Corticobasal degeneration.

Corticobasal degeneration (CBG) is an increasingly recognized neurodegenerative disease with both motor and cognitive dysfunction. The diagnosis is probably underestimated because of the heterogeneity of clinical features, overlap with symptoms, and pathologic findings of other neurodegenerative diseases. The most characteristic initial motor symptoms are akinesia, rigidity, and apraxia. Dystonia and alien limb phenomena are frequently observed. There is often a parkinsonian picture with failure or lack of efficacy of dopaminergic medical therapy. Cognitive decline, prompting the diagnosis of dementia, may be the most common presentation of CBD that is misdiagnosed. Pathology is characterized by an asymmetric frontoparietal neuronal loss and gliosis with ballooned, achromatic cortical neurons, nigral degeneration, and variable subcortical involvement. Neuroimaging and electrophysiologic studies may help with the diagnosis but are not specific. Treatment is primarily symptomatic and minimally effective, especially after the first several years of symptoms. CBD should be considered in the differential diagnosis of patients with motor and cognitive dysfunction presenting with cortical and subcortical features. Further studies to elucidate molecular abnormalities and biological markers associated with CBD are needed to improve clinical diagnosis and treatment of patients with this disorder.