Abstracts

Refractory Status Epilepticus (RSE) is a severe condition where seizures do not stop with first- and second-line antiepileptic drug (AED). The risk factors that predispose to it are still poorly defined. RSE ranges from 9% to 40% of SE in different series. Few studies have focused on clinical factors but detailed ictal EEG studies in RSE still lacks. If a stereotyped sequence of ictal patterns exist, then the most severe patterns should be found in RSE. It is also not yet clear whether ictal EEG predicts outcome of RSE. To address these points we reviewed all EEGs performed during RSE and classified them according to previously defined patterns. RSE was defined as SE that had failed to first-and second-line AED therapy, and lasted a minimum of 60 minutes. All patients had serial EEGs performed and the recordings were usually prolonged (60-120 min), and 3 patients had continuous EEG. Clinical data was reviewed and correlated to ictal patterns. EEG patterns were classified in discrete seizure (DS), merging seizures (MS), continuous ictal discharges (CID), periodic epileptiform discharges lateralized or diffuse (PLEDs/PEDs), and combination of ictal patterns (more than one pattern in the same record). Electrographically SE was defined when the ictal pattern occupied a minimum of 80% of the recording time. Fifteen patients totaling 17 episodes of RSE were analysed (2 patients had more than one episode). Ages ranged from 18 months to 84 years, mean of 33.9 years. 6/15 (40%) patients were females and 9/15 (60%) males. Etiologies were: epilepsy in 3/17 (17.6% %), brain structural lesion (tumor, metastasis, trauma) in 2/17 (11.8%), non-structural lesions (metabolic, hypoxic-ischemic, infection) in 7/17 (41.2%), and miscellanea in 5/17 (29.4%). Ninety EEGs and 3 continuous EEGs were analyzed. Pattern of first EEG recording were classified as DS (23.5%), MS (35.3%), CID (17.6%), PLEDs/PEDs (5.9%), and combination of ictal patterns (17.6%). Regarding the progression of patterns, 7/17 RSE (41.2%) had variable pattern but 10/17 (58.8%) had invariable ictal patterns. The mortality rate was 6/17 (35.3%), but 2 patients were already out of the SE when died. The analysis of mortality and ictal pattern disclosed: 2/6 PLEDs and MS, 1/6 PLEDs, 1/6 DC, 1/6 CID and 1/6 DS. The analysis of mortality and age showed 47.7yrs and 24.8 years, respectively, for the groups death and survivors. The repertoire of ictal EEG patterns in RSE includes all previously described EEG patterns. When dealing with prognosis initial as well as evolution of ictal patterns need to be carefully considered and correlated to mortality risks. Approximately half of the patients that died had PLEDs as the initial EEG pattern, but other variables including etiology and age may also play an important role. (Supported by FAPESP)