The term “otosclerosis” means abnormal hardening of body tissue (“sclerosis”) in the ear (“oto”). Otosclerosis begins in the otic capsule, which is the strong bone that surrounds your inner ear.
In the early stages of the disease, areas of soft bone appear around the otic capsule. This process is called otospongiosis and can result in bone loss from the otic capsule. Over time, the bone loss stops, and the soft areas scar and harden, causing otosclerosis.
This process of abnormal growth and scarring can extend beyond the otic capsule, usually to the nearby stapes. The stapes is one of three tiny bones in the middle ear that transmits sound vibrations from the eardrum to the inner ear. Scarring of the stapes may limit or prevent the transmission of sound, resulting in conductive hearing loss.
Otosclerosis can also injure the inner ear directly and cause sensorineural hearing loss and balance problems.
How common is otosclerosis?
Otosclerosis is more common among people with white European or Indian ancestry. Researchers estimate up to 10% of white people have otosclerosis, though only a fraction develop symptoms . Otosclerosis occurs less frequently in people who are Black or Asian. Women are twice as likely to develop otosclerosis than men.