Motility Dysfunction in Irritable Bowel Syndrome (IBS)

Motility, or the speed of the contractions of the muscles in the intestinal system, can be a problem in irritable bowel syndrome (IBS). Often, colon contractions are too fast in people with diarrhea-predominant IBS (IBS-D) and too slow in people with constipation-predominant IBS (IBS-C).

Here is what you need to know about mobility, IBS, and what may be going wrong.

Motility Triggers

A variety of common factors trigger changes in motility, whether you have IBS or not. Those that are recognized to speed up or slow down your intestinal contractions are:

• Eating
• Stress
• Emotional reactions
• Hormonal changes (women)

Motility Dysfunction Symptoms

In general, several areas of dysfunction appear when comparing IBS patients to healthy individuals.

Constipation

• There is a decrease in the number of intestinal contractions
• There is a longer time for food to pass through the small intestine and colon, known as transit time
• There is no difference in the time it takes the stomach to empty, known as the gastric emptying rate
• There is an increase in sigmoid (lower end of colon) contractions, perhaps interfering with the flow of stool
• The delay in transit time contributes to the development of small, hard to pass stools
• The delayed transit time contributes to abdominal pain

Diarrhea

• There can be rapid intestinal contractions
• There is a shorter transit time for food through the small intestine and colon
• There is no difference in gastric emptying rate, so food is not leaving the stomach any faster than normal
• There is no difference in stool weight
• The rapid transit time contributes to abdominal pain

Motility as a Diagnostic Tool

Unfortunately, little with IBS ever seems clear-cut. Although research has, for the most part, supported the above trends, there have been some inconsistencies. It may be that the inconsistencies seen in motility research are simply due to difficulties in accurately measuring intestinal contractions.

Unfortunately, this measurement difficulty and the existence of these inconsistent findings prevent the measurement of motility as a definitive tool (biological marker) for an IBS diagnosis.

Future Research on Motility Dysfunction in IBS

The good news is that while motility difficulties made up a large part of early research into IBS, research has since expanded into more complex areas. It is now thought that the motility dysfunction in IBS is entwined with visceral sensitivity issues, both of which are affected by dysfunction in the complex connections between the brain (central nervous system) and the gut (enteric nervous system). This motility dysfunction seems to start as early as the small intestine.

There has also been some additional, early research exploring the gut microbiome's impact on GI motility. While still in the early stages, some research suggests that the gut microbiome may play a role in causing IBS, possibly through a disrupted gut-brain axis (GBA), visceral hypersensitivity (VH), and altered GI motility.

As new clues to the reasons behind the motility dysfunction seen in IBS emerge, this opens the possibility for more effective treatment strategies.