What is an ear infection?

The commonly used term “ear infection” is known medically as acute otitis media or a sudden infection in the middle ear (the space behind the eardrum). Anyone can get an ear infection – children as well as adults – although ear infections are one of the most common reasons why young children visit healthcare providers.

In many cases, ear infections clear up on their own. Your healthcare provider may recommend a medication to relieve pain. If the ear infection has worsened or not improved, your healthcare provider may prescribe an antibiotic. In children younger than the age of two years, an antibiotic is usually needed for ear infections.

It’s important to see your healthcare provider to make sure the ear infection has healed or if you or your child has ongoing pain or discomfort. Hearing problems and other serious effects can occur with ongoing ear infections, frequent infections and when fluid builds up behind the eardrum.

Where is the middle ear?

The middle ear is behind the eardrum (tympanic membrane) and is also home to the delicate bones that aid in hearing. These bones (ossicles) are the hammer (malleus), anvil (incus) and stirrup (stapes). To provide the bigger picture, let’s look at the whole structure and function of the ear:

Structures of the ear include the external ear, auditory canal, eardrum (tympanic membrane) and the inner ear. The middle ear is the space between the eardrum and the inner ear.

The ear structure and function

There are three main parts of the ear: outer, middle and inner.

  • The outer ear is the outside external ear flap and the ear canal (external auditory canal).
  • The middle ear is the air-filled space between the eardrum (tympanic membrane) and the inner ear. The middle ear houses the delicate bones that transmit sound vibrations from the eardrum to the inner ear. This is where ear infections occur.
  • The inner ear contains the snail-shaped labyrinth that converts sound vibrations received from the middle ear to electrical signals. The auditory nerve carries these signals to the brain.

Other nearby parts

  • The eustachian tube regulates air pressure within the middle ear, connecting it to the upper part of the throat.
  • Adenoids are small pads of tissue above the throat and behind the nose and near the eustachian tubes. Adenoids help fight infection caused by bacteria that enters through the mouth.

Who is most likely to get an ear infection (otitis media)?

Middle ear infection is the most common childhood illness (other than a cold). Ear infections occur most often in children who are between age three months and three years, and are common until age eight. Some 25% of all children will have repeated ear infections.

Adults can get ear infections too, but they don’t happen nearly as often as they do in children.

Risk factors for ear infections include:

  • Age: Infants and young children (between 6 months of age and 2 years) are at greater risk for ear infections.
  • Family history: The tendency to get ear infections can run in the family.
  • Colds: Having colds often increases the chances of getting an ear infection.
  • Allergies: Allergies cause inflammation (swelling) of the nasal passages and upper respiratory tract, which can enlarge the adenoids. Enlarged adenoids can block the eustachian tube, preventing ear fluids from draining. This leads to fluid buildup in the middle ear, causing pressure, pain and possible infection.
  • Chronic illnesses: People with chronic (long-term) illnesses are more likely to develop ear infections, especially patients with immune deficiency and chronic respiratory disease, such as cystic fibrosis and asthma.
  • Ethnicity: Native Americans and Hispanic children have more ear infections than other ethnic groups.

What causes an ear infection?

Ear infections are caused by bacteria and viruses. Many times, an ear infection begins after a cold or other respiratory infection. The bacteria or virus travel into the middle ear through the eustachian tube (there’s one in each ear). This tube connects the middle ear to the back of the throat. The bacteria or virus can also cause the eustachian tube to swell. This swelling can cause the tube to become blocked, which keeps normally produced fluids to build up in the middle ear instead of being able to be drained away.

Adding to the problem is that the eustachian tube is shorter and has less of a slope in children than in adults. This physical difference makes these tubes easier to become clogged and more difficult to drain. The trapped fluid can become infected by a virus or bacteria, causing pain.

Medical terminology and related conditions

Because your healthcare provider may use these terms, it’s important to have a basic understanding of them:

  • Acute otitis media (middle ear infection): This is the ear infection just described above. A sudden ear infection, usually occurring with or shortly after cold or other respiratory infection. The bacteria or virus infect and trap fluid behind the eardrum, causing pain, swelling/bulging of the eardrum and results in the commonly used term “ear infection.” Ear infections can occur suddenly and go away in a few days (acute otitis media) or come back often and for long periods of time (chronic middle ear infections).
  • Otitis media with effusion: This is a condition that can follow acute otitis media. The symptoms of acute otitis media disappear. There is no active infection but the fluid remains. The trapped fluid can cause temporary and mild hearing loss and also makes an ear infection more likely to occur. Another cause of this condition is a block in the eustachian tube not related to the ear infection.
  • Chronic suppurative otitis media: This is a condition in which the ear infection won’t go away even with treatment. Over time, this can cause a hole to form in the eardrum.

What are the symptoms of otitis media (middle ear infection)?

Symptoms of ear infection include:

  • Ear pain: This symptom is obvious in older children and adults. In infants too young to speak, look for signs of pain like rubbing or tugging ears, crying more than usual, trouble sleeping, acting fussy/irritable.
  • Loss of appetite: This may be most noticeable in young children, especially during bottle feedings. Pressure in the middle ear changes as the child swallows, causing more pain and less desire to eat.
  • Irritability: Any kind of continuing pain may cause irritability.
  • Poor sleep: Pain may be worse when the child is lying down because the pressure in the ear may worsen.
  • Fever: Ear infections can cause temperatures from 100° F (38 C) up to 104° F. Some 50% of children will have a fever with their ear infection.
  • Drainage from the ear: Yellow, brown, or white fluid that is not earwax may seep from the ear. This may mean that the eardrum has ruptured (broken).
  • Trouble hearing: Bones of the middle ear connect to the nerves that send electrical signals (as sound) to the brain. Fluid behind the eardrums slows down movement of these electrical signals through the inner ear bones.

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