Robert J. DeLorenzo

This report presents the initial analysis of a prospective, population-based study of status epilepticus (SE) in the city of Richmond, Virginia. The incidence of SE was 41 patients per year per 100,000 population. The frequency of total SE episodes was 50 per year per 100,000 population. The mortality rate for the population was 22%, 3% for children and 26% for adults. Evaluation of the seizure types for adult and pediatric patients demonstrated that both partial and generalized SE occur with a high frequency in these populations. Based on the incidence of SE actually determined in Richmond, Virginia, we project 126,000 to 195,000 SE events with 22,200 to 42,000 deaths per year in the United States. The majority of SE patients had no history of epilepsy. These results indicate that SE is a common neurologic emergency.

BACKGROUND: Nonconvulsive status epilepticus (NCSE) is a form of status epilepticus (SE) that is an often unrecognized cause of coma. OBJECTIVE: To evaluate the presence of NCSE in comatose patients with no clinical signs of seizure activity. METHODS: A total of 236 patients with coma and no overt clinical seizure activity were monitored with EEG as part of their coma evaluation. This study was conducted during our prospective evaluation of SE, where it has been validated that we identify over 95% of all SE cases at the Medical College of Virginia Hospitals. Only cases that were found to have no clinical signs of SE were included in this study. RESULTS: EEG demonstrated that 8% of these patients met the criteria for the diagnosis of NCSE. The study included an age range from 1 month to 87 years. CONCLUSION: This large-scale EEG evaluation of comatose patients without clinical signs of seizure activity found that NCSE is an underrecognized cause of coma, occurring in 8% of all comatose patients without signs of seizure activity. EEG should be included in the routine evaluation of comatose patients even if clinical seizure activity is not apparent.

Using univariate and multivariate regression analysis, we studied seizure duration, seizure type, age, etiologies, other clinical features, and mortality among 253 adults with status epilepticus (SE) admitted to the Medical College of Virginia. Cerebral vascular disease and discontinuation of antiepileptic drugs (AEDs) were the most prominent causes of SE, each accounting for approximately 22% of all patients in the series. The other principle etiologies were alcohol withdrawal, idiopathic, anoxia, metabolic disorders, hemorrhage, infection, tumor, drug overdose, and trauma. When the patients were divided into two groups, the group with SE lasting < 1 h had a lower mortality as compared with seizure duration > or = 1 h. Low mortality rates were noted in alcohol and AED discontinuation etiologies. Anoxia and increasing age were significantly correlated with higher mortality. The mortality rates of partial and generalized SE were not significantly different. Race and sex did not affect mortality significantly. Our findings represent the first multivariate analysis of predictive indicators of mortality in SE and demonstrate that specific factors influence mortality rate in SE.

Summary: Purpose : Convulsive status epilepticus (CSE) is a major medical and neurological emergency that is associated with significant morbidity and mortality. Despite this high morbidity and mortality, most acute care facilities in the United States cannot evaluate patients with EEG monitoring during or immediately after SE. The present study was initiated to determine whether control of CSE by standard treatment protocols was sufficient to terminate electrographic seizures. Methods : One hundred sixty‐four prospective patients were evaluated at the Medical College of Virginia/VCU Status Epilepticus Program. Continuous EEG monitoring was performed for a minimum of 24 h after clinical control of CSE. SE and seizure types were defined as described previously. A standardized data form entry system was compiled for each patient and used to evaluate the data collected. Results : After CSE was controlled, continuous EEG monitoring demonstrated that 52% of the patients had no after‐SE ictal discharges (ASIDS) and manifested EEG patterns of generalized slowing, attenuation, periodic lateralizing epileptiform discharges (PLEDS), focal slowing, and/or burst suppression. The remaining 48% demonstrated persistent electrographic seizures. More than 14% of the patients manifested nonconvulsive SE (NCSE) predominantly of the complex partial NCSE seizure (CPS) type (2). These patients were comatose and showed no overt clinical signs of convulsive activity. Clinical detection of NCSE in these patients would not have been possible with routine neurological evaluations without use of EEG monitoring. The clinical presentation, mortality, morbidity, and demographic information on this population are reported. Conclusions : Our results demonstrate that EEG monitoring after treatment of CSE is essential to recognition of persistent electrographic seizures and NCSE unresponsive to routine therapeutic management of CSE. These findings also suggest that EEG monitoring immediately after control of CSE is an important diagnostic test to guide treatment plans and to evaluate prognosis in the management of SE.

Summary: This study presents a review of the epidemiology of status epilepticus (SE) in Richmond, Virginia, U.S.A. The data summarize some of the first population-based information on the natural presentation of SE in a controlled community setting. SE occurred with an absolute incidence rate of 41 patients per 100,000 residents per year in Richmond. The frequency of total SE occurrences was 50 patients per 100,000 residents per year. Overall mortality in this population was 22%. Absolute incidence and occurrences of SE in this population were shown to be underestimates due to the inability, for multiple reasons, to document all cases of SE. Based on the Richmond data, the number of SE cases, frequencies of occurrence, and deaths per year occurring in the United States were estimated to be 102,000-152,000, 125,000-195,000, and 22,000-42,000, respectively. In Richmond, nonwhites had a much higher incidence of SE than did whites. Partial SE was the most common form of seizure initiating SE. Age and etiology were also found to contribute to mortality. Infants <1 year of age had the highest incidence of SE, but the elderly population represented the largest number of SE cases. This study provides a review of the first prospective, population-based, epidemiological data on SE and shows that SE is a major medical and neurological emergency in both academic and community hospital settings.