Predictors of awakening from postanoxic status epilepticus after therapeutic hypothermia

Background: Postanoxic status epilepticus (PSE) is considered a predictor of fatal outcome and therefore not intensively treated; however, some patients have had favorable outcomes. The aim of this study was to identify favorable predictors for awakening beyond vegetative state in PSE. Methods: We studied six subjects treated with hypothermia improving beyond vegetative state after cerebral anoxia, despite PSE. They were among a cohort of patients treated for anoxic encephalopathy with therapeutic hypothermia in our institution between October 1999 and May 2006 (retrospectively, 3/107 patients) and June 2006 and May 2008 (prospectively, 3/74 patients). PSE was defined by clinical and EEG criteria. Outcome was assessed according to the Glasgow-Pittsburgh Cerebral Performance Categories (CPC). Results: All improving patients had preserved brainstem reflexes, cortical somatosensory evoked potentials, and reactive EEG background during PSE. Half of them had myoclonic PSE, while three had nonconvulsive PSE. In the prospective arm, 3/28 patients with PSE showed this clinical-electrophysiologic profile; all awoke. Treatments consisted of benzodiazepines, various antiepileptic drugs, and propofol. One subject died of pneumonia in a minimally conscious state, one patient returned to baseline (CPC1), three had moderate impairment (CPC2), and one remained dependent (CPC3). Patients with nonconvulsive PSE showed a better prognosis than subjects with myoclonic PSE (p = 0.042). Conclusion: Patients with postanoxic status epilepticus and preserved brainstem reactions, somatosensory evoked potentials, and EEG reactivity may have a favorable outcome if their condition is treated as status epilepticus. AED = antiepileptic drug; BR = brainstem reflexes (one or more); CA = cardiac arrest; CHUV = University Hospital of Lausanne; CLZ = clonazepam; CPC = Cerebral Performance Categories; GTC = generalized tonic-clonic seizure (prolonged); ICU = intensive care unit; LA = Lance-Adams syndrome; LEV = levetiracetam; MR = motor response to painful stimuli; PSE = postanoxic status epilepticus; NA = not assessed; PHT = phenytoin; PRO = propofol; ROSC = return of spontaneous circulation; SE = status epilepticus; SIRPID = stimulus-induced rhythmic, periodic, or ictal discharges; SSEP = somatosensory evoked potentials; VF = ventricular fibrillation; VPA = valproate.