Incidence and Predictors of Later Epilepsy in Neonates with Encephalopathy: The Impact of Electrographic Seizures

Abstract

Objectives: To determine the incidence of later epilepsy in full-term infants with neonatal encephalopathy (NE) who undergo continuous electroencephalography (cEEG) monitoring in the neonatal period and to identify potential predictors of later epilepsy both in infants with and without electrographic neonatal seizures (ENS).

Methods: This was a retrospective observational study performed at Cork University Maternity Hospital, Cork, Ireland, between 2003 and 2019. All term infants with NE had a minimum of 2 h of cEEG monitoring in the neonatal period. ENS were identified via cEEG monitoring. Pediatric medical charts were reviewed to determine if epilepsy developed after the neonatal period and to determine potential predictors of epilepsy in infants both with and without ENS.

Results: Two hundred and eighty infants were included. The overall incidence rate of epilepsy was 17.55 per 1000 person-years (95% CI: 10.91 to 28.23). In infants with ENS (n = 82), the incidence rate was 39.27 per 1000 person-years (95% CI: 22.30 to 69.16). In infants without ENS (n = 198), the incidence rate was 7.54 per 1000 person-years (95% CI: 3.14 to 18.12). The incidence rate was significantly higher in the ENS group compared to the non-ENS group (p-value = 0.002). Several potential predictors for the development of later epilepsy were identified including infants delivered vaginally, low Apgar scores at 1 and 5 min, severe HIE diagnosis, presence of ENS, a severely abnormal EEG background and an abnormal brain MRI.

Significance: Following NE, term infants are at risk of epilepsy with a significantly higher incidence rate in infants who experience ENS compared to those who did not. Close follow-up is required in both groups well into the childhood period.

Plain language summary: This study aimed to determine the occurrence of epilepsy in children who were monitored for seizures in the newborn period. The occurrence of epilepsy was higher in infants who experienced seizures in the newborn period compared to those who did not. Several potential predictors of later epilepsy were identified in both groups of infants (those with and without seizures in the newborn period). Both groups of infants require close follow-up in childhood.

Keywords: EEG; epilepsy; neonatal encephalopathy; seizures.

FIGURE 1

Study flow. ENS, electrographic neonatal seizures; PNE, post‐neonatal epilepsy. ^§ n = 1 died beyond neonatal period but no follow‐up, * Suspected but unconfirmed seizures; n = 15, transient metabolic deficit; n = 3, unknown diagnosis with unconfirmed NE; n = 2, hypotonia; n = 2, anemia; n = 1.