A Structural MRI Study Of Benign Adult Familial Myoclonic Epilepsy (BAFME) In A Large Chinese Han Pedigree

Background:Benign adult familial myoclonic epilepsy (BAFME) is an autosomal dominant inherited epilepsy syndrome. This nonprogressive syndrome is characterized by fine distal cortical myoclonic tremor at hands and generalized tonic-clonic seizures (GTCS). So far, there were only three neuroimaging MRI literatures about BAFME. And among them there was only one structural MRI study, which have found the fractional anisotropy (FA) was decreased in the cerebellum of BAFME group. This result was consistent with the functional MRI and the autopsy data in the Netherlands and South Africa, which also discovered cerebellar abnormality. However, there were several electrophysiologic researches, such as somatosensory evoked potentials (SSEPs), jerk-locked averaging analysis (JLA) and transcranial magnetic stimulation (TMS), have detected the hyperexcitability in sensorimotor cortex. From the above, some scholars have proposed the hypothesis of cerebello-thalamo-cortical loop. However, this hypothesis have been at a loss to explain the absence of cortical myoclonic tremor in a wide range of diseases which have cerebellar abnormality. Here, we critically evaluate the hypothesis of cerebello-thalamo-cortical loop regarding the pathophysiological relationship between cerebellar abnormality and cortical myoclonic tremor. Therefore, to shed light on the pathogenesis of BAFME, we did the research of white matter abnormalities in a BAFME pedigree.Methods:The participants consisted of12BAFME (mean age±SD, male/female,42.8±13.2years,9/3) patients from a Chinese Han BAFME pedigree and15healthy controls (39.5±14.5years,9/6). None of the participants had a mass lesion, traumatic brain injury or any psychiatric disorder. Diffusion tensor imaging (DTI) scans were acquired using a3T Siemens Signa Imaging System. Then, Tract-Based Spatial Statistics (TBSS) was applied to carry out voxelwise statistics across subjects on FA images.Results:Compared to controls, BAFME patients showed a significant decrease in FA in the white matter underlying right cerebellum, precuneus, precentral gyrus and bilateral putamen (p<0.01).Conclusion:Decreased FA in the white matter underlying right cerebellum, precuneus, precentral gyrus and bilateral putamen in BAFME patients may become a tool for early diagnosis of BAFME. Background:Voxel-based morphometry (VBM) is an automated technique for MRI analyses, developed to investigate the decrease or increase of gray and white matter. It has been applied to study the brain morphology in many epilepsy syndromes, but there is no study of VBM in BAFME has been reported yet. So far, a series of neuroimaging and autopsy research has confirmed cerebellar abnormality in BAFME patients, while the electrophysiological investigations showed the hyperexcitability in the primary sensorimotor cortex. Therefore, based on the above literature, scholars have proposed the hypothesis of cerebello-thalamo-cortical loop. Previous research were limited to the study of cerebellum, but the abnormities in any regeion of the cerebello-thalamo-cortical loop, including the primary sensorimotor cortex, basal ganglia and cerebellum, may result in the onset of myoclonic tremor. Therefore, we investigated the gray matter in the region of interest (ROI:primary sensorimotor cortex, basal ganglia and cerebellum).Methods:The participants consisted of12BAFME (mean age±SD, male/female,42.8±13.2years,9/3) patients from a Chinese Han BAFME pedigree and15healthy controls (39.5±14.5years,9/6). None of the participants had a mass lesion, traumatic brain injury or any psychiatric disorder. Three dimension MRI (3D-T1weighted) scans were acquired using a3T Siemens Signa Imaging System. We made a mask of the ROI (the primary sensorimotor cortex, basal ganglia and cerebellum). Then we use VBM to analyze differences between the the grey matter volume (g-MV) of the two groups in the ROI.Results:Compared to controls, BAFME patients showed a significant decrease in the g-MV of the bilateral thalamus, cerebellar vermis and right cerebellar cortex (p<0.01).Conclusion:Decreased g-MV of thalamus and cerebellar in BAFME patients suggested the abnormalities of grey matter. It provided evidence to that the cerebello-thalamo-cortical loop played an important role in pathogenesis of BAFME. And the g-MV of thalamus and cerebellar may become a imaging indicators for early diagnosis of BAFME.