What is it?

Otosclerosis is a disease causing gradual hearing impairment. It usually comes on in early adulthood, but is often not noticed until middle age.

It can affect one or both ears. Sometimes the hearing does not get worse and stays at the same level for years. Usually it steadily gets worse or can deteriorate quickly at stressful times of life e.g. pregnancy. The end result can be profound deafness.

What causes it?

Sound vibrations hitting the eardrum are transferred to the inner ear by three small bones called ossicles. The smallest of these bones is called the stapes or stirrup bone. This bone fits in the oval window of the inner ear like a piston. In otosclerosis the stapes movement is reduced by new bone formation around the "piston". At present it is not known why the body makes new bone in this area. Although 1% of the population in Britain has this condition, in most it only mildly affects their hearing. In some people they progress to have moderate, severe or even profound deafness.

What can be done?

Most patients with mild disease never seek medical treatment. Some patients take Fluoride tablets although there is no good evidence that it stops the disease getting worse. In patients who have a hearing disability, there are three options.

Hearing Aid

This is easy to fit and is an excellent way of boosting the sound entering the ear in mild or moderate hearing impairment. However, it does not stop the disease getting worse and a stronger hearing aid may be required after some time. There are also cosmetic issues and some patients dislike the "artificial sound" provided by a hearing aid.

Surgically Implanted Hearing Aid

The commonest device is a bone-anchored hearing aid, which screws to the bone of your skull in a minor operation. It overcomes some of the problems with "artificial sound" that can be suffered with a conventional hearing aid. However, it shares the other drawbacks of conventional hearing aids and in addition the small titanium screw coming out through the skin needs to be carefully looked after to prevent infection and loosening.

In profoundly deaf patients a cochlear implant can be considered. This type of hearing aid has two parts. One is completely implanted under the skin. The other sticks to the implanted bit by magnetism and fits behind the ear. In addition to the problems with "artificial sound" experienced with the hearing aids, the cochlear implant has the same surgical risks as a stapedotomy operation.

Stapedotomy

This operation was previously called stapedectomy, but has now been refined to make it safer. In patients with moderate hearing loss it is possible to restore the hearing to normal levels without the danger of further hearing impairment in the future. A small hole is drilled in the oval window and the stapes is replaced with a Teflon piston. If successful the otosclerosis is effectively cured, as the operation does not need to be repeated. The main risk of the operation is that the inner ear may be damaged by infection as a result of surgery, which could lead to permanent deafness in the operated ear. This rare complication may be accompanied by dizziness and even tinnitus. More common complications include an altered taste sensation as the nerve of taste runs across the eardrum and can get bruised (even cut)during the procedure. Some surgeons use a laser and this carries an additional rare risk of facial palsy.