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Achalasia 3

Achalasia
physiology

Question

Vignette: A 28-year-old woman presents to the clinic complaining of difficulty swallowing and regurgitating undigested food. She mentions that she has lost weight over the past few months. Barium swallow study shows a dilated esophagus with a "bird's beak" appearance at the distal end. Manometry shows high pressure in the lower esophageal sphincter. Which of the following is the most likely pathophysiological mechanism underlying this patient's condition?

Choices

A) Disruption of the myenteric plexus in the esophagus

B) Hyperactivity of the vagus nerve

C) Overproduction of acetylcholine at the neuromuscular junction

D) Inflammation of the esophageal mucosa

E) Hypersensitivity of the lower esophageal sphincter to cholinergic stimulation

Answer

A) Disruption of the myenteric plexus in the esophagus

Explanation

This patient's symptoms, radiological findings, and manometric findings are indicative of achalasia, a disorder characterized by a failure of the lower esophageal sphincter (LES) to relax. The underlying pathophysiological mechanism involves a loss of inhibitory neurons (that secrete nitrogen oxide and vasoactive intestinal peptide) in the myenteric plexus (Auerbach's plexus) of the esophagus, leading to unopposed action of excitatory neurons (that secrete acetylcholine). This results in persistent contraction of the LES, causing difficulty in swallowing, regurgitation of undigested food, and subsequent weight loss. The "bird's beak" appearance on barium swallow is a classic finding in achalasia, reflecting the dilated esophagus above the constricted LES.

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