Chin Med J (Taipei) 1998;61:S87.

The Irritable Bowel Syndrome -Brain or Gut?

Ann Ouyang

Section of Gastroenterology and Hepatology, Department of Medicine, The Milton S. Hershey Medical Center, College of Medicine of the Pennsylvania State University

Abstract

The Irritable Bowel Syndrome (IBS) is a commonly diagnosed disorder in which the clinical manifestations are well described but the pathophysiology is relatively poorly understood. The diagnosis is based on a recognized symptom complex (Rome criteria, Manning criteria) in the absence of objective findings for anatomic, neoplastic, inflammatory or infectious etiologies. The current working hypothesis is that the IBS results from a combination of alterations in gastrointestinal motility and visceral afferent neurotransmission along with a role for psychologic abnormalities. Evidence for altered gastrointestinal motility include findings of an association of abnormal contractile patterns with pain in individual patients¹, an altered gastrocolonic motor response², and an altered response of the colon to bile salts in patients with IBS. Evidence for an altered brain-gut axis, or visceral hyperalgesia, include a lower tolerance of patients with IBS to rectal and esophageal balloon distention³ and an increased awareness of Phase3 activity of the MMC⁴. The evidence for the role of psychological disorders include the finding of correlation of a number of pain syndromes with IBS and a correlation with depression and anxiety⁵. In addition, it appears that patients seeking medical attention for IBS have a higher abnormal psychological profile than those without IBS symptoms and those with an appropriate symptom complex who do not seek physician advice. An understanding of the pathophysiology of this disorder has changed the therapeutic approach to patients with the IBS to include drugs which alter the afferent neural pathway and psychological therapy in addition to the anticholinergic medications to influence motor activity.

Refs.
1. Kellow et al. Gastroenterology 92: 1885, 1987
2. Snape et al. Gastroenterology 70. 326, 1976
3. Whitehead et al. Gastroenterology 98: 1187, 1990
4 Kellow et al. Gastroenterology 101: 1621, 1991
5 Longstreth et al. Dig. Dis. Sci. 38: 1581, 1991

Reviews.
Mckee et al. Dig. Dis. Sci. 38: 1773, 1993
Camilleri et al. Alimentary Pharmacol and Therapeutics. 11: 3, 1997

[Chin Med J (Taipei) 1998;61:S87.]