Neonatal Paroxysmal Monorhythmic Alpha Activity

Abstract

• Thirteen infants with neonatal seizures showed paroxysmal monorhythmic electrographic activity, predominantly in the alpha range (8 to 13 Hz) and localized to the rolandic cortical areas. This rhythmic discharge, which is commonly lateralized, represents an electrical seizure discharge. Such discharges may exist as the only electrographic seizure activity, but in the majority of cases (8/13) independent epileptiform discharges are observed in other cortical areas. All infants with paroxysmal monorhythmic alpha activity had clinically observed seizures. Computerized tomography performed six or more weeks after observing the electrographic abnormality demonstrated diffuse as well as localized cortical atrophy in a distribution similar to the monorhythmic alpha activity. In other cases, localized monorhythmic alpha activity was correlated on subsequent evaluations with focal neurological abnormalities (eg, hemiparesis and hemiatrophy) and a high incidence of microcephaly (83%). On the basis of these findings, we suggest that encephalomalacia may be important in the pathogenesis of paroxysmal monorhythmic alpha seizures in the neonate.