Otitis Media Health Article

Definition

Otitis media is an infection of the middle ear, which is located behind the eardrum. There are two main types of otitis media. In the first, called acute otitis media (AOM), parts of the ear are infected and swollen, and fluid and mucus are trapped inside the ear. AOM can be quite painful. In the second type, called otitis media with effusion (fluid), or OME, fluid and mucus remain trapped within the ear after the infection is over, making it more difficult for the ear to fight off new infections. This fluid may adversely affect a child's hearing.

Description

One of the most common childhood infections, Otitis media is the leading cause of visits to the doctor by children. It is also the most frequent reason children receive antibiotic prescriptions or undergo surgery.

In order to fully understand otitis media, it is helpful to have a basic knowledge of ear anatomy. Deep within the outer ear canal is the eardrum, which is a thin, transparent membrane that vibrates in response to sound. Behind the eardrum is the space called the middle ear. When the eardrum vibrates, three tiny bones within the middle ear, called ossicles, transmit these sounds to the inner ear. Nerves are stimulated in the inner ear, which then relay the sound signals to the brain. The eustachian tube, which connects the middle ear to the nose, normally equalizes pressure in the middle ear, allowing the eardrum and ossicles to vibrate correctly, so that hearing is normal.

There are certain factors particular to children that make them more at risk for otitis media. In children, the eustachian tube is shorter and less slanted than in adults. Its size and position allow bacteria and viruses to travel to the middle ear more easily. Children also have clumps of infection fighting cells, commonly called adenoids, in the area of the eustachian tube. These adenoids may enlarge with repeated respiratory tract infections and ultimately block the eustachian tubes. When these tubes are blocked, the middle ear is more likely to fill with fluid, which in turn increases the risk for infection.

Demographics

Otitis media is common. Fifty percent of children have an episode before their first birthday, and 80 percent of children have an occurrence by their third birthday. It is estimated that $3 to $4 billion are spent per year on patients with a diagnosis of acute otitis media and related complications. Ear infections are found in all age groups, but they are considerably more common in children, especially those aged six months to three years. Boys are affected more commonly than girls. Other children at higher risk include those from poor families, Native Americans, children born with cleft palate or other defects of the facial structures, and children with Down syndrome. Exposure to cigarette smoke and early entrance into daycare also increase the risk. Otitis media occurs more frequently in winter and early spring. It is less common among children who are breastfeeding. Some studies show a genetic predisposition towards developing otitis media.

Causes and symptoms

The first precondition for the development of acute otitis media is exposure to an organism capable of causing the infection. Otitis media may be caused by either viruses or bacteria. Viral infections account for approximately 15 percent of cases. The majority of other cases are caused by a variety of bacteria. The three most common bacteria are Streptococcus pneumoniae (responsible for 25–50% of cases), Haemophilus influenzae (15–30%), and Moraxella catarrhalis (3–20%).

Acute otitis media often occurs as an aftereffect of upper respiratory infections, in which the eustachian tube and nasal membranes become swollen and congested. This condition can lead to an impaired clearance and pressure regulation in the middle ear, which, if sustained, may be followed by viruses and bacteria traveling from the nasopharynx to the middle ear.

Otitis media with effusion may develop within weeks of an acute episode of middle ear infection, but in many cases the cause is unknown. It is often associated with an abnormal or malfunctioning eustachian tube, which causes negative pressure in the middle ear and leaking of fluid from tiny blood vessels, or capillaries, into the middle ear.