Achalasia

Achalasia is an esophageal motility disorder in which the lower esophageal sphincter fails to relax normally and the esophagus loses effective peristalsis, obstructing passage into the stomach.

Lower esophageal sphincter: A ring of smooth muscle at the junction of the esophagus and stomach that regulates passage between them. In achalasia, this muscle fails to relax adequately during swallowing.
High-resolution manometry: Esophageal manometry that maps pressure patterns along the esophagus with closely spaced sensors. It classifies achalasia into subtypes that can guide treatment choices.
Esophageal stricture: A fixed narrowing of the esophagus, often caused by inflammation, scarring, or injury. Unlike achalasia, a stricture is a structural narrowing rather than a motility failure.
Type I achalasia: An achalasia subtype characterized by failed peristalsis without substantial pressurization in the esophageal body. It is the classic aperistaltic pattern in the Chicago Classification.
Esophageal dilation: Abnormal widening of the esophagus caused by persistent retention or impaired emptying. Long-standing achalasia can enlarge the esophagus above the obstructed junction.
Esophageal peristalsis: Coordinated muscular contractions that move swallowed material through the esophagus. Loss of effective peristalsis leaves food above the nonrelaxing sphincter.
Timed barium esophagram: An imaging test that tracks how quickly swallowed barium empties from the esophagus. Persistent barium retention can measure impaired emptying and treatment response.
Esophageal cancer: A malignant tumor arising in the tissues of the esophagus. A tumor near the junction can mimic achalasia by obstructing passage into the stomach.
Type II achalasia: An achalasia subtype marked by failed peristalsis and panesophageal pressurization during swallowing. This subtype adds whole-esophagus pressure to the shared outflow obstruction.
Megaesophagus: Severe enlargement of the esophagus associated with chronic loss of effective emptying. Advanced achalasia can progress to a markedly dilated, tortuous esophagus.

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