Postictal Generalized EEG Suppression After Generalized Convulsive Seizure:a Double-edged Sword

Objective:To investigate key facilitating factors for postictal generalized EEG suppression (PGES) in a large cohort of patients with generalized convulsive seizures (GCSs), in so doing, to further understand its implication in the mechanism of sudden unexpected death in epilepsy (SUDEP).Methods:We retrospectively reviewed the data of consecutive patients who had GCSs in epilepsy monitoring unit (EMU). Statistical analysis was performed to assess different variables as the potential risk factors for PGES.Results:208patients with366seizures were enrolled. PGES was observed in109(51.9%) patients and168(45.9%) GCSs. The duration of PGES was33.2±12.0s (34s,3-70s). PGES or severe PGES (>20s) was associated with more severe postictal coma and temporal lobe epilepsy. Moreover, PGES was independently associated with longer tonic duration, shorter entire seizure duration and lower habitual seizure frequency.Conclusions:PGES was not only strongly correlated with longer tonic duration, but also with shorter total seizure duration and lower habitual seizure frequency. Significance:PGES may represent a switch-off inhibitory mechanism in seizure termination; moreover, it may represent the efficacy of a long-lasting inhibitory network that suppresses GCS ictogenesis. There is a complex relationship between PGES and SUDEP.