Corticobasal Degeneration The Syndrome and the Disease

In 1967, Rebeiz, Kolodny, and Richardson described three patients with a progressive asymmetric akinetic-rigid syndrome and apraxia and labeled these cases as “corticodentatonigral degeneration with neuronal achromasia” (1,2). Additional reports on this disorder were almost nonexistent until the early 1990s. Over the past 10 yr, interest in this disorder has increased markedly. The nomenclature has also undergone evolution. The core clinical features that have been considered characteristic of the disorder include progressive asymmetric rigidity and apraxia, with other findings suggesting additional cortical (e.g., alien limb phenomena, cortical sensory loss, myoclonus, mirror movements) and basal ganglionic (e.g., bradykinesia, dystonia, tremor) dysfunction. The characteristic findings at autopsy have been asymmetric cortical atrophy, which is typically maximal in the frontoparietal regions, basal ganglia degeneration, and nigral degeneration. Microscopically, swollen neurons that do not stain with conventional hematoxylin/eosin (so-called ballooned, achromatic neurons) are found in the cortex. Abnormal accumulations of the microtubule-associated tau protein are found in both neurons and glia. In this chapter, the concepts and data relating to the corticobasal syndrome and corticobasal degeneration as presented in a recent review (3) are expanded.