Brain Response to Rectal Distension Different in IBS

Irritable bowel syndrome patients have increased activation of particular regions

THURSDAY, Jan. 27 (HealthDay News) -- Patients with irritable bowel syndrome (IBS) experience greater brain activation in regions associated with emotional arousal and endogenous pain modulation when subjected to rectal distension, compared to controls, according to a meta-analysis published in the January issue of Gastroenterology.

Kirsten Tillisch, M.D., of the University of California in Los Angeles, and colleagues conducted a quantitative meta-analysis of published neuroimaging studies that employed rectal distension. They studied regions of brain activation in patients with IBS and compared them with healthy controls.

The researchers found that areas associated with visceral afferent processing, such as the thalamus, insula, and anterior midcingulate, were consistently activated in both groups, but there were considerable differences in the extent and specific location of foci. Patients with IBS were found to have greater activation of areas associated with emotional arousal (pregenual anterior cingulate cortex, amygdala) and activation of a midbrain cluster, an area associated with endogenous pain modulation. Controls, however, had more consistent activation of the medial and lateral prefrontal cortex.

"These results support a role for central nervous system dysregulation in IBS. These findings provide specific targets for guiding development of future neuroimaging protocols to more clearly define altered brain-gut interactions in IBS," the authors write.

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