Abstract
The purpose of this retrospective study was to evaluate the clinical features of solitary and familial cases of idiopathic bilateral sensorineural hearing loss (IBSH), after exclusion of patients suspected to have hereditary hearing loss . We enrolled 31 patients (definite group) who were diagnosed to have IBSH by pure-tone audiometry and had been followed up for more than 3 years, and 159 patients (suspected group) who were suspected to have IBSH based on subjective symptoms. No significant differences were found in relation to the gender, age of onset, ratio of symmetric configuration in audiometry, or results of pure-tone average between the solitary and familial cases. The percentage of patients showing high-frequency or flat hearing loss in audiometric configurations was significantly higher in the familial group than in the solitary group . The hearing loss tended to progress bilaterally while keeping the same audiometric configuration in the familial cases. In the genetic analysis of GJB2, mitochondrial DNA 1555A>G and 3243A>G mutations, both mitochondrial mutations, were detected only in the familial cases. The characteristics of conventional IBSH may reflect those of the familial cases. The clinical features of solitary cases of IBSH should be evaluated to clearly elucidate the nature of IBSH.
