Functional Connectivity Study In Resting-State In Idiopathic Generalized Epilepsy

Objective:To analyze the structural changes of whole brain gray matter in patients with idiopathic generalized epilepsy (IGE) by using voxel-based morphometry (VBM) and to compare the functional connectivity within these abnormal gray matter brain areas between IGE and normal subjects in resting-state with functional magnetic resonance imaging(fMRI). To compare the functional connectivity of default-mode network (DMN) in resting-state between the IGE patients and normal subjecs.Subjects and Methods:Twenty eight IGE patients and twenty five normal subjects were recruited in our study. GE 3.0T HDX MR Scanner was used to obtain T1 WI three-dimensional Brain Volume (BRAVO) sequence and fMRI resting-state data. The data were processed with AFNI and Matlab software. The abnormal gray matter was overlapped onto MNI standard triaxiality template, MNI coordinate of the brain areas were recorded. The resulting map was used to determine those brain regions, which were considered as the group seed of the whole brain. Then identify the connectivity coefficient between the seed. Group and inter-group analysis was performed with single t-test and two t-test, to display the difference between the IGE patients and normal subjects. Thirteen brain regions were considered as the group seed of the whole brain. Matlab7.0 was used to identify the connective coefficient between the seed. Group and inter-group analysis was performed with single sample t-test and two sample t-test.Results:Compared to normal subjects, IGE patients showed extensive decreased gray matter density in widespread brain regions including bilateral cingulate cortex, bilateral middle frontal cortex, right superior frontal cortex, right rectus gyrus, right cuneus, left caudate nucleus head. Compared to normal subjects, IGE patients showed increased gray matter density in left superior temporal gyrus, left claustrum and right lentiform nucleus.Compared to normal subjects, enhanced positive correlation in IGE patients were observed in left superior temporal gyrus and right cingulate gyrus, right putamen and left caudate nucleus head; some areas showed weakened positive correlation, include left middle frontal gyrus and left caudate nucleus head, L.Mid.F and R.Sup.F (c), right middle frontal gyrus and left caudate nucleus head, R.Mid.F and R.Sup.F (c).Compared to normal subjects, enhanced negative correlation in IGE patients were observed in R.Sup.F (a) and right rectus gyrus, R.Sup.F (b) and R.Mid.F, right cuneus and left cingulate gyrus, right cuneus and right putamen, R.Mid.F and left claustrum, R.Mid.F and right putamen; some areas showed weakened negative correlation, include right cuneus and right cingulate gyrus, R.CG and left caudate head, left cingulate gyrus and left caudate head.The inner-network connective coefficients were positive in the normal subjects, while those were partly negative in IGE patients. The connective coefficient between ventral medial prefrontal cortex and post cingulated cortex were the biggest in the normal subjects. The positive inner-work connective coefficients in IGE patients were significant smaller than that of normal subjects.Conclusions:1. IGE patients showed extensive decreased gray matter density in widespread brain region involving bilateral fontal lobes, bilateral cingulate gyrus, right cuneus and left caudate head, while the gray matter density increased in L.Sup.T, left claustrum and right putamen, suggested that long-term epileptic discharges may lead to the injury of the neurons and gliosis.2. The connective coefficients between the changed gray matter areas in the IGE patients showed abnormal, inferred that these gray matter areas might be have something to do with the occurrence and development of IGE.3. The inner-network connective coefficients were positive in the normal subjects, suggest that the default-mode network is an organized network, all brain regions in the network work together to maintain the self-consciousness in resting state. 4. The DMN in IGE patients is abnormal; the positive inner-work connective coefficient is smaller than the normal subjects, inferred that epileptic discharges might have damaged the DMN, which might be one of the mechanisms of cognitive disorder.