Focal reflex myoclonus in corticobasal degeneration.

: Focal reflex myoclonus was observed in a patient clinically diagnosed as affected by corticobasal degeneration. Myoclonus was not preceded by a cortical discharge and contralateral parietal components of the somatosensory evoked potentials were reduced in amplitude. No simple pathophysiological mechanism can account for all cases of focal reflex myoclonus seen in clinical practice.