A 35-year-old woman undergoes total thyroidectomy for papillary thyroid carcinoma (PTC). Post-operatively she develops hoarseness. Flexible laryngoscopy reveals left vocal cord paralysis in the paramedian position. This injury most likely results from damage to:

• A External branch of superior laryngeal nerve
• B Internal branch of superior laryngeal nerve
• C Hypoglossal nerve
• D Recurrent laryngeal nerve in the tracheo-oesophageal groove proximal to Berry's ligament ✓

Explanation

The recurrent laryngeal nerve (RLN) is most vulnerable during thyroidectomy at two sites: where it crosses the inferior thyroid artery and at Berry's ligament where the nerve passes close to the posterior capsule of the thyroid. Injury here causes adductor and abductor paralysis, leaving the cord in paramedian (cadaveric) position due to loss of all intrinsic laryngeal muscle innervation except cricothyroid. The external branch of the superior laryngeal nerve innervates the cricothyroid muscle; its injury causes subtle pitch change and rapid voice fatigue, not cord paralysis visible on laryngoscopy. The internal branch is sensory above the vocal cords.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.