An international team of researchers including UCLA scientists has reported that epidural stimulation of the spine has allowed four young men who have been paralyzed for years to voluntarily move their legs. The therapy could lead to new interventions to restore leg movement in paraplegics. The findings were published online on April 8 in the journal Brain. The research team comprised investigators at UCLA, the University of Louisville, and the Pavlov Institute of Physiology in St. Petersburg, Russia.
Prior to the implantation of the epidural stimulator, all four men suffered from chronic, motor complete spinal cord injuries and were unable to move their lower extremities. The device delivers a continuous electrical current to the men’s lower spinal cords; thus, mimicking signals the brain normally transmits to initiate movement. The study authors note that their research is based upon a May 2011 study published in the journal The Lancet, which evaluated the effects of epidural stimulation in the first participant, Rob Summers of Portland, Oregon; Summers regained a number of motor functions following the procedure. The researchers note that the key findings of that previous study feature the impact of epidural stimulation in a total four participants, including new tests conducted on Summers. Summers was paralyzed after being hit by a motor vehicle; the other three men were paralyzed in auto or motorcycle accidents.
A revolutionary finding of the study was that the second, third and fourth man (Kent Stephenson of Mt. Pleasant, Texas; Andrew Meas of Louisville, Kentucky.; and Dustin Shillcox of Green River, Wyoming) were able to execute voluntary movements immediately following the implantation and activation of the stimulator. The researchers were surprised by this finding; they theorized that some pathways may be intact post-injury that are able to enable voluntary movements. “Two of the four subjects were diagnosed as motor and sensory complete injured with no chance of recovery at all,” explained lead author Claudia Angeli, a senior researcher with the Human Locomotor Research Center at Frazier Rehab Institute and an assistant professor at University of Louisville’s Kentucky Spinal Cord Injury Research Center (KSCIRC). She added, “Because of epidural stimulation, they can now voluntarily move their hips, ankles and toes. This is groundbreaking for the entire field and offers a new outlook that the spinal cord, even after a severe injury, has great potential for functional recovery.”
The epidural stimulation entails applying an electrical current at varying frequencies and intensities to specific locations on the lumbosacral spinal cord; these regions correspond to the dense neural bundles, which primarily control the movement of the hips, knees, ankles and toes. Among the participants, once the signal was triggered, the spinal cord reengaged its neural network to control and direct muscle movements. The impact of the epidural stimulation was intensified by pairing it with rehabilitative therapy. During the study period, the investigators found that the researchers noted that the participants were able to activate movements with less stimulation; thus, demonstrating the ability of the spinal network to learn and improve nerve functions.
In addition to regaining voluntary movement, the men have exhibited a number of improvements in their overall health, including increases in muscle mass, regulation of their blood pressure, reduced fatigue, and significant improvements to their sense of well-being. In addition, all four participants were able to bear weight independently. “This research brings up an amazing number of possibilities for how we can develop interventions that will help people recover movement they have lost,” noted co-author Reggie Edgerton, PhD, a distinguished professor of integrative biology and physiology, neurobiology, and neurosurgery at UCLA. He added, “The circuitry in the spinal cord is remarkably resilient. Once you get them up and active, many physiological systems that are intricately connected and that were dormant come back into play.”
The study offers renewed hope that clinical therapies can be developed to provide treatment for the almost 6 million paralyzed Americans, including approximately 1.3 million with spinal cord injuries. The four paralyzed men ranged in neurological level from C7 through T5 and were at least two years post-injury at the time of the intervention. Two of them had been rated “A” on the American Spinal Injury Association’s classification system, which meant that they had absolutely no sensation or cognition below the site of their injury. The researchers were highly skeptical that these men would elicit any voluntary movement as a result of the intervention; however, via the epidural stimulation, all four men recovered voluntary control of their legs. This surprising finding caused the researchers to theorize that at least some of the sensory pathway must be intact for epidural stimulation to be successful.
The research was funded by the Christopher and Dana Reeve Foundation and the National Institutes of Health, the Leona M. and Harry B. Helmsley Charitable Trust, the Kessler Foundation, the University of Louisville, the Jewish Hospital and St. Mary’s Foundation, the Frazier Rehab Institute and University Hospital.