Abstracts

Rationale: Post-ictal generalized EEG suppression (PGES) has been equivocally associated with sudden unexpected death in epilepsy (SUDEP). Many studies retrospectively focus on correlations between the two; however the incidence and duration of PGES during routine in-patient characterization of events is not commonly reported, in a prospective manner, across multiple institutions. During a prospective, multi-center, clinical trial, 199 subjects with a history of suspected generalized tonic-clonic (GTC) seizures were admitted across eleven NAEC level IV epilepsy monitoring units (EMUs) for spell characterization.¹ This study is being conducted to document the frequency and duration of PGES in patients with a suspected history of GTC seizures across multiple institutions to improve SUDEP risk quantification in the general population. Methods: Video EEG data recorded during EMU admissions was evaluated by a panel of three independent ABPN certified epileptologists to identify GTC seizures and indicate, by majority rule, whether they were primarily or secondarily generalized. A fourth ABPN certified epileptologist evaluated the GTC seizures for PGES as defined in Lhatoo et al., which is generalized EEG suppression of 10 µV or less, lasting for at least 1 second, within 30 seconds of electroclinical seizure end.² Results: In this prospective data, 29 GTC seizures were recorded from 24 patients; 4 were primarily (1°) generalized, and 25 were secondarily (2°) generalized. To date, 12 GTC seizures from 9 patients have been evaluated for PGES.  Although all seizures were followed by postictal slowing, 4 out of 12 seizures, from 2 patients, had suppression meeting criteria of Lhatoo et al². Post-ictal heart rate for both patients increased by an average of 62%. Evaluation of the entire dataset in relation to PGES duration, seizure frequency, and peri-ictal heart rate variability will be provided at the time of the conference. Conclusions: Single center estimates of PGES frequency and duration may be biased. This evaluation of prospective data from 11 independent EMUs shows that most patients admitted for diagnostic characterization of GTC seizures experience 2° generalized GTC seizures. In this preliminary analysis of 12 seizures, longer periods of PGES were observed in 1° generalized events and PGES was much shorter or not observed following 2° generalized GTC seizures.1. Halford JJ, Sperling MR, Nair DR, et al. Detection of generalized tonic-clonic seizures using surface electromyographic monitoring. Epilepsia. 2017;58:1861-1869.2. Lhatoo SD, Faulkner HJ Fau-Dembny K, Dembny K, Fau-Trippick K, Trippick K, Fau-Johnson C, Johnson C, Fau-Bird JM, Bird JM. An electroclinical case-control study of sudden unexpected death in epilepsy. Ann Neurol. 68:1531-8249 (Electronic). Funding: Brain Sentinel, Inc.