Cortical activation patterns mediating motor recovery: a randomized controlled fNIRS study of rTMS-integrated dual-task training in stroke survivors.

BACKGROUND

Stroke remains a leading cause of long-term disability worldwide, imposing a substantial burden on individuals and healthcare systems. The recovery of gait and balance is often hindered by cognitive-motor interference, necessitating effective rehabilitation strategies.

OBJECTIVES

We aimed to evaluate the synergistic efficacy of repetitive transcranial magnetic stimulation (rTMS) combined with cognitive-motor dual-task training on lower limb motor recovery in stroke survivors.

METHODS

A total of 150 stroke survivors were randomized into three groups: the single-task walking group (Group 1, n = 48), the cognitive-motor dual-task walking group (Group 2, n = 52), and the rTMS-integrated dual-task group (Group 3, n = 50). Clinical outcomes and biomechanical parameters were assessed across four timepoints (baseline, 1, 3, and 6 months post-intervention). Analysis of covariance (ANCOVA) was utilized to control for lesion characteristics. Functional near-infrared spectroscopy (fNIRS) was employed to monitor hemodynamic responses in the supplementary motor area (SMA) and premotor cortex (PMC) during dual-task walking.

RESULTS

A two-way repeated measures ANOVA revealed a highly robust group × time interaction (p < 0.001). At the 6-month follow-up, Group 3 demonstrated significantly superior recovery compared to Groups 1 and 2. Specifically, Group 3 achieved the highest walking speed (0.94 ± 0.15 m/s) with an extremely large effect size (Cohen's d = 2.07), and the greatest absolute improvement in step length (19.0 cm, p < 0.001). The clinical responder rates based on the minimum clinically important difference (MCID) in Group 3 were exceptional: 94.0% for gait speed and 96.0% for step length, both significantly higher than in the control groups. fNIRS imaging revealed that Group 3 exhibited significantly higher oxyhemoglobin (HbO) concentrations in the SMA (p = 0.010) and PMC (p = 0.008) compared to Group 1. Crucially, partial correlation analysis indicated that while the increase in SMA activation supported motor recovery, this relationship was deeply coupled with the increase in gait velocity, shifting to a marginal trend when controlling for speed changes (r = 0.255, p = 0.077).

CONCLUSION

The integration of rTMS with cognitive-motor dual-task training yields superior improvements in gait speed, stride mechanics, and balance compared to conventional therapies. This enhanced recovery is mechanistically supported by the upregulation of the supplementary motor area (SMA), suggesting that rTMS facilitates the central reorganization required for complex motor planning in concert with improved gait execution.