Kent Stephenson, of Mount Pleasant, Texas, was a competitive motocross racer until one day in June 2009, when the motor on his bike locked up while going off the face of an 80-foot tabletop jump. A cascade of flips, twists and bends prefaced the spinal cord injury in two vertebrae in his thoracic spine, rendering him motionless and senseless from mid-chest down. He had been training for his first professional race.

“I had been racing since I was 15,” Stephenson, now 28 and reliant on a wheelchair, told “It was the thrill, the rush— the sense of when you’re on your bike and racing, you’re free.”

When he enrolled in July 2010 in a clinical trial at the Frazier Rehab Institute, in Louisville, Kentucky, neither he nor researchers knew what to expect. The trial treatments would send electrical currents through his spine via an epidural stimulator with the goal of restoring movement. In the past, he only saw minimal improvements from therapy including locomotive strength work, weight training and pool exercises, but he plateaued after one year.

An epidural stimulator is a box-like device implanted on the spinal cord that generates brain signals that are then sent to the spinal cord to initiate movement. These signals no longer work in paralyzed patients.

During his first test with the device, researchers asked him to pull his leg back. And he did.

“Everyone in the room was like, ‘Holy crap,’” Stephenson said. “It was mind blowing.”

Changing the course of paraplegics’ lives

Scientists have yet to develop an interventional recovery method for spinal cord injuries, so these patients’ post-injury prescriptions are limited to therapy, medication and wheelchair use. But a growing body of research suggests stimulating the spinal cord with electrical currents can enable these patients to feel and move again, even years after becoming paralyzed.

Although clinical research on the effects of stimulating the spinal cord began only within the past decade, the method offers promise for the estimated 276,000 Americans living with a spinal cord injury.

“Currently, after you’re injured for a couple of years, you have to figure out the things you did before a different way,” Susan Harkema, a University of Louisville professor and associate director at The Kentucky Spinal Cord Injury Research Center (KSCIRC) and the Frazier Rehab Institute, told “I think that one of the good things about this research, and not just ours alone, is that there are mechanisms there that we haven’t taken advantage of.”

In a study published in July in the journal PLOS One, a team of researchers led by Harkema found that generating individualized electric fields that reach the spinal cord, a method called epidural stimulation, can enable patients with motor and sensory complete spinal cord injuries to stand and bear weight.

Harkema said researchers didn’t expect epidural stimulation would also help patients regain autonomic abilities, like bladder, bowel and sexual function, which impose one of the largest burdens to paraplegics’ finances and quality of life.

The four participants in the study— two of who were motor and sensory complete, including Stephenson, and two of who were motor complete, meaning they could feel but not move the injured portions of their bodies— received epidural stimulation by way of an electrode implanted on the lowest part of their spinal cords. The study followed up a paper published in the April 2014 issue of the journal Brain, which included the same four patients, and illustrated that epidural stimulation can help patients with a spinal cord injury execute voluntary movement.

Study participant Dustin Shillcox, 30, was injured in a car accident in 2010. He wasn’t wearing a seatbelt, and the crash left him with a thoracic vertebrae injury in his spine, as well as with a broken back, sternum, elbow and four ribs, plus collapsed lungs and bleeding in his brain. He became paralyzed, senseless and immobile from mid-chest down.

“I think the first year is, by far, the hardest because you’re still learning how to control your body, whether it be living out of a wheelchair, everything taking longer— getting dressed, taking a shower— and learning how your bathroom abilities go,” Shillcox, of Salt Lake City, Utah, told “It was depressing for me. It was tough getting used to that, and so my days were spent trying to learn a new way of life.”

With the epidural stimulator, Shillcox and Stephenson each use a remote that goes through their stomachs and connects to the stimulator, which is positioned in the middle of their backs. They manually change each of their unique configurations to perform different functions, like moving their toes or ankles, or using the bathroom. Before, Shillcox and Stephenson had to schedule going to the bathroom to prevent bladder infection, or have a relative move them in bed at night to prevent bed sores, and regulate their body temperatures because they can’t sweat— all to keep their bodies functioning healthfully on a biological level.

“What often kills people living with spinal cord injuries is these secondary injuries [like] bedsores and infections,” Peter Wilderotter, president and CEO of the Reeve Foundation, a partial funder of Harkema’s research, which is under the nonprofit’s “The Big Idea” campaign. “Imagine what would happen if you can’t evacuate your bowel or bladder effectively. If you can change that, you’re really changing the course and nature of these folks’ lives in a really profound way.”

Shillcox said regaining control over his autonomic functions and the ability to engage his core again have been two of the biggest benefits of the stimulator. The epidural stimulator enables him to sit up without help from another person, which in turn helps keep his blood pressure in check and prevent osteoporosis.

“I stand every day for my bone density, to create blood flow and circulation,” Shillcox said. “It’s beneficial for my body to keep getting stronger and healthier.”

Forging ahead on spinal cord stimulation research

Harkema’s findings are an important step forward from previous research on spinal cord stimulation that was restricted to animals. But scientists still don’t have a full grasp on the function of the spinal cord itself, nor do they know the precise mechanics of spinal cord stimulation.

“When you’re paralyzed, your ability to exercise is blocked,” said Harkema, who is also director of the Christopher & Dan Reeve Foundation’s NeuroRecovery Network. “Maybe a lot of this is just not exercising, so all of these things feed on each other and get worse. Another thing is the spinal cord may not be significant [only] for control and movement, but also critically important for other physiological systems. So, stimulation itself, just like it’s helping movement, it’s helping these other systems.”

Next, Harkema’s team is studying how epidural stimulation in patients with spinal cord injuries influences cardiovascular health, as well as analyzing the stepping movement with the technology. Before the epidural stimulator is introduced commercially, the hardware would need to be improved to deliver currents at a faster speed and change configurations in real time with a loop control mechanism. Harkema noted the software and interface would need to be redesigned as well.

“You can’t be pushing all these buttons when you’re trying to move,” she explained.

Reggie Edgerton is an integrative biology and physiology professor at the University of California, Los Angeles, who collaborated with Harkema for the Brain study, as well as their team’s initial clinical epidural stimulation study, which involved one patient and was published in the May 2011 edition of The Lancet.

Now, in a separate study published in the July edition of the Journal of Neurotrama, Edgerton has illustrated that stimulating the spinal cord transcutaneously can improve motor functions in paraplegics who have retained sensation but lost the ability to voluntarily move the affected portion of their bodies. Unlike epidural stimulation, which involves an implant that is invasively inserted, transcutaneous stimulation supplies electrical currents externally through electrodes placed on the spinal cord.

Edgerton found in his team’s study that transcutaneous electrical stimulation enabled the men to move their legs in a step-like fashion while suspended over a table. The men underwent a series of 45-minute sessions of stimulation once a week for about 18 weeks.

“One can say rightfully that we haven’t solved all the problems of the world by showing this,” Edgerton told, “but what it basically shows is maybe we’re on the right track with this intervention as well, so we have experiments going on now to test the efficacy with same intervention, with standing and maintaining trunk control of individuals with complete paralysis.”

He said transcutaneous stimulation may provide a solution for paraplegics who don’t want to undergo another invasive surgery, and that the technology is an estimated one-tenth the cost of the epidural stimulator. In some cases, the potentially more direct application of electrical currents that the epidural stimulator offers may be more beneficial to patients, he noted. Neither technology is superior to the other, but rather they may be utilized together or separately based on the severity of a patient’s injury.

“There are some conditions [for which] we expect starting out with transcutaneous stimulation may facilitate enough recovery to be on their own with continued rehabilitation,” Edgerton said, “and that the epidural stimulation would be unnecessary when they get to a certain point.”

“Almost all clinicians will say that there is no further improvement you can expect after a year and the system cannot recover after a year,” he added, “but now with all the results from epidural stimulation and transcutaneous stimulation, it’s very clear that’s not the case.”

What hasn’t been explored, Edgerton said, is whether stimulating the spinal cord immediately following injury can more effectively restore motor and sensory function.

“There’s every reason to believe that one could enhance the recovery beginning [spinal cord stimulation] at a very early stage,” he said.

As for Stephenson and Shillcox, epidural stimulation— even when applied long after their injuries— has boosted their confidence in daily life, they said.

Shillcox has dedicated his life to public speaking about spinal cord injuries, often on behalf of the Reeve Foundation, and training for the New York City Marathon in November. Stephenson works as a superintendent at his family’s dirt company, Stephenson Dirt Construction. With the help of the epidural stimulator, Stephenson was able to stand when he proposed to his fiancée, 26-year-old Misti Richerson, a registered nurse (RN) whom he began dating in 2008.

His goal, he said, is to stand again throughout his spring 2016 wedding ceremony. To do so, he’s rigorously training with the study’s home therapy model, which includes leg flexes, and twice-weekly strength training sessions with a trainer.

“From day one, I always said I was going to walk again, and I still say that now,” Stephenson said, “and it’s kind of crazy to look back because everyone looked at me plain in the face and said, ‘You have a good attitude,’ and said, ‘You messed your back up, and it’s not gonna happen.’ It’s awesome to be part of this.”