Analysis Of Surgical Prognosis And Related Factors Of Refractory Epilepsy Caused By Focal Cortical Dysplasia

Objective:Focal cortical dysplasia（FCD）is one of the most important causes of refractory epilepsy,the factors affecting its surgical efficacy have not been fully elucidated.The objective of this study was to investigate the relationship between the surgical prognosis in refractory epilepsy patients caused by FCD and clinical factors,structural neuroimaging,scalp electroencephalogram（EEG）,PET,multimodal imaging post-processing,Stereoelectroencephalography（SEEG）technology,whether the FCD related epileptogenic zone is completely resected,FCD pathological classification and the occurrence of Acute postoperative seizure（APOS）.To provide theoretical basis for improving the surgical efficacy of refractory epilepsy caused by FCD.Data and Methods:By reviewing relevant literature on surgical prognosis in patients with refractory epilepsy caused by FCD and systematically classified various factors affected surgical prognosis,and then collected and analyzed retrospectively all preoperative evaluation and clinical data of 45 refractory epilepsy patients caused by FCD from January 2015 to December 2020 in the functional neurosurgery of second hospital of Lanzhou university,these patients all accept our multimodal preoperative evaluation system of assessment.The surgical efficacy was compared according to divded into the results of head MRI examination（whether FCD epileptogenic zone was found）,the location of FCD epileptogenic zone（temporal lobe and outside temporal lobe）,the degree of resection of FCD related epileptogenic zone,FCD pathological classification,whether EEG interictal discharge was consistent with the epileptogenic zone,whether MRI-PET image post-processing was applicated,whether SEEG invasive evaluation was performed,and whether APOS occurred.Finally,Multiple Logistic regression analysis was performed to analyze the prognostic factors.Results:During the follow-up period from 12 to 72 months（32.33±17.23 months）after operation,30（67%）of 45 refractory epilepsy caused by FCD were EngelⅠgrade,6（13%）were EngelⅡgrade,4（9%）were EngelⅢgrade,5（11%）were EngelⅣgrade.The good prognosis（EngelⅠgrade）rate were 67%.Pathological classification of FCD:13 cases of FCD typeⅠ（4 cases of typeⅠa,1 case of typeⅠb,8 cases of typeⅠc）,23 cases of FCD typeⅡ（18 cases of typeⅡa,5 cases of typeⅡb）,9 cases of FCD typeⅢ（2 cases of typeⅢa,2 cases of typeⅢb,4 cases of typeⅢc,1 case of typeⅢd）.Among them,19 patients underwent surgery directly after preoperative evaluation in stageⅠ,and 26patients underwent preoperative invasive evaluation of SEEG.The results showed that the head MRI examination showed epileptogenic zone（χ~2=8.451,p=0.004）,EEG interictal discharge was consistent with the epileptogenic zone（χ~2=7.605,p=0.006）,and complete resection of FCD related epileptogenic zone（χ~2=10.045,p=0.002）were correlated with good prognosis.However,APOS（χ~2=12.656,p<0.01）was associated with poor prognosis.Gender,age of epilepsy onset,age of surgery,the location of FCD epileptogenic zone,pathological classification of FCD,post-processing of MRI-PET image and SEEG application were not significantly correlated with surgical prognosis.Multivariate analysis showed that negative head MRI examination（OR=0.071,p=0.035）,incomplete resection of FCD related epileptogenic zone（OR=0.033,p=0.010）and APOS（OR=0.008,p=0.002）were independent risk factors for poor prognosis after surgery.Conclusion:（1）The curative effect of FCD related refractory epilepsy surgery mainly depends on the precise localization of the epileptogenic zone.Anatomic-electrical-clinical identity is the cornerstone of accurate localization.The FCD epileptogenic zone visible on MRI,the consistency between EEG and the location of FCD epileptogenic zone,and the complete resection of the FCD epileptogenic zone predicted a good surgical prognosis.However,The absence of FCD epileptogenic zone on MRI,incomplete resection of FCD epileptogenic zone and APOS predicted a poor prognosis.（2）The proper application of SEEG is helpful to accurately located the epileptogenic zone and epileptic network.In this study,SEEG application showed no significant difference in surgical prognosis,which may be related to the small number of patients,the limitations of included cases,and the selection bias between the two groups.