There may be two reasons why thyroid cancer patients are unable to speak after surgery, namely, surgical injury to the recurrent laryngeal nerve and supraglottic nerve, and postoperative local compression and pulling of the recurrent laryngeal nerve, as follows: First, surgical injury to the recurrent laryngeal nerve and supraglottic nerve: surgical injury to the recurrent laryngeal nerve and supraglottic nerve is the most common situation, mainly due to inadvertent cutting, suturing, contusion and pulling of the recurrent laryngeal nerve and supraglottic nerve during surgery. The temporary or permanent damage is caused by the inadvertent severing, suturing, contusion, or pulling of the laryngeal nerve during surgery. The laryngeal nerve and superior laryngeal nerve innervate the vocal folds and muscles of the pharynx, and the hoarseness caused by nerve injury on one side can be improved by excessive inward retraction of the vocal folds on the affected side, but injury to the laryngeal nerve on both sides will lead to paralysis of the vocal folds on both sides, resulting in difficulty in articulation and inability to speak. If it is a temporary injury, it can generally recover within six months, while permanent injury cannot be recovered. Second, postoperative local compression, pulling the laryngeal nerve: postoperative wound hematoma or scar tissue compression after wound healing, pulling the laryngeal nerve and vocal cords and leading to dysphonia, which only appears a few days after surgery, is mostly a temporary injury, and after physical therapy, it can gradually recover within 3-6 months.