Vagal Nerve Stimulation in Stroke: Benefit Out to 1 Year

Use of vagal nerve stimulation in combination with intense physical rehabilitation in patients with chronic stroke led to improved hand and arm function, with benefits maintained out to 1 year, latest results from a randomized controlled trial showed.

Study author, Teresa J. Kimberley, PhD, professor of rehabilitation science and physical therapy at MGH Institute of Health Professions in Boston, Massachusetts, described this vagal nerve stimulation intervention as “an extraordinary ray of hope for people with chronic stroke.”

She explained that most of the innovation in the stroke world is being seen in the acute management of the condition. “There has been almost no innovation in the treatment of chronic stroke, but this study included patients between 9 months and 10 years post stroke, and the benefits were similar across this time range.”

The observation that improvements in hand and arm function were maintained out to 1 year was particularly promising, she noted.

“While we did not show much continued improvement after the initial intense treatment period, the fact that the benefits were maintained for a year is a good result,” Kimberley said. “Other long-term chronic stroke studies do not generally show maintenance of benefit over long-term follow-up, and it is usually the case that short-term benefits of rehabilitation interventions are gradually lost over time, with chronic stroke patients generally following a slow downward trajectory function, so these are pretty dramatic and meaningful findings.”

The study is to be presented at the upcoming International Stroke Conference 2024 (ISC 2024) to be held on February 7-9, 2024, in Phoenix, Arizona.

VNS-REHAB

The VNS-REHAB pivotal trial enrolled 108 patients with stroke who had moderate to severe impairment of function of their arm or hand. They were randomized to task-specific rehabilitation plus either active vagal nerve stimulation or sham vagal nerve stimulation.

The initial intervention period consisted of a 6-week intense in-clinic treatment phase followed by a 3-month home exercise program. The groups were then crossed over, so the initial sham group received the same active vagal nerve stimulation treatment combined with physical rehabilitation.

Before and after the stimulation and rehabilitation therapies, motor function was assessed with the Fugl-Meyer Assessment-Upper Extremity (FMA-UE) measurement, which assesses motor impairment, and the Wolf Motor Function Test (WMFT), which is a time-based method to evaluate upper extremity motor ability while providing a better understanding of joint-specific and total limb movements.

Results from this randomized part of the study, which were reported in 2021, showed significant improvements in both these measures with the active vagal nerve stimulation compared with those from the sham treatment.

Both groups continued with an active vagal nerve stimulation home exercise program through 1 year, after which changes from pretherapy baseline in both assessment measures were reported. Data available from 74 participants at 1 year were obtained, with others not available mainly due to the COVID-19 pandemic.

Results at 1 year showed that both FMA-UE and WMFT scores significantly improved from the pretherapy baseline. The FMA-UE score improved by 5.3 points, and WMFT score improved by 0.51 points.

The FMA-UE change at 1 year was not significantly different to the score after the initial randomized period of the trial, but the WMFT score showed an additional 0.09 points improvement.

Kimberley noted that for the home treatment, patients were encouraged to activate the vagal nerve stimulation at the same time as they were using or exercising their hand or arm (up to four times a day). She explained that the nerve stimulation is thought to boost the effects of physiotherapy or exercise, so the patient is asked to activate the nerve stimulation process before a half hour exercise session or when they may be using their arm in everyday activities.

She pointed out that the two measures used in the study evaluated different domains of function; the FMA-UE score assesses the severity of the impairment, while the WMFT score is a measurement of activity. Patients were also assessed for quality of life.

“The remarkable thing about this study is that the findings are consistent across all these three domains. People got better in the impairment measure, the activity measurement, and the quality-of-life measures, which suggests that these findings really are robust,” she commented.

“We know from the literature how much of a change in each of these scores is considered clinically meaningful, and roughly 50% of all people experienced clinically meaningful improvements in both the FMA and WMFT scores,” she added.

Kimberley said the positive results were all the more remarkable given that the study was conducted over the COVID pandemic. “I would imagine that the isolation, anxiety, and changes in activity levels that occurred in the COVID period may have had an adverse effect, but we were still able to show that the initial improvement was maintained.”

She pointed out a previous pilot trial, which involved just 15 patients, now has follow-up out to 3 years and that has shown people continued to improve over the long term.

The technology consists of an electrode implanted in the neck and a pulse generator implanted in the chest wall. Kimberley said patients should be able to use the nerve stimulation treatment for the rest of their lives, but the battery may need to be changed after a few years.

The device used in this study, the Vivistim (MicroTransponder), was approved by the US Food and Drug Administration (FDA) for use in patients with stroke in 2021. It is so far the only vagal nerve stimulation device indicated for stroke, although there are similar devices used for the treatment of epilepsy and for depression.

Patients in this trial had moderate to severe impairment of hand/arm function, but they had to have some hand or arm movement. Patients with no function at all in their hand or arm were not included. Similarly, people with only mild impairments were excluded, as it was thought they probably wouldn’t want to undergo this surgery.

Kimberly reported that there are 7 million people in the United States living with chronic stroke, 75% of whom are believed to have some hand or arm impairment. “I would estimate that at least half of these patients may qualify for this treatment. That’s a lot of people,” she commented.

But she added that most patients with stroke do not know about this new treatment, and even stroke neurologists are often unaware of this new therapy.

Long-Awaited Data

Commenting on the study, Joel Stein, MD, chair of the Department of Rehabilitation and Regenerative Medicine at Columbia University’s Vagelos College of Physicians and Surgeons, New York City, said the stroke rehabilitation world has been waiting for quite some time for a therapy to be proven effective in this fashion.

“We have had a lot of candidates, a lot of forms of potentially stimulating the brain to encourage it or help it recover, but this is the first treatment that really has met the bar to become an FDA-approved treatment to facilitate recovery after stroke. And that’s terribly important,” he stated.

“It’s important both as a practical matter for stroke survivors who are looking for something that will help them recover more. And it also is really establishing a new field in some sense in medicine where we now have a way to help restore function after stroke through novel means that we never had before. So, this is really the first, hopefully, of a number of treatments like this,” he added.

Stein said this vagal nerve stimulation intervention is now available in many centers in the United States, and he expects increasing numbers of people to pursue it as a treatment.

He reported that in his own practice, a number of patients have asked whether they could be a candidate, and several of them have been. “And so, we’re excited to now be able to offer something that is really new and impactful in their lives.”

The VNS-REHAB study was sponsored by MicroTransponder. Kimberley reported no disclosures.

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