Analysis Of Corticospinal Tract Injury In Stroke Based On Corticospinal Tract Template

The corticospinal tract(CST),the largest descending nerve fiber bundle in the pyramidal tract,is associated with the random movement of muscles,and its integrity is crucial for the study of motor function impairment in patients with stroke.Diffusion Tensor Imaging(DTI)can achieve three-dimensional reconstruction of the corticospinal tract to understand the integrity of the morphological structure of the CST.Therefore,the correct choice of DTI-based CST analysis method has an important positive effect on the scientific evaluation of motor function impairment in stroke patients.Based on the corticospinal tract template of healthy subjects,this study combined two different methods to assess the CST injury in patients with stroke,the correlation between the CST measurements of the patients and their limbs motor movement was also analyzed to further explain the relationship between the degree of CST injury and motor dysfunction.The main topics of the research include:(1)15 patients with chronic left-sided subcortical stroke and 15 healthy volunteers with age-and sex-matched conditions were selected for diffusion tensor image(DTI)examination.The CST was tracked by diffusion tensor tracking(DTT),The CST template was used to quantitatively evaluate the CST lesions caused by stroke lesions,the correlations of the damaged values of the CST with Fugl-Meyer assessment(FMA)were performed.The range of the damaged values of CST in stroke patients was from 0.0% to 29.6%.There were very strong negative correlation between the damaged values of the CST and FMA scores(the wrist,r=-0.660;hand,r =-0.813;and wrist plus hand,r =-0.795,respectively,P < 0.01).It showed strong negative correlation between the damaged values of the CST and FMA scores(the upper limb,r=-0.614;upper limb plus lower limb,r =-0.563,respectively,P < 0.05).Whereas,there was no correlation between the damaged values of the CST and FMA scores of lower limb(r =-0.270,P > 0.05).In addition,the lesion volumes and Fugl-Meyer assessment were not significantly correlated.(2)In the same group of subjects,the CST template of the previous healthy subjects was used to calculate the fractional anisotropy(Fractional Anisotropy,FA)mean diffusivity(Mean Diffusivity,MD),and further calculated the FA ratio(FA Ratio,r FA),FA asymmetry(FA Asymmetry,FAasy),MD ratio(MD Ratio,r MD)and MD asymmetry(MD Asymmetry,MDasy),the four indicators were used to assess the severity of the CST injury and further correlated with the FMA scores.The results showed that the r FA in stroke patients were significantly lower than those in the healthy control group(P<0.01);the FAasy in stroke patients were significantly higher than those in the healthy control group(P<0.01).The r MD and MDasy were not significantly different from the healthy control group(P>0.05).The r FA in stroke patients showed a strong positive correlation with the hand and "wrist+hand"(r=0.728,r=0.880,P<0.01,respectively);no significant correlation with motor function score FMA(upper extremities,lower extremities,wrist and "upper and lower extremities")(r = 0.499,r = 0.242,r = 0.472,r = 0.450,P>0.05).The FAasy in stroke patients showed a strong negative correlation with the hand and "wrist+hand"(r=-0.728,r=-0.880,P<0.01,respectively);without significant correlation with motor function scores of FMA(upper extremities,lower extremities,wrist and "upper and lower extremities")(r =-0.499,r =-0.242,r =-0.472,r =-0.450,P>0.05).The r MD in stroke patients had no significant correlation with motor function scores of FMA(upper extremities,lower extremities,wrist,hand,"wrist+hand" and "upper and lower extremities")(r =-0.154,r =-0.081,r =-0.236,r =-0.367,r =-0.304,r =-0.089,P>0.05).The MDasy in stroke patients had no significant correlation with motor function score FMA(upper extremities,lower extremities,wrist,hand,"wrist+hand" and "upper and lower extremities")(r = 0.154,r = 0.081,r = 0.236,r = 0.367,r = 0.304,r = 0.089,P>0.05).The distribution regression analysis showed that FAasy was more related to the patient's motor function scores of FMA(“wrist+hand” and hand)than the other two CST injury indicators(CST lesion value and r FA).Conclusion: The three indicators(the CST lesion value,r FA,and FAasy)derived from DTT reflected the injury of CST integrity in stroke,which may be considered as potentially important reference for evaluating motor dysfunction.with upper limbs,especially wrist in stroke.