The application value of stereoelectroencephalogram electrode implantation in the preoperative evaluation of refractory focal epilepsy
Objective To explore the application value of stereoelectroencephalogram(SEEG)electrode implantation in the preoperative evaluation of refractory focal epilepsy.Methods A retrospective analysis was performed on the clinical data of 24 patients with refractory focal epilepsy who were treated in the Neurosurgery Center,No.988 Hospital of the PLA Joint Logistics Support Force from January 2018 to December 2022 using a relatively small number of SEEG electrodes.Based on the patient's symptoms,ictal and interictal video-EEG,brain CT,MRI,positron emission tomography(PET)-CT and other imaging data as well as anatomo-electrophysiology-clinical correlation,the hypothesis regarding the seizure onset and propagation network was made.SEEG electrodes were implanted into relevant targets of the seizure network.SEEG monitoring was performed to determine the seizure onset zone.Electrical cortical stimulation(ECS)was administered to induce habitual seizures to verify the epileptogenic zone and locate functional areas.Radiofrequency thermal coagulation(RFTC)was then performed.Those who still had epileptic seizures underwent secondary craniotomy to remove the epileptogenic zone.The Engel classification system was used to evaluate the effect of seizure control.Results A total of 126 electrodes were implanted in 24 patients,with 3 to 8 electrodes implanted in each case,with an average of 5.3±1.1 electrodes/case.There were 6 cases of unilateral electrode implantation and 18 cases of bilateral electrode implantation.The error between the actual target point and the planned target point was 1.61±0.88 mm in 24 patients.No patient had additional implanted electrodes.The SEEG monitoring time was 10.1±2.6 days,and 3 to 20 habitual seizures were recorded.ECS induced habitual seizures in 15 cases,non-habitual seizures in 5 cases,and no seizures in 4 cases.The epileptogenic zone was identified in 23 cases,including 10 cases in the temporal lobe,10 cases in the frontal lobe,and 3 cases in the occipital lobe.The seizure onset could not be located in 1 case.Twenty-two cases were treated with RFTC.Post RFTC,there were 9 cases developing headache,1 case of contralateral upper limb weakness caused by severe cerebral edema,and 1 case of asymptomatic subdural hematoma.There were no complications such as intracranial infection,cerebrospinal fluid leakage,electrode breakage or displacement.Two cases were not treated with RFTC,of which the hypothesis could not be verified in one case and the epileptogenic area was overlapped with the motor and speech areas in one case.Both cases improved after adjusting anti-seizure medications.All 24 patients received clinical follow-up,and the follow-up time[M(Q1,Q3)]was 12.5(10.2,26.8)months.The last follow-up showed that among the 22 patients who underwent RFTC treatment,1 case was Engel grade Ⅰ and 21 cases were gradeⅡ,and 16 of underwent epileptogenic zonectomy at the second stage.After the resection,the epileptic seizures disappeared in 13 cases(Engel grade Ⅰ),3 cases had no improvement(Engel grade Ⅱ),and 5 cases were planned to undergo secondary electrode implantation and RFTC treatment.Conclusion With reasonable grasp of indications,implantation of a relatively small number of SEEG electrodes can help determine the location of the epileptogenic zone,guide surgical resection of the epileptogenic zone,the postoperative effect is good,and has certain application value in the preoperative evaluation of refractory focal epilepsy.
Drug resistant epilepsyEpileptogenic zoneStereoelectroencephalographyRadio-frequency thermocoagulationElectrical cortical stimulation
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