Updated classification of epileptic seizures: position paper of the International League Against Epilepsy
The International League Against Epilepsy (ILAE) has updated the operational classification of epileptic seizures, building upon the framework established in 2017. This revision included the published experiences with the implementation of the classification from 2017. A working group involving 37 members of the ILAE was convened by the ILEA Executive Committee. The international experts from all ILEA regions utilized a modified Delphi process, requiring a consensus threshold of more than two thirds for any proposal. Following public comments on the ILEA homepage, the Executive Committee appointed seven additional experts to the revision task force to address and incorporate the issues raised, as appropriate. The updated classification maintains the four main seizure classes: focal, generalized, unknown (whether focal or generalized), and unclassified. Taxonomic rules distinguish classifiers, which are considered to reflect biological classes and directly impact clinical management, from descriptors, which indicate other important seizure characteristics. Focal seizures and those of unknown origin are further classified by the patient’s state of consciousness (impaired or preserved) during the seizure, defined operationally through clinical assessment of awareness and responsiveness during the seizure and retained memory (recall) after a seizure. If the state of consciousness cannot be determined, the seizure is classified under the parent term, i.e., the main seizure class (focal seizure or seizure of unknown origin). Generalized seizures are grouped into absence seizures, generalized tonic-clonic seizures and other generalized seizures, now including recognition of negative myoclonus as a seizure type. Seizures are described in the basic version as with or without observable manifestations, whereas an expanded version utilizes the chronological sequence of seizure semiology. This updated classification comprises 4 main classes and 21 seizure types (and no longer 63 as in the 2017 classification, comment of the translator). Special emphasis was placed on ensuring translatability into languages other than English. The aim is to establish a common language for all healthcare professionals involved in the field of epilepsy, from resource-limited areas to highly specialized centers and to provide easily accessible terms for patients and caregivers.
