The localization-related epilepsies: some problems with subclassification.

One of the nosological problems of childhood epilepsies is the evolutionary change of foci with age. Benign childhood epilepsy with centro-temporal spike may evolve to show EEG features of childhood epilepsy with occipital paroxysms and vice versa. West syndrome is generally accepted as generalized epilepsy but is often preceded or followed by partial seizures and may have both partial seizures and tonic spasms in a single attack. Among epilepsies with both generalized and focal seizures, severe myoclonic epilepsy in infancy is more linked to generalized epilepsy whereas epilepsy with continuous spike-waves during slow wave sleep is more linked to localization-related epilepsy. Any type of partial epilepsy may develop nonconvulsive generalized seizures transiently with generalization of paroxysmal discharges during the clinical course. Moreover, nonconvulsive generalized seizures may occur even in localization-related epilepsy with spike-wave index during NREM sleep in less than 85%.