Historical aspects of idiopathic generalized epilepsies.

Early in these proceedings, the origin of the three terms in the title, "idiopathic generalized epilepsy," is discussed with respect to their significance over time, and typical misunderstandings. In the mid-20th century, a rather chaotic use of a multitude of often loosely defined terms had developed, which increasingly became an obstacle to a meaningful international discussion. The International League against Epilepsy (ILAE) took the initiative to develop an internationally accepted terminology with a classification system consisting of a classification of seizures (1981) and a classification of syndromes (1989). The Idiopathic Generalized Epilepsies are one of its four major groups emerging from a double dichotomy of generalized versus localization-related and idiopathic versus symptomatic. The inclusion of biologic aspects such as syndrome-specific ages of onset ("age-related syndromes") or syndrome-specific relations of seizure occurrence to the sleep-wake cycle ("Epilepsy with Grand Mal on Awaking") meant that the syndrome classification merged the more biological views of the German school with the more neurophysiological ones of the French. Apart from establishing a common international language concerning epilepsy, the International Classification of Epilepsies and Epileptic Syndromes became an important stimulator of research, especially concerning the idiopathic epilepsies. In particular, genetic and functional imaging investigations aim at a better understanding of these conditions. It is now understood that most idiopathic syndromes have a--sometimes complex--genetic background, but we are also becoming aware of the inappropriateness of the time-honored term "generalized" and part of our dichotomies. Both localization-related and "generalized" idiopathic epilepsies seem to share a principle of ictogenesis based on functional anatomic pathogenic networks, and we seem to move toward understanding them as functional system disorders of the brain.