Alterations in colorectal motility and sensation in irritable bowel syndrome (IBS), and other functional bowel disorders
| Measurement | Major findings |
|---|---|
| Myoelectric activity | Increased long spike bursts in IBS diarrhea; irregular short spike burst activity in IBS constipation; myoelectric activity similar in IBS and “psychologic” controls and reported increase in 3 cycles/minute activity in IBS not confirmed. |
| Contractile activity and tone | Increased colonic phasic contractions postprandially in patients with IBS with prominent gastrocolonic reflex; increased colonic contractions in IBS constipation, reduced contractions in IBS diarrhea; lower rectosigmoid motility index in IBS diarrhea than controls, fasting and postprandially; increased rectosigmoid response to distension in IBS diarrhea > IBS constipation > controls; increase in high amplitude propagated (>35 mm Hg) contractions in functional diarrhea; fasting and postprandial colonic (descending) tone normal in IBS; impaired adaptive relaxation of the rectum in IBS in response to chronic distension. |
| Compliance | Rectal and colonic compliance normal overall in IBS. |
| Transit | Accelerated and delayed whole gut transit in IBS diarrhea and IBS constipation respectively; more rapid emptying of right hemi-colon in IBS diarrhea than in controls, related to stool weight; delayed colonic transit in severe functional constipation. |
| Colorectal sensitivity | |
| Conscious perception | Reduced threshold for pain and discomfort in rectum and colon in IBS; unusual somatic referral pattern. |
| Cerebral blood flow | Increased dorsolateral prefrontal cortex blood flow in anticipation of rectal pain in IBS. |
Modified from Drossman et al,14 with permission.
For references to relevant studies, see Chapter 3, tables 6 and 7. In: Drossman D, ed. Rome II: The functional gastrointestinal disorders. McLean, VA: Degnon, 2000 (in press).