[Conductive hearing loss with a normal eardrum].

Conductive hearing loss with a normal eardrum. Conductive hearing loss with a normal eardrum is defined by a hearing loss in in relation to a disturbance in the transmission of sound waves from a normal eardrum to an intact cochlear nerve. The interest in diagnosing these kinds of hearing loss is due on the one hand to their high frequency, on the other hand to the socio-professional repercussions that they can induce and finally to the fact that a large part of them are accessible to surgical treatment or, hearing aid. The CT-scan contributes to the diagnostic orientation and the preoperative assessment. If the pathologies of the middle ear dominate in frequency the possible causes of conductive hearing loss with a normal eardrum, especially otosclerosis, abnormalities of the inner ear, which can be responsible for conductive or mixed hearing loss, have recently listed thanks to advances in modern digital imaging. After a brief anatomical reminder of the tympano-ossicular system, we will deal with their positive, differential and etiological diagnosis.