Stereo‐electroencephalography‐guided radiofrequency thermocoagulation in patients with focal epilepsy: A systematic review and meta‐analysis

Abstract

Objective: Despite the increasing number of studies reporting results of stereo-electroencephalography (SEEG)-guided radiofrequency-thermocoagulation (SEEGguided RF-TC) in the treatment of patients with drug-resistant focal epilepsy, the exact efficacy of this approach remains unclear. The seizure-freedom rate varies greatly across studies and the factors associated with efficacy have not been formally investigated. Methods: All prospective or retrospective studies reporting efficacy and/or safety of SEEG-guided RF-TC in patients with drug-resistant focal epilepsy were included. The primary outcome was the seizure-free rate 1 year after the procedure. Secondary outcomes were (1) the responder rate 1 year after the procedure and (2) the proportion of patients with permanent neurologic deficit 1 year after the procedure. Each outcome was assessed in all patients and in 4 groups of patients defined by the etiology of epilepsy. Each outcome was pooled using inverse variance weighting, logit transformation of proportion, and a randomeffects model. Results: No prospective study was identified and a total of 6 retrospective studies, reporting efficacy and safety data of 296 patients, were included. The pooled rate of permanent neurologic deficit was 2.5% (95% confidence interval [CI] 1.2%-5.3%), without heterogeneity across studies. In contrast, both the seizure-free and responder rates varied greatly across studies, and statistical heterogeneity was high. The pooled seizure-free and responder rates were 23% (95% CI 8%-50%) and 58% (95% CI 36%-77%), respectively. Both for the seizure-free and responder rates, the greatest efficacy was observed in patients with periventricular nodular heterotopia and the lowest in patients with normal magnetic resonance imaging (MRI) findings. Significance: SEEG-guided RF-TC is a safe procedure with low risk of complications. In contrast, the level of evidence regarding its efficacy remains low. Better identification of factors associated with seizure outcome are needed. K E Y W O R D Sintracranial, neurosurgery, RF-TC, SEEG-guided, stereotactic, thermo-SEEG

Stimulation Mapping Using Stereoelectroencephalography: Current and Future Directions

“…Stimulation is also used to identify eloquent areas which may not be suitable for coagulation or areas which may be targeted if a minor neurologic deficit is to be tolerated (74,75). A recent meta-analysis of SEEG RF-TC for focal epilepsy showed a pooled rate of permanent neurologic deficit of 2.5% (95% CI = 1.2-5.3%) (76). Of the five neurologic deficits observed at 1-year follow-up occurring in three studies, only one was unexpected, while the other four were expected and tolerated as the target tissue was in the primary motor cortex (76).…”

“…A recent meta-analysis of SEEG RF-TC for focal epilepsy showed a pooled rate of permanent neurologic deficit of 2.5% (95% CI = 1.2-5.3%) (76). Of the five neurologic deficits observed at 1-year follow-up occurring in three studies, only one was unexpected, while the other four were expected and tolerated as the target tissue was in the primary motor cortex (76). SEEG ESM therefore plays an essential role in the safe implementation of SEEG RF-TC.…”

“…The contribution of SEEG ESM to seizure outcomes following SEEG RF-TC is less clear, however. The meta-analysis from Bourdillon et al showed a pooled seizurefree rate at 1 year of 23% (95% CI = 8-50%) and a pooled responder rate of 58% (95% CI = 36-77%) (76). However, the included studies suffered from significant heterogeneity, which precluded any strong recommendations on the use of RF-TC for the treatment of focal epilepsy.…”

Malformations of cortical development: New surgical advances

“…More recently, studies specifically focused on SEEG-guided RF-TC as a treatment of periventricular nodular heterotopias reported very exciting results suggesting that almost all patients can reach Engel 1 status [3,27,35]. A meta-analysis pooling the sub-groups of all available studies concluded that, in this specific indication, SEEG-guided RF-TC leads to a rate of 38 % of seizure free patients and 81 % of responders [36]. These data make SEEG-guided RF-TC the first line of treatment of periventricular nodular heterotopias.…”

Technical Aspects of SEEG and Its Interpretation in the Delineation of the Epileptogenic Zone

“…Indeed, SEEG is a methodology that allows three-dimensional recording of activity anywhere in the brain, and is utilized to delineate not only the EZ 1) but also the epileptic network that contributes to the clinical manifestations of a seizure. Moreover, SEEG electrodes can be used for (1) cortical electrical stimulation in delimiting the EZ and defining the eloquent areas in relation to the EZ and (2) radiofrequency thermocoagulation (RF-TC) to treat a deep-seated EZ (or epileptogenic lesion) or EZ in the proximity to the eloquent cortex, 2) and to complement SEEG findings in delineating the EZ (details to be discussed later).…”