MCQ – 88271

A 36-year-old woman has an injury to the right external laryngeal nerve during a thyroid surgery. What symptom would be expected in this patient?

Correct Answer � D Explanation

Answer D) Dysphonia

Explanation:

External laryngeal nerve (smaller, external branch of the superior laryngeal nerve) lesion causes mono toned voice (loss of ability to produce pitched sound) that is dysphonia. 

Injury of the external branch of the superior laryngeal nerve in thyroid surgery

• The external branch of the superior laryngeal nerve (EBSLN) is at risk of injury during thyroid operations when dissection of the superior pole and ligation of the superior thyroid vessels (STV) are carried out. 

• The rates of injury to this nerve are highly variable in the literature, but can be as high as 58%. 

• The EBSLN is the sole motor nerve to the cricothyroid muscle (CTM) and its dysfunction results in lowered voice fundamental frequency, lowered voice projection, fatigue and inability to achieve high-frequency sounds.

Recurrent laryngeal nerve

Injury to the recurrent laryngeal nerves can result in a weakened voice (hoarseness) or loss of voice (aphonia) and cause problems in the respiratory tract.