Helping stroke patients regain movement in their hands

Heather Rendulic was 23 when she suffered a stroke which left her disabled. Ten years later, her left arm and hand are still so weak that she can’t tie her shoes, clap with both hands, or cut her own food.

But for one extraordinary month, while participating in an innovative study, she was suddenly able to open a padlock with a key, draw a map of Italy, dip a chicken nugget in the sauce and eat it with a fork – all with that left hand.

“It was like I actually had two arms, oh my!” Ms. Rendulic said recently.

Researchers from the University of Pittsburgh and Carnegie Mellon University implanted electrodes along her spinal cord, delivering electrical stimulation as she tried different activities. With stimulation, her left arm had greater mobility, her fingers had more dexterity, and she could make intentional movements faster and more fluidly.

The study, published monday in the journal Nature Medicine, represents the first successful demonstration of spinal cord stimulation to treat weakness and paralysis in the arms and hands of stroke patients.

The study was small and preliminary, involving only Ms Rendulic and one other patient. Several scientists said many questions remain about the technique’s effectiveness and applicability, but research suggests that spinal cord stimulation may possibly help some of the many people who have had a stroke.

“I think there are huge implications for improving quality of life,” said Dr. Lumy Sawaki-Adams, program director for the clinical research division of the National Institute of Neurological Disorders and stroke, who did not participate in the research. Still, she said, “we have to be careful not to offer hope to a lot of people when I think we’re not there yet.”

Spinal cord stimulation has been used for decades to treat chronic pain. More recently, experiments providing stimulation – either by surgically implanted electrodes Or non-invasively using electrodes placed on the skin – have shown promise in helping patients with spinal cord injury regain mobility in your legs and, in some cases, their arms and hands.

But the approach has been mostly unexplored for strokes, in part because of differences in the location and type of damage, neurological experts said.

Because strokes occur in the brain, it had been assumed that applying stimulation outside the brain would not provide “the same value for money”, said Arun Jayaraman, executive director of the technology center. and innovation of Shirley Ryan AbilityLab, a rehabilitation center. in Chicago. He said the study, in which he was not involved, contradicted that assumption, suggesting instead that stimulation of the spine, the pathway from the brain to muscles in the hands and arms, could help weakened limbs.

Each year more than 12 million people worldwide And nearly 800,000 in the United States experience a stroke, said Dr. Karen Furie, vice chair of the American Stroke Association’s Stroke Brain Health Sciences Subcommittee.

Initially, patients typically receive about six months of physical, occupational and other therapies, she said, but then progress often leveled off.

“We have next to nothing to offer people who are years away and have long-standing disabilities,” said Dr. Furie, who is also the chair of neurology at Warren Alpert Medical. School of Brown University and did not participate in the study.

About three-quarters of stroke patients have impairment, weakness or paralysis in the arms and hands, said Dr. Elliot Roth, attending physician at the Brain Innovation Center at Shirley Ryan AbilityLab, who was not involved in the study. the study. “For many people, this is the hardest part of the stroke recovery process and tends to recover the slowest,” he said.

The patients who participated in the study had suffered different types of strokes and had varying degrees of impairment. Ms. Rendulic’s stroke was hemorrhagic, caused by the bursting of blood vessels. The other, more severely affected patient, a 47-year-old woman whom the researchers did not identify, suffered an ischemic stroke, which is more common and involves blocked blood vessels.

The researchers implanted strands of eight electrodes in two locations, corresponding to where sensorineural fibers from the arm and hand enter the spinal cord.

Marco Capogrosso, assistant professor of neurological surgery at the University of Pittsburgh, said the approach stems from the fact that with strokes, certain neural areas remain intact.

“So if we can build this technology to amplify neural signals, we might have a chance of restoring movement to arms and hands,” said Dr. Capogrosso, who led the research with assistant professor Elvira Pirondini. of Physical Medicine and Rehabilitation at the University of Pittsburgh and Douglas Weber, Professor of Mechanical Engineering at Carnegie Mellon’s Neuroscience Institute.

Five days a week for four hours each day, the researchers turned on the stimulation, calibrated it to determine the optimal settings for each patient, and asked them to try out various movements and tasks. Immediately, the effect was noticeable.

“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,” Ms. Rendulic said. As her husband and mother looked on, “I immediately opened and closed my hand,” she said. “We all burst into tears.”

For four weeks, he was given increasingly difficult tasks, such as picking up and moving a can of soup. With stimulation, his left hand moved 14 small blocks over a barrier in a box, compared to six blocks without stimulation.

Typically, when Ms. Rendulic, 33, who works from home for a company’s human resources department, tries to get her left hand to do something like grab a pen, her arm feels like it’s is “made of rock”, almost disconnected from her brain, she says. With stimulation, “it felt like my brain was able to find my left arm so much easier.”

The other patient, who was given simpler tasks because her left hand was almost completely paralyzed, improved her skills like reaching.

The researchers also tested ‘mock’ stimulation, activating electrodes at random to see if patients responded to some sort of placebo effect rather than stimulation targeted specifically at their arms and hands. Both performed better with targeted stimulation.

The patients felt the stimulation, but it did not cause pain, stiffness or safety issues, the researchers reported.

The approved study protocol required electrode removal after 29 days. But a month later, the patients retained improved abilities, surprising the researchers. “We thought it wasn’t possible” after just four weeks of stimulation, Dr. Pirondini said.

It’s unclear exactly why the benefit may persist, Dr. Capogrosso said, but he hypothesized that “the same neural processes that enable these people to use this method of stimulation also lead to movement recovery when pacing is off”. He added: “We are not creating new fibers, but we are definitely strengthening what exists.”

Several experts noted that this pilot study was not designed to answer the most relevant question for patients: can improvements in laboratory tasks translate into important skills in daily life?

“It’s a first step of hundreds,” said co-author Dr. Daniel Lu, professor and vice chair of neurosurgery at the University of California, Los Angeles. a 2016 study who showed that stimulation of the spine by implanted electrodes improved hand strength and control in two patients with spinal cord injuries.

Dr Lu said he thought the stimulation showed promise, but its impact in the new study was difficult to assess because there was no comparison group and the patients did not receive the same regimen of intensive activities prior to stimulation – activities that might themselves have therapeutic benefit.

“Is it possible that you just exercised the patient and the patient without the stimulation got the same effect?” He asked.

Another question neuroscientists are asking is whether — or under what circumstances — it’s best to surgically implant electrodes or place them on the skin, a less expensive method called transcutaneous stimulation. The authors of the new study consider surgical implantation to be superior because it is “much more specific”, Dr. Weber said, allowing it to “target the muscles that control the wrist and hand”.

Others, like Chet Moritz, professor of neurotechnology at the University of Washington, have reported improvements in patients with spinal cord injuries. using electrodes on the skin, including benefits that last for months after stimulation ends. “It’s true that we can’t tune the shoulder to this degree and the elbow to this degree and the wrist to this degree, but the nervous system seems to take care of that for us,” he said.

Several neurology experts have predicted that both methods may eventually be useful and appropriate for different patients, depending on their health conditions and other factors. All of the experts, including the study authors, said stimulation would be more effective if accompanied by rehabilitation therapies.

The study authors said their ongoing research is evaluating patients of varying stroke severity, age and other stroke characteristics to determine who would benefit from their approach. They formed a company and said they envisioned that, as with similar technology for chronic pain, patients could adjust their stimulation through an app or remote control.

If stimulation becomes regularly available for stroke patients, Ms. Rendulic would welcome it. “I threatened not to show up for the operation to have it removed,” she said. “I wanted it all the time.”

Though she’s found one-handed ways to do things like drive and type, daily frustrations pile up, like needing her husband Mark, whom she calls “my left arm,” to slice a steak for She.

“During the trial, I was able to cut a steak, which was awesome,” she said. Then, a fork in her left hand, she stabbed a piece and brought it to her mouth – a previously impossible move at a time.