Spinal Cord Stimulation Helps Paralysed Man Walk Again

Akshay Naik 25 September 2018

Life

A 29-year-old man had injured his spinal cord at the thoracic vertebrae in the middle of his back during a snowmobile accident in 2013. He has now regained his ability to stand and walk with assistance after spinal cord stimulation and physiotherapy. These results, published in Nature Medicine, were achieved in a research collaboration between Mayo Clinic and University of California, Los Angeles (UCLA).

In 2016, the man participated in 22 weeks of physio-therapy and then had an electrode surgically implanted by Mayo Clinic’s neurosurgery team guided by Dr Kendall Lee, co-principal investigator, neurosurgeon and director of the Clinic’s neural engineering laboratories. This implant has been planted 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 through an external controller. Essentially, stimulation of the spinal cord by the implanted electrode enables neurons to receive the signal that he wants to stand or take a step.

When the implanted stimulator was turned on, the man was able to walk with a front-wheeled walker with trainers providing occasional assistance. Over the course of a year, he made 113 rehabilitation visits to Mayo Clinic and achieved several milestones during individual sessions when the researchers adjusted stimulation settings, trainer assistance, harness support and speed of the treadmill to allow him maximum independence. He walked for 16 minutes with assistance for about 102 metres which is about the length of a football field. As a safety precaution, the patient, currently, only takes steps under the supervision of the research team.

During the first week of his rehabilitation, the patient used a harness to lower his risk of falling and to provide upper body balance. While walking, trainers were positioned at his knees and hips to help him stand, swing his legs and shift his weight. As the patient had not regained sensation, he initially used mirrors to view his legs and trainers described leg position, movement and balance. With gradual progress, by week-25, he did not need a harness and trainers offered only occasional help. Substantial progress was made by the time the study period ended, when the patient had learned to use his entire body to transfer weight, maintain balance and propel forward, requiring minimal verbal cues and periodic glances at his legs.

“What this is teaching us is that those networks of neurons below a spinal cord injury still can function after paralysis,” says Dr Lee. “Now I think the real challenge starts, and that’s understanding how this happened, why it happened, and which patients will respond,” added his colleague Dr Kristin Zhao, co-principal investigator and director of Mayo Clinic’s assistive and restorative technology laboratory.

The research successfully demonstrated that the patient 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. More importantly, with the stimulation off, he remained paralysed.

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