Ultrasound Visualization of the Recurrent Laryngeal Nerve: A Prospective Clinical Validation Study

This study aimed to optimize a lateral transthyroid approach by using high-resolution ultrasonography (HRUS) for recurrent laryngeal nerve (RLN) visualization.

In this prospective study of 85 patients undergoing thyroidectomy, the RLN was visualized preoperatively by using a lateral transthyroid approach via HRUS. The inferior thyroid artery, thyroid nodule, and cricoid cartilage were used as landmarks. RLN visibility was graded from poor to excellent. The accuracy of the preoperative localization of the RLN was determined by intraoperative HRUS, neuromonitoring, and surgical findings.

RLN visualization and localization were verified intraoperatively by ultrasound-guided stimulation via a neuromonitoring probe in eight patients with extended incisions owing to the need for neck dissection. A total of 110 RLNs were present in 85 patients, and the locations of 103 RLNs detected by preoperative ultrasound were confirmed intraoperatively, with an accuracy rate of 93.6%. All detected RLNs were well visualized at the inferior thyroid artery and thyroid nodule levels. The RLN was visible in 83.5% of cases at the cricoid cartilage level. The maximum short-axis diameter and cross-sectional area of the RLN at all three levels were significantly larger in males than in females (p < 0.05). In total, ten RLNs were bifurcated and two showed tumor invasions. These findings were confirmed intraoperatively.

Effective RLN visualization can be achieved using a lateral transthyroid approach via HRUS. The precise localization, prediction of anatomic variation, and invasion of RLN provide significant advantages in the individualized treatment, surgical planning, and nerve protection of patients with thyroid lesions.