Technique helps stroke patient to recover hand movement – 02/24/2023 – Health

Heather Rendulic was 23 when she suffered a stroke that left her left side paralyzed. Ten years later, her left arm and hand remain so damaged that she cannot tie her shoes, type with two hands or cut her own food.

But during one extraordinary month, while participating in a groundbreaking study, she suddenly managed to open a lock with a key, draw a map of Italy, dip a chicken nugget in sauce and eat it with a fork — all with her left hand. .

“It was like I actually had two arms. Oh my God!” Rendulic said recently.

Researchers at the University of Pittsburgh and Carnegie Mellon University implanted electrodes along her spinal cord, providing electrical stimulation as she attempted different activities. With the stimuli, her left arm gained mobility, her fingers had more dexterity, and she was able to make purposeful movements more quickly and fluidly.

The study, published Monday in 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 Rendulic and one other patient. Several scientists said there were still many questions about the technique’s effectiveness and applicability, but that research suggested that spinal cord stimulation could eventually help some of the many people who suffer strokes.

“I think there are huge implications for improving quality of life,” said Lumy Sawaki-Adams, program director in the clinical research division of the National Institute of Neurological Disorders and Stroke, who was not involved in the research. Still, she said, “we must be careful not to offer too many people hope when I don’t think we’re there yet.”

Spinal cord stimulation has been used for decades to treat chronic pain. More recently, experiments that provide stimulation—through surgically implanted electrodes or non-invasively with electrodes placed on the skin—have shown promise in helping patients with spinal cord injuries regain mobility in their legs and, in some cases, , on the arms and hands.

But the approach has been largely unexplored for stroke, in part because of differences in the location and type of damage, neurology experts said.

Because strokes occur in the brain, it was assumed that applying stimulation outside the brain would not give “the same return,” said Arun Jayaraman, executive director of the technology and innovation center at the Shirley Ryan AbilityLab, a rehabilitation center in Chicago. . He said the study, in which he was not involved, contradicts that assumption, suggesting that stimulating the spine, the brain’s pathway to hand and arm muscles, can help weakened limbs.

Each year, more than 12 million people worldwide — nearly 800,000 in the United States — suffer strokes, said Karen Furie, vice chair of the brain health sciences subcommittee of the American Stroke Association.

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

“We have virtually nothing to offer people who have been sick for years and have longstanding disabilities,” said Furie, who is also chair of neurology at Brown University’s Warren Alpert School of Medicine and was not involved in the study.

About three-quarters of stroke patients have impairment, weakness or paralysis in the arms and hands, said Dr. Elliot Roth, MD, assistant physician at the Brain Innovation Center at the Shirley Ryan AbilityLab, who was not involved in the study. “For many people, it’s the most difficult part of the stroke recovery process and tends to be the slowest.”

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

The researchers implanted eight-electrode wires in two locations, corresponding to where the neurosensory 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 derives from the fact that in strokes some neural areas remain intact.

“So if we can build this technology to amplify neural signals, maybe we have a chance to restore arm and hand movement,” said Capogrosso, who led the research with Elvira Pirondini, assistant professor of physical medicine and rehabilitation at the University of of Pittsburgh, and Douglas Weber, professor of mechanical engineering at the Neuroscience Institute at Carnegie Mellon University.

Five days a week, for four hours a day, the researchers turned on the stimulation, calibrated it to determine optimal parameters for each patient, and asked them to try various movements and tasks. The effect was immediately 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 a very difficult thing for me,” Rendulic said. As her husband and mother looked on, “I immediately opened and closed my hand,” she said. “We all started crying.”

Over the course of four weeks, she was given increasingly challenging tasks, such as holding and moving a can of soup. With stimulation, her left hand moved 14 small blocks over a barrier in a box, compared to six blocks without stimulation.

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

It’s not clear exactly why the benefit might persist, Capogrosso said, but he hypothesized that “the same neural processes that allow these people to use this method of stimulation also lead to a recovery of movement when the stimulation is turned off.” He added: “We’re not creating new fibers, but we’re definitely reinforcing the ones that already exist.”

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

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

Lu said he believed the stimulation held promise, but that 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 before stimulation — activities that may have therapeutic benefits.

“Is it possible that you are just exercising the patient, and the patient without the stimulation would have had the same effect?” he asked.

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

The study authors said their ongoing research is evaluating patients with various stroke types, age and other 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 via an app or by remote control.

If stimulation became available regularly for stroke patients, Rendulic would adopt it. “I threatened not to go into surgery to have it removed,” she said. “I wanted you to stay all the time.”

^{Translated by Luiz Roberto M. Gonçalves}