Otosclerosis

The most common cause of conductive deafness, otosclerosis is the slow formation of spongy bone in the otic capsule, particularly at the oval window. It occurs in at least 10% of whites and is twice as prevalent in females as in males; usually between the ages of 15 and 30. There's a positive family history in 55% of patients. With surgery, the prognosis is good.

Causes

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. On average, a person who has one parent with otosclerosis has a 25 percent chance of developing the disorder. If both parents have otosclerosis, the risk goes up to 50 percent. Research shows that white, middle-aged women are most at risk.

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.

Signs and symptoms

Diagnosis

An examination of the ears may rule out other causes of hearing loss.

• A hearing test ( audiometry / audiology ) may determine the extent of hearing loss.
• A temporal-bone CT scan may be used to distinguish otosclerosis from other causes of hearing loss.

Treatment

Effective treatment consists of stapedectomy (removal of the stapes) and insertion of a prosthesis to restore partial or total hearing. This procedure is performed on only one ear at a time, beginning with the ear that has suffered greater damage. Alternative surgery includes stapedotomy (creation of a small hole in the stapes' footplate, through which a wire and piston are inserted).

Postoperatively, treatment includes hospitalization for 2 or 3 days and antibiotics to prevent infection. If surgery isn't possible, a hearing aid (air conduction aid with molded ear insert receiver) enables the patient to hear conversation in normal surroundings, although this therapy isn't as effective as stapedectomy.