Effects of Repetitive Transcranial Magnetic Stimulation on Electroencephalographic Activity, Lower-Limb Muscle Activation, and Balance in Patients with Stroke.

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as a neuromodulatory intervention to facilitate motor recovery after stroke. However, the frequency-specific effects of rTMS on lower-limb motor control and their neurophysiological correlates remain insufficiently clarified.

OBJECTIVE

To compare the effects of low-frequency (1 Hz) rTMS applied over the contralesional (unaffected) lower-limb motor area of the primary motor cortex and high-frequency (10 Hz) rTMS applied over the ipsilesional (affected) lower-limb motor area on electroencephalographic (EEG) activity, affected-side lower-limb muscle activation, balance, and gait in individuals with chronic stroke.

METHODS

Thirty-nine participants with chronic stroke were randomly assigned to a low-frequency rTMS group (n = 13), a high-frequency rTMS group (n = 13), or a sham group (n = 13). rTMS was delivered for 10 sessions over 2 weeks. Resting-state EEG (relative beta-band power at Cz), surface EMG of the affected-side rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius during sit-to-stand, Timed Up and Go (TUG), 10-meter walk test (10MWT), and limits of stability (LOS) were assessed before and after the intervention. A 3 × 2 mixed-design analysis of variance (ANOVA) (group × time) was conducted.

RESULTS

Significant group × time interactions were observed for rectus femoris activation (p < 0.001) and TUG performance (p = 0.037). Post hoc pairwise comparisons confirmed significantly greater improvements in TUG performance and rectus femoris activation in the low-frequency rTMS group than in the high-frequency and sham groups. Relative beta-band activity at Cz demonstrated a significant main effect of time (p < 0.001) without a significant interaction effect. Similarly, 10MWT and LOS showed significant time effects (p < 0.05) but no significant group × time interactions. No significant main effects of group were identified across outcomes.

CONCLUSION

Short-term rTMS was associated with improvements in selected neuromuscular outcomes, while changes in resting cortical activity, gait speed, and postural stability appeared to reflect general time-related effects. Low-frequency rTMS demonstrated greater improvements in rectus femoris activation and TUG performance compared with high-frequency and sham stimulation. These findings suggest that frequency-specific rTMS may preferentially influence neuromuscular strategies underlying dynamic mobility rather than steady-state gait performance.