Intraoperative ElectroCorticoGraphy (ECog): indications, techniques, and utility in epilepsy surgery

Aims. To describe the technique, indications, and utility of intraoperative ECoG monitoring during various surgeries for medically intractable epilepsy. Methods. Literature was reviewed to obtain published results on using intraoperative ECoG techniques for the surgical treatment of medically intractable epilepsy of various underlying aetiologies. Results. General intraoperative ECoG techniques were described, including effects of anaesthetic agents on intraoperative ECoG signals. Use of intraoperative ECoG in temporal lobe epilepsy with mesial temporal sclerosis (MTS) is generally considered not necessary, whereas intraoperative ECoG in temporal lobe epilepsy without mesial temporal sclerosis may provide useful information. Intraoperative ECoG in extra-temporal epilepsy with structural lesions may facilitate resection, whereas the use of intraoperative ECoG in extra-temporal epilepsy without a structural lesion is more controversial. Conclusions. Intraoperative ECoG is a useful technique to be employed in surgical treatment of medically intractable epilepsy. However, its effectiveness may vary depending on the underlying pathological causes of the seizures.