February 21, 2023
Tim Betler/UPMC and University of Pittsburgh Health Sciences
Heather Rendulic, 33, participates in a study that suggests spinal cord stimulation may help some stroke patients regain mobility.
After a massive stroke left Heather Rendulic with limited use of her left arm and hand at age 23, she had to learn how to do even simple tasks with just one hand. It took years – and the help of an experimental stimulation device – before she regained some functionality.
When Rendulic received spinal cord stimulation in 2021 – as part of a study conducted by the University of Pittsburgh and Carnegie Melon University – she found that she could maneuver her left arm more easily. Suddenly, she could tie her shoes and cut her food again.
"When the stimulation is on, I feel like I now have control of my arm and my hand again, that I haven't had in over nine years," Rendulic said in a video shared by Pitt.
The study, published Monday, suggests that stimulation instantly improves arm and hand mobility, allowing people who have had moderate to severe strokes to conduct their normal daily activities more easily. The research is promising, though the small-scale study was considered preliminary.
Rendulic, 33, of Shaler Township, about 20 minutes north of Pittsburgh, had suffered a hemorrhagic stroke, which is caused by bursting blood vessels in the brain. The other patient in the study, a 47-year-old woman, had an ischemic stroke, which is caused by blocked blood vessels.
Rendulic was 22 when she experienced her first stroke. She had a cavernous angioma, a growth in the brain made of small blood vessels, which increased her risk of stroke. She had five brain bleeds over an 11-month period before she suffered a massive stroke that paralyzed the left side of her body. She had recently turned 23.
Doctors removed the angioma during a nine-hour surgery. Rendulic then went through intensive inpatient and outpatient rehabilitation to learn how to walk again. She never fully regained use of her left hand and arm.
But the experimental stimulation instantly enabled her to do something she typically struggled to do.
Study shows spinal cord stimulation instantly improves arm and hand mobility, enabling moderate to severe stroke victims to conduct normal daily activities more easily. https://t.co/jPq4542ku2. @NatureMedicine @PittTweet @CarnegieMellon @RNELabs @MCapogrosso @upmc @cmuneurosci pic.twitter.com/612I5Kdq9a
— Pitt Neurosurgery (@PittNeurosurg) February 20, 2023
"The very first day in the lab and the first time they turned it on, I was sitting in a chair, and they asked me to open and close my hand, and that's something that's really difficult for me," Rendulic told The New York Times..
Her husband and mother were with her. "I immediately was opening and closing my hand," she told USA Today. "We all broke down in tears."
When a stroke occurs, it only takes minutes for brain cells to start to die. That is why quick, early action is so important. Though the survival rate has improved over the years, many survivors are left with impaired upper limb function and weakness – even after months of intensive rehabilitation therapy. There are no options for treating paralysis in the chronic stage of stroke, which begins about six months afterward.
Despite advancements in understanding the causes of stroke, they remain very common. Across the world, 1 in 4 adults over age 25 will suffer a stroke. And 75% of them will have some sort of lasting motor control deficit.
Even patients with mild deficits can feel isolated from others in their social and professional lives, researcher Elvira Pirondini, an assistant professor of physical medicine and rehabilitation at Pitt, said. Motor impairments that affect daily activities such as writing, eating and getting dressed can be very debilitating.
The researchers are hopeful though that their device eventually will be approved by the U.S. Food and Drug Administration to help patients with moderate to severe stroke. The device consists of two, thin metal electrodes that are implanted along a patient's neck. The electrodes then stimulate intact neural circuits.
"We discovered that electrical stimulation of specific spinal cord regions enables patients to move their arm in ways that they are not able to do without the stimulation," said Marco Capogrosso, an assistant professor of neurological surgery at Pitt. "Perhaps even more interesting, we found that after a few weeks of use, some of these improvements endure when the stimulation is switched off, indicating exciting avenues for the future of stroke therapies."
Though the study's findings appear promising, the technology will not restore patients to the same level of function they had prior to their strokes, Grégoire Courtine, a French neuroscientist who was not involved with the study, told USA Today. But it may restore some function.
"It's not a cure," Courtine said. "The more significant the damage, the less hope there is for recovery."
During the study, the two patients were asked to complete a series of tests of varying complexity, including moving a hollow metal cylinder, grasping common household objects and opening a lock. The tasks were done both with and without stimulation. Because the patient who had suffered the ischemic stroke had more extensive damage, her tests focused mostly on improving simpler skills, like reaching.
The patients underwent these tests for a month. Throughout the process, the researchers were able to calibrate the stimulation to the best parameters for each patient.
"The sensory nerves from the arm and hand send signals to motor neurons in the spinal cord that control the muscles of the limb," said Douglas Weber, professor of mechanical engineering at the Neuroscience Institute at Carnegie Mellon University. "By stimulating these sensory nerves we can amplify the activity of muscles that have been weakened by stroke."
Spinal cord stimulation technology already is used to treat intense, persistent pain. Other researchers have shown that it can help restore movement to the legs and, in some cases, arms and hands after spinal cord injury.
It hadn't been tested in stroke patients because of the differences in the location and type of damage, neurological experts told The New York Times. It previously was thought that the neural stimulation had to occur inside the brain – the location of the stroke.
But after years of computer modeling and animal testing, the Pittsburgh researchers were cleared to test their experimental device on human stroke patients.
The researchers are continuing to enroll more participants in the study, with the goal of more thoroughly exploring whether the technology can restore motion long-term in the absence of continued stimulation.
