What are the important subsets of gastroparesis?

Gastroparesis is often divided into subsets based on etiology and pathophysiology; however, the utility of these subsets in the diagnosis and treatment of gastro‐paresis is not well defined. The objectives are to consider the subsets of gastroparesis from the perspectives of etiology and pathogenesis, pathophysiology, histopathology, and clinical associations, with particular focus on similarities and differences between diabetic and idiopathic gastroparesis and consideration of the potential subset of painful gastroparesis. We conclude that idiopathic and diabetic gastroparesis has similar initial presentations and manifestations, except that idiopathic gastroparesis tends to be associated more frequently with pain. Myopathic disorders are uncommon. Extrinsic denervation was considered the most common etiology; however, with the decline in surgery for peptic ulceration and in‐depth study of full‐thickness gastric biopsies, the most common intrinsic defects are being recognized in the interstitial cells of Cajal (ICC‐opathy) and with immune infiltration and neuronal changes (intrinsic neuropathic gastroparesis). Histomorphological differences at the microscopic level between diabetic and idiopathic gastroparesis are still of unclear significance. Two gastroparesis subsets worthy of special mention, because they are potentially reversible with identification of the cause, are postviral gastroparesis, which has a generally good prognosis, and iatrogenic gastroparesis, especially in patients with non‐surgical gastroparesis, such as diabetics exposed to incretins such as pramlintide and exenatide.