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.