Hearinginfo.org  © Copyright. No copying without prior written permission	Diseases and DIsorders of the Ear
Otosclerosis - Calcium Deposits in the Middle Ear

Otosclerosis of the Middle Ear

Description of otosclerosis

The last bone in the vibration chain in the middle ear is the stapes. It is attached to the cochlea at the oval window. Otosclerosis is a metabolic imbalance condition that causes new bone to grow over the end of the stapes, where it connects to the cochlea. This leads to a reduction in movement and eventually the bone becomes fixed as no vibration occurs, causing the elimination of transfer of sound to the inner ear and permanent hearing loss.

Image of otosclerosis occurring between the stapes and the oval window of the cochlea. Notice the build up of calcium.

Very occasionally, otosclerosis can also affect the inner ear. The condition can affect either one, or more commonly, both ears. If left untreated, otosclerosis will cause the hearing to steadily get worse and can lead to profound deafness. In the early stages of otosclerosis, or when the condition is mild, no treatment may be needed. Hearing aids are very useful initially. However, as the calcium buildup on the stapes progresses you will gradually lose the hearing. Sodium fluoride tablets have been shown to help prevent the progression of otosclerosis, but only if the condition has also affected the inner ear.

Genetic causality of Otosclerosis

Otosclerosis can run in families and often begins around the age of 30. The condition is also more common in women and often gets worse in pregnancy. It is thought that this is due to the release of high levels of the hormone estrogen during pregnancy. If you have otosclerosis and are worried that the pregnancy may affect the hearing, see the doctor. You may have to have a hearing test from time to time in order to monitor the hearing.

Symptoms of Otosclerosis

Symptoms of Otosclerosis include tinnitus and hearing loss, often at lower frequencies - deeper sounds - to begin with. You may also find that the hearing is better in noisy surroundings. People with otosclerosis tend to speak quietly.

Treatments for Otosclerosis

Biological Ossicle Replacement (ossiculoplasty)

Ossiculoplasty

An ossiculoplasty operation repairs damage that has occurred as a result of infection or injury to more than one of the three bones of the ossicles. The damaged ossicles are replaced with either artificial bone, called prostheses, or small pieces of bone taken from somewhere else in the body. The prostheses can be made from man-made bone material, plastic or ceramic. The ossicles are very small and this makes the surgery very delicate. This means that although the operation can improve the hearing, it may not completely return.

Artificial Ossicle Replacement (Stapedectomy and/or stapedotomy))

This operation aims to improve the hearing by replacing the stapes - one of the ossicles - with a piston. The piston helps to restore the movement of the ossicles, so transmission of  sound into the inner ear can occur.

Photo courtesy American Academy of Family Physicians

Stapes Replacement Details

Most of the stapes bone is removed, leaving just the portion called the footplate, which sits in contact with the oval window. The oval window is the link between the middle and inner ear. A small hole is then drilled in the footplate and the piston is inserted so that it sits in contact with the oval window. At its other end, the piston is attached to the incus (anvil), the middle of the three ossicles.

About 85% of people find the operation a success and report a good improvement in hearing. However, there is a very small risk - about 1% - that fluid will leak from the inner ear and cause a complete loss of hearing in that ear. There is also a small risk of fluid loss in the years following surgery - for example, if you have a sudden blow to the head or sudden pressure change that causes the piston to penetrate the membrane of the oval window.

Occasionally the piston may move slightly and you will need a second operation to put it back into place. If you have this second operation there is a higher risk - about 5% - that you will lose the hearing completely in the ear that has been operated on.