SEEG-guided RF Thermocoagulation of Epileptic Foci:Feasibility, Safety, and Preliminary Results
Summary:Purpose:Depth electrodes recordings may be re-quired in some cases of epilepsy surgery to delineate the best re-gion for cortical resection. We usually implant depth electrodesaccording to Talairach’s stereoelectroencephalography (SEEG)method. By using these permanently implanted depth electrodes,we are able to perform radiofrequency (RF)-thermolesions of theepileptic foci. We report the technical data required to performsuch multiple cortical thermolesions, as well as preliminary re-sults in terms of seizure outcome in a group of 20 patients.Methods:Lesions were performed by using 100- to 110-mAbipolar current (50 V), applied for 10 to 50 s. Each thermocoag-ulation produced a 5- to 7-mm diameter cortical lesion. In total,two to 16 lesions were performed in each of the 20 patients.Lesions were placed without anesthesia. No general or neuro-logic complication occurred during the procedures. Two tran-sient postprocedure side effects, consisting of paresthetic sensa-tions in the mouth and mild apraxia of the hand, were observed.Results:At a follow-up time of 8 to 31 months (mean, 19months), 15% of the patients became seizure free, 40% expe-rienced a?80% reduction of their seizure frequency, and 45%were not significantly improved.Conclusions:SEEG-guided RF thermolesions is a safe tech-nique. Our preliminary results indicate that such lesions canlead to a significant reduction of seizure frequency and couldbe proposed as a palliative procedure if no resective surgery ispossible. A randomized controlled trial is needed to determinewhich patients are likely to respond to SEEG-guided RF ther-molesions.Key Words:RF—Thermolesion—Epilepsy—Depthelectrodes—SEEG.
In many people with epilepsy, invasive presurgicalinvestigations are required to define the optimal corti-cal resection (1–3). We usually implant depth electrodesaccording to the method of Talairach for stereoelectroen-cephalography (SEEG). Principles and methods of SEEG,described in the 1960s by Talairach and Bancaud, havebeen reported in detail in previous publications (3–5). Inbrief, SEEG consists of stereotactic implantation of depthelectrodes in the brain to identify the exact location(s)of the epileptogenic area(s), as well as the pathways ofdischarge propagation. Electrodes are implanted in an or-thogonal plane, by using both magnetic resonance imag-ing (MRI) and angiography. The sites of implantation de-pend, for each patient, on the outcome of prior noninvasivepresurgical investigations. Because MRI is coupled withangiography, each electrode can reach its implantation sitewithout injuring cerebral vessels. Each electrode is madeof stainless steel, and has five to 15 contacts. The dimen-sions of each contact are 2 mm in length and 0.8 mm inAccepted July 4, 2004.Address correspondence and reprint requests to Dr. M. Gu ?enot atDepartment of Functional Neurosurgery, P. Wertheimer Hospital, 59, BdPinel, 69677, Bron, France. E-mail: email@example.com.