Vagus nerve magnetic modulation facilitates dysphagia recovery in patients with stroke involving the brainstem - A proof of concept study

Stroke involving the brainstem (SBS) causes severe oropharyngeal dysphagia (OD). Research on the therapeutic efficacy of vagus nerve modulation (VNM) by using repetitive transcranial magnetic stimulation (rTMS) in SBS patients with OD has been limited thus far. We aimed to assess the effect of VNM by using rTMS in improving swallowing function after SBS.We conducted a sham-controlled, double-blinded, parallel pilot study in 28 SBS patients with OD randomly allocated to a real rTMS group (n = 13; TMSreal) or a sham group (n = 15; TMSsham). For VNM, 5-Hz rTMS was applied to the left mastoid in 10 sessions. We evaluated all patients for swallowing function before and after rTMS conditioning, assessed on the 8-point Penetration-Aspiration Scale (PAS) through videofluoroscopy and the Australian Therapy Outcome Measures-Swallowing scale (AusTOMs). We measured the amplitude and latency of cricopharyngeal motor evoked potentials (CP-MEPs) as the neurophysiological parameters.TMSreal exhibited significant improvement in all swallowing outcomes-neurophysiological, radiological, and functional-compared with TMSsham: We noted higher CP-MEP amplitude (p = 0.004), shorter CP-MEP latency (p = 0.004), a lower PAS score (p = 0.001), and a higher AusTOMs score (p < 0.001) following rTMS in TMSreal. Moreover, the neurophysiological improvements were significantly correlated with the functional outcomes (p < 0.05).Our results encourage the application of VNM by using rTMS for improving swallowing function after SBS. The immediate therapeutic effects suggest that this novel intervention can be an effective complementary therapy to traditional oropharyngeal rehabilitation.URL: https://www.clinicaltrials.gov. Unique identifier: NCT02893033.