Neuromodulation Effects of HF-rTMS and rPMS on stroke patients: an fNIRS study

Repetitive transcranial magnetic stimulation (rTMS) and repetitive peripheral magnetic stimulation (rPMS) are promising neuromodulation techniques for post-stroke motor recovery, yet their immediate cortical responses remain unclear. This functional near-infrared spectroscopy (fNIRS) study enrolled 57 patients with chronic stroke who received either high-frequency rTMS (5 Hz, 1,500 pulses over the ipsilesional M1) or rPMS (25 Hz, 1,500 pulses over the ipsilesional Erb's point). Cortical hemodynamic and network features-including oxyhemoglobin concentration (HbO), activation level (RMS), response dispersion (RMSE), laterality index (LI), and region-to-region functional connectivity (FC)-were analyzed. Clinical records indicated that both patient groups achieved significant functional recovery during hospitalization, with the rTMS group showing greater overall gains. Against this clinical background, we investigated the immediate neural mechanisms of a single stimulation session. fNIRS revealed distinct neuromodulatory patterns. rTMS produced reductions in HbO amplitude and spatial dispersion across multiple frontal and somatosensory regions, alongside decreased DLPFC-IFG functional connectivity and an LI shift, indicating a shift in interhemispheric balance. In contrast, rPMS increased M1 activation, broadened intra-regional variability, and selectively strengthened sensorimotor-frontal coupling-particularly the S1-IFG pathway-while shifting M1 laterality toward the ipsilesional hemisphere. Taken together, the findings point to differentiated mechanisms: rTMS appears to modulate cortical excitability in a top-down manner, potentially by attenuating non-essential frontal engagement and refining sensorimotor dynamics, whereas rPMS may enhance bottom-up facilitation driven by proprioceptive afferents. These complementary neuromodulatory signatures provide acute neurovascular evidence that may guide the strategic selection of central and peripheral magnetic stimulation in post-stroke rehabilitation.