Clinical characteristics and treatment approach of established New-Onset status epilepticus (eNOSE): A Real-World multicenter experience.

Introduction: Status Epilepticus (SE) can occur in patients without a previous epilepsy diagnosis, a condition identified as "new-onset status epilepticus" (NOSE). Treatment with benzodiazepine may fail in NOSE termination, requiring anti-seizure medication (ASM) employment. The term "established NOSE" (eNOSE) is generally employed in this context. This study aims to describe the main clinical characteristics of a large sample of patients suffering from eNOSE, compare the ASM efficacy, and explore the risk factors associated with ASM treatment unresponsiveness and eNOSE-associated mortality.

Methods: Adult patients diagnosed with eNOSE were retrospectively selected between January 2016 and December 2022. We reviewed demographics, clinical data, diagnostic work-up, and treatment. We considered the last ASM introduced before the eNOSE termination as effective.

Results: 123 patients were included (age: 67.9 ± 17.3). eNOSE acute etiology was mostly reported. In the overall cohort, phenytoin showed the highest response rate (p = 0.01). In the pairwise comparisons, valproate was superior to levetiracetam (p = 0.02) but not to lacosamide (p = 0.50). Phenytoin had a significantly higher resolution rate than levetiracetam (p = 0.001) but not lacosamide (p = 0.14). Thirty patients were refractory to ASM treatment. No predictors of refractoriness were identified. Thirty-nine patients died. Age and GCS were identified as eNOSE-related mortality risk factors.

Conclusion: eNOSE frequently has an acute etiology with several associated syndromes. Phenytoin is more effective in managing eNOSE, even though lacosamide, valproate, and levetiracetam can represent further therapeutic options. Age and GCS are the main risk factors for eNOSE-associated mortality.