The rate of laryngeal nerve injury caused by thyroid surgery is 0.4% to 13.3%, which can lead to postoperative hoarseness and even respiratory distress and seriously affect the quality of life of patients. Injury to the recurrent laryngeal nerve occurs mostly in the area between the inferior angle of the thyroid cartilage nerve into the larynx and the nerve crossing the inferior thyroid artery, which can reach more than 80% of the total. Reason analysis] 1. Preoperative factors: primary foci of thyroid cancer, metastatic lymph nodes in the central region invade the laryngeal recurrent nerve, or the foci are closely adhered to the nerve, making separation difficult; reoperation of the thyroid gland due to hyperplastic edema of the surgical scar, resulting in unclear local anatomy, leading to misinjury. 2, surgical factors: (1) when dealing with the lower pole of the thyroid gland. Not dissecting and separating the recurrent laryngeal nerve, clamping and ligating the main trunk of the inferior thyroid artery in large pieces, causing dissection and ligating the recurrent laryngeal nerve. (2) 40% of the laryngeal nerve will split into 2 or more branches before entering the larynx. If the branching of the laryngeal nerve is not understood, the branches can be mistaken for the trunk, thus damaging the unexposed nerve trunk. (3) Bleeding while separating the inferior thyroid artery or dealing with the small vessels at the entry of the nerve into the larynx, and clamping or suturing the recurrent laryngeal nerve while blindly stopping the bleeding. (4) Local electrothermal burns to the nearby recurrent laryngeal nerve when using an electric knife or ultrasonic knife. (5) Injury to the recurrent laryngeal nerve when suturing the posterior peritoneum of the thyroid gland during subtotal thyroid surgery, or when the suture is pulled. (6) When performing lymph node dissection in the central region, excessive exposure of the free, stretched laryngeal nerve can easily cause non-inflammatory edema of the nerve, followed by loss of nerve performance. (7) Anatomic variants, such as when the right nerve larynx does not return, break the nerve when dealing with the lateral upper pole of the thyroid. (8) When the thyroid gland is inflamed, the laryngeal nerve tends to adhere closely to the thyroid envelope, making separation difficult and leading to misinjury. 3. postoperative factors: local scar formation and adhesions after surgery, or poor drainage of effusion, can also lead to inadequate blood supply or compression of the nerve, resulting in injury. Precautions] 1. Adequate preoperative evaluation, especially for patients with thyroid cancer, thyroid reoperation or severe adhesions of bleeding cystic changes of thyroid masses should be fully estimated for the difficulty of surgery. Preoperative CT examination can detect the laryngeal non-returning nerve in advance to avoid intraoperative misinjury. 2, must emphasize the meticulous operation of surgery, should be carried out in the state of little blood loss or basic bloodlessness, the surgical field of view is very clear, only a good revealing can better protect the laryngeal recurrent nerve. The procedure should be as clear as possible, and in case of bleeding, do not panic and blindly clamp the tissue. 2.When performing total or subtotal thyroidectomy, it is advisable to dissect the entire thyroid segment of the recurrent laryngeal nerve and remove the lesion while dissecting the nerve, so as to completely remove the tumor without damaging the recurrent laryngeal nerve. When the nerve length is stretched more than 20% of the original length, it has caused irreversible damage to the nerve. When dealing with the inferior thyroid artery, avoid ligating the main trunk, but gradually ligate its branches, as long as the operation is within the perineural space, the laryngeal nerve will not be damaged. 5, the laryngeal nerve in the vicinity of the larynx and the thyroid gland, as well as some of the laryngeal nerve into the larynx before the number of branches, are prone to injury one of the reasons, at the same time, there are often crossed with the laryngeal nerve or accompanied by the small artery wrapped around, should be carefully separated, carefully ligated. 6, the rate of injury to the recurrent laryngeal nerve is higher in masses located on the dorsal side of the thyroid, and routine dissection is recommended to protect the recurrent laryngeal nerve. 7. Once intraoperative injury to the recurrent laryngeal nerve is detected, early exploration and repair should be performed. The main points of observation after treatment] 1, postoperative nerve injury is given neurotrophic drugs, such as Micropol, or nerve growth factor. 2.Once the laryngeal nerve injury is detected and confirmed by laryngoscopy, early exploration and nerve anastomosis should be performed.