WASHINGTON – A stroke left Heather Rendulic with almost no use of her left hand and arm, putting certain everyday tasks like tying shoes or cutting groceries out of reach.
“I live one-handed in a two-handed world and you don’t realize how many things you need two hands for until you have just one good one,” the Pittsburgh woman told The Associated Press.
So Rendulic volunteered for a unique experiment: Researchers implanted a device that taps into her spinal cord at points that control hand and arm movement. When they turned it on, she was able to grab and manipulate objects – move a soup can, pick a lock and, at the end of the four-week study, cut her own steak.
It’s not a cure — the improvements ended after the scientists removed the temporary implant — and the pilot study only included Rendulic and one other stroke survivor. But the preliminary results, released Monday, mark a step towards one day restoring mobility to this extremely common type of paralysis.
“You don’t just get flickering movements. You’re getting something important,” said Dr. Jason Carmel, a Columbia University neurologist who was not involved in the new experiment but is also studying ways to restore upper extremity function. “This is a very exciting proof of concept.”
In the United States alone, nearly 800,000 people suffer a stroke each year. Even after months of rehabilitation, well over half have permanently restricted arm and hand function, which can range from muscle weakness to paralysis.
This has been shown by experiments by several research groups Implantation of electrodes to stimulate the lower spine shows promise for restoring leg and foot movement in people paralyzed after spinal cord injury — some have even taken steps.
But upper extremity paralysis has received little attention and is inherently more of a challenge. The brain needs to signal multiple nerves that control how the shoulder raises, wrist rotates, and hand flexes. Stroke damage makes it harder for that message to get through.
“People still retain some of that connection, they just aren’t enough to enable exercise,” said University of Pittsburgh assistant professor Marco Capogrosso, who led the new research with colleagues at Carnegie Mellon University. “These messages are weaker than normal.”
His idea: Stimulate a path in related nerve cells so that they can better perceive and absorb the weak signal from the brain.
“We don’t circumvent their control. We’re improving her ability to move her own arm,” he said.
Researchers turned to spaghetti strap-sized implants, which are already being used to stimulate the spine to treat chronic pain. The implants carry electrodes that are placed on the surface of the spinal cord to deliver electrical impulses to targeted nerve cells – located in the cervical spine for hand and arm control.
Rendulic and a second, more impaired subject were able to move better once the stimulator was turned on — and showed improved muscle strength, dexterity and range of motion at the end of the study, researchers reported Monday in the journal Nature Medicine. Surprisingly, both participants maintained some improvement for about a month after the implants were removed.
Rendulic, now 33, performed some fine motor tasks for the first time since suffering a stroke in her 20s. This unusually young stroke, caused by weak blood vessels bleeding in her brain, initially paralyzed her entire left side. She learned to walk again but, with the exception of the four weeks of spinal stimulation, she cannot fully open her left hand or fully raise that arm.
“It feels like there’s a barrier between your brain and your arm,” Rendulic said. But with the stimulation on, “I could immediately feel that my arm and hand were still there.”
Two other researchers who helped pioneer attempts to stimulate the lower limbs of people with spinal cord injuries say it makes sense to test the technology for stroke now.
While larger and longer studies are needed, the new results are “really promising,” said Mayo Clinic assistant professor Peter Grahn.
Scientists have learned from lower-limb research that “whether it’s something in the brain or a spinal cord injury, it might not matter where that injury occurs,” University of Louisville professor Susan Harkema added, adding that there’s a lot of potential. “
With funding from the National Institutes of Health, Capogrosso is studying the approach in a few more stroke survivors. The researchers have also set up a company to further develop the technology.
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