Characteristics Of Scalp Electroencephalographic And MRI In Focal Cortical Dysplasia

OBJECTIVE: To retrospectively study the clinical characteristics of scalp EEG(scalp electroencephalographic,EEG)discharge pattern and magnetic resonance imaging in refractory epilepsy caused by focal cortical dysplasia(focal cortical dysplasia,FCD).Methods: A retrospective study was conducted to collect 94 cases of patients with focal cortical dysplasia who received epilepsy evaluation in hospital from August 2017 to April 2019.Among them,17 cases received surgical treatment and postoperative pathology confirmed FCD.All the enrolled patients underwent long-term video EEG monitoring and MRI epilepsy sequence scan,and postoperative pathological diagnosis was made according to the Blumcke classification proposed by the International League Against Epilepsy(ILAE)in 2011.By comparing each characteristic EEG discharge pattern,MRI lesion analysis and symptomatic manifestation between patients with pathologically confirmed FCD and non-operative group,univariate analysis was carried out to analyze the above three factors,and chi-square test was used to detect the correlation between different EEG discharge patterns and FCD.Results: 17 patients with FCD were diagnosed pathologically after operation,including 12 males and 5 females,aged 3-48 years,with an average age of 19.97±11.29 years.Among them,There were 6 cases of FCD II(FCDIIa+FCDIIb)(35.3%),11 cases of FCD III(65.7%),8 cases of frontal lobe(47%)and 9 cases of temporal lobe(53%).There were 77 patients in the non-operative group,including 45 males and 32 females,aged 1.5-57 years.The average age was(20.0 ±11.28).According to the intermittent discharge patterns of scalp EEG,the patients were divided into six types: a multi-spike slow wave;b focal spike wave;c continuous spike wave;d multi-spike wave;e-spike slow wave;f no epileptic discharge.Each type of discharge is regarded as a EEG biomarker.4 patients(4 /17)had 2 or more discharge patterns.Among them,the form of focal spike wave discharge was the most common in both operation group and non-operation group,followed by continuous spike wave and multi-spike wave.There was no significant difference in the proportion of all types of scalp EEG biomarkers between the operation group and the non-operation group.The proportion of a single EEG discharge pattern was different between the operation group and the non-operation group,and there was significant difference in univariate analysis between the operation group and the non-operation group.Under the condition of inconsistent location of MRI and EEG,two or more discharge modes can increase the positive rate of diagnosis compared with the presence of only one scalp EEG biomarker,and the difference is statistically significant.The discharge site of EEG was consistent with that of operation in 9 cases,and the sensitivity was(53%).The location of MRI in 14 cases was the same as that of the operation,and the sensitivity was 82.4%.Unilateral lobectomy was performed in all 17 cases.According to Engal classification,15 patients(88%)had no aura and recurrent attacks,and Engel grade was grade I.One patient developed aura and GTCs attacks less than 3 times a year within one year after operation,and the attack decreased every month before operation,which was Engel III grade.One patient had two premonitory seizures within one year after operation,and there was no recurrent attack of,Engel I grade.Conclusion: The common discharge pattern in patients with cortical dysplasia confirmed by histology is focal spike wave discharge,followed by continuous spike wave and multi-spike wave.Multi-spike slow wave,continuous spike wave and spike-slow wave can be used as biomarkers for predicting the curative effect of FCDII.FCDII and FCDIII have characteristic changes on MRI,so the characteristic changes of MRI can be used as predictors of surgical outcome.