Scientific title:
Transcutaneous auricular vagus nerve stimulation (tVNS) for upper limb motor recovery in chronic stroke.
University of Sheffield
Principal investigator:
Dr Sheharyar Baig
Grant value:
Research ID:
SA/ABN CRTF 21\100002
Research area:
Start date:
Thursday 6 October 2022
End date:
Sunday 5 October 2025
3 years
Year awarded:

This research project is co-funded by the Stroke Association and the Association of British Neurologists.

Why is this research needed?

More than three-quarters of stroke survivors experience arm weakness. For most survivors, this arm weakness persists despite treatment. At the moment, physiotherapy is the only treatment option, so we need to find ways to make it more effective. One possible way to do this is by stimulating the vagus nerve, a large nerve that has branches throughout most of the upper body, including in the ear and brain.

Vagus Nerve Illustration

Stimulating the vagus nerve during physiotherapy can prompt the brain to rewire itself around the site of the stroke, helping to recover arm strength and movement. However, we don't understand exactly what's going on in the brain, which makes it difficult to predict whether someone will benefit from vagus nerve stimulation during physiotherapy.

What are the aims of this research?

Until recently, stimulating the vagus nerve has required invasive surgery, something that is too risky for many stroke survivors. Sheharyar and his colleagues have been testing out a non-invasive alternative called transcutaneous vagus nerve stimulation (tVNS), which involves stimulating the nerve through the skin of the ear.

Early clinical trials on tVNS have shown that it may be effective as a treatment for arm weakness and is acceptable to the people using it. Sheharyar would now like to understand what changes in the brain during tVNS and who might benefit most from it.

Specifically, Sheharyar plans to:

1 - Look at a variety of brain scan measures before, during and after tVNS. He will assess what is changing in the brain; for example, how much energy the brain cells near the stroke site are using.

2 - Take blood samples from participants before and after tVNS to see whether there are signs of recovery like new blood vessels and brain cells are forming. These measures could potentially be used in the future to see if someone is likely to respond to physio with tVNS over and above standard physio.

What is the benefit of this research?

tVNS has the potential to improve outcomes for stroke survivors doing home-based arm physiotherapy, and Sheharyar's research will help us understand why it works and who will benefit. This information will help clinicians decide whether a particular stroke survivor might benefit from tVNS. It will also help increase confidence among stroke survivors and clinicians in tVNS as a treatment.

Sheharyar says, 'If it's shown to be effective, tVNS could potentially be used to treat millions of stroke survivors around the world with lasting arm weakness. It could also pave the way for tVNS to be tested for other effects of stroke such as aphasia, to see if it helps prevent more long term disability, and whether it could improve recovery in other neurological conditions such as multiple sclerosis.'

What PSP priorities does this research link to?

From 2019 to 2021, we worked with the James Lind Alliance on the Stroke Priority Setting Partnership (PSP). During the PSP process, we collaborated with people with lived experience of stroke and stroke professionals to find out what they thought were the top priorities in stroke research. From this, we identified the top ten priorities in two areas: prevention, diagnosis and short-term care, and rehabilitation and long-term care.

Now, when a researcher applies to us for funding, we require that their work addresses at least one of these priorities.

Sheharyar's project addresses the following priorities:

  • Rehabilitation 7: What is the best time, place and amount of therapy?
  • Rehabilitation 9: What are the best ways to improve strength and fitness, promote recovery and prevent another stroke?

Learn more about how the Stroke PSP worked and get a full list of stroke research priorities.  

Meet the researcher

Sheharyar Baig portrait photo

Dr Sheharyar Baig is a neurologist at the Royal Hallamshire Hospital in Sheffield and has worked on a range of research projects related to stroke, including secondary prevention and exercise interventions. During this PhD project, he will be supervised by Professor Arshad Majid and Professor Li Su of the University of Sheffield.

Sheharyar says, 'As a doctor, I regularly see the impact of stroke which has helped me understand some of the challenges that stroke survivors face. This has motivated me to want to help develop new technologies and treatments that can help recovery from stroke.'