[Magnetoencephalographic localization of epileptic foci using a 37-channel biomagnetometer]

Abstract

The magnetoencephalography (MEG) and electroencephalography (EEG) were recorded simultaneously from 10 normal subjects using a 37-channel biomagnetometer. No paroxysmal spikelike waveform was observed in MEG at rest with eyes closed. The MEG and EEG were recorded also from 16 patients with primary epilepsy and 24 patients with secondary epilepsy. The examination proved to be safe for both normal subjects and patients with epilepsy. Interictal spikes were observed in 27 cases during the examination. The percentage of spikes identified in MEG but not in EEG was found to be 2. 3% of all spikes. The foci of the spikes identified in MEG were localized and determined in 20 cases. In 10 patients with secondary epilepsy, the localization of the foci were compared with the lesion demonstrated by magnetic resonance imaging (MRI) or computerized tomography (CT) and with the findings of EEG. In 6 cases, the foci by MEG were consistent. In the 4 cases where the MEG foci did not correspond to the MRI or CT findings, MEG foci were supported by the findings of EEG. MEG allows three-dimensional localization and enables us to elucidate the propagation of paroxysms. MEG was very useful in diagnosing epilepsy.