Deep-Seated Interictal Epileptiform Activity: Another Reason to Lose Sleep

Abstract

Sleep Disruption in Epilepsy: Ictal and Interictal Epileptic Activity Matter Peter-Derex L, Klimes P, Latreille V, et al. Ann Neurol. 2020;88(5):907-920. doi:10.1002/ana.25884. PMID: 32833279. Objective: Disturbed sleep is common in epilepsy. The direct influence of nocturnal epileptic activity on sleep fragmentation remains poorly understood. Stereo-electroencephalography paired with polysomnography is the ideal tool to study this relationship. We investigated whether sleep-related epileptic activity is associated with sleep disruption. Methods: We visually marked sleep stages, arousals, seizures, and epileptic bursts in 36 patients with focal drug resistant epilepsy who underwent combined stereo-electroencephalography/polysomnography during presurgical evaluation. Epileptic spikes were detected automatically. Spike and burst indices (n/sec/channel) were computed across four 3-second time windows (baseline sleep, prearousal, arousal, and postarousal). Sleep stage and anatomic localization were tested as modulating factors. We assessed the intra-arousal dynamics of spikes and their relationship with the slow-wave component of nonrapid eye movement sleep (NR) arousals. Results: The vast majority of sleep-related seizures (82.4%; 76.5% asymptomatic) were followed by awakenings or arousals. The epileptic burst index increased significantly before arousals as compared to baseline and postarousal, irrespective of sleep stage or brain area. A similar prearousal increase was observed for the spike index in NR stage 2 and rapid eye movement sleep. In addition, the spike index increased during the arousal itself in neocortical channels and was strongly correlated with the slow-wave component of NR arousals (r = 0.99, P