Three weeks after total thyroidectomy, a 40-year-old woman reports her voice tires quickly and she can no longer raise the pitch of her voice when singing. Laryngoscopy shows a normal vocal fold position bilaterally. Which nerve was injured?

• A External branch of the superior laryngeal nerve ✓
• B Left internal branch of the superior laryngeal nerve
• C Right recurrent laryngeal nerve
• D Glossopharyngeal nerve

Explanation

The external branch of the superior laryngeal nerve runs close to the superior thyroid artery and supplies cricothyroid, the tensor of the vocal folds. Injury causes inability to tense the cords, producing hoarseness, rapid voice fatigue and loss of high pitch, with a normal resting cord position. Recurrent laryngeal injury fixes the cord in a paramedian position, and the internal branch is sensory to the supraglottic larynx.

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

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Written and medically reviewed by the StethoPrep medical team.