Classification criteria of epileptic seizures and syndromes

Abstract

Care must be exercised not to intermingle with classification of seizures and classification of epilepsies in an inconsistent fashion. Criteria for each class must be defined as clearly as possible, and these criteria must be those which are necessary for classifying any given case. The international classification first proposed by the ILAE in 1970 was an attempt to distinguish seizures from epilepsies; the seizure types defined in the 2001 diagnostic scheme are conceptually akin to the syndromes in the 1989 classification in the sense that they imply etiological, therapeutic, and prognostic significance. However, there exists no room in the new diagnostic scheme to accommodate electro-clinical seizure types, which have been used for more than three decades. The concept of epileptic syndrome in the 1989 classifications seems to have been changed to epileptic seizure type in the 2001 diagnostic scheme, and seizure type of the latter virtually becomes synonymous with epileptic syndrome of the former. In the 2001 diagnostic scheme, seizure type can be used to supplement syndrome, and can stand alone when syndrome diagnosis cannot be made. In other words, seizure types may replace syndromes, or vice versa. We should not return to an era prior to 1970 where no distinction exists between epilepsies and seizures. In a cohort of patients with active epilepsy, to what extent is syndrome classification applicable? In 300 consecutive patients hospitalized in a tertiary center, syndromic diagnosis was applicable to only 61%. Similarly, another 100 consecutive patients, classification of epilepsy was possible but not defined as a syndrome in 32% patients, according to the 1989 classification. The 1989 syndrome classification assigned in each category "other epilepsies not defined as a syndrome." These epilepsies are diagnosed only dichotomously; idiopathic focal or generalized, symptomatic focal or generalized, or undetermined whether focal or generalized. In other words, even if we could complete a list to include all the new syndromes that may exist, it is very unlikely that it would cover all epilepsies.