New operative surgical concept of two fascial layers enveloping the recurrent laryngeal nerve.

BACKGROUND

Avoiding recurrent laryngeal nerve (RLN) injury is aided by a precise anatomical understanding of the RLN before entry into the larynx where it is at greatest risk.

METHODS

A literature review and study of 977 RLNs at operation have been used to describe the last 2 cm of the anatomical course of the extralaryngeal RLN.

RESULTS

The tertiary branches of the inferior thyroid artery pass in a superficial vascular fascial layer anterolateral to the RLN. The tubercle of Zuckerkandl and the superior parathyroid glands lie within this superficial vascular fascial covering layer. The RLN lies on a deeper layer of more fibrous tissue, the ligament of Berry. In all 977 RLNs, the RLN was sandwiched between an anterolateral vascular layer and a medial layer, the ligament of Berry.

CONCLUSIONS

The site of greatest risk during thyroidectomy to the RLN is in the 2-cm course of the extralaryngeal nerve above the trunk of the inferior thyroid artery where tension forms an artificial genu of the nerve. Once the superficial vascular fascial and Berry's ligament layers are released, the nerve falls back into the tracheoesophageal groove and adopts a serpiginous appearance, indicating completeness of the dissection of the lobe from the lateral trachea and division of the ligament of Berry.