Age-Stratified Interictal Epileptiform Discharges in Scn1a-Related Epilepsy: Association With Early Sodium Channel-Blocking Antiseizure Medication Exposure Publisher Pubmed



Esteghamat S ; Mohammadi M ; Rezaei Z ; Nikbakht S ; Rashidi Nezhad A ; Badv R S
Source: Seizure Published:2026

Abstract

Purpose To characterize age-stratified distributions of interictal epileptiform discharges (IEDs) in SCN1A -related epilepsy, compare findings between genotype classes, and explore associations with early exposure to sodium channel–blocking antiseizure medications (SCBs). Methods We conducted a retrospective observational study of 57 individuals with pathogenic or likely pathogenic SCN1A variants and at least one interictal electroencephalogram (EEG). EEGs were assigned to predefined developmental age bands (0–1, 1–3, 3–6, 6–13, and 13–20 years). Within each interval, one EEG per participant was selected according to the highest degree of IED involvement. EEGs were classified as no IEDs, focal IEDs, or bilateral/multifocal IEDs. Cumulative exposure to SCBs during the first five years of life was categorized as <11 months or ≥11 months. Associations within the 6–13-year age band were examined using Firth's bias-reduced logistic regression. Results IEDs were not observed during infancy and became more frequent in later developmental stages, peaking between 6 and 13 years. No significant overall difference in the age-specific distribution of IEDs was observed between truncating and non-truncating variants. In the 6–13-year age band (n = 39), IEDs were present in 9/30 (30.0%) patients with <11 months of SCB exposure and 8/9 (88.9%) patients with ≥11 months of exposure (OR 18.67; 95% CI 2.01–173.2; p = 0.005). The association persisted after adjustment for genotype class, sex, and age at seizure onset (adjusted OR 28.74; 95% CI 3.71–497.64; p = 0.001) and was materially unchanged after additional adjustment for age at genetic diagnosis (adjusted OR 28.33; 95% CI 3.26–605.00; p = 0.001). Conclusion Prolonged early exposure to SCBs was associated with the presence of IEDs in the 6–13-year age band in individuals with SCN1A -related epilepsy. These exploratory findings should be considered hypothesis-generating and require confirmation in prospective multicenter cohorts. © 2026 British Epilepsy Association.