Change of the Corticospinal Tract in the Unaffected Hemisphere by Change of the Dominant Hand Following Stroke: A Cohort Study

We investigated the change of the corticospinal tract (CST) in the unaffected hemisphere by the change of the dominant hand in stroke patients, using diffusion tensor tractography (DTT). Forty-eight stroke patients with right-hand dominance were recruited. The patients were assigned to 3 groups: group A (12 patients)—right-hand dominance was maintained after the right-hand weakness, group B (17 patients)—right-hand dominance changed to the left-hand dominance after the right-hand weakness, and group C (19 patients)—right-hand dominance was maintained after the left-hand weakness had developed. The function of the unaffected upper extremity was evaluated using the grip strength (GS), Manual Function Test (MFT), Purdue Pegboard Test (PPT), and modified Barthel Index (MBI). DTT was performed twice (1st DTT, 2nd DTT), and the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and voxel number (VN) of the CST in the unaffected hemisphere were measured. In group B, the VN on 2nd DTT was significantly increased compared with the 1st DTT, and all other clinical data (GS, MFT, PPT, and MBI) showed a significant increase between 1st and 2nd DTT (P < 0.05). The change of the VN showed moderate correlation with the change of the GS (r = 0.499, P < 0.05), PPT (r = 0.531, P < 0.05), and MBI (r = 0.551, P < 0.05). We found that the fiber number of the CST in the unaffected hemisphere was increased by the change of the dominant hand in stroke patients. We believe that our results have important implications in terms of neurorehabilitation.