Researchers from the University of Louisville, University of California, Los Angeles, and the Pavlov Institute of Physiology said the epidural stimulator delivers a continuous electrical current to the men's lower spinal cords, imitating signals the brain transmits to trigger motion.
The research builds on an initial study involving Rob Summers of Portland, Ore., paralyzed after being struck by a vehicle, who recovered a number of motor functions after being implanted with the epidural stimulator.
In this study, published in the journal Brain, three men, paralyzed from auto or motorcycle accidents, were also implanted with the epidural stimulator and evaluated. New tests were also conducted on Summers.
The researchers said the three new men to the research were able to execute voluntary movements immediately following the implantation and activation of the stimulator.
"Two of the four subjects were diagnosed as motor and sensory complete injured with no chance of recovery at all," lead author Claudia Angeli of the Human Locomotor Research Center at Frazier Rehab Institute and an assistant professor at University of Louisville's Kentucky Spinal Cord Injury Research Center, said in a statement.
"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."
[University of California, Los Angeles]