Abstracts

Rationale: Dense-array EEG is consisted with up to 256 channel electrodes which increase spatial resolution and recently has been used in epilepsy monitoring. This study is to evaluate the accuracy of electrical source estimation of interictal discharge by dense-array EEG as compared to simultaneously recorded intracranial EEG. Methods: Three patients with medically refractory temporal lobe epilepsy underwent invasive monitoring after conventional LTM. Patients are as the followings. Case1: tumor in the right amygdala, Case2 : left hippocampal sclerosis, Case3 : no lesion on MRI. The total of 52-62 channel subdural electrodes was placed over the mesial and lateral temporal lobe. We conducted dEEG recording by Geodesic Sensor Net (Electrical Geodesics Inc.EGI) for 4-7 hours with intracranial EEG at 1 kHz sampling simultaneously. Then intracranial spikes were categorized based on its location and analyzed with dense-array EEG using GeoSource, the electrical source estimation software which applied a local autoregressive average (LAURA) to provide source estimates of the three dimensional cortical distribution of current density for dense-array EEG. Results: All cases showed the interictal discharges originating from mesial and lateral temporal region independently. Dense-array EEG also detected some of these interictal discharges and its source estimation was localized in the similar region to the intracranial EEG. Conclusions: Dense-array EEG used in conjunction with electrical source analysis can be a powerful tool in epilepsy monitoring as it shows excellent accuracy of source estimation noninvasively.