Role of motility in pathogenesis of constipation and diarrhea

Several attempts have been made in order to classify the gastrointestinal motility disorders; they are mainly based upon the type of disorder in transit and the region of the gastrointestinal tract affected. Many digestive motor disturbances do not constitute entities, but are pathophysiologic mechanisms that may contribute to the production of symptoms and signs of various diseases. The abnormal interdigestive motility pattern or the migrating motor complex often corresponds to the absence of phase 3 and several observations strongly suggest that this disordered motility pattern is the cause rather than the consequence of intestinal bacterial overgrowth. Disturbances of colonic motility are often associated with diarrhea; however, the nature of motor alterations depends on the diarrheal disease (episodic, continuous with or without pain). Finally, both gastrointestinal and colonic motor disturbances may contribute to the pathogenesis of constipation and diarrhea; however, several findings suggest that colonic motor alterations are the consequence rather than the cause of changes in bowel habits.