Ear Disorders
QUICK LOOK AT THE CHAPTER AHEAD
This chapter discusses the etiology of internal and external ear infections which commonly occur in childhood.
MIDDLE EAR STRUCTUREThe middle ear is a pea-sized, sealed, air-filled cavity that gives the paperthin eardrum the ability to vibrate easily (compliance) and to transmit sound waves from the three tiny bones in the middle ear to the inner ear and then to the brain for processing. The eustachian tube, composed of membrane and cartilage, is a narrow tube that allows air to enter behind the sealed eardrum from the back of the nose and replace the air that is normally absorbed by the body from the middle ear. It also equalizes pressure on both sides of the eardrum and drains fluid from the middle ear. Equal pressure on both sides of the eardrum is necessary for compliance to occur. If the tube is blocked by edema or thick secretions, a vacuum develops that pulls fluid and nasopharyngeal secretions/pathogens into the middle ear. Yawning, sneezing, or swallowing results in intermittent opening of the eustachian tube, allowing fluid from the middle ear to drain and pressure to be equalized.
In children the eustachian tube is short (average length 18 mm) and lies horizontally at an approximate 10-degree angle, thereby allowing reflux of nasopharyngeal secretions into the middle ear. By adolescence the average length of the eustachian tube has increased to 31-38 mm and the angle has increased to about 45 degrees, thereby making otitis media much less common as the child matures. Adults also have a more rigid eustachian tube than do children. A floppy tube increases the likelihood of developing acute otitis media (AOM).
A floppy tube increases the likelihood of developing acute otitis media.
EAR INFECTIONSEar infections may involve the outer ear (otitis externa), middle ear (otitis media), mastoid bone (mastoiditis), and/or the inner ear (labyrinthitis).
Otitis Externa
Inflammation of the skin lining the ear canal and surrounding soft tissue is called otitis externa. Cerumen (ear wax) provides a protective function, and if it is lost maceration of the underlying skin is possible, leading to otitis externa. Trauma to the ear canal can also occur because of drainage
from a perforated tympanic membrane or from tympanic drainage tubes, the insertion of cotton-tipped applicators to clean the ear canal, poorly fitting ear plugs used when swimming, dermatitis from hair spray, ear drops, and infection from Staphylococcus aureus or Pseudomonas aeruginosa.
from a perforated tympanic membrane or from tympanic drainage tubes, the insertion of cotton-tipped applicators to clean the ear canal, poorly fitting ear plugs used when swimming, dermatitis from hair spray, ear drops, and infection from Staphylococcus aureus or Pseudomonas aeruginosa.
The child with otitis externa complains of pain and itching in the ear, especially when they chew, but hearing is normal. Attempts to inspect the ear canal are met with resistance, and drainage is usually scant. The ear canal, if visualized, appears edematous.
Trauma to the ear canal can also occur because of drainage from a perforated tympanic membrane or from tympanic drainage tubes, the insertion of cotton-tipped applicators to clean the ear canal, poorly fitting ear plugs used when swimming, dermatitis from hair spray, ear drops, and infection from Staphylococcus aureus or Pseudomonas aeruginosa.If the tympanic membrane can be seen and is intact, the moist cerumen and desquamated epithelium is removed by ear irrigation, and then topical antibiotic drops are instilled two or three times a day. The role of corticosteroid ear drops is unclear. If the child has systemic symptoms such as a fever, oral antibiotics, in addition to antibiotic ear drops, may be needed. Parents should be advised not to let the child swim or use cotton ear plugs during the acute phase. Prophylactic measures in a child who is prone to develop otitis externa and who has an intact tympanic membrane include instilling two to three gtts of a 1:1 solution of white vinegar and 70% ethyl alcohol into the ears before and after swimming.
Otitis Media
Otitis media is an inflammation of the middle ear. AOM is the term used to describe an infection of the middle ear and is the most common bacterial illness in children. Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the bacteria responsible for most cases of bacterial otitis media. Signs and symptoms of AOM include a sudden onset of ear pain, erythema of the tympanic membrane, and middle ear effusion (bulging of the tympanic membrane, decreased mobility of the membrane, and otorrhea). Otitis media with effusion is defined as fluid in the middle ear that is not accompanied by infection and the inflammatory process.
Several factors, including bacterial nasopharyngeal colonization, frequent upper respiratory infections (URIs), exposure to cigarette smoke,
allergies, immunocompromised status, possible genetic susceptibility, male gender, use of a pacifier for several hours per day, and a short eustachian tube, make AOM common in children.
allergies, immunocompromised status, possible genetic susceptibility, male gender, use of a pacifier for several hours per day, and a short eustachian tube, make AOM common in children.
Infants and children in daycare acquire different serotypes of nasopharyngeal pathogens and thus develop AOM more frequently than infants and children not in daycare. Approximately 70% of infants younger than 12 months of age will have at least one episode of AOM, especially between 6 and 12 months of age. Use of a pacifier raises the soft palate, allowing nasopharyngeal pathogens to enter the eustachian tube.
Viral respiratory infections play a role in AOM by increasing the colonization of the nasopharynx with viruses causing edema of the adenoids and hindering eustachian tube function. Children who are bottle fed, exposed to cigarette smoke, placed in daycare, or have siblings are at risk for developing frequent viral respiratory infections and AOM.
Viral respiratory infections play a role in AOM by increasing the colonization of the nasopharynx with viruses causing edema of the adenoids and hindering eustachian tube function.Effects of exposure to cigarette smoke include stronger pathogen attachment to the middle ear and production of an inflammatory response that hinders eustachian tube function. Smoking also hinders normal ciliary action in the eustachian tube so that it does not drain the middle ear effectively. The impact of exposing children ages 12 to 18 months to cigarette smoke is significant. Exposure to each pack of cigarettes smoked by someone in the home and/or car increases the duration of otitis media by 11%.
Breast-feeding lowers the risk of developing AOM by reducing the number of URIs an infant develops. IgA antibodies are passed to the child via breast milk, thus reducing colonization with pathogens associated with AOM. Breast-fed infants are also less likely to aspirate contaminated secretions because of the position assumed during breast-feeding compared with infants who are bottle fed in a supine position.
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