Ear Infection

Definition

Otitis media is an infection of the middle ear space, which lies behind the eardrum (tympanic membrane). It is characterized by pain, dizziness, and partial loss of hearing.

Description

A little knowledge of the basic anatomy of the middle ear will be helpful for understanding the development of otitis media. The external ear canal is a tube that leads from the outside opening of the ear to a structure called the tympanic membrane. Behind the tympanic membrane is the space called the middle ear. Within the middle ear are three tiny bones called ossicles. These are the malleus, the incus, and the stapes. Their shapes are often described as a hammer, an anvil, and a stirrup. Sound in the form of vibration causes movement in the eardrum, and then in the chain of ossicles. The ossicles transmit the sound to the cochlea within the inner ear, which sends it to the brain for processing.

The nasopharynx is the passageway behind the nose that takes inhaled air into the breathing tubes leading to the lungs. The eustachian tube is a canal that runs between the middle ear and the nasopharynx. One of the functions of the eustachian tube is to keep the air pressure in the middle ear equal to that outside. This equalization of the air pressure allows the eardrum and ossicles to vibrate appropriately, so that hearing is normal.

By age three, almost 85% of all children will have had otitis media at least once. It is the most common pediatric complaint. Babies and children between the ages of six months and six years are most likely to develop otitis media. Children at higher risk for otitis media include boys, children from poor families, those with allergies, Native Americans, Native Alaskans, children born with cleft palate or other defects of the structures of the head and face, and children with Down syndrome. Babies whose first ear infection occurs prior to six months of age are more prone to chronic problems with otitis media. There also appears to be some genetic predisposition towards otitis media, which may be related to the structure and function of the area in and around the middle ear. Exposure to cigarette smoke significantly increases the risk of ear infections, as well as other problems affecting the respiratory system. In addition, children who enter daycare at an early age have more upper respiratory infections (URIs or colds), and thus more cases of otitis media. Although the ear infection itself is not contagious, the URIs that predispose children to them certainly are. The most common times of year for otitis media to strike are winter and early spring, which are the same times that URIs are most common.

Otitis media is an important medical problem, because it often results in fluid accumulation within the middle ear. This is known as otitis media with effusion(OME). The effusion can last for weeks to months. Effusion within the middle ear can cause significant hearing impairment. When such hearing impairment occurs in a young child, it may interfere with the development of normal speech and language processing. A chronic effusion also increases the risk for subsequent infections, as the fluid provides a growth medium for bacteria.

In adults, acute otitis media can lead to such complications as paralysis of the facial nerves. Recovery from these complications may take from two weeks to as long as three months.