Influence of vagus nerve stimulation on histamine-induced itching

Objective: To investigate whether vagus nerve stimulation (VNS) reduces pruritus in humans. Background: Recently, it has been shown that VNS has antinociceptive and antidepressant effects in humans. Methods: Eleven patients were investigated before (baseline) and during chronic VNS treatment. The experiments were performed at two different stimulation intensities: 2 to 5 days after implantation at a low stimulation intensity (mean intensity 0.7 ± 0.2 mA, second session) and after 8 to 14 weeks of VNS therapy (mean intensity 1.4 ± 0.3 mA, third session). Twelve healthy age- and sex-matched subjects were investigated using the same experimental protocol. Itch was induced by histamine–iontophoresis and quantified on a visual analogue scale (VAS). Histamine-induced flare was quantified using laser–Doppler flowmetry. Results: Itch was reduced by VNS from 24 ± 8% VAS at baseline to 15 ± 5% VAS at second session, and 19 ± 8% VAS at third session ( p Conclusions: VNS may suppress pruritus in humans.