Differences in brain responses to visceral pain between patients with irritable bowel syndrome and ulcerative colitis

Abstract

Patients with mild chronic inflammation of the rectum or ileum have reduced perceptual responses to rectosigmoid distension compared to patients with irritable bowel syndrome (IBS). The current study sought to identify differences in regional cerebral blood flow (rCBF) during rectal distension, which might correspond to these perceptual differences. In 8 male ulcerative colitis (UC) patients with quiescent disease, 7 male IBS patients and 7 healthy male controls, rCBF was assessed using 15O-water positron emission tomography at baseline and during actual and anticipated but undelivered rectal distensions. No group differences were seen in anterior insula and dorsal anterior cingulate cortex (dACC), two regions consistently activated by painful intestinal stimuli. However, IBS patients showed greater activation of the amygdala, rostroventral ACC, and dorsomedial frontal cortical regions. In contrast, no significant differences were observed between UC and controls. When these two non-IBS groups were combined, functional connectivity analyses showed that right lateral frontal cortex (RLFC) activation positively correlated with activation of the dorsal pons/periaqueductal gray, a key region involved in endogenous pain inhibition. According to the connectivity analysis, this effect was mediated by inhibition of medial frontal cortex by the RLFC. Chronic colonic inflammation is not necessarily associated with increased visceral afferent input to the brain during rectal distension. In the sample studied, the primary difference between functional and quiescent inflammatory disease of the colon was in terms of greater activation of limbic/paralimbic circuits in IBS, and inhibition of these circuits in UC and controls by the RLFC.

Regional brain activation in conscious, nonrestrained rats in response to noxious visceral stimulation

“…To date, the majority of human studies in this field have used distension of the rectosigmoid colon [4,5,8,41,44,48,52,62], stomach [37,69], and esophagus [2,3,9,73]. Activation of the insular and dorsal anterior cingulate cortex (dACC) has been most consistently reported, with other brain regions, including the prefrontal cortex, thalamus and brainstem being reported in some, but not in other studies.…”

Increased Postprandial Colonic Motility and Autonomic Nervous System Activity in Patients With Irritable Bowel Syndrome: A Prospective Study

“…28 The altered responses in the emotional-arousal network during visceral stimulation were shown in IBS patients by means of brain imaging techniques. [37][38][39] These brain regions are closely related to stress responses which often induce cardiovascular activation. However, meal stimulation may not directly affect the brain regions which mediate pathophysiological conditions of IBS.…”

Visceral Pain and Gastrointestinal Microbiome

“…These factors are abnormal in patients suffering from IBS and about 35% of the IBS patients have chronic pelvic pain. 67 Mayer et al 68 reported that IBS patients exhibit increased activation of brain regions that are linked to perception of rectal distension and Mertz et al 69 showed differences in brain activation patterns in response to a painful rectal stimulus in IBS patients compared to controls. Many studies have also shown that those with IBS have amplified visceral sensitivity in response to stress 70 or food intake.…”