Radiofrequency thermocoagulation of the seizure-onset zone during stereoelectroencephalography.
To assess long-term outcome and identify prognostic factors of radiofrequency thermocoagulation (RFTC) following stereoelectroencephalography (SEEG) explorations in particularly complex cases of focal epilepsy.



We retrospectively reviewed the medical charts, video-SEEG recordings, and outcomes for 23 patients (aged 6-53 years) treated with SEEG-guided RFTC, of whom 15 had negative magnetic resonance imaging (MRI) findings, and 10 were considered noneligible for resective surgery after SEEG. Two to 11 RFTCs per patient (mean 5) were produced by applying 40-50 V, 75-110 mA current for 10-60 s on SEEG electrode contacts within the epileptogenic region, which was very close to eloquent cortices in 12 cases. The general features, SEEG findings, and RFTC extent of the patients were analyzed to extract potential preoperative predictors of post-RFTC seizure outcomes.



After a mean follow-up of 32 months (range 2-119 months), eight patients experienced a ≥50% decrease of seizure frequency after RFTC (R+, 34.8%), of whom one had a sustained seizure freedom and 15 patients did not benefit from RFTC (R-, 65.2%). The presence of an MRI lesion was the only significant predictor of a positive outcome, whereas location of epilepsy, extent of interictal epileptiform discharges (IEDs) and of the seizure onset zone, induction of seizures by electrical stimulation, as well as the ratio of the coagulated sites did not show a significant correlation to the RFTC response. However, (sub-)continuous IEDs were more frequently found in R+ than in R- patients, thus suggesting that this EEG marker of the epileptogenic tissue might predict a positive outcome even in patients without obvious MRI lesion.



Our study confirms that RFTC, although less effective than resective surgery, can be a reasonable therapeutic option in complex cases where anatomic constraints make impossible any cortical resection. Further prospective studies are needed to better define RFTC indications and to optimize its methodology.
Epilepsy Surgery Unit, Department of Neurosurgery, St. Ivan Rilski University Hospital, Sofia, Bulgaria.
Petia
P
Dimova
Epilepsy Unit, Neurology Department and GIN, INSERM U836, University Grenoble Alpes and Michallon Hospital, Grenoble, France.|Neurology Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
Luca
L
de Palma
Epilepsy Unit, Neurology Department and GIN, INSERM U836, University Grenoble Alpes and Michallon Hospital, Grenoble, France.
Anne-Sophie
AS
Job-Chapron
Epilepsy Unit, Neurology Department and GIN, INSERM U836, University Grenoble Alpes and Michallon Hospital, Grenoble, France.
Lorella
L
Minotti
Neurosurgery Department, Michallon Hospital, Grenoble, France.
Dominique
D
Hoffmann
Epilepsy Unit, Neurology Department and GIN, INSERM U836, University Grenoble Alpes and Michallon Hospital, Grenoble, France.
Philippe
P
Kahane
D000293:Adolescent; D000328:Adult; D002648:Child; D004564:Electrocoagulation / Q000379:methods*; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013238:Stereotaxic Techniques; D016896:Treatment Outcome; D014741:Video Recording; D055815:Young Adult
Drug-resistant focal epilepsy; Epilepsy surgery; Radiofrequency thermocoagulation; Stereoelectroencephalography