Altered esophageal pain threshold in irritable bowel syndrome

Gut motility disorders and altered pain perception were reported in patients with irritable bowel syndrome (IBS). To verify foregut involvement in IBS, we studied 30 patients using esophageal manometry and 24-hr pH monitoring of the distal esophagus. Two subgroups of patients underwent esophageal provocative tests (bethanechol 50 micrograms/kg subcutaneously and esophageal balloon distension test). Twelve healthy volunteers formed a control group. A pain threshold on esophageal distension significantly lower than in healthy subjects (11.5 +/- 1 ml vs 22.2 +/- 1.7 ml, P < 0.01) was found in IBS patients. On the other hand, no differences between patients and controls were detected in lower esophageal sphincter pressure and length, esophageal body motility, or GER pattern; furthermore, bethanechol stimulation elicited similar esophageal body motility changes. Our study could confirm no detectable basal or bethanechol-induced esophageal motility disorders in IBS patients, nor enhanced GER. Esophageal involvement in IBS consists of a lower pain threshold on esophageal distension, possibly reflecting an altered visceral receptor sensitivity or modulation throughout the gut.