Anatomical and developmental aspects of iatrogenic injury to the right recurrent laryngeal nerve in surgical resections of substernal goiter

Thyroid surgery is the primary treatment for substernal goiters, and iatrogenic injury to the recurrent laryngeal nerve (RNL) is always a risk. The literature suggests that iatrogenic lesions of the RNL post resection of substernal goiter are not equally distributed, being more frequent on the right recurrent laryngeal nerve (R-RLN) in comparison to the left recurrent laryngeal nerve (L-RLN). The relative paucity of basic anatomical and clinical reportages on R-RLN iatrogenic injuries and on the developmental factors that may help explain its higher incidence justifies this study's undertaking. Here we compare incidence of right versus left iatrogenic injuries to the RLN in surgical resections of substernal goiters and discuss the anatomical and embryological factors involved. This report is part of a larger retrospective observational cohort study of 239 patients surgically treated for substernal goiter in the Gaffree and Guinle University Hospital, Rio de Janeiro, from 2006 to 2018. From 239 patients, 13 presented with iatrogenic RLN injury, one patient presented bilateral lesion, totalling 15 iatrogenic lesions. Our analysis showed that the R-RLN seems to be anatomically more vulnerable to injury due to the embryological underpinnings addressed in this review, R-RLN = 64.29% (n = 9) and L-RLN = 35.71% (n = 5). Pathological factors like malignancy and size of the mass are relevant issues to be considered. The knowledge of anatomical landmarks and embryological development of the thyroid and associated structures can improve our understanding and teaching of surgical anatomy, thus helping prevent and reduce the number of iatrogenic injuries on right RLNs.