Language-related Tracts In Patients With Post-stroke Aphasia:A Diffusion Tensor Imaging Study

Objective:Post-stroke aphasia is a common symptom in patients with stroke,impairing social communication and quality of life.It is aimed to delineate the characteristics of white matter in those patients and figure out the potential quantified tract associated with specific language function,finally contributing to enrich the modern language model.Methods:This study enrolled 14 patients with post-stroke aphasia who were evaluated with Aphasia Battery of Chinese and diffusion magnetic resonance imaging in hospital.11 age-and gender-matched healthy control subjects were also collected.Results:Whole-brain voxel-based analysis demonstrated the peak voxel of white-matter integrity difference was located in the left external capsule.Track-based spatial statistics were also performed to find decreased fractional anisotropy in bilateral external capsule and corpus callosum while decreased axial diffusivity was limited to left external capsule.Further tractography found that multiple language-related tracts including left inferior longitudinal fascicle,inferior-fronto-occipital fascicle and uncinate fascicle were impaired predominantly in patients(P<0.05).Among them,the fractional anisotropy of left inferior longitudinal fascicle showed the most significant decrease(0.324±0.023 vs.0.478±0.013;P<0.0001)and was correlated with multiple language scores including comprehension,repetition,naming and aphasia quotient(P<0.01).However,there were no significant correlations between language scores and network metrics such as global efficiency and small-worldness(P>0.05).Conclusion:Language-related tracts in the left hemisphere of subacute post-stroke aphasia patients are lesioned with impaired myelin and axon.The left inferior longitudinal fascicle is related with multiple language functions,indicating its pivotal role in evaluating the severity of aphasia.Moreover,the integrity of myelin also changes in the contralateral hemisphere without irreversible axon injury.It indicates that the non-dominal hemisphere is involved in the mobilization of neuroplasticity at subacute phase and shed light on the importance of white matter in the language model and physiopathologic processes.