VULNERABILITY OF THE RECURRENT LARYNGEAL NERVE IN THE ANTERIOR APPROACH TO THE LOWER CERVICAL-SPINE

Study Design. To perform anatomic dissections and measurements of the recurrent laryngeal nerve between the inferior thyroid artery and supe rior border of the clavicle (mid-portion) on both sides. Objectives. T o determine quantitatively the differences in course and location betw een the recurrent laryngeal nerves on both sides and to relate this to the vulnerability of the recurrent laryngeal nerve during an anterior approach to the lower cervical spine. Summary of Background Data, The midportion of the recurrent laryngeal nerve is usually encountered in the anterior approach to the lower cervical spine, especially on the right side. No quantitative regional anatomy describing the course and location of the mid-portion of the recurrent laryngeal nerve is avail able in the literature. Methods. Fifteen adult cadavers were used for dissections of the recurrent laryngeal nerve. The length of the recurr ent laryngeal nerve between the superior border of the clavicle and th e inferior thyroid artery, and the angle of the recurrent laryngeal ne rve with respect to sagittal plane, were measured bilaterally. In addi tion, six cross-sections at C7 were obtained to determine the linear d istances between esophagotracheal groove and the recurrent laryngeal n erve. Results. The recurrent laryngeal nerve on the right runs in a su perior and medial direction, with an angle of 25.0 degrees +/- 4.7 deg rees relative to sagittal plane, compared with 4.7 degrees +/- 3.7 deg rees on the left. The length of the recurrent laryngeal nerve between the superior border of the clavicle and the inferior thyroid artery is 23.0 +/- 4.4 mm on the left, and 22.8 +/- 4.3 mm on the right. The re current laryngeal nerve lies deep within the esophagotracheal groove o n the left, but 6.5 +/- 1.2 mm anterior and 7.3 +/- 0.8 mm lateral to the esophagotracheal groove on the right. Conclusions. The recurrent l aryngeal nerve on the right side is highly vulnerable to injury if lig ature of the inferior thyroid vessels is not performed as laterally as possible or if retraction of the midline structures along with the re current laryngeal nerve is not performed intermittently. Avoiding inju ry to the recurrent laryngeal nerve, especially on the right side, is a major consideration during an anterior approach to lower cervical sp ine.