Results from a new study looking at vagus nerve stimulation could be the biggest advancement for stroke rehabilitation in decades for patients with arm weakness.
The study carried out by researchers at the MGH Institute of Health Professionals has reported that stroke survivors who incorporated vagus nerve stimulation during physical or occupational therapy showed two to three times the improvement in the arm and hand function compared to those who received intense rehab with ‘sham’ stimulation.
Many stroke survivors are left with upper extremity motor deficits that persist for months or years. These findings suggest they may be able to improve upper motor function in stroke survivors and help them perform everyday tasks once again.
The results have been published in The Lancet.
The vagus nerve
The vagus nerve, which is the longest cranial nerve, controls both sensory and motor functions – reaching from the brain stem down to the colon. It provides sensory information from organs such as the heart and lungs, as well as playing a role in taste, and controls motor functions in the oesophagus and intestines, for example.
For the study, 108 patients, who ranged from nine months to ten years post-stroke, were implanted with a vagus nerve stimulation (VNS) system called Vivistim. They received stimulation of the nerve through a small electrical pulse from a cuff wrapped around the nerve, powered by a unit implanted under the skin near the clavicle. This was done over a period of six weeks of in-clinic therapy followed by three months of home-based therapy. The pulse, delivered during their rehabilitation exercises, helps the brain relearn how to perform tasks such as carrying a grocery bag, using a fork, or casting a fishing line.
Improving upper motor function
Results of a study co-authored by MGH Institute of Health Professions researcher Teresa Kimberley, PhD, PT, have the potential to be one of the most impressive advances in decades to help improve the lives of patients who have had a stroke with resulting arm weakness.
“How to optimise recovery after a stroke has been studied for decades, but there has been little shown to dramatically improve people’s daily lives,” said Dr Teresa Kimberley, who is a senior author on both the pilot and pivotal vagus nerve stimulation studies, directs the MGH Institute’s Brain Recovery Lab, and is a professor of physical therapy at the Boston health sciences graduate school. “Using vagus nerve stimulation paired with repetitions of therapeutic movement appears to help ‘rewire’ the brain to strengthen the brain pathways needed to perform the everyday tasks people want to be able to do. This may be an important new tool to improve people’s lives.”
“We are only beginning to understand how to best stimulate the brain to regain function. Rehabilitation has always been the key to maximising recovery after a stroke. Brain stimulation, including methods such as vagus nerve stimulation, may make rehabilitation activity even more impactful and lead to greater gains than we previously thought possible for people with neurologic disorders.”
There were no reports of unexpected or serious adverse events associated with the Vivistim system, which is produced by MicroTransponder, Inc., which also funded the study.