With the help of an implanted device that delivers an electrical current to the lower spinal cord, four young men who have been paralyzed for years are now able to move their legs voluntarily.

All four men were completely unable to move their legs before being implanted with the device, which sends the lower spinal cord a continuous electrical current similar to signals transmitted by the brain.

The treatment, called epidural stimulation, delivers an electrical current of varying frequency and intensity to specific parts of the lumbosacral spinal cord, which is connected to dense bundles of nerve fibers that control movement in the hips, knees, ankles and toes.

Life scientists from the University of Louisville, Kentucky, and the University of California-Los Angeles, both in the US, and the Pavlov Institute of Physiology in St. Petersburg, Russia, report the groundbreaking achievement in the journal Brain.

Lead author Claudia Angeli, an assistant professor at the University of Louisville’s Kentucky Spinal Cord Injury Research Center (KSCIRC), says two of the men “were diagnosed as motor and sensory complete injured with no chance of recovery at all,” and adds:

“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.”

One of the participants, Rob Summers of Portland, OR, was the subject of an earlier study published in the Lancet in May 2011, which reported how the shock treatment helped him recover a number of motor functions so he could stand, step with assistance and move his legs voluntarily.

This new breakthrough builds on that work. The Brain paper documents the effect of epidural stimulation in a total of four participants, including new tests on Rob Summers who was paralyzed after being hit by a vehicle.

The other three men – Kent Stephenson of Mt. Pleasant, TX, Andrew Meas of Louisville, KY, and Dustin Shillcox of Green River, WY – were paralyzed as a result of auto or motorcycle accidents.

The scientists say what is remarkable about this latest work is that the three new participants were able to move voluntarily as soon as the stimulator was implanted. They were surprised at the results – especially how quickly the men recovered. This made them think perhaps some of the voluntary movement control pathways may be intact after injury.

The results were even better when electrical stimulation was coupled with physical therapy. The team noticed that the men were progressively able to move their legs with less stimulation, showing that the spine was learning and improving nerve function.

As well as being able to move their legs and bear their weight, the participants are showing a wealth of other improvements in their overall health. These include increased muscle mass, blood pressure regulation, reduced fatigue and significant increases in self-reported well-being.

In the first part of the video below, participant Kent Stephenson demonstrates voluntary training with stimulation and training with an ankle weight. In the last segment, Rob Summers tosses a medicine ball.

The news offers hope to 6 million Americans living with paralysis, including nearly 1.3 million with spinal cord injuries. The four men’s paralysis ranged in neurological level from C7 to T5, and they had been paralyzed for at least 2 years before the treatment began.

Two of the men were classed “A” in the system used by the American Spinal Injury Association, meaning they had absolutely no sensation or awareness below the site of injury. In fact, the team doubted whether the treatment would work at all in those two participants.

Susan Howley, executive vice president for research at the Christopher and Dana Reeve Foundation, who, along with the National Institutes of Health, contributed funds to the study, says the new study shows the findings of the earlier Lancet study were not an anomaly, and adds:

At the present time, other than standard medical care, there are no effective evidence-based treatments for chronic spinal cord injury. However, the implications of this study for the entire field are quite profound, and we can now envision a day when epidural stimulation might be part of a cocktail of therapies used to treat paralysis.”

The team is optimistic that the men will continue to improve with treatment. They believe with further enhancements, the epidural stimulator will one day be helping others with complete spinal cord injury to stand up, balance and work toward taking steps.

In 2012, Medical News Today reported another study published in Brain, where researchers used stem cells to repair spinal cords in paralyzed dogs.