A 34-year-old woman undergoes total thyroidectomy. On the first postoperative day her wound, calcium, and stridor checks are all normal, but she complains that her voice tires quickly and she can no longer sing high notes. Laryngoscopy shows a normal vocal cord movement bilaterally. Which structure was most likely injured?

• A External branch of the superior laryngeal nerve ✓
• B Recurrent laryngeal nerve
• C Internal branch of the superior laryngeal nerve
• D Hypoglossal nerve

Explanation

The external branch of the superior laryngeal nerve supplies cricothyroid, the tensor of the vocal cord. Injury causes loss of high pitch and easy voice fatigability with normal cord mobility on laryngoscopy, classically after ligation of the superior pole vessels where the nerve runs close to the artery. The recurrent laryngeal nerve causes hoarseness with impaired cord mobility, so its intact laryngoscopy kills that distractor.

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

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Written and medically reviewed by the StethoPrep medical team.