A new clinical definition for epilepsy has been created by a task force of epilepsy experts, with the aim of "refining the scope" of patients diagnosed with the disease.
In 2005, the International League Against Epilepsy (ILAE) task force authored a report offering a definition of 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."
It continued: "The definition of epilepsy requires the occurrence of at least one epileptic seizure."
An epileptic seizure, meanwhile, was described as "a transient occurrence of signs and/or symptoms due to abnormal, excessive or synchronous neuronal activity in the brain."
But in December 2013, the ILAE reconsidered their position, and they are now publishing an updated version of their definition in the Wiley-owned journal Epilepsia.
Task force lead author Dr. Robert Fisher, from Stanford University School of Medicine, CA, explains:
"Why change the definition of epilepsy? 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 task force recommendation resolves these issues with the new, more practical, definition of epilepsy that is aimed at clinicians."
Dr. Fisher acknowledges, though, that some researchers might continue to use criteria similar to the older definition for the purposes of making comparisons between prior studies.
The new clinical definition of epilepsy
The new definition of epilepsy makes provision for epilepsy to become "resolved" in certain scenarios.
But what does the new definition consist of? The ILAE suggest three key components:
- At least two unprovoked (or reflex) seizures occurring more than 24 hours apart; or
- One unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years; or
- Diagnosis of an epilepsy syndrome.
This new definition makes provision for epilepsy to become "resolved" in certain scenarios.
For instance, if someone has not had a seizure for 10 years, or if they have not needed to take anti-epileptic drugs in the last 5 years, then it may not be appropriate for that person to continue to be considered as having epilepsy.
However, although the new definition allows this new status of "resolved" epilepsy, the ILAE remind that resolved is not the same as "remission" or "cure."
"The burden of determining recurrence risk does not fall on the clinician," says Dr. Fisher. "If information is not available on recurrence risk after a first seizure, then the definition defaults to the old definition."
"The published definitions were supported with factual data," acknowledge Dr. Gary Mathern and Dr. Astrid Nehling, the editors-in-chief of Epilepsia, of the previous definition. "But in some cases medical evidence did not exist and the task force used a 'consensus' approach for these definitions."
The editors invite readers to share their own opinions on this new definition in a survey.
In 2013, Medical News Today reported on a new computational model that researchers claim can accurately predict epileptic seizures.