EEG Characteristics of Successful Burst Suppression for Refractory Status Epilepticus

Abstract

Refractory status epilepticus (RSE) is often treated with continuous intravenous medications with the goal of EEG burst suppression. Standard advice is to titrate medications to at least 10-s interburst intervals; however, this has not been shown to improve outcome. We examined EEG characteristics in patients treated with IV anesthetic therapy (IVAT) for RSE to determine which EEG characteristics were associated with successful lifting of IVAT (i.e., without recurrence of status epilepticus). We screened the clinical continuous EEG database for adult patients treated with IVAT for RSE (excluding patients with anoxic injury). We measured the length of bursts and interburst intervals for each patient, calculated EEG burst suppression ratios, and graded bursts for the amount of epileptiform activity. We compared these characteristics in successful versus unsuccessful IVAT lifting attempts. We included 17 successful and 20 unsuccessful lifting attempts in 19 patients (5 used as a holdout validation set). The interburst intervals, burst suppression ratios, and length of bursts did not differentiate successful and unsuccessful lifting attempts; the amount of epileptiform activity in bursts correlated with success or failure to wean IVAT (p=0.008). Maximum burst amplitude <125μV had 84.6% sensitivity and 61.1% specificity for predicting successful lifting. The length of interburst intervals and burst suppression did not predict successful termination of RSE in this small cohort. This may suggest that EEG characteristics, rather a strict interburst interval goal, could guide IVAT for RSE.