Sudden hoarseness of voice needs to be alert to acute laryngitis, acute polyneuritis, diphtheria, posterior inferior cerebellar artery or basilar artery thrombosis and other diseases. 1. Acute laryngitis: acute laryngitis produces inflammatory lesions in the larynx under the stimulation of a number of factors, causing hoarseness, foreign body sensation in the throat, itching, dryness, and other local symptoms, and may bring about systemic symptoms such as fever, loss of appetite, chills, and so on. 2. Acute polyneuritis: acute polyneuritis will lead to paralysis of the lingual pharyngeal and vagus nerve innervated muscles, which will cause sudden hoarseness of the voice, as well as difficulty in swallowing and pronunciation, and the patient will often have paralysis of the limbs at the same time. 3. Diphtheria: Sudden hoarseness may also be caused by diphtheria, an acute respiratory infectious disease, which causes grayish-white pseudomembrane to appear in the patient’s throat, and also causes generalized toxemia. 4. Thrombosis of the posterior inferior cerebellar artery or basilar artery: Thrombosis in the cerebellum can also cause hoarseness if it involves the vagus nerve. Diseases that can cause sudden hoarseness are very diverse, and after the onset of the disease, we need to consult a doctor in a timely manner, and systematic examination to clarify the diagnosis.