Paralyzed men regain movement with spinal stimulation
Four young men paralyzed below the chest because of spinal cord injuries were able to regain control of some movement after receiving an experimental spinal stimulation therapy. If confirmed in larger studies, this type of treatment may one day improve outcomes for people living with paralysis.
In an earlier report, spinal stimulation and intense physical training enabled a man in his 20s who was paralyzed from the chest down after a car accident to stand and voluntarily move previously paralyzed limbs. The patient, Rob Summers, had an electrode array implanted on his spinal cord just below his injury. The array emits a pattern of electrical signals that can evoke muscle activity in response to sensory input or other signals. As part of his daily training, Summers was suspended in a harness over a treadmill while a team of researchers supported his legs, helping him to either stand or walk.
The follow-up study, led by Dr. Claudia Angeli of the University of Louisville, included three additional men in their mid-20s to early-30s. Each had been paralyzed for more than two years when they received the electrode implant array. The research was funded in part by NIH's National Institute of Biomedical Imaging and Bioengineering (NIBIB) and National Institute of General Medical Sciences (NIGMS). Results appeared online on April 8 in Brain.
When the trial began, one participant still had feeling in his legs but was unable to move them. This meant the sensory pathways carrying nerve signals from the legs to the brain were at least partly intact, while "motor" signals from the brain to the legs were not. The two other participants had no feeling or movement in their legs-a bidirectional breakdown in nerve signals. The researchers didn't expect electrical stimulation to help the latter patients, as sensation pathways were thought to be key to the therapy's success.
Surprisingly, within a few days of receiving electrical stimulation, all three participants regained some voluntary control of previously paralyzed muscles, even before physical training began. Over time, with daily spinal stimulation and physical training, all three patients as well as Summers enhanced their control of voluntary movement.
All four men were able to adjust their movements in response to sound and visual cues. They also could synchronize leg, ankle, and toe movements with visual cues on a computer screen. Three of the four were able to change the force used to flex their legs, depending on the intensity of sound cues. It's not known whether these improvements were due to the physical training, the cumulative effects of stimulation, or the combination.
The fact that all four patients were able to regain voluntary movement suggests that a large number of patients with paralysis might benefit from spinal stimulation. The researchers are continuing clinical studies of additional patients to gather more data. They are also working to develop an improved stimulator.
"Right now, the clinical perspective for individuals with complete motor paralysis is that there is nothing we can do. I think we need to rethink that," says study co-author Dr. Susan Harkema. "In our study, we demonstrated potential beyond any expectation. We need to relook at what the perceived potential is for this group of individuals."
--From the National Institute of Health
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