Corticospinal tract changes in acute brainstem ischemic stroke patients: A diffusion kurtosis imaging study

The present study aimed to investigate the corticospinal tract (CST) changes in patients with brainstem ischemic stroke by using the diffusion kurtosis imaging (DKI) approach..

Twenty-one patients with brainstem stroke and 21 group-matched healthy controls underwent brain DKI with 3.0 T magnetic resonance imaging (MRI). The DKI was obtained by using three b values of 0, 1,000, 2,000 s/mm² with 15 diffusion directions. Regions of interest (ROIs) were placed at four levels: the pons, posterior limb of the internal capsule (PLIC), corona radiata, and precentral gyrus. The DKI parameters, including fractional anisotropy (FA), mean diffusivity (MD), and mean kurtosis (MK) values, in these regions were measured from the contralateral to the ipsilateral side of patients and both the left and right sides of healthy controls at all the four selected levels.

The ipsilateral side of the ischemic lesion showed a decrease in FA and MD and an increase in MK when compared with the contralateral normal region at all the four selected levels with statistically differences (P < 0.05). At these four selected levels, there were no differences between the left and right sides in healthy controls with MD, FA, and MK (P > 0.05). The MD values of the contralateral side of the ischemic lesion in patients at the four selected levels were significantly higher than those in the corresponding side of the healthy controls (P < 0.05). Compared to the healthy controls, there was a decrease at the posterior limb of the internal capsule (PLIC) in FA of the contralateral side of the ischemic lesion in stroke patients (P < 0.05). However, no significant differences were observed for MK values between the groups (P > 0.05).

The current results suggest that the DKI technique could identify the early microstructural changes along the motor pathway and that these changes were not limited to the ipsilateral side of the ischemic lesion; in fact, the contralateral changes also occurred, especially at the PLIC.