Non-Invasive Seizure Localization in Patients With Medically Refractory Localization Related Epilepsy: Synchronized MEG-EEG Recordings

This study will evaluate the magnetoencephalography (MEG) alone and together with electroencephalography (EEG) in non-invasive presurgical evaluation. It will look at the contribution of those methods in determining the location of the epilepsy seizure, compared with doing so through an invasive method. EEG measures electronic potential differences on the scalp. On the other hand, MEG is a non-invasive technique for recording the activity of neurons in the brain, through recording of magnetic fields caused by synchronized neural currents. It has the ability to detect seizures. Because magnetic signals of the brain vary, this technique must balance two key problems: weakness of the signal and strength of the noise. The EEG is sensitive to extra-cellular volume currents, whereas the MEG primarily registers intra-cellular currents. Because electrical fields are quite dependent on the conductive properties of the tissues, and magnetic fields are significantly less distorted by tissue, the MEG has better spatial resolution. There is a great deal of evidence that EEG and MEG provide complementary data about underlying currents of ions.

Patients 18 years of age or older who have epilepsy that is not relieved, and who are considered candidates for surgery and who accept epilepsy surgery, may be eligible for this study.

Before they have surgery, participants will either sit or lie down, with their head in a helmet covering the entire head, with openings for the eyes and ears. Brain magnetic fields will be recorded with a 275-channel OMEGA system. Throughout the session, visual and two-way audio communication will be maintained with the patient. Acquiring data from the participant will be conducted during several sessions, each lasting from 10 to 60 minutes, not exceeding a total of 120 minutes. If the first recording is not of sufficient quality, the patient may have it repeated once or twice.

Those participants who are found to have a clear seizure focus will proceed directly to surgery that is part of their treatment. Those whose seizure focus is ambiguous will proceed to invasive monitoring.

Participants will be followed in the outpatient clinic at intervals of 1, 3, 6, and 12 months. They may periodically undergo reimaging as considered appropriate.