Study Of Brain Function In Idiopathic Generalized Epilepsy Based On Rs-fMRI With Graph Theory Analysis

Objective:To study the changes of whole-brain network properties in patients with idiopathic generalized epilepsy（IGE）based on resting-state functional magnetic resonance imaging with graph theory analysis,analyze the correlation between the different whole-brain network properties and intelligence quotient（IQ）,and provide a new imaging basis for brain function changes and cognitive impairment in patients with IGE.Methods:Thirty-two patients with IGE in pediatric outpatient and inpatient department of Zunyi Medical University from January 2014 to January 2021 were collected.Patients were diagnosed according to the 2010 version epilepsy classification criteria of the International League Against Epilepsy by at least attending pediatricians.There were fourteen cases of absence group（age±standard deviation,9.71±2.70 years old）and eighteen cases in convulsion group（age±standard deviation,12.11±2.91years old）.Meanwhile,thirty-six healthy volunteers were enrolled as the control group（age±standard deviation,11.44±2.67years old）.T₂-FLAIR,3D-T₁and resting-state functional magnetic resonance imaging（rs-f MRI）images were acquired by MRI（3.0THDxt,GE）in all subjects,and the neuropsychological assessment of IGE based on the Chinese Wechsler Intelligence Scale for Children was conducted by the specialist on the same day.GRETNA V2.0based on MATLAB 2013b was used to preprocess the rs-f MRI images and construct the brain functional network to calculate related parameters including node,global and small world properties and to get different brain regions of the three groups.One-way analysis of variance or non-parametric test was performed,then post-hoc pairwise comparison tests were performed based on SPSS 18.0.Correlation analysis between abnormal network properties of IGE group and IQ,which included verbal intelligence quotient（VIQ）,performance intelligence quotient（PIQ）and full scale intelligence quotient（FSIQ）were performed.In this study,p<0.05 was considered statistically significant.Results:（1）There were no significant differences in age,gender composition or months in education between three groups（all p>0.05）,but there were significant differences in duration,PIQ and FSIQ between the absence and convulsion groups（all p<0.05）.（2）The three groups had the characteristics of"small world":γ>1,λ≈1 andσ>1.（3）Post-hoc pairwise comparisons were performed for all network properties in the different brain regions.Global properties:The clustering coefficient in the absence group was lower than the control group,and the local efficiency was lower than the convulsion and control group（all p<0.05）.（4）Nodal properties:Nodal degree centrality and nodal local efficiency of right superior occipital gyrus,nodal local efficiency of the right olfactory cortex,nodal clustering coefficient and nodal local efficiency of right caudate nucleus in absence group were lower than the control group,but nodal clustering coefficient of left middle frontal gyrus and nodal local efficiency of left dorsolateral superior frontal gyrus were higher than the control group（all p<0.01,uncorrected）.The betweenness centrality of the right supramarginal gyrus,nodal clustering coefficient and nodal local efficiency of the right olfactory cortex in the convulsion group were higher than the absences group,and the nodal local efficiency of left dorsolateral superior frontal gyrus in absences group was higher than the convulsion group（all p<0.01,uncorrected）.（5）The network connectivity between the left posterior cingulate among the right calcarine fissure with surrounding cortex and right lingual gyrus was enhanced in convulsion group.（6）Two nodal properties in the right caudate nucleus were negatively correlated with IQ in absence group.The nodal clustering coefficient was negatively correlated with VIQ（r=-0.545,p=0.044）,PIQ（r=-0.590,p=0.026）and FSIQ（r=-0.615,p=0.019）,and the nodal local efficiency was negatively correlated with VIQ（r=-0.608,p=0.021）,PIQ（r=-0.775,p=0.001）and FSIQ（r=-0.0741,p=0.002）.Conclusion:Abnormal brain regions are mainly in the right superior occipital gyrus,right olfactory cortex and right caudate nucleus.Two nodal properties are negatively correlated with IQ in absence group.There is a subnetwork reorganization between the default network（left posterior cingulate）and the visual cortex（right calcarine fissure with surrounding cortex and right lingual gyrus）in convulsion group.These findings provide a new imaging basis for network dysfunction and cognitive impairment in absence and convulsion group of IGE.