Achalasia is the failure to relax by the smooth muscle fibers at any junction of one part of the gastrointestinal tract with another, especially failure of the esophagogastric sphincter to relax with swallowing due to degeneration of ganglion cells in the wall of the organ.

The incidence of achalasia is approximately 1:10,000. Patients with achalasia usually range in age from 25 to 60 years, but it may also be seen in teenagers. It is a chronic problem that worsens over time.

The cause of achalasia is not known; the underlying problem may have a neural origin with the involvement of Auerbach’s (myenteric) plexus. There are some histologic and physiologic alterations in the vagus nerve have been described in connection with the disorder.