A 32-year-old woman undergoes total thyroidectomy for multinodular goitre. Postoperatively her voice is breathless and weak on sustained speech, but she can cough normally and has no aspiration. Indirect laryngoscopy shows normal vocal cord mobility bilaterally but reduced tension of the left cord. Which nerve was injured?
- A Left recurrent laryngeal nerve
- B External branch of the left superior laryngeal nerve ✓
- C Internal branch of the left superior laryngeal nerve
- D Left ansa cervicalis
Correct answer: B. External branch of the left superior laryngeal nerve
Explanation
The external branch of the superior laryngeal nerve supplies cricothyroid, the tensor of the vocal cord. Injury causes loss of voice projection and inability to sustain high pitch with normal cord mobility, classically described in singers. The recurrent laryngeal nerve causes cord palsy with a bovine cough and aspiration risk, so its intact function here excludes option A. The internal branch is sensory to the supraglottic larynx and does not affect phonation.
Reference: Bailey and Love Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.