Epilepsy

New Definition Identifies Key Components of Epilepsy

An expert task force has created a new operational clinical definition for epilepsy—which is designed to provide greater detail on how to diagnose the condition.

The new definition, accepted by the International League Against Epilepsy (ILAE), identifies 3 key components1:

  • 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.
  • Diagnosis of an epilepsy syndrome.

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“Why change the definition of epilepsy?” said task force lead author Robert Fisher, MD, from Stanford University School of Medicine. “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.”

Furthermore, epilepsy is considered resolved for individuals diagnosed with age-dependent epilepsy syndrome but now past the applicable age or for those who have been seizure-free for the last 10 years and off anti-seizure medications for at least 5 years.

“The burden of determining recurrence risk does not fall on the clinician. If information is not available on recurrence risk after a first seizure, then the definition defaults to the old definition,” said Fisher.

The new operational definition of epilepsy replaces the conceptual definition of seizures and epilepsy created by the ILEA task force in 2005.

References:

  1. Fisher R, Acevedo C, Arzimanoglou A, et al. A practical clinical definition of epilepsy. Epilepsia. 2014;55(4):475-482.
  2. Wiley. New clinical definition for epilepsy improves diagnosis accuracy [press release]. 2014 Apr 14. Available at: www.wiley.com/WileyCDA/PressRelease/pressReleaseId-110630.html. Accessed April 17, 2014.