Abstracts

Rationale: Dense-array EEG (dEEG) is consisted with up to 256 channel electrodes covering whole head, portions of face and neck with 2cm inter-electrodes distance. Recently dEEG has been used in epilepsy monitoring. This study is to evaluate the accuracy of dEEG electrical source estimation of interictal discharge by comparing with simultaneously recorded intracranial EEG and down-sampled dEEG data.Methods: Six patients with medically refractory temporal lobe epilepsy underwent intracranial EEG and 256ch-dEEG recording simultaneously. All patients were surgical candidate and the total of 52-62 channel subdural electrodes was placed over the mesial and lateral temporal lobe. 256ch-dEEG recordings were performed with Sensor Net (Electrical Geodesics Inc.EGI) with intracranial EEG at 1 kHz sampling simultaneously. After EEG recording, we were categorized the intracranial spikes based on its location and applied source estimation for each categorized spike on dense-array EEG. We down-sampled 256ch-dEEG data to 128ch and then applied source estimation to the down-sampled data.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. 256ch-dEEG estimated mesial temporal spikes accurately in mesial temporal region, however these 128ch down-sampled data were estimated in more lateral region compared to 256ch data.Conclusions: 256ch-dEEG and its source estimation can provide more reliable localization of the epileptiform discharges. Greater number of dEEG electrodes and the extended sensor layout enable accurate source estimation for basal temporal discharges and support the findings that sphenoidal or nasopharyngeal electrodes can detect the mesial temporal spike.