taVNS Paired With Motor Training for Upper-extremity Rehabilitation in Stroke Patients

A Randomized, Double-blind Controlled Trial Investigating the Efficacy of Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) in Improving Upper Extremity Motor Function in Stroke Patients

Background: Recently, there has been increasing attention on the application of transcutaneous auricular vagus nerve stimulation (taVNS) in ischemic stroke. This innovative technique involves non-invasive electrical stimulation of the vagus nerve. A controlled study by Dawson et al. (2021), conducted using a randomized, double-blind approach, has demonstrated that vagus nerve stimulation (VNS) when paired with motor function training, can effectively promote the improvement of motor dysfunction in stroke patients. In the same year, the Food and Drug Administration approved the use of VNS, alongside motor rehabilitation training, for upper extremity dysfunction caused by stroke. However, it is worth noting that VNS requires surgical procedures with contraindications. Consequently, researchers are exploring taVNS as a potential alternative intervention. Compared to VNS, taVNS offers a low-risk and user-friendly intervention that eliminates the need for surgery and the associated postoperative complications. A recent meta-analysis has shown that the efficacy of taVNS in upper extremity rehabilitation for stroke patients can be comparable to that of VNS. Therefore, pairing taVNS with motor training holds promise as a valuable clinical tool for post-stroke rehabilitation.

Methods and Design: This study presents a protocol for a single-center randomized, double-blind controlled trial. A total of 150 participants will be enrolled and randomly assigned to one of three groups (Group 1, Group 2, or Group 3) in a 1:1:1 ratio. Each patient will undergo a total of 14 treatment sessions. In Group 1, patients will receive motor training paired with taVNS. In Group 2, patients will receive motor training and taVNS interventions, seperately. In Group 3, patients will receive motor training paired with sham taVNS. Primary and secondary outcome measures will be assessed at baseline and after taVNS treatment. The primary outcome will be determined by evaluating the behavioral response to treatment, using the Fugl-Meyer Assessment of Upper Extremity (FMA-UE).

Discussion: This study aims to elucidate the role of paired taVNS in the rehabilitation of upper extremity dysfunction in stroke patients. The researchers propose a novel approach by pairing taVNS with individualized training actions, utilizing electromyography (EMG) during motor training to precisely trigger taVNS.

Inclusion Criteria:

• Patients diagnosed with ischemic stroke according to a clinically qualified physician with reference to the Chinese Stroke Prevention and Control Guideline (2021).
• Patients in the acute/recovery phase (after 2 weeks of onset) with stable signs;
• No previous neuropsychiatric-related diseases;
• No significant impairment of cognitive function and able to cooperate in completing the corresponding rehabilitation training;
• With unilateral upper limb dysfunction;
• Patients who have not received various neuromodulation rehabilitation treatments;
• No contraindications to taVNS;
• Patients voluntarily cooperated with the study and signed an informed consent form.

Exclusion Criteria:

• Patients have other mental health disorders (dementia, Parkinson's disease, depression, schizophrenia, bipolar disorder, etc.)
• Patients have uncontrolled epilepsy, i.e., having had a seizure within 4 weeks prior to enrollment
• Patients have cardiac arrhythmias or other abnormalities
• Patients have a history of respiratory disease or disorder, including dyspnea and asthma;
• The presence of gastrointestinal disorders such as diarrhea and vomiting that make it difficult for the patient to cooperate
• Patients have a history of vasovagal syncope
• Patients are under treatment with other neurostimulation/modulation
• The presence of severe spasticity, other serious injuries to the upper extremities, or other medical conditions
• Patients have difficulty in communication and understanding and inability to cooperate in completing the test;
• Women who are pregnant or breastfeeding.