Abstracts

Rationale: About 40–50% of status epilepticus patients do not have any history of seizures. Although there are recent studies indicating that new-onset refractory status epilepticus without any known etiology (NORSE) are related to autoimmune diseases, the new-onset status epilepticus (NOSE) have not been systematically studied. Therefore, this study was performed in order to determine the characteristics of NOSE, especially new-onset refractory status epilepticus. We also tried to determine the frequency of NORSE among NOSE and its morbidity and mortality, to find out the relationship between etiologies of NOSE and the outcome and possible predictors of poor outcome in NOSE.Methods: The Korean Initiative for Status Epilepticus Registry (KAISER) is a Korean multi-center database of adult patients with status epilepticus. For enrollment in this registry, we excluded status epilepticus patients which is caused by hypoxia. We prospectively collected the information from the patients with status epilepticus from nine institutions in South Korea. In this study, we focused on the patients with NOSE, which was defined as status epilepticus patients who never had seizure previously. We obtained information of the patients about age, gender, etiologies, electroencephalography findings, and imaging findings. Outcome were assessed using modified Rankin scale at the time of admission and discharge.Results: Among the total of 202 admissions from our registry, 115 admissions (57%) due to NOSE were noted. Patients with NOSE were older than those without NOSE (61.0±18.4 vs. 52.1±19.7, p=0.002) Gender did not differ between these two groups. The percentages of refractory status epilepticus did not differ significantly between those with or without history of seizures (31% vs. 21%, p=0.213). Among various etiologies the most common etiology in both NOSE and non-NOSE group was cerebrovascular etiology (23% vs. 22%, respectively). Neoplasia and cortical developmental malformation was less common in NOSE group compared to non-NOSE group (4% vs. 16%, p=0.023; 0% vs. 8%, p=0.008, respectively). In contrast, metabolic cause was more common in NOSE group compared to non-NOSE group (10% vs. 0%, p=0.035). Although inflammatory cause and unknown case were more common in NOSE group than in non-NOSE group, they were not significant (19% vs. 14%, p=0.652; 18% vs. 6%, p=0.084, respectively). Although mRS at admission of NOSE patients did not differ from that of Non-NOSE patients [4(3–4) vs. 5(4–5), p=0.255], mRS at discharge of NOSE patients were worse compared to non-NOSE patients [4(1–6) vs. 2(0–2.5), p=0.12]. Furthermore, mortality of NOSE was higher in NOSE patients compared to non-NOSE patients (4% vs. 20%, p=0.02). The mortality of RSE patients in NOSE group was even higher (33%).Conclusions: NOSE patients have worse outcome than non-NOSE patients. Therefore, patients with NOSE and non-NOSE patients should be approached differently, especially during acute stages.