Esophageal Achalasia

Esophageal achalasia is a primary motor disorder of the esophagus in which the lower esophageal sphincter fails to relax on swallowing and the body of the esophagus loses its normal peristalsis. The result is impaired emptying of the esophagus into the stomach, producing dysphagia for solids and liquids, regurgitation, and, over time, dilation of the esophagus.

Definition

Esophageal achalasia is a primary esophageal motility disorder defined by impaired or absent relaxation of the lower esophageal sphincter together with loss of peristalsis in the esophageal body, causing functional obstruction at the esophagogastric junction.

Scope

This topic covers the pathophysiology of achalasia, its manometric subtypes, and its place among esophageal motility disorders, drawing on high-resolution manometry and the Chicago Classification. It is a reference and educational entry describing the disorder and how it is characterised; it does not recommend or compare treatments for any individual patient.

Core questions

• What underlies the failure of the lower esophageal sphincter to relax in achalasia?
• How does high-resolution manometry distinguish the subtypes of achalasia?
• How is achalasia separated from other causes of esophagogastric junction outflow obstruction?

Key concepts

• Loss of inhibitory myenteric neurons
• Impaired lower esophageal sphincter relaxation
• Absent peristalsis (aperistalsis)
• Integrated relaxation pressure
• Chicago Classification subtypes I, II, and III
• Esophagogastric junction outflow obstruction

Mechanisms

Achalasia results from degeneration and loss of inhibitory neurons in the esophageal myenteric (Auerbach) plexus, which normally release nitric oxide and vasoactive intestinal peptide to relax the lower esophageal sphincter and coordinate peristalsis. Their loss leaves the sphincter unable to relax fully and the esophageal body without an organised peristaltic wave, so swallowed material is not propelled and accumulates above the junction. High-resolution manometry quantifies the failure of relaxation as an elevated integrated relaxation pressure and resolves three manometric subtypes — type I with minimal pressurisation, type II with panesophageal pressurisation, and type III with premature (spastic) contractions — distinctions that carry prognostic and classificatory significance within the Chicago Classification.

Clinical relevance

Achalasia is the prototypical primary esophageal motility disorder and a key differential for dysphagia to both solids and liquids; recognising its manometric pattern separates it from structural obstruction and from other motor disorders. This entry describes the disorder and its classification for reference and education and is not a basis for selecting therapy in an individual.

Epidemiology

Achalasia is uncommon, with incidence generally reported in the range of about one per 100,000 persons per year and a prevalence severalfold higher; it can occur at any age and affects men and women similarly. Because it is rare and slowly progressive, diagnosis is often delayed, and much of the comparative evidence comes from referral-centre series and a small number of randomised trials.

History

Long described clinically as 'cardiospasm,' achalasia was reframed as a disorder of failed relaxation and absent peristalsis as esophageal manometry matured. High-resolution manometry then allowed Pandolfino and colleagues to define clinically relevant manometric subtypes, which were incorporated into successive versions of the Chicago Classification, while randomised trials such as the European Achalasia Trial provided controlled comparisons of established interventions.

Debates

Do the manometric subtypes predict outcome differently across treatments?

High-resolution manometry distinguishes types I, II, and III achalasia, and these subtypes appear to differ in their response to interventions; how strongly subtype should guide the choice among established treatments remains an active question informed by trial and cohort data.

Key figures

• John E. Pandolfino
• Peter J. Kahrilas
• Guy E. Boeckxstaens

Seminal works

• pandolfino-2008-subtypes
• boeckxstaens-2011-eat

Frequently asked questions

What goes wrong in achalasia?

The inhibitory nerves of the esophagus degenerate, so the lower esophageal sphincter cannot relax with swallowing and the esophageal body loses peristalsis, leaving swallowed food unable to pass normally into the stomach.

How is achalasia diagnosed and subtyped?

High-resolution manometry is central: it shows impaired sphincter relaxation (a raised integrated relaxation pressure) with absent peristalsis and distinguishes three subtypes within the Chicago Classification, supported by endoscopy and barium studies to exclude other causes.