Picture this: Four men, all classified with chronic, motor complete spinal cord injuries, who have been paralyzed for years are able to voluntarily raise their legs. This picture has come to life, thanks to a breakthrough therapy known as epidural electrical stimulation of the spinal cord.
According to the Christopher & Dana Reeve Foundation, nearly one in 50 people lives with paralysis, or approximately six million people, of whom 1,275,000 have spinal cord injuries. That number is nearly 33 previous higher than previous estimates showed.
The study, published in the journal Brain, was conducted by researchers at the University of Louisville, UCLA, and the Pavlov Institute of Physiology and involved four men who were unable to move their lower extremities prior to the implantation of an epidural stimulator. The stimulator delivers a continuous electrical current to the participants' lower spinal cords, mimicking signals the brain normally transmits to initiate movement.
The research comes three years after a study, published in The Lancet, evaluated the effects of epidural stimulation in the first study participant, Rob Summers, who was paralyzed after being struck by a vehicle. He recovered a number of motor functions as a result of the intervention. The other three participants in the new study were paralyzed in auto or motorcycle accidents.
The finding is revolutionary in that the other study participants were able to execute voluntary movements immediately after the implantation and activation of the stimulator, according to the researchers.
Commenting on the study, Peter T. Wilderotter, Christopher & Dana Reeve Foundation president and CEO, told Healthline, "Now, with these results, we are at a crossroad where technology has the potential to reverse “permanent” conditions like paralysis and essentially rewire how our bodies work by bridging the gap that biology is not prepared to support right now. This study challenges the notion that the spinal cord, once damaged, cannot repair or recover. This offers tremendous hope to the six million Americans living with paralysis. We may just need to redefine paralysis altogether."
What Is Epidural Stimulation?
In epidural stimulation, the electrical current is applied at varying frequencies and intensities to specific locations on the lumbosacral spinal cord, corresponding to the dense neural bundles that largely control the movement of the hips, knees, ankles, and toes. In the study, once the signal was triggered, the spinal cord reengaged its neural network to control and direct muscle movements.
When combined with rehabilitative therapy, the impact of epidural stimulation intensified, according to the researchers. Over the course of the study, the participants were able to activate movements with less stimulation, showing the ability of the spinal network to learn and improve nerve functions.
Pathways May Be Intact Post-Injury
Both the participants' results and recovery time were unanticipated, which led the researchers to speculate that some pathways may be intact post-injury and therefore able to facilitate voluntary movements.
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) said in a press statement, "Two of the four subjects were diagnosed as motor and sensory complete injured with no chance of recovery at all. 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."
Susan Harkema, a University of Louisville professor and rehabilitation research director at KSCIRC, Frazier Rehab Institute, as well as the director of the Reeve Foundation's NeuroRecovery Network, added in the release, “The belief that no recovery is possible and complete paralysis is permanent has been challenged."
The study participants also showed increases in muscle mass, regulation of their blood pressure, reduced fatigue, and dramatic improvements to their sense of well-being. They were also able to bear weight independently.
Hope for People with Paralysis
According to Roderic Pettigrew, the director of the National Institute of Biomedical Imaging and Bioengineering, epidural electrical stimulation may help a large cohort of people with spinal cord injuries.
Finally, the scientists believe that epidural electrical stimulation will continue to result in improved motor functions, and that individuals with complete spinal cord injuries will be able to bear weight independently, maintain balance, and work towards stepping as advancements in the treatment continue.