Abstracts

Rationale: The identification of a biomarker for sudden unexpected death in epilepsy (SUDEP) has the potential to save lives. Generalized convulsive seizure (GCS) and postictal generalized EEG suppression (PGES) most often precede SUDEP and are potential biomarkers. We identify the EEG and seizure characteristics associated with PGES in children with epilepsy. Methods: Video EEG (VEEG) were reviewed for seizure type, duration and semiology, and EEG features. Age at VEEG monitoring ranged from 7 days to 19 years (mean 7.7 years). Of the 977 children that underwent continuous VEEG during the study period, 399 children (41%) had electroclinical seizures (226 male, 57%) and 40 of the 399 (10%) children had one or more GCS. To identify predictors of PGES we identified; 1) 40 children with GCS; and 2) 77 GCS with PGES (34) and without PGES (43). We applied multilevel analysis to adjust for clustering at the subject level. Results: Nineteen (48%) of the 40 children demonstrated PGES after GCS. Age of seizure onset was older in 19 children with PGES (a mean 6.8 years old, 95%CI [4.7-8.9] than 21 without PGES (3 years old, [1.1-4.1], p = 0.041). PGES occurred significantly more often from sleep than awake (point of estimate 16.67; 95% CI [0.97-32.36], p < 0.0038). Shorter duration of the clonic phase was significantly associated with PGES (-0.735; [-1.338, -0.133], P = 0.018). Symmetric tonic extension posturing (STEP) significantly increased the risk of PGES compared to asymmetric tonic extension posturing (42.94; [18.77, 67.12], p = 0.001). All 15 GCS with a terminal burst-suppression pattern were followed by PGES in contrast to 19 of 62 GCS without burst-suppression (1532, p < 0.001). Conclusions: Ictal features may be used to identify children at risk of PGES. Ictal decerebration-like STEP with shorter clonic phase and terminal burst-suppression pattern identify malignant GCS, associated with PGES and a potentially increased risk of SUDEP. Funding: None