Magnetic source localization in focal epilepsy. Multichannel magnetoencephalography correlated with magnetic resonance brain imaging.

Initial results of magnetic source localization by means of multichannel recording using a 10 or a 31 channel system are reported. Simultaneous magnetoencephalographic (MEG) and electroencephalographic (EEG) (scalp, sphenoidal and foramen oval) recording, as well as magnetic resonance imaging (MRI) with a fixed head position, permits the projection of brain structures and the source localized from MEG into a three-dimensional coordinate system. From 8 patients investigated it can be clearly seen that the method is of diagnostic relevance for patients with temporal lobe epilepsy. Results are demonstrated for 3 patients with interesting findings concerning the anatomical correlation with source localization. The findings indicate that MRI-correlated magnetic source localization by means of multichannel recordings provides important advantages in epilepsy research. (1) Increased precision permits noninvasive localization. Deeper sources in the temporal lobe are localized from MEG combined with scalp or minor invasive EEG. (2) Investigation time is considerably shortened. (3) Single events can be localized for supplementary presurgical information concerning the three-dimensional anatomical localization of focal epileptic activity in the brain.