ILAE classification of the epilepsies: position paper of the ILAE Commission for Classification and Terminology

Abstract

The International League Against Epilepsy (ILAE) classification of the epilepsies has been updated to reflect the gain in understanding of the epilepsies and their underlying mechanisms following the major scientific advances that have taken place since the last ratified classification in 1989. As acritical tool for the practicing clinician, epilepsy classification must be relevant and dynamic to changes in thinking, yet robust and translatable to all areas of the globe. Its primary purpose is for the clinical diagnosis of patients but it is also critical for epilepsy research, development of antiepileptic treatment and communication around the world. The new classification is based on adraft document submitted for public comments in 2013, which was revised to incorporate extensive feedback from the international epilepsy community over several rounds of consultation. It consists of three levels starting with seizure type, where it is assumed that the epileptic seizures of the patient are defined by the new 2017 ILAE seizure classification. After diagnosis of the seizure type, the next step is the diagnosis of the epilepsy type, which includes focal epilepsy, generalized epilepsy, combined generalized and focal epilepsy and also an unclassified epilepsy group. At the third level the disease is assigned to aspecific epilepsy syndrome. The new classification incorporates etiology at each stage, emphasizing the need to consider etiology at each step of the diagnosis, as it often carries significant treatment implications. The various etiologies can be assigned to six subgroups, defined with respect to the potential therapeutic consequences. New terminology is introduced, such as developmental and epileptic encephalopathy. The term benign is replaced by the terms self-limiting and pharmacoresponsive, to be used where appropriate. It is hoped that this new framework will assist in improving epilepsy care and research in the twenty-first century.