Imaging brain mechanisms in chronic visceral pain

Abstract

Chronic visceral pain syndromes are important clinical problems with largely unmet medical needs. Based on the common overlap with other chronic disorders of visceral or somatic pain, mood and affect, and their responsiveness to centrally targeted treatments, an important role of central nervous system in their pathophysiology is likely. A growing number of brain imaging studies in irritable bowel syndrome, functional dyspepsia, and bladder pain syndrome/interstitial cystitis has identified abnormalities in evoked brain responses, resting state activity, and connectivity, as well as in gray and white matter properties. Structural and functional alterations in brain regions of the salience, emotional arousal, and sensorimotor networks, as well as in prefrontal regions, are the most consistently reported findings. Some of these changes show moderate correlations with behavioral and clinical measures. Most recently, data-driven machine-learning approaches to larger data sets have been able to classify visceral pain syndromes from healthy control subjects. Future studies need to identify the mechanisms underlying the altered brain signatures of chronic visceral pain and identify targets for therapeutic interventions.

Fig. 1. Brain networks contributing to chronic visceral pain

Schematic depiction of main brain networks identified in chronic visceral pain based on functional and structural brain imaging studies. Other brain networks including attentional and central autonomic networks are likely to be involved in the pathophysiology of chronic visceral pain syndromes, but have not been studied in detail. Reported brain abnormalities show moderate correlations with behavioral and clinical measures, even though their role in generating the subjective spontaneous pain experience remain to be determined.