Abstracts

Rationale: New onset refractory status epilepticus (NORSE) is an uncommon entity and represents a diagnostic and therapeutic dilemma, with no established treatment protocol. Due to the cryptogenic nature in up to 60% of cases, both diagnosis and treatment are often delayed while an extensive evaluation is initiated. Since an underlying inflammatory or autoimmune etiology is suspected based on the high proportion of patients who eventually are confirmed to have autoimmune antibody positivity, immunotherapy is commonly used as an empiric therapy.  Because prompt immunotherapy is thought to improve outcomes in autoimmune encephalitis, we aimed to assess the time to immunotherapy in NORSE patients since no standardized timing to first administration nor dosages exist. Methods: We conducted a retrospective chart review at Stanford University Adult and Stanford Children’s Hospitals using cohort database tools and ICD-9, ICD-10 and CPT codes from 2014  to 2017.  We identified a cohort of 10 NORSE patients using the International consensus definition of NORSE.  We included pediatric and adult cases presenting with refractory status epilepticus with no readily identified etiology established within 72 hours from time of presentation.  We collected demographic information and data on time to first administration of immunotherapy, type of immunotherapy, direct complications related to immunotherapy, autoimmune antibody status and outcomes in the form of favorable Modified Rankin Scale (mRS) =3 at discharge and 6 months follow-up. Results: Fifteen charts of patients with NORSE were reviewed. Two patients were excluded due to missing data and three were excluded from analysis due to presence of confounding medical illness. Ages ranged from 6 to 71 years old and the average time to administration of immunotherapy in our cohort of patients was 7 days  (range 4-19 days), with 9 out of 10 patients receiving some form of immunotherapy within 7 days. All subjects received at least two forms of first-line immunotherapy, including IV steroids, intravenous immunoglobulin and / or plasma exchange.  Four patients received an additional second-line immunotherapy agent such as rituximab, cyclophosphamide or mycophenolate mofetil .  Twenty percent (2/10) of patients tested positive for autoimmune antibodies in CSF or plasma. Forty percent of patients had a favorable outcome at discharge (mRS=3).  All five patients with 6-month follow-up data available had favorable outcomes. The only complication directly related to immunotherapy administration was chemical meningitis in one patient who received IVIG, which resolved with supportive care. Conclusions: This is a descriptive case series of NORSE at a single center. We demonstrate that early empiric use of immunotherapy is feasible and commonly practiced at our institution. As this is a limited cohort of patients, we are unable to determine whether early immunotherapy affects outcomes of patients presenting with NORSE. Further prospective studies are needed with pooled data to determine the optimal timing of immunotherapy in order to translate this to formal treatment protocols. Funding: None