Otosclerosis and Hearing Loss

Otosclerosis

Otosclerosis, Growth of bone near the middle ear
Fig 1: Otosclerosis (abnormal growth of bone near the middle ear)

Otosclerosis is a hereditary disorder of abnormal growth of bone near the middle ear. This disorder of the middle ear mainly affects the tiny stirrup bones (stapes). It results in the progressive hearing loss. Otosclerosis is the most common cause of progressive hearing loss in young adults.

The ear, hearing and Otosclerosis

Otosclerosis is a condition that mainly affects one of the tiny bony ossicle in the middle ear called stapes (stirrup ). To have normal hearing, when sound waves strike ossciles, they need to move freely. In otosclerosis there is a abnormal growth of bone around the stapes in the middle ear. The growth (which is gradual) usually starts on the foot of the stapes, where it is attaches to the cochlea. The abnormal bone restricts the movement of the stapes, which thereby reduces the amount of sound that is passed to the cochlea. In the course of time, as the bone grows, the stapes can become fixed (or fused) with the bone of cochlea, leaving it immovable. This results in the severe hearing loss. This type of hearing loss is classified as conductive hearing loss where sound vibrations cannot be conducted (transmitted) from stapes to the cochlea.

Generally it is just the stapes which gets affected with the bony growth. However, occasionally, otosclerosis can also spread out to the bony shell of the cochlea and the nerve cells inside it. In such a case when the nerve cells are damages, the transmission of the nerve impulses to the brain can be disturbed. Such a hearing loss is classified as sensorineural hearing loss. Generally otosclerosis affects both the ears, but sometimes only one ear gets affected.

Prevention

At the moment there is no effective drug available to treat otosclerosis, although there is high confidence on the ongoing research on the bone modelling could identify accomplishable new therapies. People suffering from mild to moderate otosclerosis can benefit from the hearing aids that amplify sound. In more severe cases surgery is often the only option. Surgical procedure known as stapedectomy, surgeon removes the tiny bone stapes (or stirrup) bone which conducts sound to inner ear. The stapes is replaced with a mobile prosthetic device to allow the conduction of sound again, thereby restoring hearing.

It is important to consult your doctor (ear specialist) for any surgical procedure to understand any potential risk of limitations associated with the surgery. It might be possible, even after stapedectomy, hearing loss will persist, or in some rare cases, surgery can actually worsen hearing loss.  

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