The epilepsies: clinical implications of the international classification. From the earliest days of neurology, the classification of epileptic seizures into those generalized from the beginning and those with a definable localization in the cortex from the onset has added to knowledge about the function of the nervous system. Further elaboration of the classification of seizures into those localized to the six-layered isocortex and those whose elaboration involves regions of the brain involved with consciousness and memory has provided the basic focus for the burgeoning subspecialty of epilepsy surgery. It is increasingly apparent that the etiology of a seizure disorder is of at least equal or of greater significance than the nature of the seizures it spawns and is the product not only of localization in the nervous system but also of causative factors with implications reaching into areas of genetics, higher cortical function, and intelligence. The prognosis concerning the outcome of the epilepsy under consideration is based on all of these facets. This pathophysiological substratum, of which the seizure is only the presenting symptom, constitutes the epilepsy or epileptic syndrome on which the formulation of a rational treatment plan is based. 