Otosclerosis is a disease of the bones of the middle and inner ear which causes hearing loss. For normal hearing the ossicles need to move freely in response to sound waves while in abnormal hearing the bone material grows around the stapes. The condition usually starts in cochlea to which the foot of the stapes are attached.
The abnormal growth of the bone restricts the movement of the stapes which reduces the amount of sound to the cochlea. Although the growth of the abnormal bone is gradual but the stapes can be fixed or fused with the bone of the cochlea eventually which often causes severe hearing. This hearing loss is known as the conductive hearing loss.
In most cases, only the stapes get affected but sometimes the otosclerosis can also affect the bony shell of the cochlea and the nerve cells within it. In case of later, the damage to the nerve cells can affect the transmission of nerve impulses to the brain causing sensorineural hearing loss.
The exact cause is not known yet but many doctors and scientists believe that otosclerosis is an inherited disorder. Viral influences have also been found in otosclerosis. According a recent hypothesis, otosclerosis requires a combination of a specific gene to specific virus like measles.
Viral materials have been found in the nucleic acid of otosclerotic stapes footplates and increased levels of antibodies to the measles virus are present in the inner ears of patient with otosclerosis. According to recent study, people who have received vaccination for measles have lower chances of otosclerosis. This disorder is the most common cause of the hearing loss in middle ear in young adults. It is more common in women than men.
If not treated on time, the condition of the disorder may get worse. Although there is no effective drug treatment yet but continued bone modelling research could help in identifying the potential new therapies. Hearing aid can be used to amplify sound in mild cases of otosclerosis. Surgery can also be done when hearing aid does not help much. Stapedectomy is a procedure in which a surgeon inserts the prosthetic device into the middle ear to bypass the abnormal bone. This is done to permit the sound waves to travel to the inner ear to restore the hearing.
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