BackgroundFew studies have investigated intravenous lacosamide use to treat cluster seizures in pediatric patients. Therefore, we aimed to investigate the efficacy and safety of intravenous lacosamide therapy in pediatric patients with cluster seizures. MethodsWe retrospectively evaluated the efficacy and safety of intravenous lacosamide therapy in 25 pediatric patients with cluster seizures at Saitama Children's Medical Center between March 2019 and June 2023. Cluster seizures were defined as a single seizure of less than five minutes duration, repeated three or more times within 12 hours, with recovery of consciousness between seizures. Response was defined as seizure freedom for at least 12 hours after lacosamide infusion. ResultsThe median age at onset of epilepsy was 1.5 (0.0 to 9.8) years. The median seizure frequency was 5 (3 to 20) times per 12 hours. The etiologies were remote (n = 17), acute (n = 4), and progressive (n = 4). The median age at which intravenous lacosamide therapy was administered was 4.2 (0.0 to 11.3) years. The median lacosamide dose was 2.6 (1.3 to 5.2) mg/kg. In total, 12 of 25 patients (48.0%) responded. Among patients treated with intravenous lacosamide as first-line therapy, nine of 17 (52.9%) had complete seizure remission. The frequency of complete seizure remission in patients with remote etiologies was 58.8% (10 of 17); among them, seven of 12 (58.3%) patients with structural abnormalities showed complete seizure remission. No adverse events were observed. ConclusionsIntravenous lacosamide therapy is a potentially useful treatment option for cluster seizures in pediatric patients.