Effect of vagus nerve magnetic stimulation on cognitive function in patients with subacute stroke: A functional near-infrared spectroscopy study

to study the efficacy of vagus nerve magnetic stimulation(VNMS) on cognitive function in patients with subacute stroke.

A single-blind, prospective, randomized controlled trial was conducted to evaluate the efficacy of VNMS on cognitive dysfunction in patients with stroke in the subacute phase. The study enrolled 40 participants with cognitive dysfunction following ischemic or hemorrhagic stroke in the subacute phase, and participants were randomly assigned to two groups: the VNMS  and the sham VNMS. All groups were received 10 interventions over a two-week period, with five sessions per week. Assessments were conducted by investigators blinded to group assignment at baseline and post-intervention. The Montreal cognitive assessment-Beijing (MoCA-B), The Digit Span Test (DST), and The Auditory Verbal Learning Test (AVLT) were used to measure cognitive function before and after the VNMS treatment. functional Near-infrared spectroscopy (fNIRS) was employed to identify network connectivity and cerebral activation in two groups of patients prior to and following the intervention.

There was no significant difference in MoCA-B, DST and AVLT scores between the two groups of stroke patients before the intervention. However, after treatment, the overall MoCA-B scores of the two groups showed a significant difference (p=0.049), as evidenced by improvements in visuospatial and executive functions (p=0.029), naming (p=0.019), language (p=0.020) and delayed memory (p=0.001), and the AVLT also showed a significant difference (p=0.025). Stroke patients showed significant differences in the functional connectivity of the right premotor and supplementary motor areas (rpSMC) with the right frontal eye fields (rFEF), the left temporal polar area (lTPA), the right dorsolateral prefrontal cortex (rDLPFC) and the left ventral lateral prefrontal cortex (lTPA) with the cortical areas of the left frontal eye fields (lFEF).

VNMS improves cognitive function, especially memory, in stroke patients in the subacute phase. VNMS was found to result in increased functional connectivity between the bilateral cerebral hemispheres as measured by fNIRS.

This study, which is the first study to investigate the feasibility of VNMS for cognitive dysfunction with stroke patients. Our findings offer the possibility of rTMS applied to vagus nerve in clinical practice.