Efficacy of QuadroPulse rTMS for improving motor function after spinal cord injury: Three case studies

Context/objective: To examine the effects of repetitive QuadroPulse transcranial magnetic stimulation (rTMS(QP)) on hand/leg function after spinal cord injury (SCI). Design: Interventional proof-of-concept study. Setting: University laboratory. Participants: Three adult subjects with cervical SCI. Interventions: Repeated trains of magnetic stimuli were applied to the motor cortical hand/leg area. Several exploratory single-day rTMS(QP) protocols were examined. Ultimately we settled on a protocol using three 5-day trials of (1) rTMS(QP) only; (2) exercise only (targeting hand or leg function); and (3) rTMS(QP) combined with exercise. Outcome measures: Hand motor function was assessed by Purdue Pegboard and Complete Minnesota Dexterity tests. Walking function was based on treadmill walking and the Timed Up and Go test. Electromyographic recordings were used for neurophysiological testing of cortical (by single-and double-pulse TMS) and spinal (via tendon taps and electrical nerve stimulation) excitability. Results: Single-day rTMS(QP) application had no clear effect in the 2 subjects whose hand function was targeted, but improved walking speed in the person targeted for walking, accompanied by increased cortical excitability and reduced spinal excitability. All 3 subjects showed functional improvement following the 5-day rTMS(QP) intervention, an effect being even more pronounced after the five-day combined rTMS(QP) + exercise sessions. There were no rTMS(QP)-associated adverse effects. Conclusion: Our findings suggest a functional benefit of motor cortical rTMS(QP) after SCI. The effect of rTMS(QP) appears to be augmented when stimulation is accompanied by targeted exercises, warranting expansion of this pilot study to a larger subject population.