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

Abstract

Objective. This study aims to explore the immediate neuromodulatory effects of a single session of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) versus repetitive peripheral magnetic stimulation (rPMS) on cortical hemodynamics and functional connectivity (FC) in patients with stroke. Approach. 57 patients with unilateral stroke at varying post-stroke durations received a single pulse-count-matched session of either HF-rTMS (5 Hz, 1500 pulses) or rPMS (25 Hz, 1500 pulses). Functional near-infrared spectroscopy (fNIRS) monitored cortical hemodynamics during a motor task immediately before and after the intervention. The acute changes in oxyhemoglobin (HbO) response magnitude (root-mean-square (RMS)), response dispersion (Root-mean-square error (RMSE)), laterality index, and region-to-region FC were measured. Main results. Within-group analyses showed that HF-rTMS reduced task-evoked HbO RMS in selected frontal region of interest (ROI)s and reduced RMSE in the dorsolateral prefrontal cortex (DLPFC) and frontopolar area (FPA), and showed an exploratory decrease in DLPFC-inferior frontal gyrus (IFG) FC and a descriptive negative laterality index tendency. Conversely, rPMS increased HbO RMS in the M1 ROI, which comprised M1 channels from both hemispheres, increased FPA RMSE, and showed an exploratory increase in S1-IFG FC with a descriptive positive laterality index tendency. No FC difference remained significant after false discovery rate correction. The disease-duration-adjusted FPA RMSE Time × Group interaction was significant (F(1,54) = 15.595, p < 0.001, partial η2 = 0.224) and remained significant after exclusion of the participant with an extreme post-stroke duration. Significance. This study provides fNIRS evidence that HF-rTMS and rPMS are associated with different acute cortical response profiles in stroke. By directly comparing central and peripheral magnetic stimulation under a pulse-count-matched design, it characterizes their differing associations with post-stroke cortical hemodynamics and network-level responses.