The Intracranial EEG Application And Analysis Of Pathological Features Of "Difficult To Locate" Intractable Epilepsy

Objective:To compare the effects,postoperative outcome and related complications of SDEG monitoring and SEEG monitoring inside of iEEG on the evaluation of preoperative epileptogenic zones in patients with �difficult to locate� intractable epilepsy;To summarize the pathological types and corresponding curative effects of patients with �difficult to locate�intractable epilepsy,and to analyze the causes of the difficulty in locating epileptogenic zones in these patients.Methods:Retrospective analysis of SDEG monitoring(49 cases)and SEEG monitoring(11 cases)of 60 patients in the epilepsy center of the First Affiliated Hospital of Fujian Medical University in 2010-2018,observed and statistically compared the differences of the assessment results of epileptogenic zones,surgical outcomes and related complications of the two groups of patients;at the same time,collect and count the characteristics of postoperative pathological types,lesion location and corresponding postoperative outcomes in patients with �difficult to locate�intractable epilepsy;Through combined with postoperative pathological type;diseased brain lobe and postoperative efficacy,to analyze the reasons of the difficult in locating the epileptogenic zones in patients with �difficult to locate�intractable epilepsy.Results:In the 49 cases of SDEG monitoring,1 patient was unable to accurately locate the epileptogenic zones after 1 month of continuous monitoring,and then the patient was discharged from the hospital.It is recommended that the patient could undergo neurological regulation.The epileptogenic zones of remaining 48 cases were accurately located after the monitoring,and 9 cases of them was suggested that the epileptogenic zones overlapped with the functional area,finally,8 cases underwent epileptogenic zones resection under protecting functional area,and 1 case underwent multiple subdural transections.11 cases who underwent SEEG monitoring are accurately located the epileptogenic zones and underwent epileptogenic resection.The results showed that the two groups of SDEG and SEEG had no significant difference in the positive rate and surgical resection rate of epileptogenic zones,but the bilateral implantation rate of SEEG(5/11,45.5%)was higher than that of SDEG(18/49,36.7%).At present,there is no significant difference in the postoperative outcome among patients with epileptic zones resected after SDEG and SEEG monitoring(P>0.05).However,due to the limitation of the number of SEEG cases,It is not yet possible to conclude that the two effects are the same.There was a statistically significant difference in the total incidence of serious complications of bleeding or infection between the two groups(SDEG 20 vs VS SEEG)(P=0.042<0.05).There was a statistically significant difference in the total incidence of significant headache or cerebral edema between the two groups(26 cases of SDEG vs 2 cases of SEEG)(P=0.031<0.05).There was a statistically significant difference in the incidence of cerebrospinal fluid leakage,subcutaneous fluid incision,and poor healing of incision after epileptic resection(SDEG 14 cases vs SEEG 0 cases)(P=0.040<0.05);There were no significant differences in dysfunction of speech,muscle strength between the two groups(p=1.000>0.05).In the postoperative pathology of 58 cases who underwent epileptogenic resection,47 cases of Malformation of cortical development(MCD),among those types,there were 12 cases of micro-Malformation of cortical development(mMCD)(20.7%),35 cases of focal cortical dysplasia(FCD)(60.3%));11 cases of others types(19.0%),among those types,there were 2 cases of hippocampal sclerosis,1 case of hippocampal sclerosis complicated with gray matter ectopic,1 case of hippocampal sclerosis complicated with scar cerebral gyrus,1 case of tuberous sclerosis,1 case of inclusion body encephalopathy,1 case of brain penetrating malformation,and 1 case lession after suffering brain trauma,1 case of scar cerebral gyrus,2 cases of no significant pathological changes.The total effective rate of postoperative patients was 86.2%(50/58),8 cases were unsatisfactory,and 5 cases(62.5%)among these cases were multi-brain lobe lesion.In 47 cases of MCD,the effective rate of mMCD was 83.3%(10/12),the effective rate of FCDI type was 100%(8/8),the effective rate of FCDII was 86.7%(13/15),and the effective rate of FCDIII was 75.0%(9 /12),Univariate analysis showed that the prognosis of patients with positive preoperative magnetic resonance and complete resection of epileptogenic focus was better(p<0.05).Multivariate analysis revealed that the complete resection of epileptogenic zones is a independent factor influencing the efficacy of postoperative outcome.Among MCD,18 cases(38.3%)were single-brain lobe lesions,29 cases(61.7%)were multi-brain lobe lesion,and 14 cases of single-brain MCD were completely satisfactory(Engel I),the effective rate was 77.8%,and 20 cases of multi-brain MCD were completely satisfactory,and the effective rate was 69.0%.There was no significant difference in the efficacy(2 = 0.431 P=0.511>0.05).Conclusion:The difference of the locating positive rate of epileptogenic zones and the effect of suegical resection after SDEG and SEEG monnitoring in the patients with �difficult to locate� refractory epilepsy still need further follow-up analysis.But SEEG has fewer complications than SDEG,SEEG is safer than SDEG.In the selection of two kind of iEEG methods for locating epileptogenic zones,two kind of iEEG monitoring methods have advantages in the localization of epileptogenic zones and the differentiation of functional areas.Effective combination will be more conducive to localization of epileptogenic zones and functional area.MCD,especially FCD is the main pathological type of patients with refractory epilepsy.Compared with single-brain lobe lesions,patients with multiple cerebral lobe lesions have a greater chance of using iEEG to accurately locate the epileptogenic zones,and because of the greater chance of residual epileptogenic zones,it resulting in postoperative high probability that epilepsy will not be completely relieved.Studies have found that multi-brain pathological changes,especially multi-brain MCD,are the main reason of it is difficult to locate epileptogenic zones for patients with refractory epilepsy,but for patients with �difficult to locate�intractable epilepsy,through effective selection of iEEG monitoring to further pinpoint the epileptogenic zones and functional area can achieve satisfactory results in most patients after completed epileptogenic resection.