Abstract
History of idiopathic sudden sensorineural hearing loss (sudden deafness) was described in association with Menière's disease. Criteria for the diagnosis of sudden deafness was established by the Research Committee of the Japanese Ministry of Health and Welfare in 1973. Using the criteria, three nationwide epidemiological surveys on sudden deafness have been conducted by the Research Committee. In 1998, the Research Committee established a grading system based on the severity of hearing loss regarding sudden deafness. The grading system will be useful for evaluation of the outcome of sudden deafness. Because the number of patients with sudden deafness has been increasing in Japan, further study to elucidate the pathophysiology will be necessary.
