Definition of Status Epilepticus Revised

The International League Against Epilepsy (ILAE) Commission on Classification and Terminology and the Commission on Epidemiology have developed a new definition and classification of the seizure disorder status epilepticus.

Status epilepticus is considered the most extreme forms of seizures and can have serious, long-term effects on those who suffer them. Yet recommendations for its definition as seizures lasting 30 minutes or more is based on observation, rather than prospective studies.

The Task Force met recently to review current knowledge about the pathophysiology of status epilepticus and the need for additional studies.

The proposed definition is “a condition resulting either from the failure of the mechanisms responsible for seizure termination or from the initiation of mechanisms, which lead to abnormally prolonged seizures (after time point t1). SE can have long-term consequences (after time point t2), including neuronal death, neuronal injury, and alteration of neuronal networks, depending on the type and duration of seizures.”

The two time points are defined as the length of the seizure and point beyond which it should be considered “continuous seizure activity” (t1) and the time of an ongoing seizure after which there is a risk of long-term effects (t2).

In addition, the Task Force proposed a classification system based on four axes:

“Axis 1−Semiology: forms of SE with prominent motor systems, those without prominent motor systems, and currently indeterminate conditions.

Axis 2−Etiology: known and unknown causes.

Axis 3−electroencephalography correlates: name of pattern, morphology, location, time-related features, modulation, and effect of intervention.

Axis 4−Age: neonatal, infancy, childhood, adolescent and adulthood, and elderly.”

The report was published online in Epilepsia on September 4, 2015.

“It is important to emphasize that the proposed classification is merely a framework and must not be treated as a doctrine, but reflect our current knowledge on status epilepticus. Future advances in basic, epidemiologic, and clinical research will undoubtedly lead to modifications and major revisions of this proposed classification of [status epilepticus],” the international Task Force members wrote in the report.