A study involving the application of continual direct electrical current — via implanted electrodes — at varying frequencies and intensities to the part of the spinal cord that controls movement of the hips, knees, ankles and toes has enabled a paralyzed man to stand and take steps on a treadmill
Summers also voluntarily can move his toes, ankles, knees and hips on command. With harness support and therapist assistance, he can make repeated stepping motions on a treadmill. He can stand up on his own and remain standing and bearing weight for up to four minutes at a time. With periodic assistance, he can stand for up to an hour.
This type of epidural stimulation mimics signals the brain normally sends to initiate movement. Once that happens, the spinal cord’s own neural networks, combined with the sensory input from the legs to the spinal cord, can direct the muscle and joint movements required to stand and step with assistance on a treadmill.
The other crucial component of the research was an extensive regimen of locomotor training while the spinal cord was stimulated and Summers was suspended over the treadmill. Rehabilitation specialists helped move his legs to retrain his spinal cord neural networks to produce the muscle movements necessary to stand and to take assisted steps.
“This procedure has completely changed my life,” Summers said. “For someone who for four years was unable to even move a toe, to have the freedom and ability to stand on my own is the most amazing feeling. To be able to pick up my foot and step down again was unbelievable, but beyond all of that my sense of well-being has changed. My physique and muscle tone has improved greatly — so much that most people don’t even believe I am paralyzed. I believe that epidural stimulation will get me out of this chair.”
The researchers envision a day when at least some people with complete spinal cord injuries will be able to use a portable stimulation unit and, with the assistance of a walker, stand independently, maintain balance and execute some effective stepping.
Relief from secondary complications of complete spinal cord injury — including impairment or loss of bladder control, sphincter control and sexual response — could prove to be even more significant.