Abstracts

Rationale: Dense array EEG (dEEG) consisted of over 100 channels has been focused in clinical Epilepsy field. The purpose of this study is to evaluate the clinical usefulness of dEEG for the detection rate and localization of interictal spikes in temporal lobe epilepsy. Methods: We conducted simultaneous recording 1) 128channel dEEG and sphenoidal electrodes in 3 patients and 2) 256 channel dEEG and intracranial EEG (icEEG) implanted over the lateral and mesial temporal lobe in patients with intractable epilepsy in another 6 patients. We calculated the dEEG spike detection rate and applied source estimation to dEEG to compare noninvasive localization to the invasive recordings. Results: 1) 90.4% of the interictal spikes detected by the dEEG were outside of the 10/20 electrode array and therefore not detected in the 10/20 montage. All spikes were localized in temporal lobe and 91% spikes were well localized in medial temporal lobe. 2) 316 of 719 interictal spikes (44%) were detected by dEEG by examining the 256 channel head surface array. The average icEEG amplitude of dEEG detectable spikes was 1036 µV, and that of dEEG undetectable spikes was 794 µV (P<0.05). All spikes detected in dEEG were localized to the temporal lobe. 262 of 316 spikes (83%) were well localized in mesial temporal lobe, close to the position confirmed by subdural electrodes. Conclusions: Dense array EEG may have a potential for providing an alternative to sphenoidal electrode monitoring in patients with temporal lobe epilepsy and be clinically useful in the presurgical work-up for epilepsy, providing accurate noninvasive guidance for the placement of intracranial electrodes.