Abstracts

Rationale: Although children with hypoxic–ischemic encephalopathy are at risk for neonatal seizures and epilepsy, few studies have examined the neonatal risk factors for developing neonatal seizures or epilepsy. We examined neonatal head magnetic resonance imaging (MRI) data and other clinical information in low-Apgar-score infants to elucidate these risk factors.Methods: This retrospective study enrolled children who were admitted to the neonatal intensive care unit (NICU) of Anjo Kosei Hospital from June 2002 to March 2014. We recruited children who met all of the following criteria: (1) gestational age (GA) of ≥ 35 weeks at birth, (2) 5-minute Apgar score of ≤5, and (3) assessment of outcome at ≥12 months of age. Clinical data, including GA at birth, birth weight, Apgar score, MRI findings, neonatal seizures, subsequent epilepsy, and developmental impairment were collected retrospectively and analyzed. We classified the distribution of injury detected on MRI as either basal ganglia/thalamus lesions or white matter lesions. The significance of differences was tested using Fisher’s exact test.Results: The study enrolled 51 boys and 27 girls. The median GA, birth weight, 5-minute Apgar score, and age at last follow-up were 38 (range 35–43) weeks, 2805 (range 1660–5828) g, 4 (range 0–5), and 26 (range 12–140) months, respectively. MRI images during the NICU stay were obtained for 54 of the 78 patients at a median age of 10 (range 1–33) days. MRI abnormalities were present in 16 newborns. Five patients had basal ganglia/thalamus lesions only, six had white matter lesions only, and five had both lesions. Of the 16 newborns with MRI abnormalities, 11 had neonatal seizures, 5 subsequently developed epilepsy, and 14 had developmental impairment. Of the 38 newborns without MRI abnormalities, 1 had neonatal seizures, 0 developed epilepsy, and 6 had developmental impairment. None of the 24 patients who were not examined using MRI during their NICU stay experienced neonatal seizures or epilepsy. Of the 11 newborns with neonatal seizures and MRI abnormalities, 2 had both basal ganglia/thalamus and white matter lesions, 5 had basal ganglia/thalamus lesions only, and 4 had white matter lesions only. Patients with MRI abnormalities had neonatal seizures, epilepsy, and developmental impairment significantly more frequently than did patients without any MRI abnormalities (p < 0.01, p < 0.01, and p < 0.01, respectively). Five patients subsequently developed epilepsy. All of them had seizures in the neonatal period. Of the three patients with basal ganglia/thalamus lesions, one developed focal seizures and the other two developed spasms. Two patients who had both basal ganglia/thalamus and white matter lesions developed spasms.Conclusions: Eleven of the 12 low-Apgar-score infants with neonatal seizures had MRI abnormalities. All of the infants who subsequently developed epilepsy had both MRI abnormalities and seizures in the neonatal period.