Abstracts

Rationale: Prolonged postictal generalized EEG suppression (PGES) in patients with generalized convulsive seizures is implicated in sudden unexpected death in epilepsy (SUDEP). The objective of our study is to determine the incidence, duration and risk factors of PGES and further understand its role in the pathogenesis of SUDEP. Methods: We reviewed the video-EEG of 80 patients (45 men and 35 women) who had a total of 98 generalized convulsive seizures (24 primary generalized convulsive seizures and 74 secondarily generalized convulsive seizures) during their long-term video-EEG monitoring. We determined the incidence and duration of PGES, and analyzed impacts of seizure onset, duration and termination on PGES. Moreover, we correlated the duration of PGES with that of postictal coma in these patients. Results: PGES was observed in 68 of 98 (69%) generalized convulsive seizures. Mean PGES duration was 43 seconds. Mean PGES was 42 seconds in primary generalized convulsive seizures and 43 seconds in secondarily generalized convulsive seizures. Mean total seizure duration was 115 seconds with PGES and 112 seconds without PGES. Mean convulsive phase was 64 seconds with PGES and 67 seconds without PGES. Mean tonic phase was 28 seconds with PGES and 17 seconds without PGES. Mean postictal coma duration was 69 seconds with PGES and 35 seconds without PGES. In addition, abrupt seizure termination was more likely to result in PGES than gradual seizure termination.Conclusions: PGES is a common feature of generalized convulsive seizures with an incidence of 69%. Seizure onset, total seizure duration and convulsive phase duration do not seem to affect PGES whereas prolonged tonic phase and abrupt seizure termination are associated with PGES. Furthermore, PGES can lead to prolonged postictal coma during which patients are unable to turn from prone to supine and their respiration can be compromised, potentially increasing the risk of SUDEP.