Evaluation of epileptic patients by means of magnetoencephalography

Studies of the magnetoencephalogram (MEG) in epileptic patients suffering from focal epilepsies showed that activities in the MEG appear which are detectable in the scalp-recorded electroencephalogram. A novel technique was developed (Anninos et al., 1987) characterized by mapping the scalp distribution of the amplitude of the spectral components (or specific bands) of the MEG and which was termed "ISO-Spectral-Amplitude (ISO-SA) mapping." The most important findings in the 19 patients we studied from these maps were that in the frequency domain 2-7 HZ the major concentrated activity were projected on the scalp of the epileptic focus. Thus with the above noninvasive method we believe that it is possible to determine the localization of epileptiform foci via a method which will be a very useful tool for clinicians.