Osteoarthritis, Transcutaneous vagus nerve stimulation, Central sensitization, Functional outcomes, Diseases of the musculoskeletal system, RC925-935

Abstract Background Our understanding of osteoarthritis (OA) has evolved from a degenerative disease to one in which low-grade, chronic inflammation plays a central role. In addition, evidence suggests that OA is accompanied by both peripheral and central nervous system sensitization that can cause pain. It has been demonstrated that transcutaneous vagus nerve stimulation (tVNS) can relieve pain, inflammation, and central sensitization in other conditions including fibromyalgia, pelvic pain, and headaches. We aimed to assess the efficacy and safety of tVNS on nociceptive pain, central sensitization, and physical function in knee OA. Methods In this 12-week study, we stimulated the auricular branch of the vagus nerve with an auricular electrode connected to a transcutaneous electrical nerve stimulation device once a day for 3 days each week for 12 weeks. A total of 68 patients with chronic knee OA were randomly assigned to the active and sham groups (34 patients in each group). We used a variety of outcome measures, including the visual analog scale (VAS), pressure pain threshold (PPT), knee injury and osteoarthritis outcome score (KOOS), PainDETECT (PD-Q) and Douleur Neuropathique 4 (DN4) questionnaires. Outcome measures were recorded at baseline, At the end of the stimulation period, and then after 4 weeks. Results In the active group, compared to baseline, there was a significant improvement in VAS scores between the first and second follow-up visits (P