Experimental human pain models in gastro-esophageal reflux disease and unexplained chest pain

Figure 5 Stimulus-response function (mean ± SEM) to mechanical stimulation in patients with non-erosive gastro-esophageal reflux disease (NERD). The controls (■, n = 15) and patients with a normal 24-h pH-profile (▲, n = 7) had similar response to the mechanical stimulation, whereas patients with pathological pH-profile (◊, n = 6) showed hypoalgesia to the stimulations. The x-axis shows the volume of the balloon in the distal esophagus and the y-axis denotes the pain response on a visual analogue scale (VAS) with 5 as the pain threshold.