Clinical outcome of generalized periodic epileptiform discharges on first EEG in patients with hypoxic encephalopathy postcardiac arrest

IntroductionThe EEG, alongside clinical examination, imaging studies, and SSEPs, is used to determine the prognosis following hypoxic encephalopathy postcardiac arrest. Generalized periodic epileptiform discharges (GPEDs) are recognized as a “malignant” EEG pattern associated with very poor outcome with previous studies reporting no or few survivors. We looked at our database of cardiac arrest patients who subsequently developed GPEDs to determine clinical outcome and profile any survivors.MethodologyWe identified all cardiac arrest patients treated at King's College Hospital between 2011-2014 who developed hypoxic encephalopathy associated with GPEDs, BiPLEDs (bilateral periodic lateralized epileptiform discharges), and periodic discharges on first EEG. We collected clinical data including age, gender, downtime, EEG reactivity, presence of seizures or myoclonus, and outcome. Survivors were defined as patients who were discharged from the hospital to home or a neurorehabilitation unit.ResultsThirty-six postcardiac arrest patients with hypoxic encephalopathy were identified, 24/36 with GPEDs, and 12/36 with BiPLEDs on first EEG. The mean age of patients was 62.8 ± 14.5 years old, with 27 males (75%) and 9 females (25%). Ten of thirty-six patients survived, which is slightly higher than previously reported. Statistical tests to compare clinical characteristics between survivors and nonsurvivors demonstrated no significant differences except for trend to significance for the presence of reactivity on first EEG (p = 0.0794). On discharge, one survivor had good functional outcome (and subsequently became independent), but all others were dependent for all ADLs (activities of daily living).ConclusionGeneralized periodic epileptiform discharges carry a grave clinical prognosis following cardiac arrest. This study did identify a higher number of survivors compared to previous studies, but most were severely disabled at hospital discharge. Reactivity of the first EEG might predict better prognosis and merit further evaluation.This article is part of a Special Issue entitled “Status Epilepticus”.