| Objective: To investigate the structural changes of white matter and its relationship with language function in patients with post-stroke aphasia(post-stroke aphasia,PSA)of different severity by diffusion tensor imaging(diffusion tensor imaging,DTI),so as to further explore the brain mechanism of PSA,improve the language processing model and provide imaging basis for objective evaluation and accurate rehabilitation of PSA.Materials and methods: A total of 32 patients with aphasia after stroke who were hospitalized in the Rehabilitation Department of our hospital were enrolled from June2016 to December 2021 according to inclusion criteria and the western aphasia battery(WAB).16 patients with mild to moderate and 16 patients with severe non-fluent PSA were enrolled,and 20 normal subjects matched by sex,age and education were recruited.In addition,all subjects completed DTI scans and MMSE,and the PSA patients completed WAB assessment.The diffusion tensor indexes of the whole brain and the left and right hemispheres were extracted by spatial statistics methods based on white matter skeleton(tract-based spatial statistics,TBSS),and the difference of white matter structure among three groups of subjects was analyzed by single factor analysis of variance(ANOVA).Finally,the diffusion tensor index of different white matter fiber structure was compared with the language function score of PSA patients by correlation analysis.Results:1.Comparison of diffusion tensor indexes of whole brain and left and right hemispheres among the three groups:(1)Comparison between the two groups of PSA patients and the normal control group.(1)Fractional anisotropy(FA): Comparing with normal control group,FA values of whole brain and left hemisphere decreased in mild to moderate PSA group and severe PSA group(p<0.05),but there was no significant difference in FA value of right hemisphere(p>0.05).(2)Axial diffusivity(AD): Comparing with normal control group,the AD value of whole brain and left hemisphere decreased in mild to moderate PSA group and severe PSA group(p<0.05),but there was no significant difference in right hemisphere(p >0.05).(3)Mean diffusivity(MD): Compared with normal control group,the MD values of whole brain,left hemisphere and right hemisphere in mild-moderate PSA group and severe PSA group were increased(p < 0.05).(4)Radial diffusivity(RD): Compared with normal control group,RD value of whole brain,left hemisphere and right hemisphere in mild-moderate PSA group and severe PSA group were increased(p < 0.05).(2)There was no significant difference in all diffusion tensor indexes between mild-moderate PSA group and severe PSA group(p > 0.05).2.White matter fiber regions with different diffusion tensor indexes between patients with PSA and normal control group.(1)Comparison between mild-moderate PSA group and normal control group:(1)FA:The FA values of left cerebral peduncle,left posterior limb of internal capsule,left corticospinal tract and left upper longitudinal tract were decreased in mild-moderate PSA group.(2)AD: The AD values of left internal capsule forelimb,hindlimb,left corticospinal tract and left cerebral peduncle were decreased in mild-moderate PSA group.(3)MD: In mild to moderate PSA group,MD of corpus callosum knee,body,left anterior limb of internal capsule,left anterior,posterior,upper,left external capsule,left superior longitudinal bundle,left posterior thalamic radiation,left uncinate tract,left superior frontal occipital tract and right anterior coronal part increased.(4)RD: In mild-moderate PSA group,the Rd values of knee,body,left anterior coronal part,left external capsule,left upper longitudinal tract,left uncinate tract and right anterior coronal part of corpus callosum increased.(2)Comparison between severe PSA group and normal control group:(1)FA: In severe PSA group,the FA values of left internal capsule forelimb,hindlimb,left external capsule,left superior frontal occipital tract,left uncinate tract,left corticospinal tract,left cerebral peduncle,left posterior thalamic radiation,left sagittal layer and left superior longitudinal bundle decreased.(2)AD: In severe PSA group,the AD values of left internal capsule forelimb,hindlimb,left corticospinal tract and left cerebral peduncle decreased.(3)MD: In severe PSA group,MD of corpus callosum knee,body,anterior limb of left internal capsule,hind limb,upper part of left radiation corona,posterior part of left thalamus,left external capsule,left sagittal layer,left superior longitudinal tract,left uncinate tract,left superior frontal occipital tract and right anterior part of radiation corona increased.(4)RD: In severe PSA group,the values of the corpus callosum knee,body,left anterior limb of internal capsule,posterior limb,upper part of left radiation corona,posterior part of left thalamus,left external capsule,left sagittal layer,left superior longitudinal tract,left uncinate tract,left superior frontal occipital tract and right anterior coronal part increased.3.Correlation analysis between differential white matter fiber structure and language function score in patients with PSA:The FA value of the left upper longitudinal tract was positively correlated with listening comprehension(r=0.398,p=0.023),repetition(r=0.356,p=0.045),structure(r=0.375,p=0.034),reading(r=0.455,p=0.008),aphasia quotient(r=0.366,p=0.038),aphasia quotient(r=0.417,p=0.017),and cortical quotient(r=0.406,p=0.020),while there was no correlation between other differential white matter fibers and language function score.Conclusion: The damage of cerebral white matter fiber structure can reduce the integrity of brain white matter fiber structure,which will lead to aphasia when language-related white matter fiber injury occurs,and the left superior longitudinal tract is closely related to the severity of aphasia and language functions such as repetition,listening comprehension and reading,and its fiber structure damage may be one of the mechanisms of aphasia and can be used as one of the reference indexes to evaluate the severity of non-fluent PSA. |
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