Neuromodulation parameters for non-invasive magnetic stimulation of the cervicothoracic Spine

Stroke is a major healthcare challenge and a leading cause of long-term paralysis, with over 80% of survivors experiencing upper limb motor impairment. Researchers are exploring effective strategies to successfully stimulate remaining sensorimotor pathways after stroke, and evidence suggests that noninvasive transcutaneous magnetic spinal stimulation (TMSS) may be a promising option. This thesis investigates TMSS parameters through three studies. The first study focused on determining optimal coil positioning to standardize TMSS protocols. Results showed that the highest motor responses were elicited when the coil was positioned 3 cm lateral to the central spinal column and the coil handle oriented at 45° or 315° to target left- or right-sided muscles, respectively. The second study examined the significant relationship between neural pathway excitability and motor performance. Findings indicated that higher spinal excitability was correlated to faster force production and better task performance but smaller improvements during the task, whereas higher cortical excitability was associated with greater force production, better overall performance, and greater corrections during task execution. The third study investigated the neuromodulatory effects of repetitive TMSS (rTMSS) at 5 Hz, 10 Hz, and 15 Hz, comparing outcomes after 5 and 10 minutes of stimulation. While no significant differences were observed between durations, 5 minutes of 5 Hz rTMSS facilitated corticospinal excitability, whereas 10 Hz and 15 Hz suppressed spinal excitability. These findings suggest TMSS can modulate sensorimotor pathways and support motor recovery. Overall, these studies provide critical insights into TMSS protocols and highlight its promise as a neuromodulation tool in neurorehabilitation.