Critical Care Medicine-Neurologic Disorders>>>>>Clinical Syndromes
Question 6#

Medical assistance is called for overhead during your flight to Hawaii. A 75-year-old man has fallen in the aisle after attempting to walk back to the restrooms. History is obtained from the son who accompanies him. He recalls a history of diabetes and hypothyroidism. The patient is returning home after visiting family and is being evaluated by a prominent dementia specialist. The son cannot name a diagnosis but remembers that a recent MRI revealed “enlarged chambers.” The patient is mumbling about having successfully made it to the restroom five times during this flight.

Which of the following is the most likely diagnosis?

A. Alcohol intoxication
B. Alzheimer dementia
C. Normal pressure hydrocephalus (NPH)
D. Diabetic peripheral neuropathy
E. Parkinson disease

Correct Answer is C

Comment:

Correct Answer: C

Limited information is provided in the stem to make a definitive diagnosis. Key pieces include presumed dementia, gait instability, frequent urination, and an MRI suggestive of ventriculomegaly. These fit the classic triad of NPH (C). Diagnosis is usually aided by cognitive evaluation, MRI, lumbar puncture, and ruling out other causes of gait and urinary dysfunction. Peripheral neuropathy may explain gait and urinary problems with his history of diabetes but likely would not explain the MRI and cognitive findings (D). Alcohol intoxication may explain frequent trips to the restroom and an unstable gait; however, this would be an unlikely explanation for his chronic problems (A). 

The differential for dementia should include Alzheimer and Parkinson disease. In fact, Alzheimer dementia is more common than NPH overall. Gait impairment and urinary incontinence can coexist in patients with Alzheimer disease; however, they are usually explained by other causes. Characteristically, dementia precedes these findings in Alzheimer disease (B). Parkinson disease can present with dementia later in the disease course. Distinguishable motor findings are typically present including tremor, bradykinesia, and rigidity but can manifest as gait instability and urinary incontinence (E). Again, the presence of ventriculomegaly makes NPH more likely than these causes of dementia.

References:

1. Espay AJ, Da Prat GA, Dwivedi AK, et al. Deconstructing normal pressure hydrocephalus: ventriculomegaly as early sign of neurodegeneration. Ann Neurol. 2017;82:503.
2. Klassen BT, Ahlskog JE. Normal pressure hydrocephalus: how often does the diagnosis hold water? Neurology. 2011;77:1119-1125.
3. Nassar BR, Lippa CF. Idiopathic normal pressure hydrocephalus: a review for general practitioners. Gerontol Geriatr Med. 2016;2:2333721416643702.