Superior laryngeal nerve (SLN) injury during thyroidectomy results in which clinical consequence?
- A Loss of the high-pitched voice (injury to the external branch — cricothyroid muscle denervation) and reduced superior mucosal sensitivity (internal branch) ✓
- B Hoarseness and breathy dysphonia due to unilateral vocal cord palsy
- C Bilateral vocal cord palsy causing stridor and airway compromise
- D Dysphagia due to cricopharyngeal muscle denervation
Correct answer: A. Loss of the high-pitched voice (injury to the external branch — cricothyroid muscle denervation) and reduced superior mucosal sensitivity (internal branch)
Explanation
The superior laryngeal nerve has two branches. The external branch of SLN (eSLN) innervates the cricothyroid muscle, which is responsible for increasing vocal cord tension to produce high-pitched sounds; its injury causes inability to produce high notes, pitch fatigue, and altered voice quality — particularly detrimental in singers and professional voice users. The internal branch of SLN is sensory to the supraglottic mucosa; its injury impairs the laryngeal protective reflexes and may cause aspiration. The recurrent laryngeal nerve (not SLN) causes vocal cord palsy.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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