Effect of Transcutaneous Vagus Nerve Stimulation in Erosive Hand Osteoarthritis: Results from a Pilot Trial

Abstract

Beyond its effect on vegetative functions, the activation of the vagus nerve inhibits inflammation and reduces pain signaling. The aim of this open-label pilot study was to determine the efficacy and tolerance of transcutaneous auricular VNS (taVNS) on erosive hand osteoarthritis (EHOA) symptoms. Symptomatic EHOA patients with hand pain VAS ≥ 40/100 mm and ≥1 interphalangeal swollen joint(s) were included. The taVNS was performed for 4 weeks using an auricular electrode applied one hour per day and connected to a TENS device with pre-established settings. Clinical efficacy was evaluated by changes between baseline and at 4 weeks with hand pain VAS and the functional index FIHOA score, using a Wilcoxon t-test. The treatment tolerance was also evaluated. Eighteen patients (median age 69 years old, 83% women) were analyzed. At baseline, hand pain VAS was 60 mm [IQR 50; 78.2] and FIHOA 15 [10.7; 20.2]. After 4 weeks, taVNS significantly reduced hand pain VAS, with a median decrease of 23.5 mm [7.7; 37.2] (p = 0.001), as well as FIHOA, with a median decrease of 2 points [0.75; 5.2] (p = 0.01). No serious adverse events were reported. One patient stopped taVNS because of auricular discomfort. This first proof-of-concept trial indicated that taVNS is feasible and may decrease joint inflammation and clinical symptoms in EHOA, arguing for a randomized controlled study versus sham stimulation.

Keywords: erosive hand osteoarthritis; function; inflammation; pain; vagus nerve stimulation.

Figure 1

TaVNS device kit. Left to right: Description of the cymba concha, a picture of the auricular electrode applied on the cymba concha, a TENSeco2 device, and the conductive gel (copyright Schwa-Medico).

Figure 2

Effect of taVNS on EHOA symptoms. Evolution of (A) hand pain VAS on a 0–100 mm scale, (B) function evaluated by FIHOA, (C) number of painful joints (0–30), (D) number of swollen joints (0–30) of erosive hand osteoarthritis for each of the eighteen patients. Paired, non-parametric Wilcoxon t-test was used. Abbreviations: VAS, visual analog scale; FIHOA, Functional Index for Hand Osteoarthritis.