[P300 findings in patients with corticobasal degeneration]

An auditory discrimination paradigm was employed to elicit the P300 component of the event-related potentials from three patients with clinically diagnosed corticobasal degeneration (CBD). Presenile and senile dementia of Alzheimer type (DAT), vascular dementia (VD) and age-matched control subjects were also examined. All patients with CBD manifested limb kinetic apraxia, hemiparkinsonism and mild dementia. Brain MRI revealed marked parietal atrophy, which was predominant in contralateral to the extremities with severe motor dysfunction. 123I-IMP SPECT analysis showed asymmetric reduction of cerebral blood flow, in accordance with the MRI findings. The P300 latencies in the two CBD patients were markedly prolonged compared to those of DAT and VD patients, although they were not as severely demented as DAT and VD patient. It should be noted that the P300 was not detected in one patient with CBD. The latencies of the N100 were not significantly different among the all groups. These abnormal findings of the P300 may be characteristic in CBD, and, furthermore, may be associated with the parietal lobe atrophy and low blood flow in cortex and thalamus revealed by brain MRI and SPECT.