Achalasia is a disorder of the the tube that carries food from the mouth to the stomach (esophagus), which affects the ability of the esophagus to move food toward the stomach
The main problem in achalasia is a failure of the a muscular ring where the esophagus and stomach come together (lower esophageal sphincter) to relax during swallowing.
Another part of the disorder is a lack of nerve stimulation to the muscles of the esophagus. Causes include:
As a result, the wave-like contractions of smooth muscles that normally force food through the esophagus and other parts of the digestive tract do not work as well. (These contractions are called peristalsis.)
Achalasia is a rare disorder. It may occur at any age, but is most common in middle-aged or older adults.