Otosclerosis is an abnormal, microscopic growth of bone in the walls of the inner ear which causes the stapes bone, commonly called the "stirrup", to become frozen in place or "fixed". Normally the stapes, the smallest bone in the body, vibrates freely to allow the transmission of sound into the inner ear. When it becomes cemented to the surrounding bone it prevents sound waves from reaching the inner ear fluids, and hearing is impaired.
Normally sound, which consists of vibrations of air molecules, is funneled by the auricle, or "outer ear", through the ear canal to the eardrum. Movements of the eardrum are transferred to the ossicles, and the stapes vibrates in and out of the oval window. The vibration of the stapes sets up a movement of the inner ear fluids. This, in turn, stimulates the fine sense organs of the inner ear, which then stimulate the nerve of hearing which carries the sound energy to the brain. It is this sequence of events that results in normal hearing.
Occasionally the otosclerotic bone involves other structures of the inner ear so that, in addition to preventing sound from entering the ear, it causes a distortion or difficulty in understanding the speech of others, regardless of how loudly they talk. This is because the nerves of the inner ear have become affected. In such cases there is not only the "conductive" deafness already discussed, whereby sound waves are obstructed in reaching the inner ear, but in addition, "sensorineural" or "nerve" deafness, in which the function of the inner ear itself has been impaired.
Otosclerosis affects the ears only and not other parts of the body. When this condition is present, both ears are usually involved. It occurs in men and women with almost equal frequency and usually begins in the teens or early twenties. Although otosclerosis tends to run in families, it does so irregularly; parents with otosclerosis do not necessarily transmit it to their offspring.
There is no known medicine available for treating otosclerosis. Although a hearing aid can be worn successfully by most patients, they prefer natural hearing if that is possible. Surgery has been found to be the most effective method of managing otosclerosis.
The stapedectomy is done using an operating microscope. The surgeon will first fold forward approximately one-half of the ear drum so that he can reach the area where the stapes is located. The diseased stapes is then removed with fine instruments. To close the opening into the inner ear made by removal of the stapes, a small bit of tissue is taken from the ear lobe. A "prosthesis" 4.5mm in length then is introduced and secured in place to bridge the gap created by removal of the stapes.
Depending upon the nature and extent of the otosclerotic diseased bone, which can only be assessed at the time of surgery, the surgeon may elect to use a piston prosthesis instead of the usual fat-wire prosthesis. This involves less removal of the bone at the base, or "footplate", of the stapes and results in a smaller opening into the inner ear. The effects and results of this operation are otherwise the same as in the usual stapedectomy operation.
An examination by an ear specialist, including a hearing test, is necessary to determine if you are a candidate for the operation. As you can imagine, there are many different causes of deafness; and in fact, not even all patients with otosclerosis are candidates for stapedectomy.
The chances of obtaining a good result from this operation are about 90 percent. This means that about 9 out of 10 patients will get an improvement of hearing up to the level at which their inner ear is capable of functioning. If the inner ear functions normally, then normal hearing can be restored. Approximately 7 percent of all patients have only partial recovery of hearing and 2 percent remain at the same level as before surgery. The main risk is a 1 percent chance of developing inner ear hearing loss following the procedure due to factors as yet not entirely understood. For this reason, only one ear is operated upon at a time, and the worst ear is always done first.
If you should catch a cold one week or less prior to the date scheduled for your operation, you should report this to your doctor. You will need to get a history and physical done with your local doctor within 30 days prior to your surgery. You may also need some laboratory work done. Be sure to bring the results of your laboratory work and your history and physical to the hospital the morning of your surgery. For this operation a local anesthetic is often used.
Because the stapes is so small, the operation is performed with the aid of a microscope. You may notice improved hearing while still in surgery and notice a decrease later. Do not become alarmed, as this is due to ear packing, swelling, and fluid buildup from surgery. It may be several weeks before the full effect of surgery can be determined, as far as hearing is concerned. You may have occasional periods of dizziness during the first few days.
The evening after the operation you should lie quietly on the unoperated ear. Do not be alarmed if you have some dizziness for the first few days after the operation.
The surgery usually takes two to three hours. If all goes well, you can go home when you are fully awake and determined ready for discharge by your doctor. Be sure to bring someone to drive you home.
Please do not:
The nurse will show you how to change the ear pad.
Stapedectomy is a well established and proven operative procedure with a 90% or greater success rate. Potential but unusual side effects include:
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