ILAE 2017 classification of seizure types expanded version

The International League Against Epilepsy (ILAE) has approved a new way of organizing seizures that reflects recent advances in our understanding of the brain and seizures. This new system will make diagnosis and classification of seizures easier and more accurate.

These terms don’t change what occurs during a seizure, but offer a different way of naming seizures. More accurate ways of naming seizures can lead to more appropriate treatment.

Listen to Drs. Joe Sirven and Bob Fisher discuss the changes in a Hallway Conversations podcast:

What are the major changes in terms used to describe seizures?

Seizures will first be classified according to where they start in the brain. There are now 3 main categories:

  • Generalized Onset: Generalized seizures affect both sides of the brain or large networks of cells on both sides from the beginning of the event. The networks can be on the surface of the brain or involve deeper areas. Generalized seizures don’t need to involve the entire brain, just part of both sides.
  • Focal Onset: The term focal seizure has been used for years, but the lay public and many professionals still use the term partial seizures. In this 2017 Classification, focal seizures will replace partial seizures and refer to those that start in an area or network on one side of the brain. They may start on the surface of the brain or in deeper areas, and can be very localized or spread to larger areas. Sometimes more than one network is involved.
  • Unknown Onset: Seizures may be of unknown onset if the beginning of the seizure is not clear. As more information becomes available over time or through testing, the type of seizure may be changed to a generalized or focal onset seizure.

Learn More About Seizure Classifications



Authored by: Patricia O. Shafer RN | MN on 4/2017
Reviewed by: Joseph I. Sirven MD on 4/2017