Clinical features of idiopathic bilateral sensorineural hearing loss.

The Research Committee of the Ministry of Health and Welfare in Japan has defined hearing loss of unknown etiology with fairly high-speed progression as idiopathic bilateral sensorineural hearing loss (IBSH). Its diagnostic criteria consist of the following: that it is (1) progressive, (2) with bilateral involvement, and (3) of unknown etiology. In this study, we evaluated the clinical course in 20 cases of IBSH. Many cases of IBSH finally showed symmetrical profound sensorineural hearing loss. The clinical course of IBSH consisted of various combinations of the following four states: (1) fixed hearing, (2) rapid progression, (3) pathological slow progression and (4) physiological slow progression.