Introduction: Cognitive and upper limb impairments are common following stroke. While transcutaneous electrical nerve stimulation, including transcutaneous vagus nerve stimulation (tVNS) and transcutaneous spinal cord stimulation (tSCS), are potential interventions to alleviate cognitive decline and promote motor recovery by activating neurotransmitter systems, current evidence remains inconclusive in people with stroke. Investigating the effects of tVNS and tSCS may clarify their therapeutic value and support the development of convenient and effective rehabilitation strategies in a clinical setting for people with stroke. Objective: This randomized controlled trial aimed to (1) investigate the effects of tVNS and tSCS and (2) compare their efficacy on improving cognitive function and upper limb motor function in people with stroke. Methods: Ninety people with chronic stroke were randomly allocated to receive 18 sessions of either tVNS, tSCS, or sham-stimulation concurrent with upper limb exercises for 45 minutes in each session, three sessions per week, for 6 weeks. Two main primary outcomes were the Montreal Cognitive Assessment (MoCA) and Fugl-Meyer Assessment for Upper Extremity (FMA-UE). Results: tVNS and tSCS groups demonstrated significantly greater improvement in the MoCA (mean difference: 1.18 and 0.88, respectively; p <0.001), FMA-UE (mean difference: 1.68 and 1.05; p <0.001 and p =0.007, respectively), and Rivermead Behavioural Memory Test (mean difference: 6.02 and 5.05, respectively; p <0.001) than the sham group after the intervention. Also, tVNS induced a greater improvement in the Wolf Motor Function Test (mean difference: 1.50; p <0.001), and tSCS induced a greater increase in the muscle strength of the elbow extensor (mean difference: 0.70; p <0.001) compared to sham-stimulation. These improvements were maintained for 1 month, but tVNS group demonstrated significantly higher FMA-UE score than tSCS group (mean difference: 0.66; p =0.010) 1 month after the cessation of intervention. Conclusions: tVNS and tSCS are both superior to sham-stimulation in improving cognitive function and upper limb motor function after stroke when combined with upper limb exercises, but tVNS seems to have a more persistent effect on upper limb motor recovery compared to tSCS. These interventions offer a safe, cost-effective, and readily transferable therapeutic approach to clinical practice to manage post-stroke cognitive and motor impairment.
Chan et al. (Thu,) studied this question.