Identification of the Nonrecurrent Laryngeal Nerve during Thyroid Surgery: Variations, Associated Vascular Malformation, Adequate Surgical Technique

Korean Journal of Head & Neck Oncology 2006;22(1):3-7.
Published online May 30, 2006.

Jan dee Lee;Ji Sup Yun;Chi Young Lim;Kee Hyun Nam;Hang Seok Chang;Woong Youn Chung;Cheong Soo Park

갑상선 수술시 발견된 비회귀성 후두신경 ; 유형, 동반 혈관 이상, 신경 손상 예방에 대한 고찰

이잔디;윤지섭;임치영;남기현;장항석;정웅윤;박정수

Abstract

Purpose
The nonrecurrent laryngeal nerve(NRLN) is a rare anomaly that is associated with the developmentally aberrant subclavian artery. Although rare on the right side and exceptional on the left, an aberrant nonrecurrent pathway for RLN represents a major surgical risk. Three course variations of right NRLN can be distinguished: descending(type I) , horizontal(type II), ascending(type III). This study is performed to characterize the variations of NRLN, associated vascular anomaly, and proper surgical methods for preventing nerve damage. Materials and Methods: Between January 1998 and March 2006 3,381 thyroidectomy were performed at our institution, and during these operations a nonrecurrent laryngeal nerve was observed in 13 cases (0.38%). There were 1 men and 12 women with a median age of 48 years(range 28-57). All of them are identified on the right side.
Results
In all cases, there were no clinical symptoms observed preoperatively. The nerve anomaly was diagnosed preoperatively in only one case. There were type I variations of right RLN in 2 cases and type II variations in 11 cases. The retroesophageal aberrant right subcalvian artery; no innominate(brachiocephalic) artery was found and the right common carotic artery was arising directly from the aortic arch, was seen in 12 cases. A vocal cord palaysis caused by NRLN damage during operation was observed in one patient(7.6%) , where the nerve was close to the superior thyroid artery. No other complications were noted.
Conclusion
It can be possible to predict NRLN from signs associated with the vascular anomaly; clinical symptoms or imaging studies. When an vascular anomaly is not detected preoperatively, overlooking possibility of NRLN may lead to severe operative morbidity. Hence, It is most important to identify all the thyroid structures carefully during thyroid surgery and to be aware of the possibility of anatomic variations of RLN.

Key Words: Nonrecurrent laryngeal nerve, Aberrant subclavian artery, Nerve injury