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Functional esophageal disorders / Irritable bowel syndrome
Irritable bowel syndrome
Abnormal intestinal motility has long been considered another factor in the pathogenesis of IBS. In studies of the small intestine during fasting, the presence of both discrete, clustered contractions and prolonged, propagated contractions has been reported in patients with IBS(6).
Another factor in motor dysfunction is the abnormal passage and handling of gas. Dysmotility and consequently difficulty in propelling gas may underlie bloating and abdominal distension in patients with IBS.
King et al.(10) have shown a greater gas production (particularly of hydrogen) in IBS patients than in control individuals, which suggests that abnormal fermentation may be responsible for gas associated symptoms in some IBS patients. Both symptoms and gas production are reduced by an exclusion diet. This reduction may be associated with alterations in the activity of hydrogen-consuming bacteria. Fermentation may be an important factor in the pathogenesis of IBS.
Overall, the differences in IBS incidence rates between genders and populations can probably be explained by viewing IBS as a biopsychosocial disorder in which not only abnormal sensation and motility, but also psychosocial factors play a role.
Primary features of the syndrome include psychosocial disturbances , bowel dismotility, abnormal fermentation, visceral hypersensitivity, imbalance of neurotransmitters and infectious enteritis and immune activation(7).
Patients who suffer from IBS have amplified colonic motility responses when compared to normal volunteers.
Dysmotility is considered to underlie altered bowel habit. Rapid small bowel and colonic transit times have been reported in patients with diarrhoea-predominant IBS(4). Patients with constipation-predominant IBS may have a component of disordered defecation, resulting, at least in part, from abnormal function of the pelvic floor and anal sphincter muscles(9). It has been reported they have a delayed transit time(9).
