Comparative study on sudden deafness by two nationwide epidemiological surveys in Japan.

Nationwide epidemiological surveys of sudden deafness were conducted in 1972 and 1987 by the Research Committee of the Japanese Ministry of Health and Welfare. Sex ratio (men over women) of definite cases of sudden deafness was 1.19 in 1972 and 0.96 in 1987. The number of patients with sudden deafness was more common between 30 and 49 years of age in 1972, whereas it was more common between 50 and 59 years of age in 1987. When the incidence of sudden deafness in the overall population was calculated, this disorder was found to be more frequent in people between 50 and 59 years of age both in 1972 and 1987. However, the incidence of sudden deafness per population was more increased in people from 50 to 75 years of age in 1987 than in 1972.