Visceral hypersensitivity following cold water intake in subjects with irritable bowel syndrome

Background Visceral hypersensitivity has been shown to be present in irritable bowel syndrome (IBS). This study sought to investigate rectal sensitivity and abdominal symptoms in IBS patients before and after 220 ml cold water intake. Methods A total of 60 IBS patients and 18 healthy controls participated in this study. Both the perception thresholds and defecation thresholds to rectal balloon distension were measured. Then, all subjects were asked to drink 220 ml 37°C warm water or 4°C cold water, and these steps were repeated 20 min later. Symptoms including abdominal pain/discomfort, bloating, and diarrhea were recorded during the study. Results Compared with the controls, the thresholds of initial sensation to rectal balloon distention in IBS patients were significantly lower while the defecation thresholds were higher in constipation-predominant IBS patients. After drinking cold water, the perception thresholds in IBS patients and the defecation thresholds in diarrhea-predominant IBS patients were further decreased. However, warm water intake did not change the perception thresholds significantly in either IBS patients or controls. A negative linear correlation was found between the symptoms and the visceral perception thresholds in diarrhea-predominant IBS patients who showed significant symptoms after cold water intake. Conclusion The results indicated that cold water intake leads to lowered visceral perception thresholds in IBS patients that were inversely relevant to the abdominal symptoms in symptomatic diarrhea-predominant IBS patients. The alteration of rectal sensitivity and abdominal symptoms following cold water stimulation provided further objective evidence for visceral hypersensitivity in IBS patients.     

Visceral perception thresholds after rectal thermal and pressure stimuli in irritable bowel syndrome patients

BACKGROUND AND AIM: Visceral hypersensitivity has been shown to be present in irritable bowel syndrome (IBS). The current study sought to compare the characteristics of visceral perception thresholds after rectal thermal and pressure stimuli between IBS patients and healthy subjects. METHODS: A total of 46 patients with IBS were diagnosed using Rome II criteria. Thirteen healthy individuals participated in the study. Rectal visceral perception thresholds were examined in patients with IBS and in normal controls after thermal and pressure stimuli. Subjects were asked to report the sensation type, location, and spread. RESULTS: Compared with healthy subjects, IBS patients demonstrated significantly initially lower perception thresholds and defecation thresholds to rectal thermal and pressure stimuli, particularly in patients with diarrhea-predominant IBS. Ice stimuli on the abdominal wall had varied effects on symptoms in patients with IBS and did not affect perception thresholds. CONCLUSIONS: Visceral perception thresholds were decreased significantly after rectal thermal and pressure stimuli in patients with IBS. Visceral hypersensitivity may be one of the important pathogenic mechanisms in IBS.     

A combination of peppermint oil and caraway oil attenuates the post-inflammatory visceral hyperalgesia in a rat model

Objective. Visceral hyperalgesia plays a pivotal role in manifestation of symptoms in patients with functional gastrointestinal disorders. In clinical studies combined treatment of peppermint- and caraway oil significantly reduced symptoms. Thus, the aim of this study was to characterize the effects of peppermint- and caraway oil, individually and in combination, on visceral nociception in a rat model of post-inflammatory visceral hyperalgesia. Material and methods. On day 28, male Lewis rats (n=80) were randomized to treatment with a rectal administration of trinitrobenzene sulphonic acid (TNBS)/ethanol or physiological saline solution. To quantify the visceromotor response to a standardized colorectal distension, bipolar electrodes were implanted into the external oblique musculature, just superior to the inguinal ligament for electromyographic recordings on day 3. On day 0, baseline measurement was performed. Thereafter, oral treatment with peppermint- or caraway oil or combination treatment was started and continued for 14 consecutive days. After 7 and 14 days of treatment a colorectal distension was performed. Colonic tissue samples were obtained on days 0, 7 and 14 to assess histological alterations due to the different treatment groups and the influence of different compounds. Results. After a single instillation of TNBS/ethanol persistent elevation of the visceromotor response at all different time-points was observed, although colonic mucosa was completely normal. After 14 days of combined treatment with peppermint- and caraway oil, a reduced visceromotor response of up to 50% compared to placebo was detected in TNBS/ethanol pretreated animals. In contrast, neither peppermint- nor caraway oil had a significant effect on post-inflammatory visceral hyperalgesia. In saline-treated controls there was no significant difference in the visceromotor response. Conclusions. These data show that combined treatment with peppermint- and caraway oil modulates post-inflammatory visceral hyperalgesia synergistically. The exact mechanisms have to be further investigated.     

Colonoscopy as an adjunctive method for the diagnosis of irritable bowel syndrome: Focus on pain perception

Background and Aim: Visceral hypersensitivity is an important component of the pathophysiology of irritable bowel syndrome (IBS). In the present study, we investigated differences in pain perception during colonoscopy between IBS patients and non‐IBS patients. We further assessed the sensitivity, specificity, and predictive values of pain scores to diagnose IBS. Methods: Patients who underwent colonoscopy for the evaluation of gastrointestinal symptoms or for screening purposes were included. All patients completed Rome III criteria questionnaires and reported pain scores on 0–100‐mm visual analog scales after colonoscopy. The patients were divided into three groups: (i) IBS; (ii) other functional gastrointestinal disorders (FGID), including functional bloating, functional diarrhea, and functional constipation; and (iii) healthy controls. Results: A total of 217 patients were included. The pain scores (median, interquartile range) of IBS patients (52, 34–71) were higher than those of the healthy controls (22, 12–35) or other FGID patients (18, 10–29) (P < 0.001). Upper gastrointestinal symptoms were observed more often in the IBS group than in the non‐IBS group (83.2% vs 34.5%, P < 0.001). At the pain score level of 31, the sensitivity, specificity, positive predictive value, and negative predictive value for IBS diagnosis were 86.1%, 75.9%, 75.7%, and 86.3%, respectively. Conclusions: The degree of pain perception during colonoscopy was higher in IBS patients than in non‐IBS patients. We concluded that colonoscopy can be useful in identifying IBS patients, with the additional benefit of excluding organic disorders of the lower gastrointestinal tract.     

Altered esophageal pain threshold in irritable bowel syndrome

Gut motility disorders and altered pain perception were reported in patients with irritable bowel syndrome (IBS). To verify foregut involvement in IBS, we studied 30 patients using esophageal manometry and 24-hr pH monitoring of the distal esophagus. Two subgroups of patients underwent esophageal provocative tests (bethanechol 50 g/kg subcutaneously and esophageal balloon distension test). Twelve healthy volunteers formed a control group. A pain threshold on esophageal distension significantly lower than in healthy subjects (11.5±1 ml vs 22.2±1.7 ml,P<0.01) was found in IBS patients. On the other hand, no differences between patients and controls were detected in lower esophageal sphincter pressure and length, esophageal body motility, or GER pattern; furthermore, bethanechol stimulation elicited similar esophageal body motility changes. Our study could confirm no detectable basal or bethanechol-induced esophageal motility disorders in IBS patients, nor enhanced GER. Esophageal involvement in IBS consists of a lower pain threshold on esophageal distension, possibly reflecting an altered visceral receptor sensitivity or modulation throughout the gut.This work has been supported in part by the grant 89.01342.11 from the Italian National Research Council and by the R. Farini Foundation for Gastro-enterological Research.     

Functional abdominal pain disorders in children

Introduction: Chronic abdominal pain is a common problem in pediatric practice. The majority of cases fulfill the Rome IV criteria for functional abdominal pain disorders (FAPDs). At times, these disorders may lead to rather serious repercussions.

Area covered: We have attempted to cover current knowledge on epidemiology, pathophysiology, risk factors related to pathophysiology, clinical evaluation and management of children with FAPDs.

Expert commentary: FAPDs are a worldwide problem with a pooled prevalence of 13.5%. There are a number of predisposing factors and pathophysiological mechanisms including stressful events, child maltreatment, visceral hypersensitivity, altered gastrointestinal motility and change in intestinal microbiota. It is possible that the environmental risk factors intricately interact with genes through epigenetic mechanisms to contribute to the pathophysiology. The diagnosis mainly depends on clinical evaluation. Commonly used pharmacological interventions do not play a major role in relieving symptoms. Centrally directed, nonpharmacological interventions such as hypnotherapy and cognitive behavioral therapy have shown both short and long term efficacy in relieving pain in children with FAPDs. However, these interventions are time consuming and need specially trained staff and therefore, not currently available at grass root level. Clinicians and researchers should join hands in searching for more pragmatic and effective therapeutic modalities to improve overall care of children with FAPDs.