The research demonstrated that the participant was able to walk over ground using a front-wheeled walker and step on a treadmill

ROCHESTER, Minn. — Spinal cord stimulation and physical therapy have helped a man paralyzed since 2013 regain his ability to stand and walk with assistance. The results, achieved in a research collaboration between Mayo Clinic and UCLA, are reported in Nature Medicine.

With an implanted stimulator turned on, the man was able to step with a front-wheeled walker while trainers provided occasional assistance. He made 113 rehabilitation visits to Mayo Clinic over a year, and achieved milestones during individual sessions:

  • Total distance: 111 yards (102 meters) — about the length of a football field
  • Total number of steps: 331
  • Total minutes walking with assistance:16 minutes
  • Step speed: 13 yards per minute (0.20 meters per second)

“What this is teaching us is that those networks of neurons below a spinal cord injury still can function after paralysis,” says Kendall Lee, M.D., Ph.D., co-principal investigator, neurosurgeon and director of Mayo Clinic’s Neural Engineering Laboratories.

In the study, the man’s spinal cord was stimulated by an implanted electrode, enabling neurons to receive the signal that he wanted to stand or step.

“Now I think the real challenge starts, and that’s understanding how this happened, why it happened, and which patients will respond, says Kristin Zhao, Ph.D., co-principal investigator and director of Mayo Clinic’s Assistive and Restorative Technology Laboratory.

Currently, as a safety precaution, the patient takes steps only under the supervision of the research team.

Early findings

The man, now 29, injured his spinal cord at the thoracic vertebrae in the middle of his back in a snowmobile accident in 2013. He was diagnosed with a complete loss of function below the spinal cord injury, meaning he could not move or feel anything below the middle of his torso.

In the study, which began in 2016, the man participated in 22 weeks of physical therapy and then had an electrode surgically implanted by Dr. Lee and his Mayo Clinic neurosurgery team.

The implant sits in the epidural space — the outermost part of the spinal canal — at a specific location below the injured area. The electrode connects to a pulse generator device under the skin of the man’s abdomen and communicates wirelessly with an external controller. Mayo Clinic received permission from the U.S. Food and Drug Administration to use the device for a condition not covered by its FDA-approved label.

After recovering from surgery, the man returned to the lab for rehab sessions and stimulation adjustments for the next 43 weeks. In a 2017 Mayo Clinic Proceedings paper, the authors reported their initial observations as they replicated research done at the University of Louisville. Those early findings showed that, within two weeks of the stimulator being turned on, the man could stand and intentionally make step-like movements while suspended in a harness.

Continued progress

The research team then tried to determine if the man could stand and walk with assistance. During 113 rehabilitation sessions, the researchers adjusted stimulation settings, trainer assistance, harness support and speed of the treadmill to allow the man maximum independence.

The research demonstrated that the man was able to walk over ground using a front-wheeled walker and step on a treadmill placing his arms on support bars to help with balance. However, when stimulation was off, the man remained paralyzed.

In the first week, the participant used a harness to lower his risk of falling and to provide upper body balance. Trainers were positioned at his knees and hips to help him stand, swing his legs and shift his weight. Because the man did not regain sensation, he initially used mirrors to view his legs, and trainers described leg position, movement and balance. By week 25, he did not need a harness, and trainers offered only occasional help. By the end of the study period, the man learned to use his entire body to transfer weight, maintain balance and propel forward, requiring minimal verbal cues and periodic glances at his legs.

Co-first authors are Megan Gill, physical therapist, and Peter Grahn, Ph.D., senior engineer. The Mayo researchers worked closely with the team of V. Reggie Edgerton, Ph.D., at UCLA on this study. Additional co-authors are Jonathan Calvert, Margaux Linde, Igor Lavrov, M.D., Ph.D, Jeffrey Strommen, M.D., Lisa Beck, Meegan Van Straaten, Dina Drubach, Daniel Veith, Andrew Thoreson and Cesar Lopez of Mayo Clinic; Dimitry Sayenko, M.D., Ph.D., Houston Methodist Research Institute; and Yury Gerasimenko, Ph.D., UCLA.

This research was funded by The Grainger Foundation, Regenerative Medicine Minnesota, Jack Jablonski BEL13VE in Miracles Foundation, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic Center for Regenerative Medicine, Mayo Clinic Rehabilitation Medicine Research Center, Mayo Clinic Transform the Practice, Minnesota Office of Higher Education Spinal Cord Injury and Traumatic Brain Injury Research Grant Program, Craig H. Neilsen Foundation, Dana and Albert R. Broccoli Charitable Foundation, Christopher & Dana Reeve Foundation and Walkabout Foundation.

Authors Lee, Edgerton and Gerasimenko note conflict of interest disclosures.

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