According to a recent epidemiological survey, the incidence of acute sensorineural hearing loss (ASNHL) is increasing yearly. The cause of ASNHL is of great interest in research. To date, viral infection, vascular occlusion, abnormal cellular stress responses within the cochlea, and immune-mediated mechanisms are considered the most likely etiologies of this disease. Among these etiologies, the relationship between viral infection and sudden deafness has been unclear. According to the course of the disease, sudden, acute and chronic forms are distinguished. When the disease starts suddenly, it develops unilaterally in a few hours without any symptoms. The acute form develops slowly over several days. The chronic form is characterized by a long period (more than 1 month) and slow hearing loss.