Changes in local and network brain activity after stereotactic thermocoagulation in patients with drug‐resistant epilepsy

Objective Stereoelectroencephalography‐guided radiofrequency thermocoagulation (SEEG‐guided RF‐TC) aims to reduce seizure frequency by modifying epileptogenic networks through local thermocoagulative lesions. Although RF‐TC is hypothesized to functionally modify brain networks, reports of changes in functional connectivity (FC) following the procedure are missing. We evaluated, by means of SEEG recordings, whether variation in brain activity after RF‐TC is related to clinical outcome. Methods Interictal SEEG recordings from 33 patients with drug‐resistant epilepsy (DRE) were analyzed. Therapeutic response was defined as a >50% reduction in seizure frequency for at least 1 month following RF‐TC. Local (power spectral density [PSD]) and FC changes were evaluated in 3‐min segments recorded shortly before (baseline), shortly after, and 15 min after RF‐TC. The PSD and FC strength values after thermocoagulation were compared with baseline as well as between the responder and nonresponder groups. Results In responders, we found a significant reduction in PSD after RF‐TC in channels that were thermocoagulated for all frequency bands (p = .007 for broad, delta and theta, p