REGIONAL CEREBRAL-ACTIVITY IN NORMAL AND PATHOLOGICAL PERCEPTION OF VISCERAL PAIN

Background & Aims: To characterize the cerebral processing of noxious visceral events, changes in regional cerebral blood flow associated wi th perception of intestinal pain were examined, Methods: The effects o f rectal pressure stimuli on regional cerebral blood flow were assesse d with O-15-water positron emission tomography (PET) in 12 subjects, h alf with irritable bowel syndrome (IBS), PET scans were obtained at ba seline and during both actual and simulated delivery of anticipated st imuli, Changes in regional cerebral blood flow were interpreted using statistical parametric mapping and region of interest methods of analy sis, Results: in healthy subjects, perception of pain during actual or simulated delivery of painful stimuli was significantly associated (P < 0.01) with activity of the anterior cingulate cortex (ACC; Brodmann 's areas 24 and 32), whereas no ACC response to perception of nonpainf ul stimuli was observed, In patients with IBS, the ACC failed to respo nd to the same stimuli, whereas significant activation (P < 0.01) of t he left prefrontal cortex (maximal in Brodmann's area 10) was seen, Co nclusions: The perception of acute rectal pain is associated with acti vation of the ACC in healthy subjects, and patients with IBS show an a berrant brain activation pattern both during noxious rectal distention and during the anticipation of rectal pain.