Abstracts

Rationale: New onset refractory status epilepticus (NORSE) is defined as status epilepticus that is refractory to two lines of anti-epileptic agents and has no initial identifiable etiology. Recent studies on NORSE report autoimmune causes as a common etiology (5), however many cases continue to remain cryptogenic despite extensive evaluation. Recent retrospective studies suggest that IT may improve functional outcome, even in those with cryptogenic NORSE (1,4,5). Our goals were to identify NORSE cases at University Hospital in San Antonio(UHS), a major catch area of southwest Texas; to identify similarities among patients with NORSE; and to identify whether IT was related to functional outcomes. Methods: We conducted a retrospective chart review of patients who underwent continuous EEG monitoring(cEEGM) during 2015 at UHS. We selected patients according to the following criteria: age?-18 years; seizures refractory to two lines of anti-seizure treatment; no etiology found within the first 2 days of seizure onset; no history of seizure disorder. Patients were divided into groups who ultimately were found to have an etiology, and those whose diagnosis remained cryptogenic. Patients were also divided into groups who received IT and those who did not. Clinical outcomes were compared using the Glasgow Outcome Scale(GCOS), and measured based on the most recent follow-up. A favorable outcome was defined as GCOS?-4. Unfavorable outcome was defined as GCOS=3. Results: 9 patients fulfilled our inclusion criteria. 6 were female; 3 were male. An etiology was found in 5 patients, all of whom were found to have an autoimmune/paraneoplastic etiology. 4 patients were cryptogenic. 4 patients had a known underlying malignancy. 2 were in the cryptogenic group. There were no differences in demographics between the autoimmune and cryptogenic groups. The most common presentation was altered mental status and seizures. Patients with confirmed autoimmune etiology experienced a trend towards increased hospital length of stay(LOS). With regard to electrographic, laboratory, and neuroimaging findings, there were no differences between the two groups. There was no difference in number of anti-seizure medications or anesthetics used. Patients with autoimmune etiology were treated with IT more often. Those who underwent IT had more favorable outcomes than those who did not. Also, there was a trend for those with favorable outcomes to experience longer hospital LOS compared to those with unfavorable outcomes. Conclusions: There were no differences in the inherent features of patients with autoimmune and cryptogenic NORSE, suggesting that cryptogenic NORSE may have an autoimmune/paraneoplastic etiology. In our hospital, those who had autoimmune etiology were treated with IT more often than those with cryptogenic. Those treated with IT had more favorable outcomes than those who were not. Our findings suggest that in patients with cryptogenic NORSE, a high suspicion for an autoimmune/paraneoplastic etiology should be maintained. IT may benefit those with cryptogenic NORSE, as well as those with autoimmune etiology. Those successfully treated for NORSE experienced longer hospital LOS. Autoimmune NORSE patients also had longer hospital LOS, and were also more often treated with IT. This suggests that treatment may have been withdrawn prematurely in those with cryptogenic NORSE, and that those with NORSE may inherently experience longer hospital courses. There is currently no prospective data on the treatment of NORSE, and there is no clear consensus on a treatment regimen. Therefore, randomized clinical trials on NORSE may be helpful to determine the efficacy of various IT agents and whether the timing of IT determines outcome. Funding: UT Health Science Center at San Antonio