What is sudden deafness? Sudden deafness is a sudden onset of sensory nerve deafness of unknown origin, also known as violent deafness, which was first described by De Klevn (1944). There is no significant difference in the incidence between the sexes and the left and right sides. The incidence increases with age, and 3/4 of the patients are 40 years old or older at the time of the disease. The causes of sudden deafness are unknown, and many causative factors may lead to sudden deafness. The main ones that have gained wide acceptance are the viral infection theory, the circulatory disorder theory, the autoimmune theory, and the membrane vagus rupture theory. Symptoms of sudden deafness. Most of them are unilateral deafness, and most of them have no aura before the onset, while a few patients have a history of mild cold, fatigue or emotional excitement first. The deafness occurs suddenly, and the patient’s hearing generally decreases to the lowest point within minutes or hours, and a few patients may reach the lowest point of hearing loss within 3 days. Some patients may experience varying degrees of vertigo, which may occur at the same time as the deafness or before or after the onset of deafness. Tinnitus may occur in most patients at the time of deafness, but it may also occur after deafness. After treatment, most patients can improve their hearing, but tinnitus can persist for a long time. Hyperbaric oxygen therapy for sudden onset deafness. Hyperbaric oxygen therapy can improve blood circulation in the inner ear, improve hypoxia, increase aerobic metabolism, accelerate the repair of inner ear nerves, and facilitate the improvement of hearing and tinnitus symptoms. The Chinese Society of Otolaryngology, Head and Neck Surgery has adopted hyperbaric oxygen as one of the main treatment methods for sudden deafness, and clinical studies have shown that the earlier the hyperbaric oxygen treatment, the higher the improvement rate. Our department treats hundreds of patients with sudden deafness every year, and the total efficiency of hyperbaric oxygen treatment can reach more than 80% when combined with medication.