Achalasia cardia or achalasia is an uncommon disorder that causes difficulty in swallowing. Although the condition cannot be cured, the aim of the treatment is relief of symptoms.

The main cause of achalasia is degeneration of the nerve cells in the esophagus (the food pipe). The exact reason why this happens is not known. The loss of nerve cells in the esophagus causes two major problems that interfere with swallowing.

Firstly, the muscles that line the esophagus do not contract normally, so that swallowed food is not pushed forward through the esophagus and into the stomach properly. Secondly the lower esophageal sphincter (LES), a valve made of of muscles, does not relax with swallowing as it does in normal people. As a result, the esophagus above the persistently contracted LES starts to dilate, and large volumes of food and saliva can accumulate in the dilated esophagus.