An expert task force has created a new definition for epilepsy that provides a greater level of detail to diagnoses by including individuals with 2 unprovoked seizures, and those with 1 unprovoked seizure and other factors that increase risk of seizure recurrence.
The report appeared in Epilepsia, on behalf of the International League Against Epilepsy (ILAE).
The 2005 report by an ILAE task force defined an epileptic seizure as “a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain” and epilepsy as “a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures, and by the neurobiologic, cognitive, psychological, and social consequences of this condition. The definition of epilepsy requires the occurrence of at least 1 epileptic seizure.”
However, the 2005 definition does not allow a patient to outgrow epilepsy, nor does it take into account some clinicians’ views that epilepsy is present after a first unprovoked seizure when there is a high risk for another, the report’s lead author said in a press release. The task force recommendation resolves these issues with the new, more practical, definition of epilepsy that is aimed at clinicians.
The task force suggests that epilepsy can be defined by:
• at least 2 unprovoked (or reflex) seizures occurring more than 24 hours apart,
• 1 unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after 2 unprovoked seizures, occurring over the next 10 years, or
• diagnosis of an epilepsy syndrome.
The burden of determining recurrence risk does not fall on the clinician, the lead author stated. If information is not available on recurrence risk after a first seizure, then the definition defaults to the old definition.
Epilepsy is “resolved” in individuals who are past the applicable age of an age-dependent epilepsy syndrome, or those that have been free of seizures for the last 10 years and off anti-epileptic drugs (AEDs) for 5 years or more. The authors note that, the meaning of “resolved” is not identical to that of “remission” or “cure.”
The authors noted that the new practical definition could make clinicians more sensitive to the risk of recurrence after a single unprovoked seizure and more comfortable in starting treatment after some initial unprovoked seizures. And, a practical definition allowing earlier diagnosis will be especially useful to prevent physical injuries and social consequences of recurrent seizures. Finally, it will also allow for disease-modifying interventions that prevent the progression of epilepsy and of comorbidities.