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Question Date: 11/10/2023

Question: A 66-year-old man is referred for evaluation of right arm clumsiness. The symptoms developed 2 years ago with difficulty writing and manipulating tools. Over the next 2 years, the symptoms gradually worsened, and he felt as if the arm became much less useful. At times, he felt that the right arm was not under my control. When he was distracted, the arm would rise on its own and do things that he had not intended. He also noted overall slowness with tasks. On examination, he has full strength in the right arm with associated rigidity and bradykinesia and is unable to demonstrate how to salute, brush his teeth, or screw in a lightbulb. He also extinguishes the sensory response on the right arm to dual simultaneous sensory stimulation. When walking, his right arm becomes dystonic <br><br>What is the most likely diagnosis?

Options:

• Corticobasal syndrome
• Lewy body disease
• Multiple system atrophy
• Progressive supranuclear palsy

Correct Answer: Corticobasal syndrome

Explaination: This patient has presented with asymmetric parkinsonism with associated dystonia and significant apraxia. He also has cortical sensory loss as well as the alien limb syndrome. All of these symptoms are typical of corticobasal syndrome, most likely due to corticobasal degeneration. The only other disorder listed with asymmetry at onset is Parkinson disease, but the apraxia, alien limb, and sensory deficits would be quite atypical. Progressive supranuclear palsy can be the underlying etiology of the corticobasal syndrome, but this phenotypic presentation is less likely in progressive supranuclear palsy.

Reference: Williams DR, Litvan I. Parkinsonian syndromes. Continuum (Minneap Minn). 2013 Oct19(5 Movement Disorders)1189-212. doi 10.121201.CON.0000436152.24038.e0. PMID 24092286 PMCID PMC4234134.