Pathophysiology of achalasia

Schematic representation of the pathophysiology of achalasia which results from the degeneration of neurons in the esophageal wall. Histologic examination reveals decreased numbers of neurons (ganglion cells) in the myenteric plexuses, and the ganglion cells that remain often are surrounded by lymphocytes and, less prominently, by eosinophils. This inflammatory degeneration preferentially involves the nitric oxide-producing, inhibitory neurons that effect the relaxation of esophageal smooth muscle, resulting in an elevation in basal lower esophageal sphincter (LES) pressure and an inability of the sphincter muscle to relax normally; the cholinergic neurons that contribute to LES tone by causing smooth muscle contraction are relatively spared^[1]. In some patients, degenerative changes also are found in the ganglion cells of the dorsal motor nucleus of the vagus in the brainstem, and Wallerian degeneration has been observed in the vagal fibers that supply the esophagus.