Excerpt from Otitis Media

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Background

The American Academy of Pediatrics (AAP) and the American Academy of Family Physicians (AAFP) define acute otitis media as an infection of the middle ear with acute onset, presence of middle ear effusion (MEE), and signs of middle ear inflammation. Acute otitis media most commonly occurs in children and is the most frequent specific diagnosis in children who are febrile. Clinicians, including those in the ED, often overdiagnose acute otitis media.

Bulging of the tympanic membrane is the highest predictive value when evaluating the presence of MEE. Other findings that indicate the presence of MEE include limited mobility of the tympanic membrane with pneumatic otoscopy and fluid visualized behind the tympanic membrane or in the ear canal (with perforation).

Distinguishing between acute otitis media and otitis media with effusion (OME) is important. OME is more common than acute otitis media. When OME is mistaken for acute otitis media, antibiotics may be prescribed unnecessarily. OME is fluid in the middle ear without signs or symptoms of infection. OME is usually caused when the eustachian tube is blocked and fluid becomes trapped in the middle ear. Signs and symptoms of acute otitis media occur when fluid in the middle ear becomes infected.

Recurrent otitis media is defined as 3 episodes of acute otitis media within 6 months or 4 or more episodes within 1 year.

Pathophysiology

Acute otitis media usually arises as a complication of a preceding viral upper respiratory infection (URI). The secretions and inflammation cause a relative occlusion of the eustachian tubes. Normally, the middle ear mucosa absorbs air in the middle ear. If air is not replaced because of relative obstruction of the eustachian tube, a negative pressure is generated and causes a serous effusion. This effusion of the middle ear provides a fertile media for microbial growth, and, with the URI, introduction of upper airway viruses and/or bacteria into the middle ear may occur. If growth is rapid, the patient will have a middle ear infection. If the infection and the resultant inflammatory reaction persist, perforation of the tympanic membrane or extension into the adjacent mastoid air cells may be present.

Frequency

United States

Otitis media is common, with 50% of children having an episode before their first birthday and 80% of children having one by their third birthday. An estimated $3-4 billion are spent each year on care of patients with acute otitis media and related complications.

Mortality/Morbidity

• Mortality is rare in countries where treatment of complications is available, and it is not frequent in countries where treatment is not available.
• Morbidity may be significant for infants in whom persistent MEE develops. MEE leads to hearing deficits and speech delay. Most spontaneous perforations eventually heal, but some persist. Frequent recurrences of acute otitis media are relatively common.  
• Otitis is not considered a major source of bacteremia or meningeal seeding, but local brain abscess has been documented, demonstrating that it is possible for acute otitis media to extend.

Race

Otitis media is more frequent in certain racial groups (eg, Inuit and American Indians) than in others.

• Other factors in the environment (eg, crowding, daycare setting, nutrition) may be more important than race, but they have not been fully delineated.
• Otitis media is less common in groups with high rates of breastfeeding than in groups with low rates of breastfeeding.

Sex

Boys are affected more commonly than girls, but no specific causative factors have been found. Male sex is a minor determinant of infection.

Age

• Ear infection occurs in all age groups, but it is considerably more common in children, particularly those aged 6 months to 3 years, than in adults. This age distribution is presumably due to immunologic factors (eg, lack of pneumococcal antibodies) and anatomic factors (eg, a low angle of the eustachian tube with relation to the nasopharynx).
• Children with significant predisposing factors (eg, cleft palate) acquire infections so frequently that some authors advocate the routine placement of polyethylene tubes in their tympanic membranes to maintain aeration of the middle ear.

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