Damaged bones of the middle ear (ossicles)- symptoms, diagnosis, and treatment

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Damaged Ossicles

The middle ear

The middle ear is a space about 1.3cm or 1/8" across, filled with air. This space is connected with the back of the throat by the Eustachian tube. Most of the time the tube is closed, but if you yawn, swallow or blow your nose, it opens, often with an accompanying clicking sound in the ear when this happens.

The above diagram displays a chain of three tiny bones that stretch across the middle ear space from the eardrum to the oval window on the inner ear. The oval window is one of two membrane-covered openings of the inner ear. The three middle ear bones – the ossicles – are called the malleus, the incus and the stapes. Nicknames for them are: the hammer, anvil and stirrup.

The middle ear bones are joined together in the following "string":

The malleus is attached to the inner side of the eardrum.
The incus stretches between the malleus and the stapes.
The base of the stapes fits into the oval window of the inner ear.

Together the middle ear bones work together like this:

Sound enters the ears and makes the eardrum vibrate.
Vibrations pass from the eardrum along the ossicles.
The stapes pushes like a piston against the membrane in the oval window of the inner ear.

Damaged Ossicles (Ossicular chain disruption)

There are three possible causes of Ossicular disruption: a genetic defect, an infection, or a physical object penetrating into the middle ear chamber.

1. Babies are sometimes born with malformed ossicles.

2. Serious infections and head injuries such as a concussion can damage one or all three of the bones that make up the ossicles. In the case of a concussion, the swelling of the brain tissue can force tissues surrounding the middle ear to disrupt the connecting membranes of the three ossicles.

3. A sharp object penetrates the ear drum and causes damage to one or all of the three ossicles.

Depending on the severity of the event that damages the ossicles and the resultant scar tissue, it might be possible to repaired or replace one or more of the ossicles by having an operation called an ossiculoplasty. An ossiculoplasty operation is performed by an ENT micro-surgery specialist (Ear Nose Throat). The surgery attempts to repair the damage due to infection or injury to more than one of the three bones of the ossicles. The damaged ossicles are replaced with either artificial bone, called prostheses, or small pieces of bone taken from somewhere else in the body. The prostheses can be made from man-made bone material, plastic or ceramic. The ossicles are very small and this makes the surgery very delicate. This means that although the operation can improve the hearing, it may not completely return.