The difference between Engel Ⅰ and Engel Ⅱ in epileptogenicity biomarkers after stereotactic thermocoagulation

Abstract

Objective Stereoscopic electroencephalography(SEEG) is an important invasive assessment method in epilepsy surgery. After electrode implantation, radiofrequency thermocoagulation(RF-TC) guided by Stereoscopic electroencephalography(SEEG) is performed on the discharge initiation and rapid propagation areas by monitoring intracranial electroencephalography.High-frequency oscillations (HFOs) and spikes, are quantifiable epileptogenic biomarkers before and after RF-TC.In this study, we sought to evaluate, using SEEG signals recorded before and after thermocoagulation, whether a difference between Engel Ⅰ and Engel Ⅱ patient.Methods 3 minutes segments of SEEG signals were analyzed in 22 patients before and after thermocoagulation.We used Anywave software to quantify the rate of spikes, rate of HFOs(80-512Hz), rate of HFOs(80-250Hz) and rate of HFOs(250-512Hz).We analyzed the differences both at an individual level(paired t-text and pencentage) and at a group level(Fisher exact test).Results After RF-TC guided by SEEG,12 patients showed Engel Ⅰ,10 patients showed Engel Ⅱ.In EZ, an intra individual decrease in HFOs was significantly more frequent in Engel grade Ⅰ patients than in Engel grade Ⅱ patients (80-513Hz:p = .038; 80-250Hz:p = .026;250-513Hz:p = .038).In thermocoagulated zones was an intraindividual decrease of HFOs (250-512Hz) significantly more frequent in Engel grade Ⅰ patients than in Engel grade Ⅱ patients (p = .038) .Conclusion Quantified changes in the rate of spikesand rate of HFOs can be observed after RF-TC guided by SEEG.There may be difference between Engel Ⅰ and Engel Ⅱ in HFOs and no difference in spikes after stereotactic thermocoagulation.