Abstracts

Status epilepticus (SE) has been estimated to be refractory to first-line anticonvulsants in 30-50 % of cases. The further management of such patients usually requires the administration of anticonvulsant anesthetics. In an as yet undefined number of cases even this aggressive approach fails to terminate SE. We have coined the term [italic]malignant status epilepticus[/italic] (MSE) for this most severe variant and looked at frequency, risk factors, and outcome. A retrospective analysis was performed including all patients that were treated between 1993 and 2002 on the neurological intensive care unit (NICU) of the Charité - University Medicine in Berlin with SE that was refractory to first-line anticonvulsants. MSE was defined as SE that persisted 5 days or more after tapering of the maximal dosage of anesthetic anticonvulsants that had been titrated to a burst suppression pattern (BSP) in the EEG before. Refractory status epilepticus (RSE) was defined as continuing epileptic activity not responding to benzodiazepines and (fos)phenytoin in adequate dosages, excluding episodes of MSE. Frequency distributions of epidemiological, etiological, therapeutic, and prognostic features were compared in MSE and RSE in order to identify characteristics of MSE, and were calculated by the Chi-square-test. In the current study, 34 patients were included. There were 7 episodes of MSE and 28 episodes of RSE. A female preponderance was found in both groups with 85.7 % in MSE and 57.1 % in RSE but the difference was not significant. Patients with MSE had a mean age of 38.7 [plusmn]13 years and were significantly younger compared to patients with RSE (55,4 [plusmn]18,2; p [lt] 0.01). Pre-existing epilepsy was found in one episode of MSE and in 8 episodes of RSE (28.6 %). Infectious encephalitis was the primary cause of status epilepticus in 71.4 % of cases in MSE and in 10.7 % of cases in RSE (p [lt] 0.01). Inadequate levels of antiepileptic drugs as main cause for SE were neither seen in MSE nor in RSE. The anesthetic was titrated to a BSP per definition in all cases with MSE, 35.7 % of RSE episodes were treated with an anesthetic (p [lt] 0.01), and in 40 % of these cases anesthetics were titrated to a BSP (p [lt] 0.01). Duration of SE was 17 days in MSE and 2 days in RSE (median; p = 0.061). Length of stay on the NICU was 53 days in MSE and 10 days in RSE (median; p [lt] 0.01). In-hospital mortality was comparable in both groups with 14.3 % in MSE and 17.9 % in RSE. We have coined the term malignant status epilepticus to denote a most severe variant of SE. In the current series the condition is not rare. The underlying pathophysiological processes are elusive but our study indicates that female sex, young age (patients in their fourth decade of life) and infectious encephalitis without previous history of epilepsy represent important risk factors. Such patients should be treated aggressively in the early course of SE to prevent the development of MSE.