Relationship Between Corticospinal Tract Injury And Recovery Of Limb Motor Function After Ischemic Stroke

Objective:To investigate the relationship between the ratio fractional anisotropy(rFA)of the bilateral corticospinal tract(CST)and the changes of motor function of the limb in patients with ischemic stroke before and after rehabilitation treatment,and to explore the value of diffusion tensor imaging(DTI)in the evaluation of the clinical prognosis of ischemic stroke patients.Methods:Twenty-two patients with acute ischemic stroke in the basal ganglia,who hospitalized from March 2017 to February in the Neurology department,Interventional Stroke department,and Rehabilitation department of the First Affiliated Hospital of Kunming Medical University,were selectedThey were provided with systematic rehabilitation guidance and training.The patients were also respectively assessed by Barthel index(BI)and Fugl-Meyer assessment(FMA),and were afforded MRI and DTI 2 weeks after attack and 6 weeks after rehabilitation treatment.Fractional anisotropy(FA)of the infarct and the corresponding corticospinal tract in the contralateral region were measured on DTI.DTI was processed using diffusion alignment software to obtain diffusion tensor trcatography(DTT).DTT objectively presents the complete morphology of the CST,while Pearson's linear correlation analysis was used to analyze the relationship between rFA of the CST and motor function.Results:1.A total of 22 patients with acute ischemic stroke were included in this study.Among the enrolled patients,22 patients completed the pre-treatment MRI,and 20 patients completed the post-treatment MRI.Paired-sample t-test showed that there was a statistically significant difference in pre-treatment FA(t=8.267,P<0.05)and post-treatment FA(t=12.273,P<0.05)in both brains.2.The FA,FMA,and BI of the 20 patients who completed the second MRI and exercise evaluation were compared before and after treatment.The paired t-test revealed that there were statistical differences in the FMA(t=12.580,P<0.05),BI(t=-10.232,P<0.05),affected side FA(t=10.098,P<0.05),and ratio FA(t=8.294,P<0.05)before and after treatment,but there was no statistical difference in the unaffected side FA(P>0.05).3.According to Pearson's linear correlation analysis,there was a moderate negative linear correlation between decreased rFA in the affected side and increased FMA among stroke patients,r=-0.513,P<0.001.Meanwhile,there is no linear relationship between decreased rFA and increased BI in the affected side of brain(P>0.05).4.Using DTT to three-dimensionally reconstruct CST,to find that 6 patients had a significant discontinuation of CST,the early FMAs which were below 50 points,and severe dyskinesia in the affected limbs.After 6 weeks of rehabilitation,some limb functional disorders remained.Among 10 patients,the CSTs were significantly compressed but not interrupted.Their FMAs were 50 to 80 points.They showed significant motor disorders in the affected limbs.After 6 weeks of rehabilitation treatment,only limb fine motor disorder was left.In 4 patients,whose CSTs were intact,there was no leison to their CST.Their FMAs were above 80 points,showing mild motor disorders of the affected limbs.After 6 weeks of rehabilitation,the limb functions returned to normal.Conclusions:1.The FA of infarct foci in patients with ischemic stroke was significantly lower than it in the intact side.DTTshowed that CST in the affected side was sparse comparing with the intact side.2.After the early rehabilitation training for patients with ischemic stroke,the motor function was significantly improved,but the FA still decreased due to the Wallerian degeneration of nerve fibers.3.There is a negative correlation between decreased rFA and increased FMA in ischemic stroke patients.The lower the rFA within 8 weeks of onset,the better the recovery of motor function There was no linear correlation between the changes of rFA and BI.4.DTT can reveal the CST damage information of patient with ischemic stroke so that it could be used to assess the prognosis of patient's limb motor function.Patients who sustainssignificant CST disruption may have physical dysfunction.Those,whose CSTs are significantly compressed but not interruption,may suffer from fine motor disorders.And other patients whose CSTs are not affected by infarct lesions may restore full limb motor function.