[Identification and surgical anatomy of the external branch of the superior laryngeal nerve]. / Der Ramus externus des Nervus laryngeus superior (RELS): Ein Stiefkind in der Chirurgie der Schilddrüse.

ABSTRACT

Injury to the external branch of the superior laryngeal nerve (EBSLN) during thyroid surgery can cause serious consequences for patients who depend on control of pitch and a clear and forceful voice, like singers or professional speakers. We used the Neurosign 100(R) nerve monitor to identify 157 nerves in 108 patients undergoing thyroid surgery. The EBSLN was successfully identified in 98.7 % of cases. The recording electrode could be placed either into the cricothyroid muscle or the vocal cord. The latter position proved superior if the recurrent laryngeal nerve had to be identified as well. 16 percent of the nerves crossed the branches of the superior thyroid artery at or below the upper pole of the gland, posing a "high risk" for intraoperative lesions. Our data confirm the results of smaller studies reporting this type of nerve course in 12 % to 14 % of patients. The present findings show a significant number of EBSLN to be in danger of injury when the superior thyroid artery is ligated during thyroid surgery. Neuromonitoring proofed to be a reliable method to identify the nerve, which is an important element in concepts to prevent its injury.