What is the definition or description of: esophageal achalasia?

Achalasia. This is a disease that destroys the nerves coordinating esophageal muscle contraction. The normal ability to push food into the stomach is lost, and the valve entering the stomach becomes tight and stiff, allowing food to collect in the esophagus and empty by gravity alone. Solids generally worse than liquids. Onset is gradual. Weight loss & malnutrition common. Treatment directed at opening valve.
Motility Disorder. Achalasia is an esophageal motility disorder. It is diagnosed by manometry, showing a lack of relaxation of the distal esophagus and decreased peristalsis. Primary achalasia (most common) is due to loss of inhibitory neurons in the distal esophagus. Secondary achalasia is caused by chagas disease. "pseudo-achalasia" is seen with cancers. Surgical treatment remains the gold standard.