J. C. Lee1,2 1The Alfred, Melbourne, Victoria, Australia 2Monash Health, Dandenong, Victoria, Australia
Introduction: Over the last 150 years thyroid surgery has been transformed from a procedure with high mortality to a very safe one. However, recurrent laryngeal nerve (RLN) injuries continue to occur. This study examined the differential palsy rates between the left and right RLNs, and the role of intraoperative nerve swelling as a risk factor of postoperative palsy.
Methods: Thyroidectomy data of patients of the Monash University Endocrine Surgery Unit were collected from 13 institutions, including demographics, pathology, and change in RLN diameter (subgroup). Voice quality was scored subjectively using the Voice Disorder Index and objectively using the Dysphonia Severity Index (DSI), before and after operation, in a subgroup.
Results: A total of 5,334 RLNs were at risk in 3,408 thyroidectomies in this study. The overall RLN palsy rate was 1.5%, greater on the right side than the left for bilateral cases (P = .025), and greater on the left side than the right for unilateral cases (P = .007). The diameter of the right RLN was larger than the left RLN, both at the beginning and end of the dissection (P = .001). The RLN diameter increased by approximately 1.5-fold (P < .001). In hemithyroidectomy patients, the greater the increase in recurrent laryngeal nerve diameter, the worse the post-operative DSI score (P = .03). Patients who underwent either hemi- or total thyroidectomy both reported significant deterioration of voice. However, on objective assessment, only total thyroidectomy patients showed significant deterioration (Mean DSI 4.0 ± 0.3 – 2.5 ± 0.3, P < .01). Conclusion: As we embark on new and innovative thyroidectomy techniques, it is important to review the anatomical and functional details of the RLN. It is also paramount that we do not compromise patient outcomes while developing minimally invasive techniques.