During right thyroid lobectomy, the surgeon identifies a nerve entering the larynx directly without looping under any vessel. Preoperative CT had shown the right subclavian artery arising aberrantly from the descending aorta and passing behind the oesophagus. What anomaly explains this operative finding?

• A Duplication of the recurrent laryngeal nerve distal to the inferior thyroid artery
• B Non-recurrent LEFT laryngeal nerve associated with a retro-aortic vessel
• C Non-recurrent right laryngeal nerve associated with arteria lusoria ✓
• D External branch of the superior laryngeal nerve mistaken for the recurrent nerve

Explanation

When the right subclavian artery arises aberrantly from the descending aorta (arteria lusoria) and passes behind the oesophagus, the right recurrent laryngeal nerve never hooks around it and instead runs directly from the vagus to enter the larynx. This non-recurrent right laryngeal nerve occurs in under 1 percent of people and carries a high iatrogenic injury risk because surgeons expect the classic loop. Non-recurrence on the left is far rarer and requires a right-sided aortic arch.

Reference: Schwartz Principles of Surgery, 11th ed.

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Written and medically reviewed by the StethoPrep medical team.