The role of neuroimaging in the surgical treatment of epilepsy

Abstract

Resective surgical treatment of medically intractable epilepsy requires accurate identification of the site and extent of the epileptogenic zone responsible for habitual seizures. Epileptogenicity per se is demonstrated electrophysiologically, but interictal and ictal EEG transients, whether recorded extracranially or intracranially, propagate widely and can give rise to false lateralizing and false localizing information. Neuroimaging techniques provide additional important information which greatly enhances confidence in localization derived electrophysiologically. Structural imaging with X-ray computed tomography and magnetic resonance imaging, as well as functional imaging with positron emission tomography, single photon emission computed tomography, and computerized mapping of electromagnetic activity, used together with other tests of focal functional deficit, 1) increase the confidence with which surgical resection can be performed on the basis of noninvasive tests alone, 2) aid in developing appropriate strategy for intracranial electrode recording when this is necessary, and 3) supplement results of invasive studies sufficiently to justify surgical resection in some patients who otherwise might be rejected for surgery. Addition of these new techniques, therefore, has increased the number of patients considered candidates for surgery, decreased the number of invasive procedures necessary before surgery can be performed, and increased the accuracy of surgical resection.