Five years ago, Rob Summers was 20 years old and about to enter his junior year at Oregon State University in Corvallis, where he was a pitcher on the baseball team. One night when he went out to retrieve a gym bag from his car, another car jumped the curb, hit him, and then took off. Summers was paralyzed from the chest down. Today, in a case report published in The Lancet, doctors and researchers reveal that Summers has regained the ability to stand for a few minutes and to perform some voluntary movements of his lower extremities, thanks to electrodes they implanted in his spinal cord.
Other researchers say the degree of recovery is remarkable, perhaps even unprecedented, but they caution that the procedure didn't produce a complete cure and may not work as well for patients who are older or have more severe injuries. At a press conference today announcing the findings, the researchers who led the study, neuroscientists V. Reggie Edgerton of the University of California, Los Angeles, and Susan Harkema of the University of Louisville in Kentucky, framed their method as a way to make the most of the neural circuitry that remains intact after a spinal injury, as opposed to restoring severed connections.
After his injury, Summers was unable to move his trunk or legs, although he did have some ability to feel a light touch or pinprick to these areas. Two years of intensive physical therapy failed to restore voluntary movements. The reason spinal injuries cause lasting paralysis is that neurons in the adult spinal cord can't sprout new axons, the armlike extensions that neurons use to connect with one another. As a result, the parts of the cerebral cortex that plan and initiate movements remain disconnected from the spinal neurons that normally help execute their orders.
In December 2009, Summers became the first patient enrolled in a clinical trial of a method pioneered in studies with rodents and cats by Edgerton and others. Surgeons in Louisville placed a small strip of electrodes on the dura, the protective layer surrounding the spinal cord. Summers underwent regular physical therapy sessions during which researchers passed pulses of electric current through the electrodes to stimulate neurons in the spinal cord. After just a few sessions, Summers was able to stand with assistance. By the end of 80 sessions over 7 months, Summers was able to stand and support his own weight for several minutes and, with assistance, take a step. Lying in bed, he was able to move his toes, feet, and legs on command. Although these feats require the stimulator to be on, Summers also reports improved bladder control and sexual function even with the stimulator off, Edgerton and colleagues reveal in The Lancet paper.
Research in animals with spinal injuries has shown that this type of epidural stimulation can activate neural circuits in the spinal cord and enable them to use sensory information from the legs to coordinate the muscle contractions necessary for standing and taking a step, Edgerton said at the press conference. The results show for the first time that this method works in humans, Edgerton said.
"This is the very first time that someone with complete, chronic motor paralysis has demonstrated any kind of voluntary movement," says Grégoire Courtine, a neuroscientist at the University of Zurich in Switzerland.
"It's a single individual, so you have to take it with a grain of salt," says Michael Beattie, a neuroscientist at the University of California, San Francisco. "On the other hand, it's really quite impressive." The fact that Summers regained some voluntary movement suggests that at least some nerve fibers from the cortex to the spinal cord must have been spared by his injury, Beattie says. He notes that patients with severed spinal cords probably could not recover any voluntary movements.
In a press release issued by The Lancet, Summers says the treatment has done wonders for his sense of well-being: "This procedure has completely changed my life. For someone who for 4 years was unable to even move a toe, to have the freedom and ability to stand on my own is the most amazing feeling."
Even so, Courtine thinks there's still plenty of room for improvement. Refinements to the design of the stimulating electrodes and more sophisticated patterns of electrical stimulation might produce even better effects. So might stimulation in conjunction with injections of drugs into the fluid bathing the spinal cord to enhance neuronal repair, he says.