Assessment of acute morbidity and mortality in nonconvulsive status epilepticus

Objectives: The natural history of nonconvulsive status epilepticus (NCSE) is not well defined, especially mortality and morbidity. The authors hypothesized that the mortality of NCSE is higher when NCSE is due to acute medical causes ( systemic or neurologic) or associated with severe impairment of mental status or with acute complications, and lower when associated with generalized spike-wave ( SW) discharges on EEG. Methods: The authors retrospectively identified 100 consecutive patients with NCSE from an EEG database. Data were collected from systematic review of medical records and actual EEG tracings. Specific etiologies were divided into three groups: acute medical, epilepsy, and cryptogenic. Results: Of the 100 patients, 18 died. Fourteen of 52 patients in the acute medical group died, 1 of 31 in the epilepsy group died, and 3 of 17 in the cryptogenic group died. Mental status impairment was severe in 33, complications occurred in 39, and generalized SW discharges occurred in 36. Mortality rates were higher in patients 1) in the acute medical group (27%) vs the epilepsy (3%) and the cryptogenic (18%) groups ( p < 0.02), 2) with severe mental status impairment (39%) compared to those with mild impairment (7%, p < 0.001), and 3) with acute complications (36%) when compared with those without complications ( 7%, p < 0.0002). The presence of generalized SW discharges on EEG did not correlate with mortality. Mental status impairment and etiology were independently associated with mortality ( p < 0.001). Conclusion: NCSE is associated with substantial mortality. Mortality is associated with an acute medical cause as the underlying etiology, severe mental status impairment, and development of acute complications, but not the type of EEG discharge.