NCS Advantage Practice Exam

Corticobasal degeneration is a Parkinson-plus disorder in which cortex-driven motor problems appear alongside parkinsonism. The combination of dystonia, limb apraxia, and focal rigidity reflects this cortex–basal ganglia involvement. Dystonia causes abnormal, twisting postures; limb apraxia is difficulty performing purposeful movements despite intact strength and sensation; focal rigidity means rigidity localized to a specific limb or side rather than generalized. In CBD, these features tend to be asymmetric and prominent early on because the disease affects both cortical areas and the basal ganglia, producing this distinctive motor picture.

Other Parkinson-plus conditions differ in their hallmark signs: progressive supranuclear palsy typically features early postural instability and vertical gaze palsy; multiple system atrophy often has autonomic failure and cerebellar signs; vascular parkinsonism usually presents with parkinsonism that is more prominent in the lower body and linked to vascular disease.