Middle Ear Infections

Next to the common cold, ear infections are the most commonly diagnosed childhood illness in the United States. More than three out of four children have had at least one ear infection by the time they reach 3 years of age. To understand how ear infections develop, it's important to first understand how the ear works.

A Close Look at the Ear

Think about how you can feel speakers vibrate as you listen to your child's favorite CD in the car or how you feel your throat vibrate when you speak. Sound, which is made up of invisible waves of energy, causes these vibrations. Every time you hear a sound, the various structures of the ear have to work together to make sure the information gets to your brain.

The ear is responsible for hearing and balance and is made up of three parts - the outer ear, middle ear, and inner ear. Hearing begins when sound waves that travel through the air reach the outer ear, or pinna, which is the part of the ear you can see. The sound waves then travel from the pinna through the ear canal to the middle ear, which includes the eardrum (a thin layer of tissue) and three tiny bones called ossicles. When the eardrum vibrates, the ossicles amplify these vibrations and carry them to the inner ear.

The inner ear translates the vibrations into electric signals and sends them to the auditory nerve, which connects to the brain. When these nerve impulses reach the brain, they're interpreted as sound.

To function properly, the middle ear must be at the same pressure as the outside world. This is taken care of by the eustachian tube, a small passage that connects the middle ear to the back of the throat behind the nose.

By letting air reach the middle ear, the eustachian tube equalizes the air pressure in the middle ear to the outside air pressure. (When your ears "pop" while yawning or swallowing, your eustachian tubes are adjusting the air pressure in your middle ears.) The eustachian tube also allows for drainage of mucus from the middle ear into the throat.

Sometimes, the eustachian tube may malfunction. For example, when a child has a cold or an allergy affecting the nasal passages, the eustachian tube may become blocked by congestion in its lining or by mucus within the tube. This blockage will allow fluid to build up within the normally air-filled middle ear. Bacteria or viruses that have entered the middle ear through the eustachian tube can also get trapped in this way. These germs can breed in the trapped fluid, eventually leading to an ear infection.

About Middle Ear Infections (Otitis Media)

Otitis media refers to inflammation in the middle ear area. There are different forms of otitis media. Typically, when the doctor refers to an ear infection, he or she is most likely talking about "acute otitis media" (although there's also the common ear infection called swimmer's ear, or otitis externa).

Acute otitis media is the presence of fluid, typically pus, in the middle ear with symptoms of pain, redness of the eardrum, and possible fever.

Other forms of otitis media are either more chronic in nature (meaning that there's fluid in the middle ear for 6 or more weeks) or there's fluid in the middle ear that's temporary and isn't necessarily infected (this is called otitis media with effusion).

The reason that doctors try to distinguish between the different forms of otitis is because it affects treatment options. Not all forms of otitis need to be treated with antibiotics.

Causes

Children develop ear infections more frequently in the first 2 to 4 years of life for several reasons:

• Their eustachian tubes are shorter and more horizontal than those of adults, which allows bacteria and viruses to find their way into the middle ear more easily. Their tubes are also narrower and less stiff, which makes them more prone to blockage.
• The adenoids, which are gland-like structures located in the back of the upper throat near the eustachian tubes, are large in children and can interfere with the opening of the eustachian tubes.
• Children's immune systems aren't fully developed until the age of 7. Therefore, they have more trouble fighting infections.

There are also a number of other factors that contribute to children getting ear infections. The more common ones are exposure to cigarette smoke, bottle-feeding, and day-care attendance.

Ear infections also occur more commonly in boys than girls, in children whose families have a history of ear infections, and more often in the winter season when upper respiratory tract infections or colds are most frequent.

Signs and Symptoms

The signs and symptoms of acute otitis media may range from very mild to severe:

• The fluid in the middle ear may push on the eardrum, causing ear pain. An older child may complain of an earache, but a younger child may tug at the ear or simply act irritable and cry more than usual.
• Lying down, chewing, and sucking can also cause painful pressure changes in the middle ear, so a child may eat less than the normal amount or have trouble sleeping.
• If the pressure from the fluid buildup is high enough, it can cause the eardrum to rupture, resulting in drainage of fluid from the ear. This releases the pressure behind the eardrum, usually bringing on relief from the pain.

Fluid buildup in the middle ear also blocks sound, which can lead to temporary hearing difficulties. A child may:

• not respond to soft sounds
• turn up the television or radio
• talk louder
• appear to be inattentive at school

Other symptoms of acute otitis media may also include:

• fever
• nausea
• vomiting
• dizziness

However, otitis media with effusion often has no symptoms at all. In some children, the fluid that's in the middle ear may create a sensation of ear fullness or "popping." As with acute otitis media, the fluid behind the eardrum can block sound, so mild temporary hearing loss can happen, but it may not be obvious.

Ear infections are also frequently associated with upper respiratory tract infections and, therefore, with their common signs and symptoms, such as a runny or stuffy nose or a cough.

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Source: The Nemours Foundation