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Corticobasal Syndrome – Alien Limb — SCE Neurology MCQ

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ModerateMovement DisordersCorticobasal Syndrome – Alien LimbSCE Neurology

A 55-year-old man presents with progressive asymmetric limb apraxia, 'alien limb' phenomenon (his left hand involuntarily grasps objects and interferes with his right hand's actions), cortical sensory loss in the left hand, and asymmetric rigidity. MRI brain shows asymmetric right frontoparietal cortical atrophy. What is the most likely diagnosis?

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Correct answer: B — Corticobasal syndrome (CBS)

Corticobasal syndrome is characterised by: asymmetric limb apraxia (inability to perform learned movements), alien limb phenomenon (involuntary purposeful-appearing movements of the affected limb), cortical sensory loss (astereognosis, agraphaesthesia), asymmetric rigidity and dystonia, and myoclonus. MRI shows asymmetric frontoparietal cortical atrophy. CBS is a clinical syndrome — the underlying pathology may be corticobasal degeneration (CBD), AD, PSP, or FTLD-TDP. A: PD is symmetric initially and lacks cortical signs. C: PSP has vertical gaze palsy and axial predominance. D: AD has memory impairment primarily. E: FTD has behavioural/language features.

Reference: MDS CBS/CBD Criteria; ABN Movement Disorders Guidelines