[Preservation of the external branch of the superior laryngeal nerve in thyroid surgery. An anatomic study of 30 dissections].

The authors stress the importance of the external branch of the superior laryngeal nerve in laryngeal physiology, by noting the consequences of its section during thyroid surgery. A rigorous anatomical study carried out on 15 fresh cadavers, i.e. 30 superior laryngeal nerves, reproducing the conditions of thyroid surgery, allowed precision of the time during surgery when the external branch is at risk of being damaged, especially during sectioning of the vascular pedicle of the upper pole and at the time of separation of the thyroid pole from the laryngeal axis. The study considers the anatomical variations of the territory of the superior thyroid artery and the various technical problems that are posed in preserving the external branch of the nerve. In the light of their findings, the authors advise that this nerve axis should be identified before ligature of the upper thyroid pedicle; if the advice is not followed then the external branch of the superior laryngeal nerve may be damaged or sectioned in approximately 15% of cases.