Persistent Nonconvulsive Status Epilepticus After the Control of Convulsive Status Epilepticus

Abstract

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 VirginiaNCU 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. Key Words: Epilepsy-Status epilepticus-Nonconvulsive status epilepticusElectroencephalographic monitoring.Status epilepticus (SE) is a major neurological and medical emergency that requires acute medical management (1-10). SE is still associated with significant morbidity and mortality despite advances in treatment of this condition (1,ll-13). Population-based epidemiological studies have indicated that the mortality of SE in the general population is almost 22% and can be as high as 30% in the elderly (1,6,12). Several factors have been shown to contribute to the morbidity and mortality of SE, including seizure duration, age, etiology, and time to first treatment (9,ll-13). Understanding the pathophysiology and response of SE to treatment may provide important insights into decreasing the mortality and morbidity associated with this condition.Nonconvulsive SE (NCSE) is an important type of SE (14-16) that has been described as absence (17-1...

The Utility of EEG, SSEP, and Other Neurophysiologic Tools to Guide Neurocritical Care

“…Multivariate regression revealed a doubling in the odds of mortality among these patients who transitioned to nonconvulsive status epilepticus and an independent doubling in the odds of mortality among patients >60 years of age [63].…”

“…After the convulsive status subsides, 30% of those patients with subtle or nonconvulsive seizures develop nonconvulsive status epilepticus [63]. Status epilepticus itself results in 21% mortality, with age (odds ratio [OR], 1.1) and acute symptomatic cause for the seizure activity (OR, 6.0) found to be multivariate predictors of mortality.…”

“…Gauging the response to treatment therapy is best accomplished with EEG at the bedside, even for convulsive status epilepticus, given its high likelihood of transforming to subtle or nonconvulsive status epilepticus [63]. EEG may also be used to gauge success at achieving electrographic suppression or burst suppression, which has been associated with decreased likelihood of relapsed status epilepticus following barbiturate therapy [95] with fewer breakthrough seizures [96].…”

Current Trends in Treatment of Status Epilepticus and Refractory Status Epilepticus

“…A study of patients appropriately treated for convulsive SE found that 48% went on to have continued nonconvulsive seizures and 15% were diagnosed with NCSE, underscoring the importance of continuous EEG to identify RSE and guide its treatment. 42 Although data are limited, more recent studies estimate that 23 to 43% of patients in SE will progress to RSE, and the mortality of RSE ranges from 17 to 39%. 22,[43][44][45][46] Similar to nonrefractory SE, mortality is largely dependent on the underlying etiology for RSE and the patient's age.…”

Early withdrawal of non-anesthetic antiepileptic drugs after successful termination of nonconvulsive seizures and nonconvulsive status epilepticus

“…The incidence of NCS and NCSE ranges between 8 and 48% depending on the patient population studied [1][2][3][4][5][6][7][8]. The mortality rate of neurologically critically ill patients afflicted with NCSE is 18-57% [9,10] while the presence of NCS is associated with a mortality rate of 33% [10].…”