Magnetoencephalography in Epilepsy: Role and Principles.

Magnetoencephalography (MEG) is a clinical neurophysiological diagnostic test that is noninvasive, passive, simple, and painless for the patient, and which provides precise localization of epileptic activity. Like electroencephalography (EEG), MEG is a direct measure of neuronal activity with very high temporal resolution, enabling the study of propagation but with a much higher spatial resolution than EEG. For guidance of stereo-electroencephalography electrode implantation, MEG has become an indispensable precursor, which is then incorporated with all of the other localizing data into the planning of surgical or ablative procedures.