Surgical Anatomy and Monitoring of the Superior Laryngeal Nerve

The technical aspects of operations on the thyroid gland have changed very little since the original papers by Kocher. Usually, the complication rate of thyroidectomy is very low when an experienced surgeon performs the operation. The most common complications include injury of the recurrent laryngeal nerve (RLN) and hypoparathyroidism. However, injury to the external branch of the superior laryngeal nerve (EBSLN) can occur during the dissection and control of the superior thyroid vessels. This injury causes paralysis of the cricothyroid muscles (CTMs), impairing the production of high tones, and altering the voice’s fundamental frequency; this is especially problematic for women and professional singers. The effects of EBSLN paralysis are difficult to detect during routine postoperative laryngoscopy; however, functional consequences can be disastrous for those people who depend professionally on their voices. Armed with complete knowledge of the anatomic variations of the superior thyroid pole area, and through meticulous dissection of the superior thyroid pedicle, one may avoid such injury. In addition, this chapter will briefly discuss the use of the internal branch of the superior laryngeal nerve (IBSLN) to continuously monitor vocal fold function via the laryngeal adductor reflex (LAR).