Transcutaneous Vagus Nerve Stimulation Improves Motor Function of Upper Extremity in Adults with Chronic Ischemic Stroke: A Randomized Controlled Trial.

BackgroundUpper limb motor dysfunctions are common after stroke affecting daily activities. About 60% of survivors still have impairment despite rehabilitation.ObjectiveTo assess the effect of transcutaneous auricular vagal nerve stimulation (taVNS) on upper limb motor function in chronic stroke patients.MethodsForty patients with chronic ischemic stroke in the middle cerebral artery territory were randomly assigned equally to; real group received 30 min of real taVNS followed by 30 min of upper limb exercises and sham group received identical program with sham taVNS. Intervention was conducted three sessions / week for four weeks. Upper extremity motor functions; Isometric (shoulder abductor, elbow flexors) and isokinetic (elbow flexors, extensors) muscle strength; and hand grip were evaluated through Fugl-Meyer Assessment for upper extremity (FMA- UE), Biodex system, and electronic hand dynamometer, respectively pre and post intervention.ResultsPost-intervention between-group comparisons favored real taVNS for FMA-UE (MD = 3.95, 95% CI 0.21-7.69), IMSA (MD = 4.78, 95% CI 1.89-7.66), IMEF (MD = 4.16, 95% CI 1.02-7.30), IKEE (MD = 5.34, 95% CI 3.23-7.61), and IKEF (MD = 4.72, 95% CI 2.71-6.72, p < 0.05). The HG improved significantly within the real taVNS group; however, the between-group difference was not significant (MD = 1.33, 95% CI -1.21 -3.85, p = 0.297).ConclusionstaVNS was associated with significant between-group improvements in upper-limb motor function and shoulder and elbow muscle strength. Clinical relevance of FMA-UE should be interpreted cautiously because its 95% CI was below the reported minimal clinically important difference.