The feasibility and effectiveness of Reversed Tracking Method for the identification and protection of extralaryngeal nerve branches in thyroid surgery were analyzed. Evidence-based medical evidence was used to evaluate the importance of EBSLN recognition and protection in thyroid surgery.

The incidence of thyroid cancer in the world is growing rapidly. The current incidence of thyroid cancer in China is about 4.2/100,000, ranking the fourth in the incidence of female malignant tumors. Surgical treatment is the first and most important treatment for thyroid cancer. According to the existing literature, the injury rate of EBSLN in thyroid surgery can be as high as 58%. The quality of sound changes caused by EBSLN injury affects the quality of life of patients after surgery, and even affects the work and career of patients. therefore, seeking better EBSLN protection The method has great social and economic benefits.

Inclusion criteria：

1. thyroid papillary cancer patients
2. thyroid adenoma patients
3. tumor diameter less than 4cm
4. patients who require only unilateral thyroid surgery as required by the guidelines

Exclusion criteria:

1. The upper pole tumor invades the anterior dorsum and may accumulate the area of the superior laryngeal nerve;
2. Patients who have previously performed head and neck surgery;
3. Preoperative laryngoscopy and sound assessment abnormalities or previous vocal cord surgery history;
4. If there is a language or hearing impairment, the follow-up assessment cannot be completed;
5. The assessment failure of nerve function due to the technical deficiency of the IONM equipment

Elimination criteria:

1. Patients with recurrent laryngeal nerve palsy after surgery affect the evaluation of the laryngeal nerve.
2. The patient is asked to withdraw from the follow-up assessment midway.