Electrocorticography for the Evaluation of Focus Resection

Abstract

Electrocorticography(ECoG)with intracranial electrodes has a higher spatial resolution and higher sensitivity than conventional electroencephagrahy. Chronic VIDEO-ECoG with subdural grid electrodes has been used to determine the resection border of epileptic focus, and to evaluate cortical function prior to resective surgery. Recording multiple seizures is necessary to determine whether they are the same as habitual seizures and whether they are reproducible, to allow subsequent identification of the seizure onset zone. It is also necessary to understand the ictal ECoG patterns of various seizure onsets. Recent advances in engineering technology have made wideband(0.01 Hz-600Hz)analysis possible. The resection of the area with the ictal DC shift and high frequency oscillation is reported to improve surgical outcome. Although the procedure of subdural grid insertion is technically easy, high rates of complications, such as infections and bleeding, have been reported. Intraoperative acute ECoG was used to validate the extent of resection area. Overall, intraoperative ECoG is greatly affected by anesthetics, and the interictal epileptic discharge should be evaluated carefully.