Relationships of abdominal pain and reports to visceral and temperature pain sensitivity, conditioned pain modulation, and heart rate variability in irritable bowel syndrome

Authors: JARRETT, M - University Of Washington; HAN, C - University Of Washington; CAIN, K - University Of Washington; BURR, R - University Of Washington; SHULMAN, R - Children'S Nutrition Research Center (CNRC); BARNEY, P - University Of Washington; NALIBOFF, B - University Of California (UCLA); ZIA, J - Washington University School Of Medicine; HEITKEMPER, M - University Of Washington

Submitted to: Neurogastroenterology & Motility
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2016
Publication Date: 7/1/2016
Citation: Jarrett, M.E., Han, C.J., Cain, K.C., Burr, R.L., Shulman, R.J., Barney, P.G., Naliboff, B.D., Zia, J., Heitkemper, M.M. 2016. Relationships of abdominal pain and reports to visceral and temperature pain sensitivity, conditioned pain modulation, and heart rate variability in irritable bowel syndrome. Neurogastroenterology & Motility. 28(7):1094-1103. https://doi.org/10.1111/nmo.12812.
DOI: https://doi.org/10.1111/nmo.12812

Interpretive Summary: Irritable bowel syndrome (IBS) is a common health care problem in the United States, as well as around the world. It is characterized by abdominal pain and alterations in stooling - diarrhea, constipation or both. Why people with IBS have pain remains unclear. It also is not well understood why people with IBS may have different stooling patterns. In this study both healthy adults and those with different stooling types of IBS underwent testing. As a group, people with IBS had stomachs that were more sensitive to pain than healthy adults. However, people with IBS who had a combination of diarrhea and constipation were the most sensitive the different levels of heat applied to the skin. These studies highlight how IBS is a heterogeneous condition and that the symptoms are likely to be caused by different abnormalities in the different subtypes of IBS and different nutritional approaches may be a means to address this.

Technical Abstract: Irritable bowel syndrome (IBS) is a heterogeneous condition with a number of pathophysiological mechanisms that appear to contribute to symptom chronicity. One of these is altered pain sensitivity.Women between ages 18-45 were recruited the community. Of those enrolled, 56 had IBS and 36 were healthy control (HC) women. Participants completed questionnaires, kept a 4-week symptom diary and had a 12-h Holter placed to assess nighttime heart rate variability including high frequency power (HF), low frequency power (LF), and total power (TP). At mid-follicular phase approximately 80% of women completed a thermal pain sensitivity test with conditioned pain modulation and visceral pain sensitivity using a water load symptom provocation (WLSP) test.As expected, daily abdominal pain was significantly higher in the IBS compared to HC group. There were no differences between the bowel pattern subgroups (IBS-diarrhea [IBS-D], IBS-constipation plus mixed [IBS-CM]). Thermal pain sensitivity did not differ between the IBS and the HC groups, but was significantly higher in the IBS-CM group than the IBS-D group. In the WLSP test, the IBS group experienced significantly more symptom distress than HCs and the IBS-CM group was higher than the IBS-D group. Heart rate variability indicators did not differ between the groups or IBS subgroups. Daily abdominal pain was positively correlated with LF and TP in the IBS group.Despite similar levels of abdominal pain in IBS, the IBS-CM group demonstrated greater sensitivity to both thermal and visceral testing procedures.