Renovated Prediction Model for Difficult Transoral and Submental Endoscopic Thyroidectomy

The investigators have previously proposed a prediction model for difficult transoral and submental thyroidectomy through a retrospective study. In order to better promote transoral and submental endoscopic approach for thyroid surgery and to set up an appropriate training course, the investigators aim to refine the procedure through a prospective study. As a procedure refinement, a modified strap-muscle dissection technique will be introduced during transoral and submental endoscopic thyroidectomy.

Inclusion Criteria: * Clinical diagnosis of differentiated thyroid cancer with a maximum diameter not exceeding 4 cm * Clinical diagnosis of benign thyroid nodule with a maximum diameter not exceeding 6 cm * Absence of suspicious lateral lymph nodes or distant metastases Exclusion Criteria: * Participants with fusion or fixation of lymph nodes in the neck * Participants with history of neck surgery or radiation * Participants with vocal fold fixation by preoperative fibrolaryngoscope * Participants with preoperative examination suggestive of extrathyroidal invasion * Participants with a significantly restricted neck and/or jaw