AB1170 TRANSCUTANEOUS VAGUS NERVE STIMULATION AS A PAIN MODULATOR IN KNEE OSTEOARTHRITIS

Background

We no longer consider Osteoarthritis (OA) as a degenerative disease, but rather as a multifactorial disorder in which low grade, chronic inflammation has a central role. In addition, evidence points to the presence of both peripheral and central nervous system sensitization as sources of pain in OA. Transcutaneous Vagus Nerve Stimulation (tVNS) has shown efficacy on pain, inflammation and central sensitization in other conditions such as fibromyalgia, pelvic pain, and headaches and therefore we hypothesized that tVNS could be an additional line of management for knee OA.

Objectives

To assess the efficacy and safety of tVNS on nociceptive pain, central sensitization, neuropathic pain, depression, anxiety, and physical function in individuals with knee OA.

Methods

Afferents of the auricular branch of vagus nerve were stimulated using an auricular electrode connected to a transcutaneous electrical nerve stimulation (TENS) device. We conducted 30 minutes session once a day for 3 days per week for 12 weeks. Sixty-eight patients with chronic knee OA were allocated randomly into active and sham group (34 patients in each group). The outcome measures included visual analogue scale (VAS), pressure pain threshold (PPT), PainDETECT and Douleur Neuropathique 4 (DN4) questionnaires, hospital anxiety and depression scale (HADS), and knee injury and osteoarthritis outcome score (KOOS). These outcome measures were assessed at baseline, at the end of the stimulation period then after 4 weeks later.

Results

There was a significant improvement in VAS for pain score in the active tVNS group between the baseline and first follow-up visit, and between the baseline and second follow-up visit (P <0.001). The median VAS improvement was 4.0 (3.0 – 5.0) in active group versus 1.0 (1.0 – 2.0) in sham group (p <0.001). PPT in right knee, left knee and right elbow was significantly improved compared to baseline in active tVNS and maintained till 4-weeks post-intervention. On the other hand, in the sham group tVNS, right knee PPT was improved but not maintained. PainDETECT and DN4 questionnaires were statistically improved in active tVNS (p <0.001). In contrast, DN4 questionnaire showed no improvement at all and PainDETECT showed improvement that was not maintained at the end of follow up in sham group. A statistically significant improvement in HADS immediately post intervention in active and sham tVNS (p <0.001), this improvement was maintained only in the active group 4 weeks after intervention. Regarding functional outcomes, the improvement in KOOS was significant in the active group only (31.44 ± 18.49, p > 0.001). No serious adverse events were reported in both study groups.

Conclusion

This study provides preliminary evidence for the beneficial effects of tVNS in OA and raises the possibility of using neuromodulation as an add-on treatment to existing pharmacological and non-pharmacological measures.

REFERENCES:

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Acknowledgements:

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Disclosure of Interests

None Declared.