BY ED SUSMAN
HOUSTON—The use of vagus nerve stimulation to help patients who have limited arm movement had mixed but promising results in a blinded, randomized sham-controlled trial, researchers reported here on Friday at the 2017 International Stroke Conference sponsored by the American Heart Association/American Stroke Association.
The randomized trial failed to achieve its primary endpoint — a clinically meaningful change in scores in the upper-limb Fugl-Meyer scale, which assesses motor recovery, sensory functioning, balance, joint range of motion, and joint pain, after stroke — 30 days after vagus nerve stimulation. [Motor scores ranges from 0 (hemiplegia) to 100 points for normal motor performance.] But at 90 days, there were significant differences in the Fugl-Meyer scale between those who received the active and sham treatments, said Jesse Dawson, MD, a consultant at the Institute of Cardiovascular and Medical Services of the University of Glasgow in Scotland.
At 90 days, patients getting the stimulation showed a significant improvement of 9.5 points on the Fugl-Meyer score compared to an improvement of 3.8 points for those patients getting a sham treatment.
The research team enrolled patients who had experienced an ischemic stroke and had severe arm weakness four months to five years after the initial event. The patients were assessed at one day, 30 days, and 90 days after completing six weeks of rehabilitation training and home exercise. Eight patients were fitted with vagus nerve stimulators, but the devices in nine control patients were not turned on until after the study was completed.
Despite the failure to achieve the study's primary endpoint, Dr. Dawson said that the other secondary endpoints were good enough to encourage the researchers to plan a 120-patient pivotal study, which will begin recruiting in the summer.
He noted that experimental models indicated that vagus nerve stimulation improved outcomes in animals with various types of strokes. In a previous 20-patient pilot study, it appeared that motor function improved, suggesting that the treatment was feasible and that it warranted moving forward to the current trial.
"We have seen that the results of vagus nerve stimulation are consistent across two small trials," he said at a news briefing prior to his presentation. "This technique is acceptably safe and in-clinic and home-based vagus nerve stimulation is feasible."
Commenting on the study, Philip Gorelick, MD, MPH, FAAN, medical director of the Hauenstein Neuroscience Center and clinical professor of translational science at Michigan State University College of Human Medicine in Grand Rapids, said the study is very promising, but a lot more work is needed.
"Arm movements are very critical to better functional outcome for our patients, so this is a great target," he said. "I'd like to see a quality-of-life study on this project, specifically to determine if this improvement helps patients to do things with their fingers, rather than just move their arm more," said Dr. Gorelick.
Functional magnetic resonance imaging studies would be helpful as well, he said, "so we can understand how the brain is reorganizing when it receives these stimulations."
Dr. Dawson said the Canadian group is planning to conduct these studies with the next trial.
The study was funded by Micro Transponder, Inc.
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