A patient undergoing total thyroidectomy develops hoarseness on the first postoperative day. Laryngoscopy shows a paralysed right vocal cord in the paramedian position. Which nerve and which branch was most likely injured?
- A External branch of superior laryngeal nerve
- B Internal branch of superior laryngeal nerve
- C Recurrent laryngeal nerve — non-branched segment ✓
- D Vagus nerve at the level of the carotid sheath
Correct answer: C. Recurrent laryngeal nerve — non-branched segment
Explanation
A paralysed vocal cord in the paramedian (adducted) position with hoarseness indicates recurrent laryngeal nerve (RLN) injury — the cord is immobilised near midline because adductor fibres dominate. The external branch of the SLN innervates cricothyroid, and its injury causes monotone voice without cord palsy. The internal SLN is sensory. Vagal injury would affect both SLN and RLN causing a flaccid, laterally placed cord.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.