Corticobasal degeneration

Corticobasal degeneration (CBD) is a neurodegenerative disorder characterized clinically by a combination of cortical and basal ganglia signs. Pathologically, it is classified as a tauopathy. The most distinctive clinical feature is its unilateral or markedly asymmetric presentation; among parkinsonian syndromes, with rare exceptions, only Parkinson’s disease presents with such asymmetry. The most common presenting cortical features include apraxia (patients often complain of a “useless” limb), aphasia (usually nonfluent), parietal lobe sensory signs (agraphesthesia, extinction, astereognosis), frontal dementia, or myoclonus. Basal ganglia signs include rigidity, akinesia, limb dystonia, and postural instability.