Cortical physiological arousal following termination of absence seizures

Although the brain state preceding and during absence seizures has been well-characterized, the postictal brain state remains largely unexplored due to the prevailing assumption that absence seizures have minimal or no postictal changes. To address this gap, scalp EEG recordings from 55 patients with 3-4 Hz spike-wave discharges across four multi-site cohorts were analyzed. Spectral power was measured relative to each seizure's preictal baseline, and the postictal period was compared to a time-matched preictal window. Rather than an immediate return to baseline after seizure offset, a significant broadband increase in EEG power was observed in the gamma (>25 Hz) and delta (<4 Hz) frequency bands, followed by a gradual decline over the next 15 s to 30 s. In contrast, no comparable change preceded the seizures. This suggests that recovery from an absence seizure is an active process with a characteristic electrophysiological signature consistent with cortical activation and arousal. Thus, postictal arousal may facilitate exit from the seizure state, and with further work could serve as an electrophysiological marker and therapeutic target for recovery in absence epilepsy.