Electroclinical patterns in patients with nonconvulsive status epilepticus: Etiology, treatment, and outcome.

INTRODUCTION: This study investigated the clinical and electroencephalography (EEG) features and prognostic factors of patients with nonconvulsive status epilepticus (NCSE). MATERIALS AND METHODS: We retrospectively reviewed the clinical files and EEG data of 45 (28 females, mean age 54 ±â€¯22.6 years) consecutive patients with NCSE over a five-year period. An EEG interpreter who was blinded to the clinical findings evaluated the EEGs according to the Salzburg Consensus Criteria (SCC) for NCSE. Patient demographics, etiology, neuroimaging and laboratory data, EEG features, treatment, and outcome measures were analyzed. RESULTS: The most common etiology for NCSE was acute symptomatic etiologies (57.8%) and cerebrovascular disease (48.9%). The majority (68.9%) of the patients presented with new-onset status epilepticus (SE). NCSE was refractory to treatment in 31.1% of patients. The most common status pattern consisted of rhythmic delta/theta activity in 62.3% of EEGs. Twenty-five status patterns on the EEGs were classified as definite, 30 as possible, and six as no NCSE according to the SCC. The in-hospital mortality rate was high (33.3%) showing an association with potentially fatal etiology, refractory SE, treatment with continuous I.V. anesthetics and also the presence of multiple status patterns and nonreactivity in EEGs (p < 0.05). CONCLUSIONS: The SCC for NCSE have high diagnostic accuracy but do not affect prognosis. Potentially fatal etiology, multiple status patterns on EEG and non-reactive EEGs may carry significantly greater risk for short-term mortality.