[Small bowel motility in the irritable bowel syndrome]

The presently available methods of study of small bowel motility in humans include manometry (or electromyography) which records the temporospatial organization of bowel contractions and determination of intestinal transit time. Investigation of subjects with the irritable bowel syndrome has shown that the small intestine has its part in the motor disturbances. The characteristics of normal motility of the small intestine are well known: the migrating motor complex (MMC) develops during the interdigestive period, typical contractions are seen during phases 2 and 3 of the MMC, the nature and the duration of the motor response to alimentation have been described. In patients with IBS, the production of the MMC is irregular during the day hours; this is most likely due to environmental solicitations and it is recognized that intensive aliess can cause transient interruption of the development of cycles. On the other hand, the MMC develops normally during sleeping hours. Contraction derangements such as non propulsed repeated contractions in the proximal intestine and contractions propulsed too frequently in the small intestine may be found during phase 2. Some of the abnormal contractions coincide with abdominal pain. After meals, the duration of interruption of the MMC is shorter than in the normal subject. Transit time is shortened in patients with diarrhea, lengthened in patients with constipation. Patients with IBS respond excessively to certain stimuli: for instance, the motor response to cholecystokinin is increased compared to the normal subject. Intake of fatty ingesta is followed by the same type of reaction: pain is often associated with abnormal contractions.(ABSTRACT TRUNCATED AT 250 WORDS)