Abstracts

Rationale: Rationale: The accuracy of EEG source localization in determining seizure onset depends on a number of factors, including the density and head coverage of the EEG sensors and the specification of head anatomy and conductivity used for the electromagnetic analysis. An important question is whether a useful approximation can be achieved with a generic atlas, based on an average or typical head geometry. Methods: Methods: We created an atlas finite difference model of head tissues, from the Montreal average MRI, using typical positions of the cortical gray matter modeled as xyz triples without specifying dipole orientations. We contrasted EEG source localization of seizure onset with the atlas-based model with an individual head model constructed for that patient, using the cortical surface to orient dipoles normal to the surface. Results: Results: For this patient, the atlas-based model provided clinically useful localization of seizure onset. At the same time, the individual cortical surface constraints allowed interpretations for how the shifting dipole fields at seizure onset reflected localization specific gyral and sulcal features of the patient s cortex. Conclusions: Conclusions: Further research is required to determine whether there is significant clinical utility in constructing individual electromagnetic models of head tissues and cortical surface orientations.