Electroencephalographic Foci Associated With Epilepsy

One of the chief clinical assets of electroencephalography is its power to localize gross cortical lesions. The early work of Berger¹and of Foerster and Altenburger²called attention to the possibilities of the method, but the practical value of electroencephalography for the localization of gross lesions prior to operation was first clearly demonstrated by Walter.³The closely related problem of localization of a discharging lesion or seizure focus was the subject of early reports by Jasper⁴and by Gibbs, Lennox and Gibbs⁵and of later reports by Jasper and Hawke⁶and by Casamajor and his co-workers.⁷Reviews of the literature on electroencephalographic localization and lengthy bibliographies have been published elsewhere.⁸ As a result of their studies, Jasper and his associates⁹concluded that the most important characteristics of a seizure discharge are the degree and direction of spread. Jasper proposed that seizure