Focal cortical surface cooling is a novel and safe method for intraoperative functional brain mapping.

ABSTRACT Objective Electrical cortical stimulation (ECS) has been the gold standard for intraoperative functional mapping in neurosurgery, yet it carries the risk of induced seizures. Here we assess the safety of focal cortical cooling (CC) as a potential alternative to ECS. Methods We reviewed 40 subjects (n=13 tumor, 27 mesial temporal lobe epilepsy) who underwent intraoperative CC at the University of Iowa Hospital and Clinics (CC group), of which thirty-eight subjects had ECS performed preceding CC. Intra- and postoperative seizure incidence, postoperative neurological deficits, and new postoperative radiographic findings were collected to assess CC safety. Fifty-five subjects who underwent ECS mapping without CC (ECS-alone group) was reviewed as a control cohort. Another 25 subjects who underwent anterior temporal lobectomy (ATL) without CC nor ECS (No ECS/No CC-ATL group) were also reviewed to evaluate long-term effects of CC. Results Seventy-nine brain sites in CC group were cooled: IFG (44%), PrCG (39%), PoCG (6%), SubCG (4%) and STG (6%). The incidence of intraoperative seizure(s) were 0% (CC group) and 3.6% (ECS-alone group). The incidence of seizure(s) within the first postoperative-week did not significantly differ amongst CC (7.9%), ECS-alone (9.0%) and No ECS/No CC-ATL groups (12%). There was no significant difference in the incidence of postoperative radiographic change between CC (7.5%) and ECS-alone groups (5.5 %). Long-term seizure outcome (Engel Ⅰ+Ⅱ) for MTLE did not differ amongst CC (80%), ECS-alone (83.3%) and No ECS/No CC-ATL groups (83.3%). Conclusions CC when used as an intraoperative mapping technique is safe and may complement electrical cortical stimulation.