| Objective:The epileptogenic brain regions of patients with refractory temporal lobe epilepsy were determined using a multimodality preoperative evaluation system supported by stereotactic electroencephalography(SEEG),and the SEEG data were analyzed with magnitude squared coherence(MSC)to elucidate the epileptogenic network of patients with temporal lobe epilepsy by studying the connectivity between epileptogenic related brain regions to further accurately guide surgical treatment.Data and Methods:The data of 18 patients with refractory temporal lobe epilepsy who underwent preoperative evaluation,intraoperative SEEG precision evaluation and surgery in the Department of Functional Neurosurgery of the Second Hospital of Lanzhou University from March 2016 to December 2019 were retrospectively analyzed,including detailed medical history,ictal symptomatology,seizure frequency and time regularity,long-range video-EEG monitoring results,imaging and image post-processing results,deoxyglucose positron emission tomography results and neuropsychological examination results,as well as the data of localizing the epileptogenic zone according to the results of multimodality multi-parameter evaluation and applying the high-frequency epileptogenic index(HFEI)and individualizing the type of surgery,extent of surgical resection,postoperative pathological results and epilepsy prognosis evaluation(Engel classification)for each patient.The relationship between SEEG epileptogenic contacts identified by manual identification and HFEI,respectively,was also analyzed and compared to assess the clinical significance of HFEI.Through amplitude square coherence analysis,the network connectivity between epileptic and epileptic areas(PP),between epileptic and non-epileptic areas(PN),and between non-epileptic and non-epileptic areas(NN)was analyzed to explore the epileptic network.Results:All 18 patients in this group underwent preoperative multimodality assessment,and the EEG data were preprocessed for computational analysis of HFEI.The correlation between the localization results of EZ visual analysis and HFEI localization results was analyzed according to clinicians,and the temporal lobe epilepsy network was analyzed in combination with MSC method to guide the surgical treatment of patients with temporal lobe epilepsy.(1)A total of 123 electrodes were implanted in 18 patients,with an average of 6.8 electrodes/case;the number of electrode contacts was a total of 1549,excluding one bad electrode contact,with a total of 1548 electrodes,with an average of 86 electrodes/case.HFEI was calculated in each patient,and the number of contacts calculated by HFEI was significantly less than that obtained by visual analysis by clinicians.Through correlation analysis,the two were correlated in the localization of epileptic areas,and the consistency between the calculated epileptic areas and the clinically judged epileptic areas was high.The mean sensitivity of HFEI in EZ localization was(35.84 ± 15.95)% and the specificity was(95.56 ± 1.88)%.(Fig.2)Eighteen patients were treated surgically.During a mean follow-up of 20.44 ± 11.82 months(range,3 to 42 months)after surgery,15 patients(83.33%)had a good prognosis(Engel grade I),3 patients(16.67%)had a poor prognosis(Engel grade II-III),and none had Engel grade IV.3),the results of MSC coherence analysis of SEEG showed that all 18 patients presented the characteristics of PP > PN > NN,reflecting that the connectivity between epileptic and non-epileptic areas was better than that between epileptic and non-epileptic areas,and also better than that between non-epileptic and non-epileptic areas;the connectivity between epileptic and non-epileptic areas was better than that between non-epileptic and non-epileptic areas.(Fig.4),the results of network analysis showed that in the medial temporal lobe group of 7 patients,the involved structures mainly included the hippocampus,cauda equina,hippocampal head,cingulate gyrus,amygdala,long posterior insular gyrus,and short posterior insular gyrus,and MSC connectivity analysis showed that the hippocampal formation was the main brain region of origin,followed by transmission to brain regions such as the amygdala,insular lobe,and cingulate gyrus.Among the 10 patients in the medial and lateral temporal lobe group,the medial-external type accounted for 9 cases,and the epileptic area involved medial and lateral temporal lobe structures,including the hippocampal head,hippocampus,cauda equina,cingulate gyrus,superior temporal gyrus,middle temporal gyrus,transverse temporal gyrus,middle frontal gyrus,and superior frontal gyrus,all of which had a hippocampal origin in the conduction direction and conducted to other limbic systems and temporal lobe neocortical structures.External-internal type accounted for one case,which conducted to the hippocampus and frontal lobe from the origin of the temporal neocortex.In this group,there was only one case in the lateral temporal lobe group,and the site of origin was limited to the middle temporal gyrus and transverse temporal gyrus,which did not show transmission to other structures.Conclusion :(1)Good surgical results support that the SEEG-based multimodality assessment system is important in the accurate localization of EZ in temporal lobe epilepsy,and the high specificity of high-frequency epileptogenic index in the localization of epileptic areas is of great reference value for assisting in the determination of EZ.2)The hippocampal formation is the most important epileptic network node of mesial temporal lobe and medial and lateral temporal lobe temporal lobe epilepsy,which is most closely related to the amygdala,island lobe,and temporal lobe neocortex and plays an important role in the occurrence,propagation,and evolution of epilepsy. |
