Table 1.
Clinical study of taVNS intervention for motor function after stroke.
| Author (reference number) | Sample size (N) | Group | Stimulation site | Stimulation parameters and time | Course of treatment and follow-up | Assessment tools | Effects of taVNS | Type of stroke and motor impairment | Accompanying treatments |
|---|---|---|---|---|---|---|---|---|---|
| Wu et al. [18] | 21 | taVNS group and sham taVNS group | The cymba conchae of the left ear | 600 pulses (20 Hz, each pulse duration 0.3ms), lasting 30 s each, stimulated every 5 min for 30 min per day. The intensity was selected according to the subject's individual body tolerance. | 15 days, 12 weeks | FMA-U, WMFT, FIM, Brunnstrom | taNVS improves upper limb motor function in subacute ischemia stroke patients without obvious adverse effects. | Ischemia stroke; between 0.5 and 3 months postonset; single upper limb motor function impairment | Postural control, proprioception exercises, neuromuscular facilitation, and gait training |
| Zhu Lin et al. [27] | 113 | Control group and observation group | The cymba conchae of the left ear | The current intensity was the maximum value for which the patient did not feel pain. The stimulation interval was 30 s, rest 30 s, and the pulses were set in biphasic waves with 25 Hz and a wave width of 0.1ms for 20–30 min each time, 5 times per week. | 1 month, none | FMA-U, MFAS, MBI | Occupational therapy combined with taVNS regulates the level of norepinephrine, acetylcholine, and dopamine, improve upper limb motor function. | Ischemia stroke; between 0.5 and 3 months postonset; single upper limb motor function impairment | Upper limb motor function and activity participation ability training |
| Redgrave et al. [19] | 13 | None | The concha of the left ear | The intensity was at the patient's maximum tolerance level, with a wave width of 0.1ms and 25 Hz. The stimulation was turned on when the patient began to move their arm, and the movements were repeated more than 300 times per treatment, three times per week. | 6 weeks, none | FMA-U, ARAT, MRS, BI, SIS, Motor Activity Log, PHQ9, GAD7, Fatigue Assessment Scale | taVNS combined with upper limb repetitive movements is feasible, and improves upper limb function. | Ischemia stroke; at least 3 months postonset; upper limb motor function impairment | Large- range arm movements and repetitive task-specific movements training |
| Fioravante Capone et al. [29] | 14 | Randomly divided into sham stimulation group and stimulation group | The left external acoustic meatus at the inner side of the tragus | The pulse frequency was 20 Hz and the pulse duration was 0.3ms, which was repeated every 5 min for 60 min of continuous operation. A current intensity slightly below the patient's pain threshold. | 10 days, 2 weeks | FMA, NIHSS, Rankin Scale, BI, Modified Ashworth Scale | taVNS combined with robotic training is feasible in stroke patients, and slightly improves upper limb function. | Ischemic or haemorrhagic stroke; at least 1 year postonset; hand function impairment | Robotic training delivered at proximal or distal segment of the affected limb according to the degree of impairment |
| Zhang Liping et al. [25] | 42 | Randomly divided into sham stimulation group and stimulation group | The cymba conchae of the hemiplegic side of the body | 20 Hz square wave with a current intensity of 0.5mA. Each session lasted 30 s and was stimulated every 2 min. Each treatment lasted 30 min, once a day, five times a week. | 3 weeks, none | FMA-U, WMFT, FIM | taVNS improves upper limb function with no obvious adverse effects. | Ischemia stroke; within 3 months postonset; hemiplegia | Internal medicine treatment and comprehensive rehabilitation training |
| Li et al. [26] | 60 | Randomly divided into taVNS group and control group | The left auricular cavum conchae | 5 times a week, once for 20 min. 0.3ms square wave at 20 Hz for 30 s, repeated every 5 min. The current intensity (1.71 ± 0.5 mA) was adjusted according to the tolerance of each patient. | 4 weeks, 1 year (as well as 1, 3, and 6 months after the start of treatment) | WMFT, FMA-U, FMA-L, FMA-S, SIS, HADS | taVNS combined with conventional rehabilitation training is safe and effective. | Ischemic or haemorrhagic stroke; within 1 month postonset | Postural control, neuromuscular facilitation and sensory integration exercises |
| Chang et al. [28] | 34 | Sham stimulation group and taVNS group | The left cymba conchae | 30 Hz, with a pulse width of 0.3ms and a current intensity slightly below the patient's pain threshold (0.1–5 mA), 3 times a week for 1 hr each treatment. | 3 days, 3 weeks | FMA-U, MRC, WMFT, MTS | taVNS combined with robotic training improves upper limb function. | Ischemic or haemorrhagic stroke; at least 6 months postonset; upper limb hemiparesis | Robotic training |
| BAIG et al. [20] | 12 | None | The concha of the left ear | Pulse width of 0.1ms, 25 Hz, and pulse amplitude as maximally tolerated by the participant. | 6 weeks, none | FMA-U | taVNS combined with motor rehabilitation may improve sensory recovery. | Ischemia stroke; at least 3 months postonset; upper limb motor function impairment | Repetitive upper limb task training |
Notes: ARAT: Action Recovery Arm Test, BI: Barthel Index, FIM: Functional Independence Measurement, FMA-L: Fugl–Meyer Assessment-Lower Limb, FMA-S: Fugl–Meyer Assessment-Sensory, FMA-U: Fugl–Meyer Assessment-Upper Limb, GAD7: Generalized Anxiety Disorder 7, HADS: Hospital Anxiety and Depression Scale, MBI: Modified Barthel Index, MFAS: Motor Function Assessment Scale, MRC: Medical Research Council Motor Power Scale, MRS: Modified Rankin Scale, MTS: Modified Tardieu Scale, NIHSS: National Institute of Health Stroke Scale, PHQ9: Patient-Health Questionnaire, SIS: Stroke Impact Scale, taVNS: Transcutaneous Auricular Vagus Nerve Stimulation, WMFT: Wolf Motor Function Test.