Etiology and Mortality of Nonconvulsive Status Epilepticus

Objectives: Nonconvulsive status epilepticus (NCSE) is a disease with a high mortality rate and a very diverse etiology. The disease prognosis is related to the etiology. We aimed to investigate the etiology, mortality rates, and factors affecting mortality in patients diagnosed with NCSE in a tertiary epilepsy center in Turkey. Methods: All electroencephalograms (EEGs) were taken in the EEG laboratory of the Department of Neurology, Antalya Training and Research Hospital, between June 2021 and February 2024. Patients who met the Salzburg Consensus Criteria (SCC) for NCSE were included. Demographic data, etiologic factors, comorbidities, neuroradiological imaging, laboratory data, treatments administered for NCSE and responses to treatment, short- and long-term outcomes, and EEG findings at follow-up, if any, were noted from the medical records of all patients who met the criteria. Results: A total of 200 patients were included in the study. Mortality was observed in 76 (38.4%) patients with NCSE. There was a statistically significant correlation between NCSE etiology and mortality (p < 0.001). Mortality was most common in patients with cerebral tumors as the etiology, with a rate of 63.6%. The lowest mortality rate was observed in patients with autoimmune encephalitis and epilepsy (14.3% and 17.2%, respectively). After appropriate antiseizure medication (ASM) treatment, 117 (58.5%) patients with NCSE improved. When post-treatment improvement and etiologic factors were analyzed, the highest rate of improvement was observed in the autoimmune encephalitis and CVD groups. Conclusions: Our study showed that advanced age and the presence of stroke are associated with mortality and that patients with NCSE due to autoimmune encephalitis respond well to treatment.