Role of abnormal central processing of pain
- Abnormal central processing, such as down-regulation of incoming visceral sensations, has also been found in patients with IBS.
- In IBS patients, rectal distention fails to activate the perigenual anterior cingulated cortex (ACC), the area containing large amounts of B-endorphin activity, which may serve to down-regulate pain, but instead shows increased activation of the rostral ACC, an area associated with unpleasantness and attention.
- Also, patients with IBS and a history of abuse reported greater activation of the middle and posterior dorsal cingulate regions, and reduced activity of the supragenual anterior cingulate, and are implicated in pain inhibition and arousal.
- Therefore IBS patients may have an alteration of the pain modulatory system, as well as up-regulation of afferent signals at the primary splanchnic afferent or its spinal connections.
