Abstract
Stereotactic electroencephalography (SEEG) is an important invasive assessment method in epilepsy surgery. After electrode implantation, SEEG-guided radiofrequency thermocoagulation (RF-TC) 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. This study aimed to quantitatively assess the changes in electrophysiological biomarkers - spikes and HFOs - before and after SEEG-guided RF-TC in drug-resistant epilepsy patients. We also sought to determine whether these changes, along with clinical characteristics, could serve as predictive factors for postoperative seizure outcomes. Three-minute segments of SEEG signals were analyzed in 44 patients before and after RF-TC. We used Anywave software to quantify the rate of spikes, rate of HFOs (80-512 Hz), rate of HFOs (80-250 Hz), and rate of HFOs (250-512 Hz). We analyzed the differences both at an individual level (paired t test and percentage) and at a group level (Fisher exact test). Logistic regression was used to analyze the possible influencing factors. After SEEG-guided RF-TC, 44 patients were included in the study; 25 patients showed clinical improvement, on the contrary 19 patients did not show clinical improvement. At an individual level of 44 patients, in the epileptic zone (EZ), 23 patients (52.3%) showed a significant intra-individual reduction of spikes. In the EZ, an intra-individual decrease in spikes was significantly more frequent in clinically improved patients than in not clinically improved patients (17 [68%] vs 6 [31.6%], P = .017). Duration of epileptic seizures (t = -2.052 P = .046 95% CI [-131.19--1.10]), frequency of seizure (χ = 8.636 P = .012), performance of magnetic resonance imaging (MRI) (χ = 3.889 P = .049) and spike of EZ (χ = 5.740 P = .017) had statistically significant effects on prognosis. Both faster frequency of seizure (OR = 0.025, 95% CI [0.001-0.469], P = .014) and positive performance of MRI (OR = 29.29, 95% CI [1.656-518.065], P = .021) presented a significant effect on clinically improved patients. Only both faster frequency of seizure (area under the curve = 0.739, 95% CI [0.588-0.890, P = .007) and spike ruduced of EZ (area under the curve = 0.682, 95% CI [0.520-0.844], P = .040) was predictive of clinical improvement. There may be difference in spikes in the EZ between clinically improved patients and clinically non-improved patients. Duration of seizure, frequency of seizure, positive MRI, and decreased spike rate in EZ after RF-TC were significantly associated with clinical improvement of seizures. More frequency of seizure and decreased spikes rate in EZ after RF-TC are significant in predicting the improvement of epileptic seizures.