Origin and control of gastrointestinal motility.

As a result of improved understanding of the origin and control of motility at both the whole organ and the cellular level, a scientific approach to the diagnosis and treatment (both medical and surgical) of motility disorders has evolved. Examples are present for all levels of the gastrointestinal tract. Manometric, myoelectric, and pharmacologic studies have elucidated the role of the lower esophageal sphincter and stomach in the pathogenesis of gastroesophageal reflux and determined the mechanism of successful medical and surgical treatment. Better evaluation of colorectal motility using colonic transit studies, pelvic floor radiography, and rectoanal manometrics has led to a better identification of both the etiology of severe constipation and patients who will have a successful surgical outcome. Studies of normal and abnormal gallbladder motility and responsiveness to hormonal stimulation have shed light on the cellular abnormalities in gallbladder myocytes that predispose to gallstone formation. Finally, since we have learned that certain surgical procedures affect motility in an adverse manner, a better basic understanding of gastrointestinal physiology has led to a better clinical understanding of the mechanism by which the changes occur and to the development of more directed physiologic operations. The classic example is seen in ulcer surgery, where the introduction of highly selective vagotomy instead of truncal vagotomy preserved antral innervation and decreased the incidence of postvagotomy complications. All these concepts and more are addressed in more detail in subsequent articles in this issue.