Electrode stimulator gives quadriplegic control over hands
Image credit: Ronald Reagan UCLA Medical Center
A paralysed man was able to regain the ability to move his hands thanks to a new electrode stimulator developed by researchers at UCLA Medical Center.
The patient, 28-year-old Brian Gomez, broke his neck in a motorcycle accident five years ago. Since then, he has been paralysed from the neck down. After the medical team implanted the 32-electrode stimulator into his spine below the damaged area, he was able to regain some control over the paralysed limbs.
“The spinal cord contains alternative pathways that it can use to bypass the injury and get messages from the brain to the limbs,” said 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.”
The technology 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.”
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 stimulator is powered from a small battery and controlled by a processing unit implanted under the skin of the patient’s lower back. The doctors can regulate the frequency of the stimulator using a remote control device.
“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.”
The team has previously used similar technology in paraplegics, allowing them to regain the ability to stand and move their legs.
“There was considerable scepticism in the field that we could use a similar approach to regain hand function in quadriplegic patients with injury to the upper spine,” said UCLA neuroscientist Reggie Edgerton. “Brian’s strong response to the implant has been very exciting.”
The researchers don’t expect to restore Gomez’s hand function completely. They hope to improve it enough to allow him to perform everyday tasks.
“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.
“It’s making a huge difference for me,” said Gomez, who owns a coffee-roasting business in his hometown of San Dimas, California.