To explore the effects and mechanisms of high-frequency repetitive transcranial magnetic stimulation (rTMS) targeting the contralesional primary motor cortex (cM1) or the contralesional dorsal premotor cortex (cPMd) on upper limb motor function in patients with severe stroke, based on the compensation model theory. The study utilized functional near infrared spectroscopy (fNIRS) to analyze the characteristics of brain network reorganization.

This study recruited 23 patients with first-onset stroke within a disease course of 3～12 months and conducted a randomized single-blind controlled experiment. Participants were randomly assigned to the cM1 group, cPMd group, and the control group (sham stimulation group). The cM1 group received stimulation at 5 Hz, 100% resting motor threshold (rMT), with 1 000 pulses per session. The cPMd group received stimulation at 5 Hz, 100% rMT, with 1 000 pulses per session. The treatment was administered once daily, five days per week, for a total of two weeks. Participants underwent Fugl-Meyer assessment of upper extremity function (FMA-UE) and resting-state fNIRS detection before and after the intervention. The regions of interest (ROIs) for fNIRS were located in the bilateral Brodmann areas 4 (BA4) and 6 (BA6), with the resting-state fNIRS focusing on the changes in functional connectivities (FC) between these ROIs.

There were no significant statistical differences in the baseline FMA-UE scores among the three groups (P>0.05). Compared with pre-intervention, the results after two weeks of intervention showed that the FMA-UE scores in the cM1 group and the cPMd group significantly increased (P<0.05). The intergroup comparison revealed that the change in FMA-UE scores in the cM1 group was significantly different from that in the control group (P=0.007). For the resting-state fNIRS results, the FC between the left BA4 and right BA4 (LBA4-RBA4) in the cM1 group was significantly greater than that in the cPMd group (P=0.046), and the FC between LBA4 and RBA4 in the control group was significantly greater than that in the cPMd group (P=0.011). No other significant differences were found.

High-frequency rTMS targeting cM1 and cPMd based on the compensation model theory can improve upper limb motor function in patients with upper limb motor dysfunction after severe stroke, with clinical feasibility and safety. The rTMS treatment targeting the cM1 area significantly enhances the interhemispheric functional connectivity of the motor cortex, thereby improving upper limb motor function in patients with severe stroke. Moreover, cM1 appears to be more advantageous than cPMd in promoting functional recovery in patients with upper limb motor dysfunction after severe stroke.