Abstracts

Rationale: In order to diagnose neonatal seizures correctly and objectively, we must understand ictal EEG findings on neonatal EEG. Neonatal seizures have generally been identified in most NICUs only by direct clinical observation. However, there is usually a lack of objectivity as to whether seizures are categorized as epileptic or non-epileptic. A major characteristic of neonatal seizures is electro-clinical dissociation and some of the electrographic seizures are not associated with clinical symptoms. These facts strongly suggest that ictal EEG recording is essential for the accurate identification of neonatal seizures of cortical origin and distinction from non-epileptic paroxysmal events of non-cortical origin. We described ictal and background EEG findings, and a variety of EEG patterns in infants with neonatal seizures of acute symptomatic origin. Methods: We recorded over 10 ictal EEGs from the neonates at 1 to 10 days of age associated with several pathologies in our NICU using the digital EEG recording system (NicoletOne TM monitor). The underlying disorders included hypoxic-ischemic encephalopathy, acute metabolic disorders such as hypoglycemia and hypocalcemia, central nervous system infections, cerebrovascular disorders and inborn errors of metabolism. Results: There were electrographic features of seizures in the neonates that were unique to this period. Ictal EEG changes of neonatal seizures were characterized by rhythmic, repetitive, and stereotyped discharges lasting for at least 10 seconds on two or more EEG channels. EEG seizure discharges were principally focal and restricted to relatively circumscribed regions of the brain regardless of underlying etiologies. All ictal EEG changes in neonates began focally, except for the more generalized activities associated with myoclonic jerks or epileptic spasms. Ictal EEG changes were unifocal or multifocal. Even in an individual infant, ictal EEG changes could arise from different foci at different times. EEG foci often migrated from one to another even during a single sizure, within one cerebral hemisphere or from one hemisphere to the other. Conclusions: Ictal EEG recording is essential for the accurate identification of neonatal seizures of cortical origin and distinction from non-epileptic paroxysmal events of non-cortical origin for appropriate treatments with anticonvulsants.