Ictal electroencephalographic findings of neonatal seizures in preterm infants.

The aim of this study is to clarify the characteristics of ictal EEG findings of neonatal seizures in preterm infants. Seizures associated with ictal EEG changes were recognized in nine infants with gestational age of less than 37 weeks. Propagation, migration, shifting, changes in morphology of ictal EEG discharges were evaluated. Seizure manifestation was divided into the following categories; motor seizure, apneic seizure, automatic seizure and seizure without clinical symptoms. The types of the seizures were motor seizures in five infants, apneic in two, automatic in one and those without clinical symptoms in five. All seizures were of focal onset. The foci of seizures were temporal in six infants, occipital in two, central in one, and frontal in one. The morphology of ictal discharges was low voltage spikes or sharp waves in six infants, spikes in two, theta waves in one and high-voltage spiky theta in one. The propagation of ictal discharges was focal in five infants and regional in five. The migration of ictal discharges was observed in two infants and a shift in two. There was no clear relation between seizure manifestation and ictal EEG foci, duration of seizures and morphology or propagation of ictal discharges.