Effects and safety of vagus nerve stimulation on upper limb function in patients with stroke: a systematic review and meta-analysis

Vagus nerve stimulation (VNS) is used to deliver electric current to stimulate the vagus nerve. The aim of this study is to carry out a systematic review and meta-analysis to determine its effects on motor function in patients with stroke. PubMED, Embase, Web of Science (WoS), and Scopus were searched. Data on time since stroke, and mean scores and standard deviation on outcomes such as level of impairment and motor function were extracted. The results showed that invasive (MD 2.66, 95% CI 1.19–4.13, P = 0.0004) and non-invasive (MD 24.16, 95% CI 23.56–24.75, P = 0.00001) VNS are superior at improving level of motor impairment than the control post intervention and at follow-up respectively. Similarly, VNS improved motor function post intervention (MD 0.28, 95% CI 0.15–0.41, P < 0.0001); and there was no significant difference in adverse events between invasive VNS and control (OR 2.15, 95% CI 0.97–4.74, P = 0.06), and between non-invasive VNS and control (OR 4.54, 95% CI 0.48–42.97, P = 0.19). VNS can be used to improve motor function in patients with stroke.