Abstracts

Rationale: To investigate the demographic, clinical and electrophysiological characteristics of postictal generalized electroencephalography (EEG) suppression (PGES) and thereby facilitate the recognition of PGES and provide clues regarding its risk factors, pathophysiology and relationship with sudden unexpected death in epilepsy patients (SUDEP). Methods: We retrospectively reviewed 237 generalized convulsive seizures (GCSs) in 126 patients during long-term video-EEG (VEEG) recordings. The associations of PGES and prolonged PGES (duration>20 s) with person- and seizure-specific variables were evaluated independently using SPSS software. Results: Eighty patients (63.5%) exhibited PGES after 127 GCSs (53.6%) with an average duration of 41.31±24.03 s. The tonic phase was significantly prolonged in patients with PGES and prolonged PGES. PGES was independently associated with ictal semiology, which was attributable to the different proportions of GCS type 1. After seizure termination, patients with PGES had a higher percentage of postictal unresponsiveness and immobility, including oropharyngeal immobility. Prolonged PGES was more likely to phase out gradually with subsequent immediate body movement, while short-duration PGES was predisposed to have an evoked abrupt termination followed by delayed body movement. Conclusions: Prolonged tonic duration, GCS type 1, postictal unresponsiveness and immobility were more prone to occur with PGES, which might imply that hyperactivation of inhibitory neural networks underlies the pathophysiology of PGES and subsequent SUDEP. Any form of periictal bedside care, whether constituting effective medical intervention or not, would be advised for its possible contribution to interruption of PGES. Regardless of the PGES termination pattern, the neural network resuscitation process was progressive. Funding: National Natural Science Foundation of China (Grant No. 81601133, 81420108014 and 81771402)