Thyroid lobe size predicts risk of postoperative temporary recurrent laryngeal nerve paralysis

Objectives In patients who had undergone thyroidectomy in Japan for benign tumor, we determined whether thyroid lobe size correlates with temporary recurrent laryngeal nerve paralysis (T‐RLNP). Methods We retrospectively collected medical record data on usage of intraoperative neuromonitoring, laterality of thyroidectomy, amount of bleeding during surgery, duration of surgery, and whether the surgeon was a board certified otorhinolaryngologist as determined by the Oto‐Rhino‐Laryngological Society of Japan. Thyroid size was measured in preoperative axial computed tomography (CT) images. Receiver operating characteristic (ROC) curve analysis was used to determine the thyroid size that predicted a high risk of T‐RLNP or permanent recurrent laryngeal nerve paralysis (P‐RLNP). Results Of the 146 eligible patients identified, 9 (6.2%) developed T‐RLNP and 2 (1.4%) developed P‐RLNP. The amount of bleeding during thyroidectomy was significantly greater in T‐RLNP patients than in P‐RLNP patients. Thyroid sizes in CT images were significantly larger in T‐RLNP patients compared to patients who did not develop RLNP (referred to hereafter as N‐RLNP). ROC analysis revealed that 1.3% of thyroid lobes with an area of less than 1000.0 mm 2 , and 9.9% of thyroid lobes with an area of greater than 1000.0 mm 2 were at risk for T‐RLNP. Conclusion We presented evidence that thyroid sizes, as measured on preoperative axial CT images, were larger in T‐RLNP patients than in N‐RLNP patients. Our results indicate a connection between benign thyroid tumor stretch injuries and T‐RLNP. Level of Evidence IV.