Non-invasive localization of the epileptogenic focus by EEG dipole modeling.

Localization of epileptogenic foci by traditional visual inspection of EEG traces is simplistic. Voltage topography and subsequent spatio-temporal multiple dipole modeling are new techniques to assess the character of cerebral generators of EEG spikes and seizure rhythms. These predictions have been validated by intracranial monitoring. Patients with mesial temporal seizures have ipsilateral spikes and early ictal rhythms with a strong tangential (vertical) dipole component that often leads any radial source activity. This suggests propagation from baso-mesial to lateral cortex. Those with infero-lateral temporal cortical seizures have similar findings, but tangential sources are synchronous with or lag radial sources. Patients with lateral temporal cortical seizures have spikes and ictal activity that are modeled principally by radial dipoles.