Ictal video-polygraphic features of perioral myoclonia with absences.

There have been few case reports of perioral myoclonia with absences (POMA) because of the lack of video-polygraphic recordings clarifying the electroencephalogram (EEG)-electromyogram (EMG) correlations. We describe one of the first video-polygraphic studies of POMA in a patient who underwent repeated and prolonged split-screen video-polygraphic recordings. The ictal EEG showed generalized and irregular discharges of spikes or multiple spikes and slow waves, while two concomitant EMG patterns appeared: (1) a rhythmic enhancement of the orbicularis oris and masseter muscles on both sides with minimal asymmetry corresponding to perioral movements, and (2) a progressive increment in muscular tone in the mylohyoideus muscle corresponding to oroalimentary automatisms. Myoclonic jerks were inconstantly time-locked to the spike component of the spike-wave complex. The evidence of a complex pattern of activation of the facial muscles suggests that the involvement of subcortical central pattern generators, related to masticatory activity, through the disinhibitory effect of the spike-wave discharge is a possible pathophysiological mechanism underlying POMA.