Intraoperative nerve monitoring (IONM) is used during thyroidectomy. The recurrent laryngeal nerve (RLN) is most at risk during thyroidectomy at which anatomical location?

• A Where the RLN enters the cricothyroid membrane at the level of the thyroid cartilage
• B Where the RLN passes posterior to the common carotid artery in the carotid sheath
• C Where the RLN crosses under the inferior thyroid artery near the inferior pole of the thyroid ✓
• D At the crico-tracheal junction just before the larynx

Explanation

The RLN is most vulnerable at its crossing with the inferior thyroid artery — the nerve may pass anterior to, posterior to, or between branches of the artery, and this relationship is variable. Unilateral RLN injury causes hoarseness (adductor palsy); bilateral injury causes stridor and respiratory distress requiring tracheostomy. The nerve must be definitively identified and traced to the laryngeal entry point. The non-recurrent laryngeal nerve (right side, associated with aberrant right subclavian artery) is a rare but important anatomical variant that can be injured if unidentified.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.