Abstracts

Rationale: This study examined the relationship between the timing of the onset of neonatal seizures and the clinical course, including the efficacy of anticonvulsant therapy, neurodevelopmental outcome, and subsequent epilepsy. Methods: This was a retrospective analysis of term infants who had electrographically confirmed neonatal seizures between 2002 and 2015 in the neonatal intensive care unit of Anjo Kosei Hospital. We divided the infants into two groups based on the timing of seizure onset. The early onset group comprised the infants who had experienced their initial seizures during the first 24 h of life, and the late onset group had had their seizures after that time. Clinical data were collected retrospectively, including gestational age at birth, birth weight, anticonvulsant therapy efficacy, etiology, subsequent epilepsy, and developmental impairment. We regarded the anticonvulsant therapy efficacy as good if the infant required one antiepileptic drug to achieve electrographically confirmed seizure control. The causes of the seizures were divided into two categories: acute symptomatic seizures (hypoxic ischemic encephalopathies, intracranial hemorrhage, hypoglycemia, etc.) and neonatal onset epilepsy (brain malformation, neonatal onset epilepsy syndromes, etc.). The significance of differences was tested using the Mann–Whitney U-test and Fisher’s exact test. Results: Forty-one neonates with electrographically confirmed neonatal seizures were identified, 14 in the early onset group and 27 in the late onset group. There were 23 males and 18 females. The gestational age ranged between 37 and 41 weeks, with a median of 39 weeks. The median birth weight was 2980 (range 1901–4280) g. There were no significant differences in gestational age or birth weight between the early and late onset groups. Twenty-six neonates (early onset 10, late onset 16) had acute symptomatic seizures and 15 neonates (early onset 4, late onset 11) had neonatal onset epilepsy. The anticonvulsant therapy efficacy was good in 1 (7%) neonate in the early onset group and in 17 (63%) in the late onset group (p < 0.01). The neurological outcome was normal in 5 (38%) in the early onset group and in 15 (58%) in the late onset group (N.S.). For the 26 neonates with acute symptomatic seizures, the efficacy of the anticonvulsant therapy was good in 0 (0%) in the early onset group and in 11 (69%) in the late onset group (p < 0.01); epilepsy subsequently developed in 2 (20%) in the early onset group and in 4 (25%) in the late onset group (N.S.); and the neurological outcome was normal in 5 (50%) in the early onset group and in 8 (50%) in the late onset group (N.S.). Conclusions: In terms of subsequent epilepsy and neurological outcome, there were no significant differences between the early and late onset groups. Anticonvulsant therapy was more efficacious in the late onset group than in the early onset group. For better anticonvulsant therapy, in addition to the cause of seizures, seizure frequency, and general condition of the neonates, physicians should consider the timing of seizure onset. Funding: None to declare