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June 6, 2011
Trial Restores Movement to Paralyzed Man’s Legs
Specialized physical therapy and electrical stimulation to the spine have enabled a man with a spinal cord injury to stand and move paralyzed muscles, according to a new report.
When we decide to move, our brains send signals that travel through our spinal cords to our muscles. The spinal cord is more than just a conduit between the brain and the body, though. It contains local circuits that, with appropriate sensory feedback, can coordinate standing or stepping without the brain’s control.
In previous work, Dr. V. Reggie Edgerton at the University of California, Los Angeles found that a combination of treatments can activate these circuits in rats with spinal cord injury, enabling the rats to walk. The approach was developed through research funded by NIH’s National Institute of Neurological Disorders and Stroke (NINDS). Edgerton and Dr. Susan Harkema at the University of Louisville in Kentucky are now heading an ongoing clinical trial to test a similar approach in people. The study is supported by NIH’s National Institute of Biomedical Imaging and Bioengineering (NIBIB), with additional support from the Christopher and Dana Reeve Foundation.
Rob Summers is the first of 5 patients participating in this new study. A car accident in 2006 left him completely paralyzed from the chest down. Now 25 years old, Summers received a combination of 2 treatments: locomotor training and epidural stimulation. Locomotor training involves being supported over a treadmill, by a harness or hand rails, while a team of physical therapists manipulates his legs. During epidural stimulation, electrical pulses are delivered to the surface of his spinal cord.
For more than 2 years, Summers received locomotor training without epidural stimulation. Such treatment is increasingly common for people with incomplete spinal cord injuries, who retain some ability to move and feel below the injury. But it didn’t help Summers stand or move. In December 2009, electrodes were implanted over his spinal cord below the injury.
The researchers described Summers' improvement in the May 20, 2011, online edition of the Lancet. With the stimulator on during training sessions, Summers was gradually able to support his own weight and could stand for up to 4 minutes. He is still not able to walk. While lying down with the stimulator on, however, he can flex one leg at the knee and ankle, and extend his big toe.
Summers received the training and stimulation without a third component — serotonin-like drugs — that the researchers had used in their rat studies. Remarkably, the 2-part treatment not only activated intact circuits in Summers’s spinal cord but also put the power of movement under his control. The researchers can only speculate about how this happened. One possibility is that the treatment amplified weak signals from the brain to the spinal cord that persisted after Summers’ injury.
Although this initial result is promising, the clinical trial is still under way. “We still have much to learn about how different people will respond to this type of stimulation,” says Dr. Naomi Kleitman, a program director at NINDS.
“There is still much work to be done to optimize the multi-electrode stimulator technology,” adds Dr. Grace C.Y. Peng, a program director at NIBIB.
— by Daniel Stimson, Ph.D