A Study Of Juvenile Myoclonic Epilepsy Based On Magnetic Resonance Imaging

Idiopathic generalized epilepsy(IGE) is a common epilepsy syndrome,with the clinical manifestations of generalized tonic-clonic seizure,myoclonic and absence.Juvenile myoclonic epilepsy(JME)is a common subtype of IGE,which occurs in the 12-18 years old population and is mainly characterized by myoclonus.The typical electroencephalogram(EEG)characteristics of JME is 4-6Hz generalized spike-wave discharge(GSWD),and the propagation mechanism is not clear.The thalamocortical network has been demonstrated to be related to GSWD in IGE using simultaneous electroencephalogram and functional magnetic resonance imaging(EEG-fMRI).Resting state fMRI is widely applied to epilepsy studies to investigate the spontaneous neuronal synchronic activity and the neural network mechanism.To examine the local brain function of JME patients,we obtained fMRI data from 19 patients with JME and 22 healthy subjects.Regional homogeneity(ReHo)indicator was used to analyze the spontaneous activity of the whole brain.Using two sample t-test analysis,we found that JME patients showed significantly increased ReHo in bilateral thalamus and motor-related cortical areas and reduced ReHo in the cerebellum and occipital lobe when compared with healthy controls.Further analysis of the correlation between ReHo values and seizure characteristics was performed.The larger ReHo values in the left paracentral lobule were found to be associated with older age.These results revealed the abnormalities in thalamiocortical network in JME and suggested that it might be associated with the generation and propagation of epileptic activity.Furthermore,to study the neural network mechnism underlying the manifestations of myoclonus in JME,we collected absence epilepsy patients as a contrast group to achieve our goal.The absence epilepsy is another common subtypes of IGE,with GSWD performance in routine EEG and without motor symptom.So we collected 21 patients with absence epilepsy.We assume the choice of making absence epilepsy patients as a contrast group could help to reveal the motion related underlying meachnism of JME.First,compared with healthy controls,we used independent component analysis(ICA)and functional network connectivity methods to study altered functional connectivity in resting state brain networks in patients with JME.And the using the absence epilepsy patients as a control group to investigate the specific alterations of functional connectivity in JME patients.Using ICA,we identified 12 resting state brain networks in three groups.Our findings suggest that JME patients demonstrated abnormal functional conectivity within and between brain networks,particularly in the motor-related brain networks,when compared with patients with absence epilepsy and healthy subjects.In addition,abnormal connectivity associated with the default mode network,dorsal attention network,frontal network and cerebellar network may be related with impairment of cognitive and executive function in patients with epilepsy.Our work has studied the brain function of patients with JME from the voxel and network levels.The results showed that the increased ReHo in the thalamo-motor cortex network in JME patients and the reduced homogeneity of cerebellar activity.It was also found that abnormal functional connectivity between resting brain networks.Using absence epilepsy patients as a control group,the results further revealed the altered connectivity of motor network,which indicated that the dysfunctional information interaction between supplementary motor areas,cerebellum and other brain networks might contribute to the mechanism of motor abnormalities in JME patients.In addition,our study also proved that local brain spontaneous activity and functional connectiviy are effective methods to study epilepsy activity and could provide valuable information to further understand the pathophysiological mechanisms of JME.