Retrospective study on neonatal seizures in a tertiary center of northern Italy after ILAE classification: Incidence, seizure type, EEG and etiology.

Objective: We aimed to evaluate epidemiology, seizure type, EEG, and etiology of neonatal seizures (NS) in a tertiary neonatal intensive care unit.

Methods: Data on infants with a neurophysiological confirmation of NS were collected between 2009 and 2022. Seizure types and epileptic syndromes were classified by the ILAE classification and EEG by the Italian Neonatal Seizure Collaborative Network (INNESCO) score.

Results: Out of 91,253 neonates, 145 presented with NS; 69.7 % were born at term and 30.3 % were preterm infants. The incidence of NS in neonates born at our center was 1.2 per 1,000 live newborns (96/80697 neonates) while in the entire neonatal population admitted to our center it was 1.6 per 1,000 live births, increasing with lower preterm age. Compared to previous studies, we found a lower proportion of hypoxic-ischemic encephalopathy (HIE) (23.4 %) and a higher rate of genetic contribution (26.2 %). The infection rate was higher in preterm (31.8 %) than in full term (9.9 %) infants. Electrographic seizures were associated with acute provoked seizures (35.9 %), preterm age (52.3 %), and HIE (52.9 %). Vascular etiology was associated with focal clonic seizures (56.8 %). Non-structural neonatal genetic epilepsy was associated with sequential seizures (68.2 %), particularly KCNQ2 and SCN2A epilepsy. Background EEG was abnormal in all HIE, infections (85.7 %) and metabolic NS (83.3 %). In genetic epilepsy, background EEG depended on the epileptic syndrome: normal in 80 % of self-limited neonatal epilepsy and abnormal in 77.8 % of developmental and epileptic encephalopathy. Electroclinical seizures were associated with focal onset, while electrographic seizures correlated with a multifocal onset.

Conclusions: A low incidence of HIE and a high incidence of genetic etiology were observed in our cohort of NS. Seizure type and EEG features are fundamental to address etiology.