Identification of the external branch of the superior laryngeal nerve (EBSLN) in large goiters

Abstract

Background: Intraoperative injury to the external branch of the superior laryngeal nerve (EBSLN) can result in significant postoperative voice problems. This injury can be avoided by intraoperative nerve identification. The EBSLN has a close anatomic relationship with the superior thyroid pedicle. According to a previous anatomic classification, the type 2b nerve, which crosses the vessels below the superior thyroid pole and is considered high risk, is found in 14% to 20% of persons with normal or slightly enlarged thyroid glands. Objective: To analyze the frequency of this type 2b nerve in a population with large goiters and to compare it with the previously mentioned proportions. Design: Nonrandomized prospective study. Patients and Methods: During a 15-month period, patients with large uninodular or multinodular goiters were entered in the study. The EBSLN was searched with the help of a nerve stimulator and the type was annotated. If the patient had to be submitted to a bilateral thyroidectomy, each superior thyroid pole, with the correspondent nerve, was considered as a separate unit. Results: Nine patients, all women, underwent surgery. The average size of the goiters was 10.9 cm x 7.3 cm x 5.0 cm, and the average weight of the specimens was 431 g. There were four bilateral procedures, totalling 13 nerves analyzed. Seven (54%) were type 2b. Conclusion: The frequency of the type 2b EBSLN is considerably higher in large goiters. This finding suggests that it is even more advisable to try to positively identify the nerve in these situations, in order to prevent its injury, which is permanent and troublesome for voice professionals.