Brief Articles
Copyright ©2009 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Jul 14, 2009; 15(26): 3254-3260
Published online Jul 14, 2009. doi: 10.3748/wjg.15.3254
Thermal hypersensitivity in a subset of irritable bowel syndrome patients
QiQi Zhou, Roger B Fillingim, Joseph L Riley III, G Nicholas Verne
QiQi Zhou, G Nicholas Verne, Department of Medicine, Ohio State University, Columbus, Ohio 43210, United States
Roger B Fillingim, Joseph L Riley III, College of Dentistry, University of Florida, Gainesville, Florida 32610, United States
Roger B Fillingim, North Florida/South Georgia Veteran Health System, Gainesville, Florida 32610, United States
G Nicholas Verne, Research Service, Cincinnati VAMC, Cincinnati, Ohio 45220, United States
Author contributions: Zhou Q and Verne GN performed all of the experiments and wrote the majority of the manuscript; Fillingim RB and Riley JL helped to edit the manuscript and provided support in the analysis of the data.
Correspondence to: G Nicholas Verne, MD, Division of Gastroenterology, Hepatology, and Nutrition, Ohio State University, 288A Office Tower, 395 West 12th Avenue, Columbus, OH 43210, United States. ginick@gmail.com
Telephone: +1-614-3667095
Fax: +1-614-2476924
Received: January 16, 2009
Revised: May 11, 2009
Accepted: May 18, 2009
Published online: July 14, 2009
Abstract

AIM: To characterize thermal hypersensitivity in patients with constipation- and diarrhea-predominant irritable bowel syndrome (IBS).

METHODS: Thermal pain sensitivity was tested among patients with diarrhea-predominant IBS (D-IBS) and constipation-predominant IBS (C-IBS) compared to healthy subjects. A total of 42 patients (29 female and 13 male; mean age 27.0 ± 6.4 years) with D-IBS; 24 patients (16 female and eight male; mean age 32.5 ± 8.8 years) with C-IBS; and 52 control subjects (34 female and 18 male; mean age 27.3 ± 8.0 years) participated in the study. Thermal stimuli were delivered using a Medoc Thermal Sensory Analyzer with a 3 cm × 3 cm surface area. Heat pain threshold (HPTh) and heat pain tolerance (HPTo) were assessed on the left ventral forearm and left calf using an ascending method of limits. The Functional Bowel Disease Severity Index (FBDSI) was also obtained for all subjects.

RESULTS: Controls were less sensitive than C-IBS and D-IBS (both at P < 0.001) with no differences between C-IBS and D-IBS for HPTh and HPTo. Thermal hyperalgesia was present in both groups of IBS patients relative to controls, with IBS patients reporting significantly lower pain threshold and pain tolerance at both test sites. Cluster analysis revealed the presence of subgroups of IBS patients based on thermal hyperalgesia. One cluster (17% of the sample) showed a profile of heat pain sensitivity very similar to that of healthy controls; a second cluster (47% of the sample) showed moderate heat pain sensitivity; and a third cluster (36% of the sample) showed a very high degree of thermal hyperalgesia.

CONCLUSION: A subset of IBS patients had thermal hypersensitivity compared to controls, who reported significantly lower HPTh and HPTo. All IBS patients had a higher score on the FBDSI than controls. Interestingly, the subset of IBS patients with high thermal sensitivity (36%) had the highest FBDSI score compared to the other two groups of IBS patients.

Keywords: Irritable bowel syndrome, Visceral pain, thermal hypersensitivity, Heat pain threshold, Heat pain tolerance