Gastrointestinal Motility and Functional Disorders

Gastrointestinal (GI) motility disorders represent diseases characterized by abnormal, predominantly impaired, sometimes exaggerated, movement of contents through the GI tract due to neuromuscular dysfunctions in the absence of mucosal disease and mechanical causes of impaired passage. By contrast, functional GI disorders represent illnesses, defined only by GI symptoms, which occur in the absence of mucosal or structural abnormality or of known biochemical or metabolic disorders. The first section of this chapter discusses the enteric and extrinsic neural regulation of GI sensorimotor functions and normal GI motility in humans. Disorders such as gastroparesis (including diabetic gastroparesis, idiopathic gastroparesis, and postsurgical gastroparesis), dumping syndrome, intestinal pseudo-obstruction, small intestinal bacterial overgrowth, megacolon (including Hirschsprung disease, toxic megacolon, and colonic pseudo-obstruction), chronic constipation (including defecatory disorders, normal transit constipation, and slow transit constipation), functional dyspepsia, functional diarrhea and irritable bowel syndrome, and fecal incontinence are then discussed in depth. Tables present a comparison of GI motility and functional disorders, the causes of gastroparesis, the etiology of intestinal pseudo-obstruction and fecal incontinence, common medical conditions and medications associated with constipation, and the symptom severity scale in fecal incontinence. Illustrations, graphs, magnetic resonance images, and algorithms are provided. This chapter contains 10 highly rendered figures, 6 tables, 92 references, and 5 MCQs.