Background: Robot-assisted gait training (RAGT) can improve walking ability after stroke but the underlying mechanisms are unknown.

Objective: We evaluated the changes in the injured brain after RAGT and compared the effects of early start and late start of RAGT.

Methods: Eleven patients with hemiplegia after stroke undergoing inpatient rehabilitation were examined within 3 months of stroke onset and were randomly assigned into two groups. Group 1 started RAGT with conventional physiotherapy immediately after enrollment, whereas Group 2 underwent conventional physiotherapy for 4 weeks before starting RAGT. We acquired diffusion tensor imaging data after enrollment and at 4 and 8 weeks after treatment. Fractional anisotropy (FA) and mean diffusivity (MD) maps were used to analyze the neural changes.

Results: Repeated measures analysis of variance of the data at 4 weeks after treatment showed a significant interaction between time and groups (RAGT versus control) for the FA and MD values in the non-lesioned hemisphere, indicating that the non-lesioned hemisphere was significantly reorganized by RAGT compared with conventional physiotherapy. Analysis of the data at 8 weeks after treatment showed a significant interaction between time and groups (early and late start of RAGT) for the MD values in the motor-related areas bilaterally, indicating that early start of RAGT significantly accelerated bi-hemispheric reorganization as compared with late start of RAGT.

Conclusions: Our findings indicate that RAGT can facilitate reorganization in the intact superior temporal, cingulate, and postcentral gyri. Furthermore, early start of RAGT can accelerate bi-hemispheric reorganization in the motor-related brain regions.