Stereo-electroencephalography-guided cross-electrode radiofrequency thermocoagulation in focal epilepsy: A review of current methodologies and outcomes.

Advances in stereo-electroencephalography-guided radiofrequency thermocoagulation (SEEG-guided RFTC) have led to the development of cross-electrode RFTC, which has been shown to result in significantly larger lesions and higher seizure-freedom rates compared to standard RFTC methods. Given the novelty of cross-electrode RFTC, herein we review the reported surgical techniques and treatment-related outcomes to date to identify current research gaps and future directions. Ten articles were identified for review including 187 participants who underwent cross-electrode RFTC. Hypothalamic hamartoma (HH) and hippocampal sclerosis (HS) accounted for 52% and 26% of all cases, respectively. The proportion of cases with seizure freedom at last follow-up was 71%, including 84% of the HH cases, 54% of all temporal lobe cases, and 56% of the HS cases. Long-term efficacy in one HS study dropped from 72% at 12 months to 43% at 5 years post-treatment. Most (94%) reported complications resolved. One study reported favorable neuropsychological outcomes in HS cross-electrode RFTC compared to standard resective epilepsy surgery; however, it did not use memory tasks known to be reliable proximal markers of mesial temporal dysfunction/disease. In conclusion, extending RFTC boundaries through cross-electrode methods may improve RFTC efficacy and produce seizure-freedom rates comparable to established epilepsy surgical interventions in the treatment of HH and HS at 12 months, with a low risk of postoperative complications. There is limited research exploring efficacy in non-lesional epilepsy despite these cases often undergoing SEEG for diagnostic purposes and being well placed for cross-electrode RFTC. In addition, there is a lack of research exploring the neurocognitive and psychiatric risks of cross-electrode RFTC.