Objective: We will use magnetoencephalography (MEG) alone, and in combination with EEG (MEG-EEG), to study the contribution of each method and their combination to the localizing yield of the non-invasive pre-surgical evaluation as compared to the invasive method. We will also correlate seizure origin and localizing data with surgical outcome, and, in retrospect, calculate the proportion of patients in whom invasive monitoring could have been avoided. Study Population: Participants in this study will be patients with medically refractory localization-related epilepsy who will be undergoing epilepsy surgery as part of their standard clinical care. Study Design/Methods: We will use a 275-channel whole-head MEG System (CTF Systems 2001 Inc). Patients will undergo a supine resting MEG-EEG recording prior to any surgical procedure. The resulting data will be integrated with the data obtained during the patient's standard pre-surgical evaluation, and compared with the invasive data obtained during chronic invasive monitoring (if clinically indicated), and/or intra-operative electrocorticography (all patients-standard of care). When analyzing the data, readers will be blinded to the results of the other modality (MEG vs. EEG, non-invasive vs. invasive). The patients will be followed in the outpatient clinic at 1-, 3-, 6- and 12-month intervals. Surgical outcomes will be graded according to the Engel and International League Against Epilepsy (ILAE) outcome scales. The findings from this protocol will not in themselves indicate or lead to epilepsy surgery. Outcomes: The primary outcome measure will be the proportion of seizure foci detected and delineated both non-invasively and invasively. The secondary outcome measures will be the proportion of patients with seizure foci co-localized invasively and non-invasively, the correlation of the obtained localizing data from both modalities with surgical outcome, and the correlation between the anatomical location of the epileptogenic zone and surgical outcome.
- INCLUSION CRITERIA: Patients older than 18 years of age. Patients of both sexes and any race or ethnicity who have intractable epilepsy who are deemed surgical candidates and accept epilepsy surgery. EXCLUSION CRITERIA: Patients younger than 18 years of age. Pregnant women. Patients who are not surgical candidates. Patients who do not accept epilepsy surgery. Patients with progressive neurological disorders. Patients who are unable to cooperate adequately with MEG/EEG recordings Patients who had brain surgery. Patients unable to understand and sign consent for the study.