Abstracts

Rationale: Patients with epilepsy often experience acute repetitive seizures or seizure clusters, which can be associated with adverse long-term outcomes and status epilepticus. We investigated clinical factors associated with seizure clusters in pediatric patients. Methods: Prospective observational study conducted at two tertiary epilepsy centers. We included pediatric patients (1 month-18 years old) with a documented diagnosis of epilepsy. Those with psychogenic/non-epileptic seizures, epileptic spasms, or more than one seizure per hour were excluded. Based on baseline data, patients were categorized into 3 risk groups using reported seizure frequency in the year prior to enrollment: 1- High risk (prior “day-cluster”: =2 seizures/day), 2- Intermediate risk (“active epilepsy”): seizures without clustering, 3- Low risk (“seizure free”): seizure free during the prior year. Participants were followed up for one year through monthly phone calls, and were asked to keep a log of their seizures using online or paper diaries. Based on prospective data, we determined the prevalence of seizure clusters in each of the risk groups. We defined clusters as =2 seizures/6 hours, or =4 seizures/day. Results: Among 375 enrolled patients, 80 (21.3%) opted out or were lost to follow-up. Of the 295 patients who remained in the study, 54.2% were female, and the median age was 10 years (IQR: 7-14). Overall, 70.2% identified as white, 11.5% as Black/African American, 4.4% as Asian, and 13.9% as other races or unknown. Median age at seizure onset was 27 months (IQR: 12-60 months). The median number of previously trialed anti-epileptic drugs (AEDs) was 2 (IQR: 0-3) (Table 1).At baseline, 79 patients (26.8%) were categorized into group 1 (prior day-clusters), 124 (42.0%) in group 2 (active epilepsy), and 92 (31.2 %) in group 3 (seizure free). During the follow-up period, 101 (34.2%) experienced 6-hour clusters, 70 (23.7%) had seizures without clusters, and 124 (42.0%) were seizure free. The overall prevalence of 6-hour clusters among patients with active seizures at baseline (groups 1 and 2) was 49.3% (100/203) (Table 2). Patients with 6-hour clusters were younger than the seizure-free group (p=0.003), and had higher baseline seizure frequency and higher number of failed AEDs (p<0.001) (Table 1). Overall, 79.7% of patients had a rescue plan at the time of enrollment, including 88.3% of the “prior day-clusters” group, and 80.3% of patients with active epilepsy. During the follow-up period, 44.5% (45/101) of patients in the 6-hour clusters group reported use of rescue medication for aborting seizure clusters. The most frequently reported rescue medication in this group was rectal diazepam (40.4%), followed by oral lorazepam (35.2%), oral clonazepam (12.2%), and intranasal midazolam (3.8%). Conclusions: Seizure clusters are common in pediatric epilepsy patients. Younger age, frequent baseline seizures, and refractory epilepsy were associated with seizure clusters. Rectal diazepam was the most frequently used rescue medication for aborting seizure clusters. Funding: This study was supported by Upsher-Smith Laboratories and Proximagen.