Functional Dyspepsia and Irritable Bowel Syndrome: Is There a Common Pathophysio
Functional Dyspepsia and Irritable Bowel Syndrome: Is There a Common Pathophysiological Basis?
ABSTRACT & COMMENTARY
Synopsis: Functional dyspepsia and irritable bowel syndrome cannot be distinguished on the basis of altered small intestinal sensory thresholds.
Source: Holtmann G, et al. Am J Gastroenterol 1997;92: 954-959.
Many symptom surveys have shown considerable overlap between a variety of "functional" disorders, such as non-cardiac chest pain, gastroesophageal reflux disease, non-ulcer or "functional" dyspepsia, irritable bowel syndrome (IBS), and "functional" constipation. Clinical research studies in patients with non-cardiac chest pain, non-ulcer dyspepsia, and IBS have suggested that for at least some of these patients, visceral hypersensitivity may play an important role in pathogenesis. The aim of this particular study was to evaluate the extent of overlap of symptoms and visceral sensitivity between patients with functional dyspepsia and IBS. Among 157 patients, Holtmann and associates found that 43% reported simultaneous symptoms of functional dyspepsia and irritable bowel, whereas symptoms of functional dyspepsia or of IBS alone occurred in 43% and 14% of patients, respectively. When they tested visceral sensation by measuring the threshold for first perception to intestinal distention, they found that while the patients with the functional disorders in general were significantly more sensitive than control subjects, there were no differences in sensitivity between the patients with functional dyspepsia alone, those with features of both functional dyspepsia and IBS, and those with IBS alone. They conclude that there was significant overlap between functional dyspepsia and IBS and that functional dyspepsia and IBS cannot be distinguished on the basis of altered small intestinal sensory thresholds.
COMMENT BY EAMONN M. M. QUIGLEY, MD
Non-ulcer dyspepsia and IBS are extremely common disorders in the offices of both the primary care physician and the gastroenterologist. In the absence of any consistent and objective abnormality in these disorders, on biochemical, physiological, and pathological testing, the clinical definition of these disorders is based entirely on symptoms and the absence of "organic" disorders. One remarkable feature of almost all community surveys of these disorders is the extent of overlap between the principal "functional" disorders, namely, non-cardiac chest pain, functional dyspepsia, and IBS. This overlap has proved particularly problematic when one comes to design clinical trials of new therapies for these disorders, as the outcome of these trials may be significantly biased by the inordinate inclusion in an IBS study, for example, of an excessive number of patients with features of "functional" dyspepsia.
Many hypotheses have been advanced to explain the pathophysiology of symptoms in these disorders: psychopathology, dysmotility, food allergy, disturbed perception of gut function, and visceral hypersensitivity. Recently, clinical research has focused, in particular, on the latter, and several studies have described a relative hypersensitivity to luminal stimuli among patients with non-cardiac chest pain, non-ulcer dyspepsia, and IBS. Some studies have, indeed, suggested that these disorders may be differentiated on the basis of a relative organ specificity of visceral hypersensitivity. Thus, in non-cardiac chest pain, visceral hypersensitivity is localized to the esophagus, in non-ulcer dyspepsia to the stomach, and in IBS to the small intestine and rectum. This study addresses the overlap between non-ulcer dyspepsia and IBS and attempts to correlate this with results of tests of visceral sensation.
In this study, the authors provide further evidence for extensive overlap between these disorders and also conclude that these disorders cannot be differentiated on the basis of the presence or absence of intestinal hypersensitivity, which is equally common among the non-ulcer dyspepsia patients, those who have both non-ulcer dyspepsia and IBS, and those who have IBS alone, thus casting considerable doubt on the concept of selective intestinal/colonic hypersensitivity in IBS. To my mind, the conclusions of this study are very much in accord with clinical experience, namely, the more one probes the more one unearths symptoms among these patients at sites in the intestine distant from those of the presenting symptomatology. To me, this study cautions against the temptation to compartmentalize functional disorders. In many patients, the presenting symptomatology may be but a single manifestation of what is a fairly diffuse gastrointestinal disorder.
References
1. Quigley EMM. Non-ulcer dyspepsia: Pathophysiology update. Hosp Pract 1995;31:141-162.
2. Drossman DA, et al. Irritable bowel syndrome: A technical review for practice guideline development. Gastroenterol 1997;112:2120-2137.
Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.