Researchers from the Hong Kong Polytechnic University found that both transcutaneous vagus nerve stimulation (tVNS) and transcutaneous spinal cord stimulation (tSCS) are promising adjuncts to exercise for improving cognitive and upper limb function after stroke.
According to the authors, the study was the first randomized, sham-controlled clinical trial to investigate the effects of tVNS and tSCS, combined with upper limb exercise, on cognitive function and upper limb motor function in stroke patients. The three-arm, single-blind, parallel-group trial conducted between 2023 and 2025 included 90 Hong Kong community-dwelling people (mean age, 65.12 years) who were diagnosed with first-ever stroke or recurrent stroke on the same side at least 6 months prior, and had volitional control of the non-paretic arm and at least minimal antigravity movement of the paretic shoulder, defined as at least 5 degrees of shoulder flexion or abduction without support or assistance, measured by goniometer. [GeroScience 2026;doi.org/10.1007/s11357-026-02351-3]
The subjects were randomly assigned to receive 18 sessions of either tVNS, tSCS, or sham stimulation, each delivered concurrently with upper limb exercises for 45 minutes, three times per week, for 6 weeks. The primary outcomes were global cognition assessed with the Montreal Cognitive Assessment (MoCA), and upper limb motor impairment assessed with the Fugl-Meyer Assessment for Upper Extremity (FMAUE), measured at baseline, after nine and 18 sessions, and at 1 month after the intervention.
Subjects in the tVNS and tSCS groups demonstrated significantly greater improvements than those in the sham group in global cognition and upper limb motor impairment (mean differences vs sham: MoCA score, 2.37 and 1.77, respectively; p<0.001; FMAUE score, 3.37 and 2.10, respectively; p<0.001 and p=0.007, respectively) after the intervention. Improvements in cognition persisted for 1 month in both groups, as indicated by within-group changes from post-intervention to follow-up assessments, whereas motor improvements were sustained only in the tVNS group.
Compared with sham stimulation, tVNS, in particular, led to greater improvements in upper limb functional performance, while tSCS resulted in greater improvements in working memory and muscle strength of elbow extensors. However, no significant between-group differences in participation, activity, and health-related quality of life were observed after the intervention.
“As all groups received the same upper limb exercise programme, these findings reflect the additive effects of tVNS or tSCS rather than stimulation alone. This distinction is crucial for interpreting the magnitude and clinical relevance of the observed benefits,” noted the authors.
“Given the limited sample size and absence of direct physiological measures, these findings should be interpreted as preliminary,” the authors further noted. “[Nevertheless], the findings support the potential of noninvasive neuromodulatory interventions as an adjunct to rehabilitation in stroke,” they concluded.