Perceptual responses in patients with inflammatory and functional bowel disease

Background and aims-Enhanced visceral sensitivity following a transient inf lammatory process in the got has been postulated as an aetiological mechani sm of irritable bowel syndrome (IBS). In this study we compared perceptual responses to rectosigmoid distension in patients with mild chronic inflamma tion of the rectum (ulcerative colitis (UC)) and patients without mucosal i nflammation (IBS) to determine if chronic low grade mucosal inflammation ma y be a plausible explanation for rectosigmoid hypersensitivity reported in both IBS and UC patients. Methods-UC disease activity was quantified using activity index scores. Per ception thresholds for discomfort during rectosigmoid distension were compa red between 11 UC patients with quiescent or mild disease activity, 18 IBS patients, and 13 healthy controls. Results-Although UC activity index scores negatively correlated with percep tual thresholds for discomfort (r=-0.76, p=0.016), UC patients had higher d iscomfort thresholds compared with IBS patients and controls before (p=0.02 ) and after (p<0.001) a noxious sigmoid conditioning stimulus. Conclusions-Rectal perception was attenuated in UC but enhanced in IBS. in chronic mild inflammation, activation of antinociceptive mechanisms may pre vent the development of visceral hyperalgesia. Low grade mucosal inflammati on alone is unlikely to be responsible for symptoms in functional gastroint estinal disorders.