[Investigating the descending motor tracts in patients with chronic ischemic stroke with diffusion tensor imaging]

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).

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 includingcorticospinal tract (CST) and alternate motor fibers (aMF) were constructed. The descending motor tracts numberswere acquired and the relationships between laterality indices(LI) of descending motor tracts numbers and FMA were assessed. The patients were grouped into (CST + aMF) group (group1), 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.

Ipsilesional CST and theentiredescending motor tracts numbers (aMF + CST) were lower in the patient group as compared to the control group (P < 0.01, CST: 26 ± 30, CST + aMF: 37 ± 37). The FMA were statistically different between group 1, 2, 3 (55 ± 12, 16 ± 10, 34 ± 15, F = 24.2, P < 0.01). The LI of CST and (CST + aMF) significantly diagnosed motor impairment (P < 0.01, 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.

The integrity of entire descending motor tracts, not merely the CST, appears to account for stroke recovery. Our results highlight the role of aMFin compensatory function, which may be used as a target in future rehabilitative treatmentsto promoting motor function recovery at the most extent.