A 64-year-old right-handed woman develops 18 months of progressively clumsy left-hand movements. She reports that the left hand sometimes grasps objects or moves 'on its own' and interferes with the right hand during tasks. Examination shows marked ideomotor apraxia of the left limbs, cortical sensory loss, stimulus-sensitive myoclonus, and asymmetrical rigidity that responds poorly to levodopa. What is the most likely diagnosis?
- A Progressive supranuclear palsy
- B Multiple system atrophy, parkinsonian type
- C Corticobasal degeneration ✓
- D Dementia with Lewy bodies
Correct answer: C. Corticobasal degeneration
Explanation
The alien limb phenomenon, strikingly asymmetrical rigidity and apraxia, cortical sensory loss, and stimulus-sensitive myoclonus with a poor levodopa response are characteristic of corticobasal degeneration. Progressive supranuclear palsy is defined by early vertical gaze palsy and falls, multiple system atrophy by autonomic failure with cerebellar or symmetrical parkinsonian signs, and Lewy body dementia by fluctuating cognition and visual hallucinations, none of which feature here.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.