Otosclerosis

Published by Bupa's Health Information Team, December 2010.

This factsheet is for people who have otosclerosis, or who would like information about it.

Otosclerosis is a disease in which the bone structure inside your ear changes, leading to hearing loss. It may also be called otospongiosis. Otosclerosis is a common cause of deafness in young adults.

About otosclerosis

Your ear is made up of three parts: the outer ear, the middle ear and the inner ear. Inside the middle ear, there are three tiny bones called the ossicles. When sound waves enter your ear, they hit your eardrum, causing the three ossicles to move backwards and forwards. This transmits the sound waves to your cochlea in your inner ear, where they are converted into nerve signals and sent to your brain.

In otosclerosis, one of these three ossicles – the stapes – begins to fuse with the surrounding bone. Eventually, this causes the stapes to become fixed in a certain position, so that it can’t move. The sound waves can no longer be easily transmitted into the inner ear. This can lead to a type of hearing loss called conductive hearing loss.

Otosclerosis usually develops when you are in your 20s or 30s. It is more common in white people and in women.

Symptoms of otosclerosis

The main symptom of otosclerosis is deafness, often in both ears. You may notice this before you reach the age of 30, but it can take years to become obvious. You might be able to hear better in noisy surroundings.

You might also get tinnitus (a ringing sound in your ears). Some people get mild vertigo (a feeling of dizziness even when standing still), but this is rare.

These symptoms aren’t necessarily a result of otosclerosis but if you have any of them, you should visit your GP.

Complications of otosclerosis

Rarely otosclerosis can spread to the cochlea in your inner ear (the organ responsible for hearing). This damages the tiny hair cells in the cochlea that turn sound waves into electrical signals, causing more hearing loss. This type of hearing loss is known as sensorineural deafness and cannot be improved by surgery.

If otosclerosis spreads to the area of the inner ear responsible for balance, it can also cause balance problems.

Otosclerosis and pregnancy

Female hormones may speed up the progression of otosclerosis. This means that if you are a woman and become pregnant, you might find that your condition gets worse. There is also some suggestion that taking the contraceptive pill or hormone replacement therapy (HRT) may worsen otosclerosis. If you have otosclerosis, your GP should discuss this with you before prescribing the contraceptive pill or HRT.

Causes of otosclerosis

Otosclerosis is usually caused by a faulty gene, inherited from one of your parents. However, it can also occur without either of your parents having the disease.

If a family member has the condition, you may develop similar symptoms, starting at a similar age and progressing at about the same rate as your relative.

Other, non-genetic factors may be involved. For example, the measles virus can cause otosclerosis.

Diagnosis of otosclerosis

Your GP will ask about your symptoms and examine you. He or she may also ask you about your medical history and may carry out a basic hearing test.

If your GP thinks you have hearing loss, he or she will usually refer you to an ear, nose and throat (ENT) surgeon or an audiovestibular physician at your local hospital. You will need to have several tests.

• Pure tone audiogram. This is a hearing test in a soundproof room. Your doctor or audiologist (a health professional who specialises in hearing problems) will ask you to wear headphones, and he or she will play notes of different pitches and volume to you. He or she will ask you to press a button when you can hear the sounds.
• Tuning fork. Your doctor will place a tuning fork near your ear, and he or she will ask if you can hear the sound. This can help your doctor work out whether your hearing loss is due to otosclerosis or another problem with your ears.

You may also have a computed tomography (CT) scan. A CT scan uses X-rays to make a three-dimensional image of part of your body. In otosclerosis, it lets your doctor determine which parts of your ear have been affected.

Treatment of otosclerosis

The two treatment options for otosclerosis are hearing aids or surgery. Your ENT surgeon or audiovestibular physician will discuss both options with you. The treatment you have depends on how severe your symptoms are and your individual circumstances. If your hearing loss is mild, you may decide that you can manage without any treatment at all.

Hearing aids

Having a hearing aid may be enough if you have only a slight hearing loss. A hearing aid is a small electronic device that fits in or behind your ear, and works by making sound loud enough for you to hear.

If you decide to have a hearing aid, you will see an audiologist who will discuss the different types of hearing aid available with you, and advise which is best for you. Hearing aids that can transmit sound waves straight through the bone in your skull may be particularly useful for people with otosclerosis. These are called bone-anchored hearing aids (BAHAs).

Surgery

You will be offered surgery only if your hearing loss has reached a certain level and you’re having trouble understanding other people speaking, even with a hearing aid.

Surgery for otosclerosis is often able to improve your hearing, but carries a risk of complications – such as losing more, or all of your hearing. Your surgeon will discuss the benefits, potential risks and possible alternatives to the procedure with you before you have the operation. You will also have a chance to ask any questions you have about the procedure.

The operation is usually done under general anaesthesia. If you have a general anaesthetic, you will be asleep during the procedure. If you have a local anaesthetic, you will stay awake during the procedure but feeling from your ear will be blocked.

During the operation, which is called a stapedotomy, your surgeon will make a small cut just above the opening to your ear and behind it, or inside your ear canal. He or she will then make a small opening in the footplate of the stapes bone with tiny instruments or a laser. Sometimes, your surgeon may completely remove the stapes bone. An artificial piece of bone, made out of plastic or metal (and called a prosthesis) is inserted into your ear and connected to the other two ossicles, allowing sound to be transmitted to your inner ear.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.