Achalasia 1

Question

Vignette: A 45-year-old woman presents to your clinic complaining of progressive difficulty in swallowing solid foods for the past several months. She also reports a sensation of food getting stuck in the lower part of her throat. She denies any weight loss, vomiting, or abdominal pain. Upon examination, it is found that the esophagus is dilated with retained food. A barium swallow study further reveals an absence of peristalsis in the lower two-thirds of her esophagus and a narrowing at the level of the gastroesophageal junction.

Question: What is the main mechanism underlying the patient's condition?

Choices

A. Defect in the vagus nerves

B. Defect in the glossopharyngeal nerves

C. Defect in the phrenic nerves

D. Defect in the recurrent laryngeal nerves

E. Defect in the superior laryngeal nerves

Answer

A. Defect in the vagus nerves

Explanation

The patient's symptoms and diagnostic results are consistent with achalasia, a disorder characterized by failure of the lower esophageal sphincter to relax, leading to difficulty in swallowing, esophageal dilation, and absence of peristalsis. The primary underlying mechanism in achalasia is the loss of inhibitory neurons in the myenteric (Auerbach's) plexus. These inhibitory neurons normally release nitric oxide and vasoactive intestinal polypeptide to cause relaxation of the lower esophageal sphincter. The myenteric plexus is innervated by the vagus nerve (choice A), and a defect in this nerve can lead to the symptoms seen in this patient. The other choices involve nerves that do not primarily supply the lower esophageal sphincter and therefore would not directly cause the symptoms of achalasia.