Transcutaneous vagus nerve stimulation prevents the development of, and reverses, established oesophageal pain hypersensitivity

Summary Background The vagus nerve exerts an anti‐nociceptive effect on the viscera. Aim To investigate whether transcutaneous vagal nerve stimulation (t‐VNS) prevents the development of and/or reverses established visceral hypersensitivity in a validated model of acid‐induced oesophageal pain. Methods Before and after a 30‐minute infusion of 0.15M hydrochloric acid into the distal oesophagus, pain thresholds to electrical stimulation were determined in the proximal non‐acid exposed oesophagus. Validated sympathetic (cardiac sympathetic index) and parasympathetic (cardiac vagal tone [CVT]) nervous system measures were recorded. In study 1, 15 healthy participants were randomised in a blinded crossover design to receive either t‐VNS or sham for 30 minutes during acid infusion. In study 2, 18 different healthy participants were randomised in a blinded crossover design to receive either t‐VNS or sham, for 30 minutes after acid infusion. Results Study 1: t‐VNS increased CVT (31.6% ± 58.7 vs −9.6 ± 20.6, P = 0.02) in comparison to sham with no effect on cardiac sympathetic index. The development of acid‐induced oesophageal hypersensitivity was prevented with t‐VNS in comparison to sham (15.5 mA per unit time (95% CI 4.9 ‐ 26.2), P = 0.004). Study 2: t‐VNS increased CVT (26.3% ± 32.7 vs 3 ± 27.1, P = 0.03) in comparison to sham with no effect on cardiac sympathetic index. t‐VNS reversed established acid‐induced oesophageal hypersensitivity in comparison to sham (17.3mA/unit time (95% CI 9.8‐24.7), P = 0.0001). Conclusions t‐VNS prevents the development of, and reverses established, acid‐induced oesophageal hypersensitivity. These results have therapeutic implications for the management of visceral pain hypersensitivity.