Role Of Descending Motor Tracts On Motor Function After Ischemic Stroke

Part 1Investigating the descending motor tracts in patients with chronic ischemic stroke with diffusion tensor imaging (DTI)Objective To evaluate the relationship between structural integrity of descending motor tracts and motor status in patients with chronic ischemic stroke using diffusion tensor imaging(DTI). Methods From April 2012 to December 2013,47 patients with chronic ischemic strok were recruited along with 20 matched normal controls. The DTI data was acquired and preprocessed. Bilateral descending motor tracts including corticospinal tract (CST) and alternate motor fibers (aMF) were constructed. The regional fractional anisotropy (FA) values of posterior limb of internal capsule (PLIC) and descending motor tracts numbers were acquired and the relationships between laterality indices(LI) of regional FA value and descending motor tracts numbers and FMA were assessed. The patients were grouped into (CST+aMF) group(groupl),no (CST+aMF) group(group2),CST group(group3) and aMF group(group4) according to the damage morphology of descending motor tracts.observing the changes of each group. Results Ipsilesional FA value of PLIC,CST and the entire descending motor tracts numbers (aMF +CST) were lower in the patient group as compared to the control group(P<0.01, FA: 0.45±0.08,CST:26.32±29.98,CST+aMF: 36.72±37.34). The FMA were statistically different between group1,2,3 (55±12.2,15.8±9.6, 34.3±14.7, F=24.2, P<0.01).The LI of regional FA value,CST and (CST+aMF) significantly diagnosed motor impairment (P<0.01, r=-0.730,r=-0.653; r=-0.692). Meanwhile, it is a stronger parameter when entire descending motor tracts were combined comparing to using the CST only. Conclusions The integrity of entire descending motor tracts, not merely the CST, appears to account for stroke recovery. Our results highlight the role of aMF in compensatory function, which may be used as a target in future rehabilitative treatments to promoting motor function recovery at the most extent.Part 2Fully automated detection of corticospinal tract damage in chronic ischemic stroke patientsObjective To evaluate the structural integrity of CST in patients with chronic ischemic stroke using the tract-based spatial statistics procedure(TBSS) automatically. Methods we used tract-based spatial statistics (TBSS) together with a CST template with healthy volunteers to quantify structural integrity of CST automatically. Two Age, gender, hand dominance, time, degree of education after stroke are matched subgroups of 22 subjects after ischemic stroke were enrolled, group 1 (10 patients,7 men, and Fugl-Meyer assessment (FMA) scores< 50) and group 2 (12 patients,12 men, and FMA scores = 100). CST of FA ipsi, FA contra, and FAratio was compared between the two groups. Results Relative to group 2, FA was decreased in group 1 in the ipsilesional CST (p<0.01), as well as the FA ratio (p< 0.01). There was no signifiant difference between the two subgroups in the contralesional CST (p= 0.23). Compared with contralesional CST, FA of ipsilesional CST decreased in group 1 (p< 0.01). Conclusions FA was decreased in group 1 in the ipsilesional CST, as well as the FA ratio, which shows that t the integrity of the ipsilesional CST damaged severely. These results suggest that the automated method used in our study could detect a surrogate biomarker to quantify the CST after stroke, which would facilitate implementation of clinical practice.