What is the eardrum and how do we hear?
The eardrum (also called the tympanic membrane) is a thin skin-like structure in the ear. It lies between the outer and middle ear.
The ear is divided into three parts – the outer, middle, and inner ear. Sound waves come into the outer (external) ear and hit the eardrum, causing the eardrum to vibrate.
Behind the eardrum are three tiny bones (ossicles). The vibrations pass from the eardrum to these middle ear bones. The bones then transmit the vibrations to the cochlea in the inner ear. The cochlea converts the vibrations to sound signals which are sent down a nerve to the brain, which we ‘hear’.
The middle ear behind the eardrum is normally filled with air. The middle ear is connected to the back of the nose by the Eustachian tube. This allows air in and out of the middle ear.
What is a perforated eardrum and what problems can it cause?
A perforated eardrum is a hole or tear that has developed in the eardrum. It can affect hearing. However, the extent of hearing loss can vary greatly. For example, tiny perforations may only cause minimal loss of hearing. Larger perforations may affect hearing more severely. Also, if the ossicles are damaged in addition to the eardrum then the hearing loss would be much greater than, say, a small perforation which is not close to the ossicles.
Also, with a perforation, you are at greater risk of developing an ear infection. This is because the eardrum acts as a barrier to bacteria and other germs that may get into the middle ear.
What can cause a perforated eardrum?
- Infections of the middle ear, which can damage the eardrum. In this situation you often have a discharge from the ear as pus runs out from the middle ear.
- Direct injury to the ear. For example, a punch to the ear.
- A sudden loud noise. For example, from a nearby explosion. The shock waves and sudden sound waves can perforate the eardrum. This is often the most severe type of perforation and can lead to severe hearing loss and tinnitus (ringing in the ears).
- Barotrauma. This is when you suddenly have a change in air pressure and there is a sharp difference in the pressure of air outside the ear and in the middle ear. For example, when descending in an aircraft. Pain in the ear due to a tense eardrum is common during altitude changes. However, a perforated eardrum only happens rarely in extreme cases. See separate leaflet called ‘Barotrauma of the Ear’.
- Poking objects into the ear. This can sometimes damage the eardrum.
- Grommets. These are tiny tubes that are placed through the eardrum. They are used to treat glue ear as they allow any mucus that is trapped in the middle ear to drain out from the ear. When a grommet falls out, there is a tiny perforation in the eardrum (that usually soon heals).
How is a perforated eardrum diagnosed?
A doctor can usually diagnose a perforated eardrum simply by looking into the ear with a special torch called an otoscope. However, sometimes it is difficult to see the eardrum if there is a lot of inflammation, wax or infection present in the ear.
What is the treatment for a perforated eardrum?
No treatment is needed in most cases
A perforated eardrum will usually heal by itself within 6-8 weeks. It is a skin-like structure and, like skin that is cut, it will usually heal. In some cases, a doctor may prescribe antibiotics if there is an infection or risk of infection developing in the middle ear whilst the eardrum is healing.
It is best to avoid water getting into the ear whilst it is healing. For example, your doctor may advise that you put some cotton wool or similar material into your outer ear whilst showering or washing your hair. It is best not to swim until the eardrum has healed.
Occasionally, a perforated eardrum gets infected and needs antibiotics. Some ear drops can potentially damage the nerve supply to the ear so your doctor will select a type that does not have this risk, or will give you medication by mouth.
Surgical treatment is sometimes considered
A small procedure is an option to treat a perforated drum that does not heal by itself. There are various techniques ranging from placing some chemicals next to the torn part of the drum to encourage healing, to an operation called tympanoplasty to repair the eardrum. Tympanoplasty is usually successful in fixing the perforation, and improving hearing.
However, not all people with an unhealed perforation need treatment. Many people have a small permanent perforation with no symptoms or significant hearing loss. Treatment is mainly considered if there is hearing loss as this may improve if the perforation is fixed. Also, swimmers may prefer to have a perforation repaired as getting water in the middle ear can increase the risk of having an ear infection.
If you have a perforation that has not healed by itself, an ear specialist will advise on the pros and cons of treatment versus leaving it alone.
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