What is the pathophysiology of altered GI motility in irritable bowel syndrome (IBS)?

Updated: Dec 11, 2019
  • Author: Jenifer K Lehrer, MD; Chief Editor: BS Anand, MD  more...
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Answer

Altered GI motility includes distinct aberrations in small and large bowel motility.

The myoelectric activity of the colon is composed of background slow waves with superimposed spike potentials. Colonic dysmotility in irritable bowel syndrome manifests as variations in slow-wave frequency and a blunted, late-peaking, postprandial response of spike potentials. Patients who are prone to diarrhea demonstrate these alterations to a greater degree than patients who are prone to constipation.

Small bowel dysmotility manifests in delayed meal transit in patients prone to constipation and in accelerated meal transit in patients prone to diarrhea. In addition, patients exhibit shorter intervals between migratory motor complexes (the predominant interdigestive small bowel motor patterns).

Current theories integrate these widespread motility aberrations and hypothesize a generalized smooth muscle hyperresponsiveness. They describe increased urinary symptoms, including frequency, urgency, nocturia, and hyperresponsiveness to methacholine challenge.


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