**Question:** Dysphagia lusoria is a condition which results from

A. compression of the trachea by the right subclavian artery
B. narrowing of the esophagus due to inflammation
C. abnormal course of the right subclavian artery
D. congenital abnormality of the esophagus

**Correct Answer:** A. compression of the trachea by the right subclavian artery

**Core Concept:** Dysphagia lusoria is a rare congenital abnormality of the cardiovascular system. It occurs due to an abnormal course of the right subclavian artery, which instead of following a normal course between the trachea and esophagus, it moves anteriorly and laterally, compressing the trachea.

**Why the Correct Answer is Right:** The correct answer is right because the condition is associated with the abnormal course of the right subclavian artery, which is the primary cause of dysphagia lusoria. This abnormal course compresses the trachea, leading to the symptoms and signs of dysphagia lusoria.

**Why Each Wrong Option is Incorrect:**

A. Compression of the trachea by the right subclavian artery is not the primary cause of dysphagia lusoria. The correct answer explains the condition's pathogenesis, while this option discusses the potential consequence of the condition but not the cause.

B. Inflammation of the esophagus is not the primary cause of dysphagia lusoria. The condition is primarily caused by the abnormal anatomy of the right subclavian artery, not inflammation.

C. This option is incorrect as it describes an unrelated anomaly, not the cause of dysphagia lusoria. The correct answer explains the primary cause, while this option describes an unrelated abnormality.

D. Dysphagia lusoria is a condition resulting from compression of the trachea by the right subclavian artery, which is the primary cause explained in the correct answer. This option is incorrect as it discusses an unrelated abnormality.

**Clinical Pearls:**

Dysphagia lusoria is a rare condition that affects approximately 0.2% of the population. It is more common in females than males and is usually diagnosed in childhood. Symptoms include difficulty swallowing solid foods, regurgitation, and occasionally aspiration. Treatment options include medication, lifestyle modifications, and, in severe cases, surgery.

**Why This is Important:** Understanding the primary cause of dysphagia lusoria, which is compression of the trachea by the right subclavian artery, is crucial for accurate diagnosis and appropriate treatment.