What is "achalasia"

n. A neuromuscular problem where a ring of muscles is unable to fully relax.

Achalasia (; a- + -chalasia "no relaxation") is a failure of smooth muscle fibers to relax, which can cause a sphincter to remain closed and fail to open when needed. Without a modifier, "achalasia" usually refers to achalasia of the esophagus, which is also called esophageal achalasia, achalasia cardiae, cardiospasm, and esophageal aperistalsis. Achalasia can happen at various points along the gastrointestinal tract; achalasia of the rectum, for instance, in Hirschsprung's disease.

Esophageal achalasia is an esophageal motility disorder involving the smooth muscle layer of the esophagus and the lower esophageal sphincter (LES). It is characterized by incomplete LES relaxation, increased LES tone, and lack of peristalsis of the esophagus (inability of smooth muscle to move food down the esophagus) in the absence of other explanations like cancer or fibrosis.

Achalasia is characterized by difficulty in swallowing, regurgitation, and sometimes chest pain. Diagnosis is reached with esophageal manometry and barium swallow radiographic studies. Various treatments are available, although none cures the condition. Certain medications or Botox may be used in some cases, but more permanent relief is brought by esophageal dilatation and surgical cleaving of the muscle ( Heller myotomy).

The most common form is primary achalasia, which has no known underlying cause. It is due to the failure of distal esophageal inhibitory neurons. However, a small proportion occurs secondary to other conditions, such as esophageal cancer or Chagas disease (an infectious disease common in South America). Achalasia affects about one person in 100,000 per year. There is no gender predominance for the occurrence of disease.