Differences in gastric mechanosensory function after repeated ramp distensions in non-consulters with dyspepsia and healthy controls

Abstract

Background - Abnormal visceral mechanosensory function has been reported in 50% of non-ulcer (functional) dyspepsia patients. However, only a minority of subjects with functional dyspepsia ever seek medical attention. Whether factors promoting health care seeking behaviour explain visceral hypersensitivity is unknown. Decreased rectal thresholds following sigmoid mechanical stimulation have been observed in irritable bowel but this mechanism has not been evaluated in functional dyspepsia. Aims - To compare visceral mechanosensory function in healthy asymptomatic subjects and non-consulters with chronic unexplained dyspepsia. Methods - Forty two volunteers were recruited: 10 had a history of chronic or recurrent upper abdominal pain or discomfort as assessed by a standardized questionnaire, and Helicobacter pylori status was determined (ELISA and 13C urea breath test). Eight H pylori negative, currently asymptomatic dyspeptic subjects who were non-consulters and eight asymptomatic age and sex matched H pylori negative controls were enrolled. With a barostat bag in the proximal part of the stomach, visceral perception thresholds were determined by random tracking. Thereafter, standardized ramp distensions were performed (2 mm Hg increments, duration of each pressure step 30 seconds, maximum pressure 35 mm Hg (or occurrence of pain)) and tracking of sensory thresholds and ramp distension repeated every 30 minutes for a total of two hours. Result - Overall, thresholds for first perception were significantly lower in dyspeptic subjects compared with asymptomatic controls (12.5 (0.6) mm Hg v 17.5 (1.0) mm Hg; p<0.02). After repeated ramp distensions, thresholds for first perception significantly increased by 3.6 (0.7) mm Hg in healthy subjects compared with 0.1 (1.4) mm Hg in subjects with dyspepsia (p<0.05 dyspeptics v controls). Conclusions - (1) Repeated mechanical stimulation increases visceral sensory thresholds in asymptomatic subjects while thresholds remain unchanged in dyspeptics. (2) Visceral hyperalgesia occurs in dyspeptic subjects who are not health care seekers.