Study Of The Efficacy And Influencing Factors Of SEEG-guided Radiofrequency Thermocoagulation In The Treatment Of FCD-related Refractory Epilepsy

Objective:Focal cortical dysplasia(FCD)is a common cause of drug-resistant epilepsy.With the development and application of stereotactic techniques,radiofrequency thermocoagulation(RFTC)guided by stereoelectroencephalography(SEEG)has shown certain efficacy in the treatment of FCD related refractory epilepsy.The purpose of this study is to explore and analyze the effectiveness and safety of SEEG guided RFTC in the treatment of FCD related refractory epilepsy,and to analyze the relevant factors that affect patient prognosis,in order to provide theoretical guidance for improving the prognosis of SEEG guided RFTC in treating FCD related drug refractory epilepsy patients.Methods:We retrospectively reviewed the clinical data of patients with FCD related refractory epilepsy treated by SEEG guided RFTC in the Department of functional neurosurgery of the second hospital of Lanzhou University from September2019 to June 2022 using a multimodal preoperative evaluation system for preoperative evaluation,and all included patients were followed up in an outpatient or telephone department and evaluated prognostically using the modified Engel grade to achieve Engel Ⅰ versus Engel Ⅱ grade as good prognosis,Engel III versus Engel IV grade were considered poor prognostic.All included patients were divided into a good prognosis group and a poor prognosis group to analyze the efficacy and safety of SEEG guided RFTC for the treatment of FCD related refractory epilepsy,as well as to explore patient age,gender,age at onset,disease course,presence or absence of aura before onset,presence or absence of previous history,presence or absence of secondary generalized tonic clonic seizure(GTCS),FCD lesion location,number of implanted roots on electrodes,head MRI,and brain PET-CT for positive findings,Whether or not the low volatility fast activity during ictal period were recorded by SEEG,whether or not there was anatomical electrical clinical consistency,whether or not cortical electrical stimulation induced the habitual seizure,whether the epileptogenic focus was totally thermal coagulation disfigurement and the protocol of thermal coagulation were related to the prognosis of RFTC.Results: A total of 25 patients with FCD related refractory epilepsy were included in this study,and the epileptogenic focus in all patients was identified as FCD by multimodal presurgical evaluation.Fllow-up time: 7 to 41(23.2 ± 10.4)months,at the last follow-up,7(28%)patients had reached Engel I grade,3(12%)had reached Engel II grade,6(24%)had reached Engel III grade,and the remaining 9(36%)had Engel IV grade.Of these,10 patients had a favorable prognosis,representing 40%;Seizure free rate was 28%;The responder to RFTC was 16 patients and the response rate was 64%.The differences between the seizure free rate at 2 months and 1 year after RFTC,the proportion of patients with a good prognosis,and the response rate to RFTC were statistically significant(p-values: 0.011,0.023,and 0.025,respectively).14 patients underwent epileptogenic focal resection surgery within one year after SEEG guided RFTC.Prognostic evaluation at 2 months after SEEG guided RFTC was used to evaluate whether the prognostic outcome of RFTC could be used as a predictive factor for the success of epileptogenic focal resection surgery,and the results showed a positive predictive value of 88% and a negative predictive value of 50%.There were 3(12%)patients who experienced adverse effects after RFTC.After contrasting the relevant factors that might have an impact on patient outcome between the good prognosis and the poor prognosis groups,we found: positive findings on cranial MRI(p = 0.020),positive findings on brain PET-CT(p = 0.020),low amplitude fast activity recorded by SEEG at ictal onset(p = 0.005),with anatomical electrical clinical consistency(p = 0.049),and with habitual onset induced by cortical electrical stimulation(p = 0.041)Whereas complete thermocoagulation disfigurement of the epileptogenic focus(p = 0.005)and radical thermocoagulation protocol(p < 0.001)were associated with a good prognosis in RFTC.RFTC age,age at first seizure onset,epilepsy course,patient gender,presence or absence of preeclampsia,presence or absence of previous history,presence or absence of secondary GTCS,FCD lesion location and number of roots implanted with electrodes were not significantly associated with RFTC prognosis.It is important to note that although the difference in overall pathologic type between the 2 groups was not statistically significant,the subtype of FCD type IIB was statistically significantly different between the 2 groups,and pathologic type FCD type IIB was a predictor of good prognosis for RFTC(p =0.005).Conclusion:SEEG guided RFTC for FCD related refractory epilepsy is a very safe treatment with certain efficacy,but the stability of efficacy is suboptimal,the shortterm efficacy is better,and the long-term efficacy is decreased;Positive findings on cranial MRI and brain PET-CT,low volatility fast activity recorded by SEEG during ictal period,anatomical electrical clinical consistency,habitual seizure induced by cortical electrical stimulation,the complete thermocoagulation disfigurement of the epileptogenic focus,the pathological type was FCD type IIB and the radical thermocoagulation protocol are predictors that suggest a favorable outcome for the patient;Good patient outcome at 2 months after SEEG guided RFTC is a predictor of good outcome after subsequent epileptogenic focal resection surgery in patients with FCD related refractory epilepsy.