Otosclerosis is an abnormal growth of bone of the middle ear. This bone prevents the three middle ear bones from working properly and causes hearing loss. Otosclerosis usually affects the last bone in the chain, the stapes, which rests in the entrance to the inner ear (the oval window). The abnormal bone fixates the stapes in the oval window and interferes with sound passing waves to the inner ear. Otosclerosis usually causes a conductive hearing loss, a hearing loss caused by a problem in the outer or middle ear.

The cause of otosclerosis is not fully understood, although research has shown that otosclerosis tends to run in families and may be hereditary, or passed down from parent to child. People who have a family history of otosclerosis are more likely to develop the disorder. Some research suggests a relationship between otosclerosis and the hormonal changes associated with pregnancy. While the exact cause remains unknown, there is some evidence associating viral infections (such as measles) and otosclerosis.

How is otosclerosis diagnosed?

An examination by an otolaryngologist (ear, nose and throat physician) or neurotologist (ear physician) is needed to rule out other diseases or health problems that may cause these same symptoms. An audiologist uses a variety of tests and procedures to assess hearing and balance function.

How is otosclerosis treated?

In many cases surgery is an option for treatment of otosclerosis. In an operation called a stapedectomy or stapedotomy, the surgeon will lift the eardrum, the stapes bone will be surgically opened and a stainless steel prothesis will be placed into position. After doing so, the eardrum will be placed back into position.

If the hearing loss is mild, surgery may not be an option. Also, on occasion, some hearing loss persists after surgery. A properly fitted hearing aid may help some people with otosclerosis in situations that include persistent hearing loss.