the pathology.
3
Synthesize the findings to establish the underlying etiology.
The clinical picture strongly points to Normal pressure hydrocephalus, caused by decreased cerebrospinal fluid absorption leading to enlarged ventricles that stretch the corona radiata.
The triad of 'wacky, wet, and wobbly' is the hallmark presentation of this potentially reversible condition.

Key Concept

Normal pressure hydrocephalus presents with the classic clinical triad of gait apraxia (magnetic gait), urinary incontinence, and cognitive decline (dementia), and is characterized by enlarged ventricles out of proportion to sulcal enlargement.
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Topics

Neurocognitive Disorders

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