Achalasia is a relatively rare disorder of the smooth muscle of the esophagus. The esophagus is a muscular tube that carries food and liquids from the mouth to the stomach. Achalasia makes it difficult for food and liquid to pass into the stomach from the esophagus.

There is a muscle called the lower esophageal sphincter (LES). This is where the esophagus meets the stomach. When not swallowing, the LES remains closed to keep food, liquid, and stomach acid from moving back into the esophageal tube. When swallowing, nerve signals tell muscles to contract to push food down the esophagus (an action called peristalsis). This allows the LES to open.

In people with achalasia, the nerve cells in the lower esophageal tube and the LES do not work correctly. This results in:

  • Missing peristaltic (muscular) activity
  • Failure of the LES to open completely

While achalasia is associated with the loss of nerve cells in the esophagus, the cause of this process is unknown.