ESSENTIALS OF DIAGNOSIS
The three most common causes of gastroparesis are idiopathic, diabetic, and postsurgical.
Chronic intestinal pseudo-obstruction (CIPO) involves intermittent failure of intestinal peristalsis in the small or large intestine, or both.
Noninvasive imaging or endoscopy, or both, should be used to rule out mechanical obstruction in patients being worked up for gastroparesis or CIPO.
The standardized 4-hour gastric emptying scintigraphy scan using a low-fat, egg-white meal is the recommended test for gastroparesis.
Accelerated gastric emptying and dumping syndrome are often related to postgastric surgery and may have symptoms that mimic delayed emptying.
Altered gastric and small bowel motility result in either delayed gastric emptying or rapid transit. Among the disorders of gastric and small bowel motility discussed in this chapter are gastroparesis, CIPO, dumping syndrome, and rapid transit dysmotility of the small bowel.
Gastroparesis and CIPO are chronic long-term problems that have a variety of causes and can be neuropathic or myopathic. Treatment of these conditions includes dietary, medical, and, rarely, surgical therapies. Research in gastroparesis is ongoing with a focus on improving diagnostics and newer therapeutic agents. Dumping syndrome is a postsurgical iatrogenic problem that is occurring less often in relation to gastric ulcer surgery, but may be increasing among bariatric surgery patients in tandem with the increase in surgical treatment of obesity. Patient education, dietary change, and treatment of underlying medical problems are important factors in the overall management of these motility disorders.
Normal gastric emptying requires coordinated efforts by the muscles that control the four regions of the stomach, nerves that modulate the actions of these muscles, and chemical mediators. Important events that occur during gastric filling and emptying include fundic relaxation (accommodation) in response to food ingestion, antral contractions and churning (trituration) of large food particles, and finally pyloric relaxation.
The neurogenic network of the stomach includes elements of both the central nervous system (CNS) and the enteric nervous system (ENS). The CNS elements involve both sympathetic and parasympathetic fibers. Sympathetic fibers arise from the thoracic spinal nerves, extending to postganglionic nerves that run along the celiac plexus and the vascular supply to the stomach. The sympathetic innervation includes afferent pain fibers that arise from the stomach, as well as motor fibers that innervate the pyloric sphincter. The parasympathetic innervation stems from the right and left vagal trunks, which eventually divide into multiple branches that course throughout the stomach wall and synapse with the ENS.
The ENS is an independent branch of the peripheral nervous system that is divided into two plexuses: the submucosal (Meissner) and the myenteric (Auerbach) plexuses. The submucosal plexus receives only parasympathetic input and innervates the cells of epithelial layer and muscular externa. The myenteric plexus, on the other hand, is situated between the middle circular and the outer longitudinal muscle layers, receiving both ...