Localization of epileptic focus

Localization and delimitation of the epileptic focus is a crucial step in presurgical evaluation of patient with drug-resistant focal epilepsy. The more precise focus localization of electric source imaging also allows better preparation for intracranial electrode implantations if it's requested.

Localization of epileptic focus can be achieved with different techniques, we can classify them in two categories: non-invasive and invasive.
 * Non-invasive techniques include EEG recording, ictal SPECT (Single Photon Emission Computed Tomography), interictal PET (Positron emission tomography) and  interictal MEG (Magnetoencephalography).
 * Invasive techniques can be carried out with implantation of intracranial electrodes (such as subdural, epidural or depth electrodes) that are inserted under stereotactic guide.