Abstracts

Rationale: New-onset refractory status epilepticus (NORSE) was recently defined in children.  We aimed to outline the clinical profile of NORSE in a pediatric population, compare it with the febrile illness related epileptic syndrome (FIRES) and identify features associated with outcome.  Methods: We enrolled patients within the pediatric Status Epilepticus Research Group (pSERG) cohort with the following inclusion criteria: 1) age 1month-18years; 2) first episode of refractory status epilepticus (RSE) requiring more than 2 anti-seizure medications (ASM); 3) RSE episode between January 2011 and October 2016. We excluded patients with a history of epilepsy or a readily identifiable cause of status epilepticus (SE), according to the consensus NORSE definition: patients without history of epilepsy and new onset of RSE without readily identifiable cause. FIRES is a subgroup of  NORSE that requires a prior febrile illness. Since this was an observational study, there was no standardized protocol regarding the management of RSE. The primary outcome was no return to baseline function at hospital discharge or death (worse outcome). Bonferroni’s correction was applied for multiple comparisons. Adjusted p-values are provided and considered significant if less than 0.05. Results: Of 244 patients with a first episode of RSE, 46 patients met criteria for NORSE. Median age was 2.4 years and 25 (54%) were female. A definitive etiology was found in 6 patients (13%): genetic (2.2%), auto-immune (4.3%) or infectious (6.5%). Twenty-one (45%) patients were diagnosed with febrile SE (FSE) and 19 (41%) patients remained with an unknown cause (Table 1). Fourteen (30%) patients correspond to FIRES. CSF results were abnormal in 16 (39%) cases, including 10 FIRES cases. Twenty eight (60%) patients returned to baseline function and 18 (40%) did not, including 12 (86%) FIRES. Three (6.5%) patients died. Patients with worse outcome were older (5.8 vs 1.2 years; p=0.0072), more often presented with a preceding febrile illness (13[72%] vs 6[39%]; p=0.016), longer ICU stay (45 vs 3 days; p=0.0016) and longer electroclinical SE duration (264 vs 12 hours; p=0.0063). They required more ASM (2.5 vs 2; adjusted p=0.048), anesthetics in continuous infusion (2 vs 0; p=0.023), ketogenic diet (8 vs 1; p=0.018) or immunotherapies (10 vs 2; p=0.0072). Patients with FSE had better outcome (20 vs. 1; p < 0.001) (Table 2). Conclusions: The etiology of NORSE in children is unknown in almost half of the cases, with FIRES and FSE constituting the largest subgroups. Our study shows outcomes better than adult NORSE patients. Consistent with previous literature, cases of NORSE attributed to FIRES (preceding febrile illness) and prolonged super-refractory cases were associated with worse outcome. Funding: Epilepsy Foundation of America (EF-213583, Targeted Initiative for Health Outcomes), American Epilepsy Society/Epilepsy Foundation of America Infrastructure Awards, Pediatric Epilepsy Research Foundation, International Federation of Clinical Neurophysiology (IFCN), Epilepsy Research Fund.