Effectiveness of Intraoperative Neuromonitoring of External Branch of Superior Laryngeal Nerve in Thyroid Surgery

With increased interest in quality of life after thyroidectomy, preservation of proper vocal cord function and voice quality is an important issue in thyroid surgery. External branch of the superior laryngeal nerve (EBSLN) and recurrent laryngeal nerve (RLN) are crucial organs for innervation and integration of laryngeal muscular system. The EBSLN innervates the cricothyroid muscle (CTM), which is important in adjusting the tension and length of the vocal cords. Damage of the EBSLN leads to CTM dysfunction, resulting in difficulty with high pitch phonation and decreased pitch range and reduced voice projection, which are important for voice professionals. As the intraoperative neuromonitoring was utilized as an adjunctive and objective tool to confirm the nerve presence and integrity, application of the intraoperative neuromonitoring system to confirm EBSLN function pre- and post-dissection of the upper thyroid pole can be regarded as an effective method to preserve cricothyroid muscle function. However, it remains unclear whether there is any intraoperative neuromonitoring techniques-added value to the clinical outcome of thyroidectomy in terms of identification of EBSLN and preserved voice performance. Therefore, this study could provide strong evidence of the application of the intraoperative neuromonitoring during thyroid surgery to identify and preserve EBSLN function.

Inclusion criteria

• Patients who are scheduled to undergo thyroid surgery
• Patients who understand and agree to take part in this study

Exclusion criteria

• If the thyroid tumor is suspected to invade adjacent organs (esophagus, trachea, carotid artery, jugular vein etc.)
• Patients who are required with lateral compartment neck dissection
• Patients with recurrent thyroid cancer
• Patients with palsy of recurrent laryngeal nerve or superior laryngeal nerve external branch in the past or present
• Patients with a history of vocal cord and larynx disease
• History of hyperthyroidism (e.g., Graves' disease)
• Taking anticoagulants (aspirin, warfarin, etc.) before surgery
• Disorders of coagulation
• In the case of women, pregnant women and breastfeeding patients
• Patients judged inappropriate by clinical trial researcher