Interictal triple ECoG characteristics of temporal lobe epilepsies: An intraoperative ECoG analysis correlated with surgical outcome

Objective Recent reports showed that intraoperative ECoG activities can be analysed with respect to more complex spike patterns. We have systematically investigated different characteristic epileptiform activities in intraoperative ECoG and correlated them to postoperative outcome. Methods Intraoperative ECoG findings of patients with non-tumorous epilepsies (20 patients with Engel outcome 1a, 20 patients with Engel outcome 2–4) were analysed in order to differentiate ECoG characteristics in temporal lobe epilepsies (TLE). Results In addition to focal spiking with or without propagation, focal slowing in the theta or delta range and so-called ictaform ECoG patterns were found. These ictaform patterns occurred in 40% of the patients with TLE. Conclusions Leading spikes in combination with focal slowing and ictaform patterns can contribute to a better delineation of mesial temporal epileptic activity in the anterior–posterior alignment. They provide an additional information which can be used for the extent of resection. Significance If the resected area included the anterior mesial regions, where interictal spikes, ictaform activity and slowing were localized, the postoperative outcome was good.