[The presurgical evaluation of epilepsies]

In this article, we present an overview of the principles, practices and procedures of the presurgical evaluation of the epilepsies in use in our center and in the majority of French teams. Surgery for epilepsy is offered to patients presenting with severe epilepsy with partial seizures. Its aim is to stop the seizures, or to significantly reduce their frequency. To do that, the epileptogenic zone should theoretically be removed and/or the propagation pathways of the seizures should be cut. Discussion of these indications inevitably includes prior assessment of the functional sequels (sensory, motor, cognitive or behavioral) which surgery is liable cause. The presurgical evaluation involves a multidisciplinary approach involving epileptologists, neurophysiologists, neuroradiologists, neuropsychologists and neurosurgeons and is carried out in two phases. The phase I is based on non-invasive investigations, including functional and structural neuroimaging, neuropsychological assessment, source localization of interictal spike and video-EEG recordings of seizures. The phase II is often required and is aimed to precisely define the anatomical localization of the epileptogenic zone and the relationships with a structural lesion. This invasive phase is mainly based on stereoelectroencephalography (SEEG). Finally, the surgical procedure must be adapted according to the distribution and dynamics of the anatomical and functional abnormalities which individually define each case of epilepsy.