Extratemporal epilepsy: clinical presentation, pre-operative EEG localization and surgical outcome

To summarize, the most commonly encountered problems in the pre-operative EEG localization of the epileptogenic zone in patients with extra-temporal epilepsy are dependent upon: 1) Poor EEG localization of the interictal epileptic abnormality and poor localization of seizure onset. 2) Presence of a widespread epileptogenic area during interictal and ictal tracings, often involving two or more lobes synchronously or independently, thus suggesting a multilobar or a multifocal epileptic disorder. 3) Absence or paucity of interictal epileptiform discharges is not an uncommon finding and clinical seizures without accompanying ictal EEG manifestations are also not uncommon. 4) Different paths of seizure propagation might occur even in individual patients. This may reflect clinically as different seizure patterns resembling a multifocal seizure problem. From this review, one could envisage that the future research challenge in extra-temporal epilepsy resides in the development of a technology or system which will provide a better localization of the seizure generator, as well as a better identification of the mechanisms of seizure spread, ideally indicating anatomical pathways involved.