New epilepsy/seizure classification

The international efforts to provide common terms and concepts for classifying seizures and epilepsy were first formalized in the late 1960s in the reports of Merlis and Gastaut. Over time, these were revised culminating in the most widely used system for classification of epilepsies that was proposed in 1989 by the Commission on Classification and Terminology of the International League Against Epilepsy (ILAE).This epilepsy classification remains in place despite ongoing discussions and proposals. ILAE’s 1981 seizure classification and its 1985 and 1989 classifications of the epilepsies have given physicians around the world a common language.These classifications were mainly based on two features: (a) thedistinction between generalized and focal features and (b) etiologic considerations. To bring terminology and concepts up to date and reflect advances in theneurosciences such as imaging and genetics and the advances in understanding of brain function, new approaches have been suggested (2010 Report of the ILAE Commission on Classification and Terminology), in which new concepts and terminologyfor epilepsy classification, most notably etiology, were introduced. This document engendered much debate within the epilepsy community and began 7 years of an iterative process in which worldwide public engagement, further publications from the Commission, and online comments have resulted in the 2017 classification of seizures and epilepsies. The 2017ILAE classification of seizure types, largely based upon the existing classification formulated in 1981. Primary differences include:Specific listing of certain new focal seizure types that may previously only have been in the generalized category, Use of awareness as a surrogate for consciousness, Emphasis on classifying focal seizures by the first clinical manifestation (except for altered awareness), A few new generalized seizure types, Ability to classify some seizures when onset is unknown, Renaming of certain terms to improve clarity of meaning.As knowledge grows and concepts evolve, classifications will change. However, this must be balanced against the requirement for consistency over time and a shared language for clinical practice and research.

Keywords:

Classification , Epilepsy syndromes , Terminology , Etiology