Effect Of Cerebellar Atrophy On White Matter In SCA3

Spinocerebellar ataxia type 3(SCA3)is an autosomal dominant genetic disorder characterized by progressive cerebellar ataxia and exhibits significant age-related heterogeneity,and the significant atrophy of cerebellum in SCA3 has been widely reported in previous studies.Based on the fact that SCA3 cerebellum was significantly atrophied,this thesis investigates the abnormalities of white matter in SCA3 cerebellum and cerebellar efferent pathway by using structural magnetic resonance imaging(SMRI)and diffusion tensor imaging(DTI)respectively.The main work of this thesis is as follows:1.At present,most studies have not evaluated the structural integrity of bundles of white matter fibers of cerebellum in SCA3 using MRI-based network analysis methods.Therefore,This thesis used the structural connective network analysis method to analyze the differences in the topological attributes of the cerebellar structural network and the abnormalities of structural integrity of bundles of white matter fibers in the cerebellar between SCA3 patients and healthy controls.this thesis analyzed the differences in the topological attributes of the cerebellar structural network and the abnormalities of the white matter connections in the cerebellar between SCA3 patients and healthy controls.The results showed that there was no significant change in the clustering coefficient of the cerebellar structural network of SCA3 patients,but the network efficiency of these networks decreased significantly,and there was a significant "disconnection" of the white matter fiber bundles associated with the dentate nucleus in the cerebellum.There is a negative correlation between these abnormalities and the severity of the ataxia in the patients.This indicates that the cortex of the cerebellum is not obviously involved,but the damage of the white matter fiber bundle structure related to the dentate nucleus in the cerebellum may affect the ability of information transmission,thus reducing the efficiency of the overall network communication in the cerebellum.2.Meanwhile,studies on the structural integrity of the SCA3 cerebellar efferent pathway are still lacking.In this study,structural magnetic resonance data were first used to analyze the differences between the two groups of subjects in the white matter volume of cerebellum,thalamus and primary motor area,and the fiber tract tracking analysis method based on the region of interest was used to explore the abnormalities of structural integrity of bundles of white matter fibers of SCA3 cerebellar efferent pathway.The results showed that there was significant atrophy of thalamic white matter in SCA3 patients,and there was a closely negative correlation between the white matter volume of the right thalamus in SCA3 patients and the severity of ataxia.Meanwhile,there was no unilateral difference in the influence of injury or degeneration of cerebellar-thalamic-cerebral motor cortex pathway on the severity of ataxia in SCA3 patients.This suggests that atrophy of thalamic white matter is one of the factors exacerbating the severity of ataxia in SCA3,and that the laterality difference in the cerebellar-thalamic-cerebral motor cortex pathway in the severity of ataxia may exist only in patients with focal unilateral lesions,but not in patients with ataxia with degenerative diseases affecting the entire cerebellum.