Functional brain imaging in irritable bowel syndrome with rectal balloon-distention by using fMRI

AIM:Irritable bowel syndrome (IBS) is characterized byabdominal pain and changes in stool habits.Visceralhypersensitivity is a key factor in the pathophysiology ofIBS.The aim of this study was to examine the effect ofrectal balloon-distention stimulus by blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) in visceral pain center and to compare the distribution,extent,and intensity of activated areas between IBS patientsand normal controls.METHODS:Twenty-six patients with IBS and eleven normalcontrols were tested for rectal sensation,and the subjectivepain intensity at 90 ml and 120 ml rectal balloon-distentionwas reported by using Visual Analogue Scale.Then,BOLD-fMRI was performed at 30 ml,60 ml,90 ml,and 120 mlrectal balloon-distention in all subjects.RESULTS:Rectal distention stimulation increased the activityof anterior cingulate cortex (35/37),insular cortex (37/37),prefrontal cortex (37/37),and thalamus (35/37) in most cases.At 120 ml of rectal balloon-distention,the activation area andpercentage change in MR signal intensity of the regions ofinterest (ROI) at IC,PFC,and THAL were significantly greaterin patients with IBS than that in controls.Score of painsensation at 90 ml and 120 ml rectal balloon-distention wassignificantly higher in patients with IBS than that in controls.CONCLUSION:Using fMRI,some patients with IBS can bedetected having visceral hypersensitivity in response to painfulrectal balloon-distention,fMRI is an objective brain imagingtechnique to measure the change in regional cerebral activationmore precisely.In this study,IC and PFC of the IBS patientswere the major loci of the CNS processing of visceral perception.