Irritable bowel syndrome (IBS) is usually regarded as a functional disorder in humans and diagnosis is currently based on symptom clusters. This study was designed to find out if human patients with severe IBS might have neuromuscular or inflammatory abnormalities of the small bowel. Because bowel function is governed mainly by nerve plexuses in the bowel wall, this study used full-thickness intestinal laparoscopic biopsy of 10 patients with severe IBS to investigate any possible underlying pathology. Routine preparation and staining, immunohistochemistry, and light microscopy were used. As a control, 15 autopsy specimens including the myenteric plexus were obtained from patients with no known bowel disorder and 20 colorectal adenoma biopsy specimens and 10 specimens from patients with visceral degenerative neuropathy were used for intraepithelial lymphocyte counts.

Nine of the ten patients with IBS exhibited infiltration of lymphocytes in the myenteric plexus in peri- and intraganglionic locations. No intraganglionic lymphocytes were found in the control group and only a few periganglionic lymphocytes were found. Four patients had concomitant intraepithelial lymphocytosis. Neuron degeneration was evident in 6 of 9 patients with and 1 patient without ganglionic lymphocyte infiltration.
The researchers concluded that inflammation and neuronal degeneration in the myenteric plexus may be involved in the pathogenesis of IBS, and that future studies should focus on histopathology rather than clusters of symptoms. As these studies characterize the nature and significance of the inflammatory process, new therapeutic options for patients with IBS will be developed.

COMMENTARY: Irritable bowel syndrome (IBS) is the most common gastrointestinal disease in people and the major reason why we consult a gastroenterologist. The disease causes a variety of symptoms including constipation, diarrhea, and postprandial abdominal pain. No specific cause has been identified but the disease has a high incidence in females and has been associated with certain psychological and behavioral profiles. Treatment is frustrating and difficult. It was with great excitement then that the observations of Tornblom and colleagues were received in the gastroenterological community. Most intestinal biopsies are taken via endoscopy and reveal changes only in the superficial mucosa. Nobody had ever looked deeper because full thickness specimens required a laparotomy before the advent of laparoscopic biopsy. If these observations hold up, they may well revolutionize the approach to this frustrating and widespread disorder. 

Full-thickness biopsy of the jejunum reveals inflammation and enteric neuropathy in irritable bowel syndrome. Tornblom H, Lindberg G, Nyberg B, Veress B. GASTROENTEROLOGY 123:1972-1979, 2002.