Abstracts

Rationale: Postictal generalized EEG suppression (PGES) has been reported in adult with sudden unexpected death in epilepsy (SUDEP). We characterize PGES in children undergoing prolonged scalp video EEG.Methods: A retrospective review of video EEG at The Hospital for Sick Children (2009-2011) was performed to identify episodes of PGES. PGES was defined as generalized voltage attenuation <10 V and >1sec. We analyzed age, duration of PGES, type and duration of seizures, EEG awake background activity and sleep features, and posture of generalized tonic-clonic seizure (GTCS).Results: We reviewed 977 reports of video EEG including 399 (41%) with electroclinical seizures. 26 (7%; 16 male; mean 9.9 years old) children demonstrated 48 (37%) seizures with PGES from a total of 129 seizures. Duration of PGES ranged 1.7-54.3 seconds (mean 31.9 seconds). 26 patients with PGES were significantly older (mean 9.9 years old) than 373 patients (7.6 years old) without PGES (p<0.05). 45 (35%) partial seizure with secondary GTCS highest correlated with PGES among 84 other type of seizures including generalized tonic seizure, epileptic spasm, myoclonus and partial seizure alone (p<0.001). 48 seizures with PGES were longer (mean 92.1 seconds) than 81 seizures (30 seconds) without PGES (p<0.001). Duration (mean 35 seconds) of 42 PGES with GTCS was longer than that (9.6 seconds) of 6 PGES without GTCS (p<0.005). Older children demonstrated longer duration of PGES (R=0.74, p<0.001). Duration of PGES was longer in 14 children with normal awake EEG background (p<0.001); 19 with normal sleep spindles (p<0.001) and 18 with normal REM sleep (p<0.005) than in 11 with disorganized awake background, 6 with disorganized sleep spindles and 7 without REM sleep, respectively. 38 (50%) of 76 GTCS in 399 patients with electroclinical seizures presented with all limb tonic-extension posture (ALTP). The incidence of PGES was higher in 26 (70%) patients with ALTP, than in 11 (30%) patients without ALTP.Conclusions: PGES was significantly associated with older age, longer seizure duration, GTCS and ALTP in children. Longer duration of PGES was significantly correlated with older age, GTCS and normal EEG awake background activity and sleep features.