A new non-invasive spinal cord stimulation technique allowed five subjects with complete motor paralysis to generate voluntary leg movements.
The technology, called transcutaneous stimulation, delivers electrical currents to the spinal cord via electrodes places on the skin of the lower back. Spinal cord stimulation previously enabled four paralyzed subjects to produce voluntary movements, however this latest trial is the first to use non-invasive technology.
During the trial, the four men were able to generate step-like movements while their legs were suspended in braces hanging from the ceiling to free them of the resistance from gravity. While body movement in this environment is not comparable to walking, the results are a huge step forward for research for victims of spinal cord injury.
“These encouraging results provide continued evidence that spinal cord injury may no longer mean a life-long sentence of paralysis and support the need for more research,” said Roderic Pettigrew, PhD, MD, director of the National Institute of Biomedical Imaging and Bioengineering at NIH. “The potential to offer a life-changing therapy to patients without requiring surgery would be a major advance; it could greatly expand the number of individuals who might benefit from spinal stimulation. It’s a wonderful example of the power that comes from combining advances in basic biological research with technological innovation.”
The study, which was reported in the Journal of Neurotrauma, was led by researchers from the University of California, Los Angeles and Pavlov Institute in Russia.
While the results are very preliminary, researchers are perhaps most excited by the potential of a non-invasive treatment for patients who have likely already undergone countless surgeries.
“There are a lot of individuals with spinal cord injury that have already gone through many surgeries and some of them might not be up to or capable of going through another,” said researcher V. Reggie Edgerton, PhD, in a news release. “The other potentially high impact is that this intervention could be close to one-tenth the cost of an implanted stimulator.”
During the 18-week study, the subjects underwent 45-minute weekly stimulation sessions as well as conditioning in which their legs were moved manually in order to assess the effects of physical training and electrical stimulation on voluntary movements. During the final four weeks of the study, the subjects were given buspirone, which has been shown to produce locomotion in mice with spinal cord injuries.
At the beginning of the study, the men’s legs only moved when electrical stimulation was strong enough to generate involuntary step-like movements, however range of movement significantly increased when the men attempted to move their legs further during stimulation. After four weeks, the men were able to double their range of motion when voluntarily moving their legs during stimulation – a phenomenon that researchers believe is linked to the reawakening of dormant connections between the brain and spinal cord due to stimulation.
By the end of the study, the men were, who continued to receive buspirone, were able to move their legs without stimulation and at the same range of movement that was achieved during stimulation. The researchers also noted that electrical signals in the calf muscles grew stronger over time even as the level of stimulation remained the same.
“It’s as if we’ve reawakened some networks so that once the individuals learned how to use those networks, they become less dependent and even independent of the stimulation,” said Edgerton.
The researchers are now exploring whether the men can become weight bearing, as well as if the non-invasive stimulation has any effect on restoring autonomic processes lost during paralysis such as the ability to sweat, regulate blood pressure, and control the bladder, bowel, and sexual function. They also plan to test the technology in subjects who are partially paralyzed.