Multichannel Magneto-electroencephalography Recordings of Interictal and Ictal Activity

A lobar or even a intralobar congruence was found when comparing the findings of magnetic source localization with presurgical evaluation (EEG, MRI and intraoperative ECoG) in temporal lobe epilepsy. The first dipolar activity that can be recognized during a spike-wave event (primary focal epileptic activity (PFA)) was localized in temporal neocortical or mesial regions. Further centres of epileptic activity could be localized by the method of spike averaging by correlation. This was interpreted as propagation of the electric activity. The comparison of interictal and ictal MEG localization results showed congruency in a patient with temporal lobe epilepsy. The combination of MEG and MRI helps to build a bridge between morphological and functional localization. MEG can serve as a pointer to discrete lesions in MRI.