Curriculum · Gastroenterology
Achalasia
What it is
Achalasia is the inability of the lower esophageal sphincter (LES) to relax and allow food to pass into the stomach, together with absent esophageal peristalsis. It is caused by degeneration or absence of the ganglion cells of the myenteric plexus of Auerbach, so the LES fails to relax in response to swallowing and there is retention of food and liquids in the esophagus. On high-resolution manometry (HRM) there are three subtypes, and they influence treatment choice: Type I (classic), Type II (with esophageal pressurization) and Type III (spastic). Type II achalasia has the best prognosis with treatment. The degeneration is of the inhibitory neurons within the esophageal wall.
Among the esophageal motility disorders it is the disorder of hypomotility, while diffuse esophageal spasm is the disorder of hypermotility. The two share a similar presentation, dysphagia with liquids and solids.
Causes and risk
The cause is degeneration or absence of the ganglion cells of the myenteric plexus of Auerbach. If the patient has a history of travel to South America, suspect Chagas disease as the cause of achalasia. Achalasia secondary to Chagas disease can reach grade III megaesophagus, with esophageal dilation and a typical rat-tail sign in the distal portion of the esophagus on barium swallow.
It divides into two kinds. Primary or idiopathic achalasia is the most common and its cause is unknown, though an autoimmune process or viral infections such as HSV-1 or measles could be involved. Secondary achalasia, that is pseudoachalasia, is a mechanical cause of obstruction that mimics achalasia in presentation and manometric findings: esophageal cancer, stomach and other extraesophageal cancers, Chagas disease, amyloidosis, neurofibromatosis type I and sarcoidosis.