Anatomical Variations of the Recurrent Laryngeal Nerve and Implications for Injury Prevention During Surgical Procedures of the Neck

Introduction: Injury of the recurrent laryngeal nerve (RLN) during surgical procedures of the neck may result in vocal cord paralysis which leads to dysphonia and dysphagia. Accurate knowledge of anatomical variations of RLN provides information to prevent inadvertent intraoperative injury, improving patient safety, optimizing clinical outcomes, and ultimately guiding best clinical and surgical practices. The present study aims to assess the potential anatomical variability of RLN pertaining to its course, branching pattern, and relationship to the inferior thyroid artery, which potentially makes it vulnerable to injury, compression, or stretch during surgical procedures of the neck.

Materials and Methods: 55 formalin-fixed cadavers were carefully dissected and examined, with the course of recurrent laryngeal nerve carefully evaluated and documented bilaterally. Cadavers with anatomical variation were photographed and the data was analyzed quantitatively.

Results: Our findings indicate that extra laryngeal branches coming off of the RLN on both the right and left side innervate the esophagus, trachea, and mainly intrinsic laryngeal muscles. On the right side, 89.1% of the cadavers demonstrated 2-5 extra laryngeal branches. On the left side, 74.6% of the cadavers demonstrated 2-3 extra-laryngeal branches. In relation to the inferior thyroid artery (ITA), 67.9% of right RLNs were located anteriorly, while 32.1% were located posteriorly. On the other hand, 32.1% of left RLNs were anterior to the ITA, while 67.9% were related posteriorly. On both sides 3-5% of RLN crossed in between the branches of the ITA.

Concluding remarks: Anatomical consideration of the variations in the course, branching pattern, and relationship of the RLNs is essential to minimize complications associated with surgical procedures of the neck, especially thyroidectomy and anterior cervical discectomy and fusion (ACDF) surgery. The information gained in this study emphasizes the need to preferentially utilize left-sided approaches for ACDF surgery whenever possible