Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 8-05: Diseases of the Middle Ear + Key Features Download Section PDF Listen +++ ++ A progressive disease with a marked familial tendency that affects the bony otic capsule + Clinical Findings Download Section PDF Listen +++ ++ Slowly progressive hearing loss that is usually bilateral and asymmetric, although unilateral disease may occur in up to 30% of patients Normal tympanic membrane on otoscopic examination Lesions involving the footplate of the stapes result in increased impedance to the passage of sound through the ossicular chain, producing conductive hearing loss When otosclerotic lesions involve the cochlea ('cochlear otosclerosis'), permanent sensory hearing loss occurs + Diagnosis Download Section PDF Listen +++ ++ Otoscopic examination is to exclude other causes of chronic hearing loss such as cholesteatoma and middle ear effusion Audiogram to document conductive hearing loss Weber test should lateralize to the ear with the greater conductive deficit + Treatment Download Section PDF Listen +++ ++ The conductive hearing loss may be treated either through the use of a hearing aid or surgical replacement of the stapes with a prosthesis (stapedectomy)