Regional cerebral activation in irritable bowel syndrome and control subjects with painful and nonpainful rectal distention.
OBJECTIVE
Irritable bowel syndrome (IBS) is characterized by visceral hypersensitivity, possibly related to abnormal brain-gut communication. Positron emission tomography imaging has suggested specific central nervous system (CNS) abnormalities in visceral pain processing in IBS. This study aimed to determine (1) if functional magnetic resonance imaging (fMRI) detects CNS activity during painful and nonpainful visceral stimulation; and (2) if CNS pain centers in IBS respond abnormally.


METHODS
fMRI was performed during nonpainful and painful rectal distention in 18 patients with IBS and 16 controls.


RESULTS
Rectal stimulation increased the activity of anterior cingulate (33/34), prefrontal (32/34), insular cortices (33/34), and thalamus (32/34) in most subjects. In IBS subjects, but not controls, pain led to greater activation of the anterior cingulate cortex (ACC) than did nonpainful stimuli. IBS patients had a greater number of pixels activated in the ACC and reported greater intensity of pain at 55-mm Hg distention than controls.


CONCLUSIONS
IBS patients activate the ACC, a critical CNS pain center, to a greater extent than controls in response to a painful rectal stimulus. Contrary to previous reports, these data suggest heightened pain sensitivity of the brain-gut axis in IBS, with a normal pattern of activation.
Mertz
H
H
Division of Gastroenterology, Department of Medicine, Vanderbilt University, Nashville, Tennessee 37232-5340, USA. howard.mertz@mcmail.vanderbilt.edu
Morgan
V
V
Tanner
G
G
Pickens
D
D
Price
R
R
Shyr
Y
Y
Kessler
R
R
D000328:Adult; D000344:Afferent Pathways / Q000503:physiopathology; D001931:Brain Mapping; D003109:Colonic Diseases, Functional / Q000503:physiopathology*; D004106:Dilatation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000503:physiopathology*; D010865:Pilot Projects; D011312:Pressure; D012007:Rectum / Q000503:physiopathology*