Experimental implant shows promise for restoring voluntary movement after spinal cord injury
A spinal stimulator being tested by doctors at Ronald Reagan UCLA Medical Center is showing promise in restoring hand strength and movement to a California man who broke his neck in a dirt bike accident five years ago.
In June, Brian Gomez, now 28, became one of the first people in the world to undergo surgery for the experimental device.
UCLA scientists inserted the 32-electrode stimulator below the site of Gomez’s spinal cord injury, near the C-5 vertebrae in the middle of his neck. That’s the area most commonly associated with quadriplegia, the loss of function and feeling in all four limbs.
UCLA Health - Brian Gomez with Dr. Daniel Lu at UCLA
“The spinal cord contains alternate pathways that it can use to bypass the injury and get messages from the brain to the limbs,” said Dr. Daniel Lu, an associate professor of neurosurgery at the David Geffen School of Medicine at UCLA and director of the school’s Neuroplasticity and Repair Laboratory. “Electrical stimulation trains the spinal cord to find and use these pathways.”
Although other devices have shown promise recently for treating paralysis, they were either tested in animals or relied on robotic limbs. The approach used by the UCLA doctors is unique because it is designed to boost patients’ abilities to move their own hands, and because the device is implanted in the spine instead of the brain.
The technique essentially gets the nerve signal to behave like a driver who avoids rush-hour traffic by taking side streets instead of a busy highway.
“If there is an accident on the freeway, traffic comes to a standstill, but there are any number of side streets you can use to detour the accident and get where you are going,” Lu said. “It’s the same with the spinal cord.”
In addition to the stimulator, doctors implant a small battery pack and processing unit under the skin of the patient’s lower back. Small enough to fit in the palm of your hand, the implant is paired with a remote control that patients and doctors use to regulate the frequency and intensity of the stimulation.
“We can dial up or dial down different parameters and program the stimulator to activate specific electrodes,” Lu said. “It is an ongoing process that retrains the spinal cord and, over time, allows patients to strengthen their grip and regain mobility in their hands.”
Prior to Gomez’s operation, the UCLA team performed the world’s first two surgeries in which these types of electrodes were implanted in patients’ necks, with the aim of restoring function after cervical spinal cord injuries. Lu and his colleagues saw an increase in finger mobility and grip strength of up to 300 percent.
The researchers’ work on the new approach is funded by the National Institute of Biomedical Imaging and Bioengineering, part of the National Institutes of Health. Lu is working with UCLA neuroscientist Reggie Edgerton to build upon the success of their previous findings in patients with lumbar spinal cord injuries.
“We’d used electrical stimulation to recover paraplegic patients’ abilities to stand and move their legs on their own following injury to the lower spine,” said Edgerton, a distinguished professor of neurosurgery at the David Geffen School of Medicine at UCLA and of integrative biology and physiology in the UCLA College. “There was considerable skepticism in the field that we could use a similar approach to regain hand function in quadriplegic patients with injury to the upper spine. Brian’s strong response to the implant has been very exciting.”
“It’s making a huge difference for me,” said Gomez, who owns a coffee-roasting business in his hometown of San Dimas, California.
Brian Gomez with Dr. Daniel Lu
As part of his job, Gomez uses an industrial roaster that reaches 450 degrees.
“A few months ago, I reached up to pull a lever to empty a batch of beans after they’d finished roasting,” he said. “But because I didn’t have the arm or core strength, I burned myself. That doesn’t happen anymore because of the strength and dexterity I’ve developed.”
Gomez’s improvement is especially encouraging given the five years that passed between his injury and the surgery. People who suffer spinal cord injuries usually have a window of only a few months when rehabilitation can help them maintain at least partial use of their hands. Meaningful improvement is rare more than a year after injury.
“Even though he was injured in 2011, in many ways Brian is a perfect candidate for this experimental treatment,” Lu said. “He still has head-to-toe sensation, so he can give us feedback as we fine-tune the stimulator. And he is such a positive and motivated young man.”
Several times a week, Gomez returns to a laboratory at UCLA, where a team of scientists put him through rehabilitation exercises and recalibrate the device.
“It takes a lot of time and commitment to do this, but I’m determined,” said Gomez. “Things are about to change for the better, so I’m excited about what’s to come.”
The UCLA team’s goal is not to fully restore hand function, but to improve it enough to allow patients to perform everyday tasks — still a remarkable achievement considering the length of time since their injuries. As the technology develops, patients might be able to expect further improvements.
Researchers evaluate hand strength by a unit of measure called a newton.
“A normal hand is able to impart about 100 to 200 newtons of force, but after an accident, that often drops to only 1 or 2 newtons of force,” Lu said. “Our goal is to get these patients back to the 20 to 30 range. That will make a huge difference in the quality of their lives.”
That level of improvement, Lu said, would help people with everyday tasks like tying their shoelaces and brushing their teeth — or, in Brian Gomez’s case, holding a cup of coffee that he roasted and brewed himself.
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