Sudden deafness is a sudden, unexplained hearing loss that occurs in a normal person within a short period of time. It can occur all year round, especially in winter and spring, and is more common in young and middle-aged people. 1.Common causes and pathogenesis: The causes of the disease are unclear, and may be related to vascular factors, infectious factors, neurohumoral factors, toxic factors, rupture of the round window membrane and other factors. In terms of age, the elderly are more thrombosis, atherosclerosis, middle-aged people are more vasospasm, juveniles are more infection factors, specific to a case there is no confirmatory examination method. However, regardless of the cause, most of them are related to hypoxia, for example, vasospasm leads to ischemia and hypoxia, thrombosis leads to ischemia and hypoxia, and infection causes local edema when the tissue gap increases and also causes hypoxia away from the vascular area. In addition, sudden deafness is mostly seen in brain workers, which also indicates a close relationship with hypoxia from another perspective. 2. Clinical manifestations: Some patients may complain of certain triggers before the onset of deafness, such as exertion, cold, anger, staying up late, etc., but most of them have no obvious triggers, and most of them occur in the morning or when they wake up from a nap. (1) Deafness: Most of the patients have hearing loss in one ear, partial deafness or total deafness. They often feel that the affected ear is blocked, stuffy, full or feel that the sound cannot come out, as if swimming with water in the ear. (2) Tinnitus: About 70% of patients have low tone, high tone or mixed high and low tone tinnitus. Tinnitus can occur before, after or at the same time as deafness, and tinnitus is felt more obviously in quiet state, and even affects sleep or work in severe cases. (3) Vertigo: 36-68% of patients have vertigo, nausea, or even vomiting, mainly in the early stage of severe deafness, which can last for a few hours to a few days, and its mechanism is related to the involvement of the semicircular canal in the inner ear. (4) Very few patients may have symptoms of trigeminal nerve, linguopharyngeal nerve and vagus nerve involvement. (5) Otologic examination: In addition to hearing loss, the tympanic membrane is normal (some patients may have mild invagination), the eustachian tube is normal, and nystagmus is sometimes seen in severe patients. (6) Electrical audiometry: normal hearing should be within 25 decibels, our usual language communication with the most is 250 ~ 2000 Hz, therefore, different frequencies of hearing loss patients feel is obviously different. Hearing curve decline can be divided into four types: Type I – low-frequency decline is the main, accounting for about 17%. Type II – full-frequency decline predominates, accounting for about 41%. Type III – high-frequency decline predominates, accounting for about 29%. Type IV – total deafness, about 13%. It is important to note that electroaudiometry is a subjective test, and the difference in equipment and concentration can cause errors, generally up or down by 10 decibels. The degree of deafness is classified as: normal – within 25 decibels, mild deafness – 25 to 40 decibels, moderate deafness – 40 to 55 decibels, severe deafness – 55 to 90 decibels, total deafness – more than 90 decibels. (7) Auditory brainstem evoked potential: This test is an objective test, which consists of a set of waveforms that appear in a regular and sequential manner, divided into seven waveforms Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ, VI and Ⅶ. The waveform, amplitude, latency and conduction time of each waveform are used to determine the degree of damage to the corresponding area. 3.Treatment As mentioned before, many factors causing deafness are closely related to hypoxia, so how to improve hypoxia is very important in the treatment of deafness. Hyperbaric oxygen, vasodilation and nerve nutrition are the three pillars of treatment for sudden deafness. (1) Hyperbaric oxygen therapy: It is the most important treatment for sudden deafness. Hyperbaric oxygen can rapidly increase the blood oxygen level, increase the effective diffusion distance of oxygen, reduce edema, and improve the ischemic and hypoxic state of inner ear. Conventional hyperbaric oxygen therapy can increase the oxygen content of blood by 10 times, but if we rely on single transfusion of vasodilator drugs, the increase of blood flow is limited, and the increase of blood oxygen content is also very low when it comes to improving hypoxia. The earlier the timing of hyperbaric oxygen treatment, the better. For those who cooperate with infusion, it is recommended that infusion first and then oxygen is administered, and this arrangement of treatment sequence is more reasonable. ① Treatment pressure: generally 2~2.5 atmospheres (0.2~0.25Mpa). ② Oxygen inhalation program: At present, it is mostly 30 minutes × 2, with 10 minutes rest in between, and 10 times as a course of treatment. ③ Number of treatments: there is no hard and fast rule, generally do 6-7 times will feel the improvement of hearing, individual more than a dozen times to be effective, if the second course of treatment is still not effective is very difficult to be effective. As long as it is effective but still not back to normal, we should continue to do it clinically. (2) Drug therapy ① vasodilators: is an essential treatment link in the comprehensive treatment. (2) Nerve-nourishing drugs: also indispensable in the treatment. (3) Anticoagulation therapy: Anticoagulation therapy can be given to those with high possibility of thrombotic factors. (4) Symptomatic treatment and anti-edema treatment 4, precautions (1) Patients must treat their condition with a normal mind, mental tension is very detrimental to hearing recovery. (2) It is recommended to use comprehensive treatment, preferably infusion followed by hyperbaric oxygen therapy, this arrangement is more reasonable. (3) The effect is often unstable at the beginning, sometimes good and sometimes bad, later will gradually become better and stable. (4) You should pay attention to rest and avoid staying up late. (5) Should avoid wearing headphones and listening to music loudly. (6) Individual cases of re-aggravation by eating spicy food are recommended to be controlled appropriately during treatment.