Achalasia is best characterized as a esophageal motor disorder. It provides an example of a disease of the enteric nervous system in which there is a degeneration of the myenteric neurons that normally innervate the lower esophageal sphincter (LES).
Studies conducted in the US indicate an incidence of 0.6 cases per 100,000* per year, with an equal occurrence in men and women.
The most commonly reported symptoms are dysphagia and regurgitation. Regurgitation can occur during meals or long after, and even at nighttime, or in my case even the next morning. With progressive achalasia during a prolonged period, weight loss will occur.
Chest pain in achalasia has been reported in as few as 17% and as many of 63%* of patients. Its mechanism is unclear. Proposed reasons include: Spontaneous esophageal contractions, Esophageal distention by retained food, Esophageal irritation by retained medication, or bacterial or fungal overgrowth.
Heartburn is another notable symptom, although patients with untreated achalasia should be “immune” to gastroesophageal reflux, because of the failure of the LES relaxation.
The majority of people with achalasia report difficulty with belching. The belch reflex requires not only relaxation of the lower but also upper sphincter. Some people fail to relax their upper sphincter in responce to distention of the esophagus and are thereby unable to belch. Episodes of upper airway obstruction as a result of a massively dilated esophagus may occur during the course of achalasia.
*Numbers and percentages taken from: Clinical Perspectives in Gastroenterology Vol 5, No 3 May/June 2002