Otosclerosis

Key Features

• A progressive disease with a marked familial tendency that affects the bony otic capsule

Clinical Findings

• 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 impinge on the cochlea ('cochlear otosclerosis'), permanent sensory hearing loss occurs

Diagnosis

• 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

• 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)