Clinical, imaging and electrophysiological studies of corticobasal degeneration.

Corticobasal degeneration (CBD) is a rare neurodegenerative disorder characterized by distinctive clinical manifestations including asymmetric akinetic-rigid syndrome and higher cortical dysfunctions. We characterized the clinical, electrophysiological and imaging presentations in four patients with CBD. All patients exhibited unilateral hand dystonia, rigidity and apraxia, but showed no significant response to levodopa therapy. Surface electromyography demonstrated short duration and stimulus-sensitive myoclonus in three of the four patients. On the other hand, there was no "giant" SEPs (somatosensory evoked potentials), and the backaveraged electroencephalography did not show any jerk-locked cortical potentials. Brain magnetic resonance imaging showed asymmetrical cortical atrophy. [99mTc]HMPAO single-photon emission computed tomography (SPECT) revealed decreased regional cerebral blood flow in the frontoparietal areas and thalamus opposite to the more severely affected limb. [99mTc]TRODAT-1 SPECT showed decreased uptake in the striatum of the affected hemisphere. These data supported that there are abnormal cortical excitability and asymmetric pathological change of the affected hemisphere in the patients with CBD.