EPILEPTIC NEGATIVE MYOCLONUS

Five patients with partial epilepsy of diverse etiology insidiously de veloped action-activated jerks. The disorder was limited to one arm in two patients and to the legs in another, and was multifocal in the re maining two. Each jerk was related to an EMG silent period lasting 100 to 400 msec, causing a lapse followed by resumption of posture. Simul taneous EEG-EMG recording showed each postural lapse to be time-locked with a sharp or spike and slow-wave transient over the contralateral sensorimotor cortex, where almost continuous paroxysmal activity occur red. The three patients who were able to cooperate during neurologic e valuation also exhibited motor neglect in the most affected body segme nt and decreased awareness of the disorder. In three patients, the phe nomenon was medically resistant, and in two of them it was continuous and could be defined as epilepsia partialis continua. In the other two , medical treatment induced remission of EEG, motor, and neuropsycholo gical abnormalities. This disabling movement disorder can be classifie d as ''epileptic negative myoclonus'' and may result from focal-discha rge-related transient disruption of cortical function in the sensorimo tor cortex.