Sudden deafness is a sudden onset of sensorineural hearing loss of unknown origin that can occur within minutes, hours or 3 days, with a hearing loss of at least 20 dB in at least 2 connected frequencies. The diagnosis of sudden deafness is based on: sudden onset, which can occur within minutes, hours or 3 days. Non-fluctuating sensorineural hearing loss, which can be mild, moderate or severe, or even total deafness. Hearing loss of at least 20 dB or more in at least 2 connected frequencies. It is mostly unilateral, occasionally bilateral at the same time or sequentially. The cause is unknown. Tinnitus and blocked ears. With vertigo, nausea and vomiting, but not recurrent. No symptoms of cranial nerve damage other than the eighth cranial nerve. The incidence of sudden deafness is gradually increasing and tends to be younger, and it has become a common otologic disease that poses a serious health risk to the population. The cause of sudden deafness is not known, but there are two main theories: the viral infection theory and the inner ear blood supply disorder theory. About 50% of patients experience vertigo before or after the onset of hearing loss.