Vagus Nerve Stimulation Improves Arm Function After Stroke

human brain and vagus nerve stimulation:VNS, image illustration
Researchers aimed to determine whether vagus nerve stimulation paired with rehabilitation is a safe and effective treatment for improving arm function lost after a stroke.

After ischemic stroke, vagus nerve stimulation with rehabilitation is a potential treatment for long-term moderate to severe arm impairment, according to findings of a randomized, triple-blind, sham-controlled study published in The Lancet.

Patients (N=108) with arm impairment after stroke were recruited from 19 sites in the UK and US between 2017 and 2019. Patients were randomly assigned in a 1:1 ratio to receive rehabilitation paired with either active (n=53) or sham (n=55) vagus nerve stimulation.

All participants had a nerve stimulation device implanted. During treatment sessions, all participants received an initial 0.8 mA stimulation that was reduced by 0.1 mA each step. They then completed tasks while they were receiving active or sham stimulation. The active treatment comprised 0.8 mA for 100 ms followed by 30 Hz for 0.5 seconds during each repetition (>300 per session).

Patients in the active and sham groups had a mean age of 59.1±10.2 and 61.1±9.2 years, 64% and 65% were men, and 79% and 78% were White. Stroke had occurred 3.1±2.3 and 3.3±2.6 years previously, paresis was on the left side among 53% and 53%, baseline Fugl-Meyer Assessment-Upper Extremity (FMA-UE) scores were 34.4±8.2 and 35.7±7.8, and Wolf Motor Function Test (WMFT) scores were 2.71±0.70 and 2.83±0.65, respectively.

The first day after treatment, the active group reported an improvement of 2.6 (95% CI, 1.0-4.2; P =.0014) points in FMA-UE scores compared with the sham group. Site location was a significant contributor to these findings (P =.036).

At 90 days, the active treatment group reported an FMA-UE score improvement of 3.0 (95% CI, 0.8-5.1; P =.0077) points compared with the sham group. The change in scores corresponded with 47% of the active and 24% of the sham group reporting a meaningful clinical response (P =.0098).

There was a change from baseline of 0.30 (95% CI, 0.16-0.43; P <.0001) points in WMFT score among the active cohort compared with the sham group at 90 days, in which 57% and 22% had meaningful clinical responses (P <.0001), respectively.

Adverse events were reported by 81% of the active and 76% of sham treatment recipients. Of the 5 severe events, none were attributed to the trial device; however, many participants in both groups reported postoperative pain after device implantation.

The study researchers were not able to determine whether vagus nerve stimulation could be effective for patients with more severe stroke-related symptoms or whether benefits persisted beyond 90 days.

The study authors concluded that vagus nerve stimulation combined with rehabilitation may improve impairment and function. Additional studies are warranted.

Disclosure: Some authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please refer to the original reference for a full list of authors’ disclosures.


Dawson J, Liu CY, Francisco GE, et al. Vagus nerve stimulation paired with rehabilitation for upper limb motor function after ischaemic stroke (VNS-REHAB): a randomised, blinded, pivotal, device trial. Lancet. 2021;397(10284):1545-1553. doi:10.1016/S0140-6736(21)00475-X