Otosclerosis - insidious hearing loss

Beethoven was undoubtedly one of the great European composers. He composed some of his best-known works when, due to his deafness, he was only able to communicate with "conversation books". His progressive hearing loss began at age 26. Today, most researchers believe that its cause was otosclerosis of the inner ear.

What is Otosclerosis?

Behind the eardrum are three tiny bones in the tympanic cavity: hammer, anvil and stirrup. They are movably connected like a chain, dampen the incoming sound waves and transmit them further into the inner ear. The stapes, the smallest bone of the body, is attached to the membrane of the oval window, the connection to the inner ear.

In otosclerosis, remodeling and increased neoplasm of the bone occur at different sites of the middle and inner ear. Hence the name derived from the Greek for this disorder: "Oto" for ear, "Sclerosis" for hardening. Almost always the oval window and the stirrup, in one third of cases also structures of the inner ear like the snail or the organ of balance, are affected.

The new bone can grow around the point of attachment of the stirrup and virtually wall it. As a result, this auditory ossicle increasingly loses its flexibility (stapes fixation) and is doing worse and worse its task to transmit the sound. Hearing disorders (conductive hearing loss) are the result.

If the inner ear is affected by the ossification, it can also cause tinnitus and - rarely - dizziness. There are also cases in which only the inner ear is affected (capsule otosclerosis); then there is a pure sensorineural hearing loss, the sound conduction is intact.

Who is affected and what are the causes?

Otosclerosis almost always begins between the ages of 20 and 40 years. Research has shown that women suffer a good one and a half times more disease than men and whites are particularly susceptible. In two-thirds of cases, both ears are affected during the course of the disease. It is estimated that 2 percent of all hearing impairments in middle age are due to otosclerosis. However, the frequency figures vary between 4 and 80 people per 1, 000 inhabitants in the literature.

Exactly how new bone is formed is still unknown. For a long time one suspected a genetic component. This theory of heredity has recently been confirmed: a Belgian team of researchers has identified a gene (TGFB1) that is altered at a specific site in many of the examined otosclerosis patients.

However, it still can not be ruled out that there are more triggers. For example, the symptoms of many affected women during pregnancy worsen, suggesting hormone involvement. In some patients, antibodies against measles were found in the inner ear fluid, which is why viruses are also discussed as triggers.

What symptoms does otosclerosis show?

For most people affected hearing loss is noticeable after the age of 20, usually first in one ear, later often in both ears. This progresses slowly, but steadily up to complete deafness. Many additionally suffer from ear noises (tinnitus). If the inner ear is affected, dizziness may be added.

It is typical that the sufferers hear better in the case of environmental noise - the reason is probably that on the one hand the other people in such situations automatically speak louder, on the other hand, that the annoying noises then less noticeable. The affected persons speak rather quietly, because their own voice is passed on over the bone, which works.

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