Introduction: Paired associative stimulation (PAS) is a combination of transcranial magnetic stimulation (TMS) and peripheral nerve stimulation (PNS) and induces plastic changes in the human corticospinal tract. We have previously shown that PAS consisting of TMS pulses given at 100% of stimulator output and high-frequency PNS is beneficial for motor rehabilitation of patients with a chronic incomplete spinal cord injury (SCI). The therapeutic possibilities of this PAS variant for walking rehabilitation of paraplegic patients are unexplored.
Case presentation: A 47-year old man with traumatic incomplete paraplegia (AIS D, neurological level T7) received PAS to his left leg for 3 months at 12 months post injury (PAS1) and for an additional 3 months at 24 months post injury (PAS2). The right leg had normal AIS scores and was not stimulated. Before PAS, the patient was nonambulatory, could not stand without weight support, and was consequently not eligible for conventional walking rehabilitation. After PAS1, the patient could stand for 1.5 min and take 13 steps (24 steps in follow up) on parallel bars without weight support and was enrolled into conventional walking rehabilitation. He achieved independent walking ability with a rollator. During PAS2, walking distance increased 2.4 times faster than during the preceding year. The left leg AIS score and spinal cord independence measure mobility subscore increased. No adverse effects were detected.
Discussion: This is the first report of PAS with a high-frequency peripheral component that enabled and promoted walking rehabilitation. Together with previous reports on this technique, this result encourages further research into its therapeutic potential and mechanism.