Intraoperative investigation and the significance of extralaryngeal division of recurrent laryngeal nerve                       QIAN Jun，SU Yan-jun，ZHANG Jian-ming，et al. Department of Thyroid Surgery, First Affiliated Hospital of Kunming Medical University, Kunming 650032, China
Corresponding author：CHENG Ruo-chuan, E-mail：cruochuan@yahoo.com.cn
Abstract    Objective    To analyze the frequency of extralaryngeal branching（ELB）of the recurrent laryngeal nerve (RLN) in thyroidectomy and discuss the clinical significance of preserving extralaryngeal branching of RLN. Methods Intraoperative study the ELB of RLN in 1346 patients performed thyroidectomy by the same group of surgeons from January 2009 to January 2011 in the First Affiliated Hospital of Kunming Medical University was performed combined with pertinent literatures reviewed. Results    There were 943 patients enrolled in the research. Among them, 1701 RLNs were exposed and indentified (843 in left and 858 in right) and bilateral RLNs were exposed in 758 patients simultaneously. A total of 528 RLNs (31.0%) had extralaryngeal branches (306 in left and 222 RLNs in right), while 218 cases were bilaterally. Bifurcation occurred in 82.4% of the patients, while the other 17.6% were trifurcations. The median distance from branching point to entering point was 7.5mm on the left and 8mm on the right. Branching point above the inferior thyroid artery occurred in 85.6% nerves. There were 8 patients with nerves iatrogenic injured. Among them, 2 patients were temporary and 6 were permanent. Conclusion    The incidence of extralaryngeal branching of RLN and location of branching may be varied. However, the motor fiber of RLN is located in the anterior branch which controls the movement of vocal cord. Recognition of the frequent anatomical variation and meticulous preservation of all branches are of great importance to decrease postoperative vocal cord paralysis.