Description Achalasia affects the esophagus, the tube that carries swallowed food from the back of the throat down into the stomach. A ring of muscle called the lower esophageal sphincter encircles the esophagus just above the entrance to the stomach. This sphincter muscle is normally contracted to close the esophagus. When the sphincter is closed, the contents of the stomach cannot flow back into the esophagus. The act of swallowing causes a wave of esophageal contraction called peristalsis.
Peristalsis pushes food along the esophagus.
Normally, peristalsis causes the esophageal sphincter to relax and allow food into the stomach. Normal peristalsis is interrupted and food cannot enter the stomach. Achalasia is caused by degeneration of the nerve cells that normally signal the brain to relax the esophageal sphincter. The ultimate cause of this degeneration is unknown. Autoimmune disease or hidden infection is suspected.