Inhibitory repetitive transcranial magnetic stimulation of the contralesional premotor and primary motor cortices facilitate poststroke motor recovery

Purpose: The premotor cortex plays a major role in motor planning and control, exhibiting hierarchical importance comparable to that of the primary motor cortex (M1). In this study, we compared the effects of cPMd modulation, which was achieved using inhibitory repetitive transcranial magnetic stimulation (rTMS), with those of contralesional M1 (cM1) modulation, to elucidate the roles of both regions on longitudinal motor recovery following a stroke.

Methods: Forty-four patients who had sustained hemiplegia for 3 to 12 months were randomly allocated to a cPMd group, cM1 group, or sham group and received 10 sessions of 1-Hz rTMS. The Medical Research Council (MRC) Scale, Fugl-Meyer Assessment (FMA), Wolf Motor Function Test (WMFT), and a cortical excitability test were administered pre- and post- rTMS intervention.

Results: cPMd modulation yielded significant improvements in MRC, FMA, and WMFT scores compared with sham stimulation and a significant effect on cortical excitability suppression equivalent to that of cM1 modulation, but engendered effects on motor improvement inferior to those of cM1 modulation.

Conclusions: In patients with chronic stroke, the cPMd can fulfill a role similar to that of the cM1 in interhemispheric imbalance, which can be ameliorated by applying inhibitory rTMS to achieve substantial motor restoration.