Different approaches of dissecting the recurrent laryngeal nerve during total thyroidectomy affect postoperative parathyroid function

PURPOSE: This study aimed to compare the effects of proximal versus distal dissection of the recurrent laryngeal nerve (RLN) on the preservation of parathyroid function in patients undergoing total thyroidectomy for malignant thyroid tumors. METHODS: In this retrospective study, 209 patients were categorized into two groups based on the RLN exposure technique: a proximal approach (identification within 1 cm of the laryngeal entry point, n = 59) and a distal approach (identification within the tracheoesophageal groove, n = 150). Serum parathyroid hormone (PTH) and calcium levels were measured preoperatively and postoperatively. Parathyroid function preservation was quantified as the ratio of postoperative to preoperative PTH levels. RESULTS: Although postoperative PTH levels and rates of transient hypoparathyroidism were comparable between the groups, the long-term parathyroid function preservation ratio was significantly higher in the proximal approach group at the 180-day follow-up (1.016 ± 0.396 vs. 0.826 ± 0.347, p = 0.009). Additionally, the proximal approach was associated with superior early calcium homeostasis, evidenced by a lower incidence of transient hypocalcemia (23.7% vs. 41.3%, p = 0.026) and higher serum calcium levels on postoperative day 1 (2.19 ± 0.11 vs. 2.13 ± 0.14 mmol/L, p = 0.003). The rates of permanent hypoparathyroidism were low and did not differ between groups (1.7% vs. 8.0%, p = 0.116). CONCLUSION: Compared with the distal approach, the proximal approach of RLN dissection during total thyroidectomy is associated with better long-term preservation of parathyroid function and improved early calcium homeostasis, presumably by reducing injury to the vascular supply of the parathyroid glands. This strategy may be considered to optimize functional outcomes, especially in extensive surgical procedures.