Short term prognosis of nonconvulsive status epilepticus in adults: 75 consecutive patients from a teaching hospital in Genova, Italy

Purpose: Nonconvulsive status epilepticus (NCSE) is an under recognised health problem associated with substantial morbidity and mortality. There is limited epidemiological information on NCSE. The object of this study is to determinate the natural history of NCSE in a series of 75 adult patients evaluated in a teaching hospital in Genova. Method: We analysed 75 patients with NCSE over a period of 7 years (1995-2002). Diagnosis was based on EEG and clinical manifestation. Data regarding the clinical presentation, aetiology, concomitant medical complication, EEG, duration of status, EEG pattern, clinical and EEG response to benzodiazepine and short-term outcome were analysed. Results: The 75 patients of our study included 26 men and 49 women. The medium age was 66.6 f 15.2 years. A previous history of epilepsy was present in 14 cases (18.6%). 37 patients had absence status epilepticus (ASE), 3 I had complex partial status epilepticus (CPSE) and 7 had aphasic status epilepticus. The initial manifestation in most of the patients was confusional state (60%) or severe impaired consciousness (stupor or coma) in 30.6%. The mean duration of the state was 6.3 days (ranging from I to 28 days) with a mean delay to the diagnosis of 2.5 days. A precipitating factor was found in all cases and toxic-metabolic (48%) and cerebrovascular (21.3% ) aetiology were the most frequent. We found that 31 patients had a poor prognosis (41 %) including death, persistent cognitive or behaviour impairment (28% of ASE and 64.5% of CPSE). The global mortality was 6.6% (2.7% of ASE patients vs 10.8% of CPSE patients). All patients with aphasic status epilepticus had a good recovery. A statistical analysis showed that response to benzodiazepine (BZD) was a predictor of the outcome. Our data indicated that ASE due to toxic- metabolic factor had a prompt resolution after BZD administration in most of the patients. The duration of NCSE is an important predictor of outcome in patients with ASE. The impairment of consciousness also had a significant prognostic value. Death could he attributed to the underlying aetiology in 5 patients and in 1 case to systemic complication. Conclusion: Our study showed that mortality due to NCSE is lower than previously reported, although long-term consequences usually due to underlined aetiology or the consequent medical complication, occurred in about 41%. Lesional aetiology (particularly stroke) and consequently the type of NCSE, severe mental state impairment, the duration of the status and the absence of clinical and EEG response to BZD administration are associated with poor prognosis. The underlying illness seems to he the strongest determinant of the outcome. Although there is no consensus over a classification system for NCSE, this is important for appropriate management of the condition.