What happens in otosclerosis?
Otosclerosis is a condition that affects the stapes, one of the tiny bony ossicles in the middle ear. To have normal hearing, the ossicles need to be able to move freely in response to sound waves. What happens is that abnormal bone material grows in and around the stapes. The foot of the stapes, where it attaches to the cochlea, is usually where the condition starts. In time, more and more of the stapes becomes affected. The abnormal bone reduces the movement of the stapes, which reduces the amount of sound that is transferred to the cochlea. The laying down of the abnormal bone is very gradual. However, eventually the stapes becomes ‘fixed’ which causes severe hearing loss. In most cases, only the stapes is affected. Sometimes the disease also affects the bony shell of the cochlea. Both ears are usually affected but sometimes only one.
