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 < 0.05 multivariate analysis of variance). In the control group, itch remained unaltered in all three sessions (26 +/- 5% at baseline, 23 +/- 5% in the second session, and 25 +/- 5% in the third session, not significant). The flare was unaltered in both patients and control subjects.


CONCLUSIONS
VNS may suppress pruritus in humans.
Kirchner
A
A
Neurologische Klinik, Friedrich-Alexander-Universität Erlangen, Germany. annette.kirchner@neuro.imed.uni-erlangen.de
Stefan
H
H
Schmelz
M
M
Haslbeck
K M
KM
Birklein
F
F
D000328:Adult; D004599:Electric Stimulation Therapy; D004827:Epilepsy / Q000628:therapy; D005260:Female; D006632:Histamine / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D007478:Iontophoresis; D008297:Male; D011537:Pruritus / Q000139:chemically induced / Q000628:therapy*; D014630:Vagus Nerve / Q000502:physiology*
D006632:Histamine