Achalasia, or esophageal achalasia, is a rare disorder of the esophagus, the tube that carries food from the mouth to the stomach.
At the point where the esophagus meets the stomach is a ring-like muscle called the lower esophageal sphincter (LES). The LES normally relaxes during swallowing to allow food from the esophagus to enter the stomach. When the LES fails to relax, the condition is called achalasia.
Caused by damage to the nerves of the esophagus, achalasia is most common in middle-aged or older adults, but may occur at any age. In some people, the condition may be inherited.
Early in achalasia, there is inflammation in the LES, especially around the nerves, when viewed under a microscope. As the disease progresses, the nerves - particularly those that cause the LES to relax - begin to degenerate and ultimately disappear. Eventually, muscle cells also degenerate. The result of these changes is an LES that cannot relax and muscles in the lower part of the esophagus that do not contract normally. In time, the body of the esophagus stretches and becomes enlarged (dilated).