Washington: In a groundbreaking progress, four young men who have been paralyzed for years, could move their legs as a result of epidural electrical stimulation of the spinal cord.
The study, conducted by researchers from the University of Louisville, UCLA and the Pavlov Institute of Physiology, was funded in part by the Christopher and Dana Reeve Foundation and the National Institutes of Health.
All four participants were classified as suffering from chronic, motor complete spinal cord injuries and 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 builds on an initial study, published in May 2011 in the journal The Lancet, that evaluated the effects of epidural stimulation in the first participant, Rob Summers of Portland, Ore., who recovered a number of motor functions as a result of the intervention.
Now, three years later, the key findings documented in Brain detail the impact of epidural stimulation in a total four participants, including new tests conducted on Summers. Summers was paralyzed after being struck by a vehicle, and the other three participants were paralyzed in auto or motorcycle accidents.
What is revolutionary, the scientists said, is that the second, third and fourth participants - Kent Stephenson of Mt. Pleasant, Texas; Andrew Meas of Louisville, Ky.; and Dustin Shillcox of Green River, Wyo. - were able to execute voluntary movements immediately following the implantation and activation of the stimulator.
The participants' results and recovery time were unexpected, which led researchers to speculate that some pathways may be intact post-injury and therefore able to facilitate voluntary movements.
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. With the participants, once the signal was triggered, the spinal cord reengaged its neural network to control and direct muscle movements.
The research is published in the medical journal Brain.