Thirty-eight-year evaluation of a surgical technique to protect the external branch of the superior laryngeal nerve during thyroidectomy.

The purpose of this study is to evaluate a surgical technique for the preservation of the function of the external branch of the superior laryngeal nerve (EBSLN) during total thyroid lobectomy and total thyroidectomy. Permanent injury to this nerve can be a disaster, especially in singers and professional speakers who depend on control of pitch, and a clear and forceful voice. Voice changes may be either obvious or subtle. For better voice analysis, a detailed questionnaire is necessary. Thus, the evaluation in this study is based on laryngoscopy of 934 nerves in 675 patients and detailed subjective voice evaluation of 66 patients during the last 2 years of the study. There are 2 surgical principles. First, the EBSLN is not routinely exposed; the distal 1.5 to 2.0 cm (critical area) of the superior thyroid vessels are carefully dissected, exposed, and ligated, preferably independently. Careful observation ensures that the EBSLN is not included in the ligature. Second, the ultimate evaluation of the surgical technique is the effect of voice changes on the patient's lifestyle. Laryngoscopy of 934 nerves found bowing, temporary in 4 patients and permanent in 1 patient (limited follow-up). Of the 66 patients with voice evaluations, 14 had changes: 9 had temporary changes, while 5 had permanent changes. In these 14 patients, voice changes had no effect on lifestyle in 13, and the effects were indeterminate in 1 (unavailable for follow-up). The estimated deleterious effect of voice changes on lifestyle is no greater than 1.5% of the 66 patient responders.