Asymmetric changes in somatosensory evoked potentials correlate with limb apraxia in corticobasal degeneration.

To clarify the underlying mechanism of limb apraxia in corticobasal degeneration (CBD), we investigated somatosensory evoked potentials in 5 patients with CBD, as compared with 12 age-matched control subjects. All patients presented with asymmetric limb apraxia, particularly of limb-kinetic type. N20 latencies were significantly prolonged following median nerve stimulation on the more apraxic side, but not on the less apraxic side. These results suggest that limb apraxia in CBD may, at least in part, be due to a disorder of somatosensory information processing involving the parietal cortex.