PROPERTIES OF ADVANCED HEADMODELLING AND SOURCE RECONSTRUCTION FOR THE LOCALIZATION OF EPILEPTIFORM ACTIVITY

During the last decade multiple work has been done to determine the so urces of epileptiform activity by means of dipole source localization based on recordings of the magnetoencephalogram (MEG) or the electroen cephalogram (EEG). The actual available advanced volume conductor mode ls and the multiple source reconstruction by regularization may give n ew impulse to EEG based source analyses in epilepsy patients. This stu dy demonstrates the principal properties of these techniques. We appli ed two different EEG source reconstruction techniques within different volume conductor models to localize induced spike activity in a selec ted patient suffering from medically intractable temporal lobe epileps y: 1) single moving dipole solution in a 3-shell spherical model versu s individual head models (boundary-element-model, BEM, and finite-elem ent-model, FEM); 2) a regularization technique for current density rec onstructions using both BEM and FEM. When compared to findings of inva sive recordings no adequate source locations were derived from the mov ing dipole solution in both the 3-shell head model and BEM. In contras t, a high congruence of source reconstruction and invasive determinati on of the focus was obtained using the regularization techniques in bo th BEM and FEM, indicating the high spatial accuracy of this technique in individual head models.