Efficacy Analysis Of Transcranial Direct Current Stimulation On Post-stroke Aphasia And Study Of White Matter Fiber Tracts

Objective: Aphasia is a common advanced brain dysfunction after stroke.Current studies suggest that transcranial direct-current stimulation（t DCS）on language-related brain regions not only modulates language ability in healthy individuals,but also improves language performance in patients with aphasia.t DCS has been used to modulate and induce changes in brain function and excitability.A growing number of studies have found that t DCS could lead to behavioral and neurological improvement in the treatment of post-stroke aphasia.Although the improvement of t DCS at the behavioral assessment level is widely recognized,its mechanism at the neuroimaging level remains to be further elucidated.The aim of this study was to explore the effect of t DCS on post-stroke aphasia and the mechanism at the imaging level.Methods: A double-blind randomized controlled trial using high-definition transcranial direct-current stimulation（HD-t DCS）in 20 right-handed patients with post-stroke aphasia.They were randomized to receive a left-sided Anodal Transcranial directcurrent stimulation（A-t DCS）treatment or sham stimulation on Broca area.Traditional speech and language therapy was given at the same time.Each session lasted 20 minutes,with a frequency of 5 times a week for 4 weeks.Language function was assessed using the Western Aphasia Battery（WAB）and multimodal MRI scans（including high-resolution structural imaging,diffusion tensor imaging,and resting-state f MRI sequences）were used to explore imaging mechanisms.Results: A total of 20 patients with post-stroke aphasia participated in the study,and 4patients dropped out due to changes in their condition during treatment.At the behavioral level,the repitition,naming and aphasia quotient（AQ）of the WAB scale changed significantly before and after A-t DCS treatment（P<0.05）.The correlation between the left superior longitudinal fasciculus and language function is relatively strong,which is mainly reflected in the positive correlation between the FA of the left superior longitudinal fasciculus after treatment and the AQ after treatment,and the change of the left middle longitudinal fasciculus and AQ.The change also showed a strong negative correlation.The change of MD/RD before and after forceps major were strongly negatively correlated with the changes before and after naming.The FA after treatment of the left superior longitudinal fasciculus was strongly positively correlated with the naming values after treatment.The change of MD/RD before and after the forceps major was strongly negatively correlated with the change before and after reading.Conclusions: HD-t DCS stimulation of the left dorsolateral prefrontal cortex in patients with subacute stroke aphasia can have significant effects on domains of repetitionand naming.The changes of some white matter fibers in imaging are correlated with the recovery of language function in aphasia.