There are two types of vocal cord paralysis: unilateral and bilateral. Unilateral vocal cord paralysis is more common due to surgery, tumors, viral infections, cerebral infarction bleeding and other rare causes such as trauma. Surgery is most common for thyroid surgery, followed by surgery of the lungs and mediastinum. Viral infections often have a sudden onset, while tumors have a slowly progressive hoarseness. Definitive diagnosis can be made with dynamic laryngoscopy alone, but it is important to identify joint dislocation. It is important to rule out tumor-induced vocal cord paralysis first. Usually we do thyroid ultrasound and a chest X-ray and esophagogram. Benign tumors will not be considered for surgery until they are large enough, while particularly fast tumors will have poorer efficacy even after surgery. If it is determined that the tumor is not the cause, we can use nerve-nourishing drugs and voice training. After six months, 60-70% of patients will gradually recover on their own. The method we usually use is type I thyroid chondroplasty, which is very effective. If there is bilateral vocal cord paralysis and respiratory distress, surgery is required. Usually, the majority of people have breathing difficulties, but nearly half of them have a slightly worse voice.