Abstracts

Rationale: The incidence of seizures among preterm neonates ranges from 4 to 48% in the literature. Associated risk factors include hypoxic injury, very low birth weight, and high-grade intraventricular hemorrhage (IVH).

Despite the increased recognition of high seizure risk, the current consensus guidelines are based on limited data. Studies differ in data ascertainment. Most are retrospective and with much variation in neurophysiologic assessment, not only in timing but also in regards to type and duration of data acquisition. Predominantly, the EEG is performed only when there is clinical suspicion of seizures.

To better characterize the risk of seizures in the preterm population, we focused on the extremely premature neonates of < 30 weeks gestation with high-grade IVH.

Methods: This prospective study included all preterm infants of less than 30 weeks gestation admitted to our NICU at the University of Alabama at Birmingham. If an initial ultrasound performed (on Day 3-7) showed a grade III or IV IVH, a 24-hour VEEG was performed within 7 days of the IVH diagnosis (or when the infant was deemed clinically stable to undergo an EEG). Whenever feasible, a full neonatal montage was employed.

Results: Between June 2018 and June 2021, 28 infants (15M/13F) underwent 24-hour VEEG recording with a mean gestational age of 25 weeks (23-29) and post-menstrual age (PMA) of 26 weeks (24-30). All had lateralized or bilateral IVH with at least a Grade III. Mean birth weight was 741g (450-1145).

Seizures were seen in 10 patients (35%, 6M). Two of 10 had both clinical and subclinical seizures. The remaining 8 had subclinical seizures with no definitive clinical correlate. The average PMA at seizure diagnosis was 25-26 weeks.

Conclusions: High-grade IVH and extreme prematurity have conventionally been considered significant risk factors for seizures. Using the gold standard of continuous video EEG recording x 24 hours, our prospective study found that a third (35%) of this population had seizures shortly after high-grade IVH was diagnosed. In the vast majority, seizures were solely subclinical.

Our findings indicate that the current literature markedly underestimates the incidence of seizures in this high-risk group since typically, the decision to perform an EEG relies on the suspicion of clinical seizures.

Limited resources at most institutions necessitate the identification of those preterm infants at the highest risk of seizures. This pilot study further underscores the need for routine assessment of extremely preterm neonates with additional risk factors such as high-grade IVH, irrespective of the clinical suspicion of seizures.

Funding: Please list any funding that was received in support of this abstract.: no.