Electroencephalographic characteristics of epileptic seizures in preterm neonates

•Most seizures in preterm newborns are subclinical, thus EEG is required for diagnosis.•Seizures in preterm neonates have smaller regions of onset and propagate less frequently.•Ictal EEG features undergo changes depending on corrected age likely reflecting maturational changes.

ObjectiveAlthough seizures are more common in the neonatal period than in any other stage of childhood, those in preterm neonates are still poorly described. The aim of this study was to assess electro-clinical characteristics of seizures occurring before a corrected age of 40 weeks in neonates born prematurely.MethodRetrospective analysis of EEG-documented seizures in neonates born prematurely. Seizures in a group of term neonates served as controls.ResultsFifty-six prematurely born and 46 term born neonates were included. Median duration of seizures was 52 s in preterm and 96 s in term neonates. Seizures were focal or multifocal. In least mature neonates, they involved smaller regions of onset and remained localised. With increasing corrected age, propagation became more frequent. The electrographic pattern – maximal frequency of oscillation and the onset pattern also evolved with age. Electro-clinical seizures were observed in 25% of preterm versus 50% of term neonates; almost all electro-clinical seizures involved the central (motor) regions.ConclusionIctal EEG features undergo changes depending on corrected age. Most seizures are subclinical, thus EEG is essential for diagnosis.SignificanceRelating ictal EEG pattern to corrected age can improve diagnosis and ultimately management.