ELECTROPHYSIOLOGICAL STUDY OF MYOCLONIC SEIZURES IN CHILDREN

To investigate the neurophysiological mechanisms underlying myoclonic seizures in childhood, we measured the latency between the onset of el ectromyogram (EMG) potentials and that of corresponding spikes obtaine d by the back-averaging method. The subjects were nine patients, with various epileptic syndromes, ranging in age from 2 months to 15 years, 11 months. The numbers of seizure events obtained by averaging ranged from five to 51 with a mean of 25. The latencies between averaged spi ke-and-wave complexes and deltoid EMG potentials ranged from 21 to 80, with a mean of 38 ms. Comparing these results with reported age-match ed physiological conduction times, these latencies appeared to be slig htly prolonged in all of our patients. Our results support the hypothe sis that myoclonic seizures are produced through either a cortical or a subcortical generator, via a polysynaptic mechanism acting on muscle s, rather than a monosynaptic corticospinal pathway. (C) 1997 Elsevier Science B.V.