Otitis Media

Introduction
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 often overdiagnose acute otitis media.

Distinguishing between acute otitis media (AOM) and otitis media with effusion (OME) is important. Otitis media with effusion is more common than acute otitis media. When otitis media with effusion is mistaken for acute otitis media, antibiotics may be prescribed unnecessarily. Otitis media with effusion is fluid in the middle ear without signs or symptoms of infection. Otitis media with effusion 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 acute otitis media is defined as 3 episodes 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 obstruction of the eustachian tubes. Normally, the middle ear mucosa absorbs air in the middle ear. If this air is not replaced because of obstruction of the eustachian tube, a negative pressure is generated, which pulls interstitial fluid into the tube and creates a serous effusion. This effusion of the middle ear provides a fertile media for microbial growth. If growth is rapid, a middle ear infection develops.
Frequency
United States

Acute otitis media is the most frequent diagnosis made by pediatricians, second only to the common cold. Two thirds of all American children have had at least one episode of AOM prior to 1 year of age, and 80% have had one by 3 years of age.1 Despite advances in pubic health and medical care, middle ear infections are still prevalent around the world, and the incidence in the United States has actually increased over the past 10-20 years. AOM is the most common indication for antimicrobial therapy in children in the United States.2,3

In 2006, 9 million children aged 0-17 years were reported to have an ear infection or AOM.4 Of those, 8 million children reported visiting a physician or obtaining a prescription drug to treat the condition.4 As such, the diagnosis and management of AOM has a significant impact on the health of children, the direct cost of health care, and the overall use of antibacterial agents.
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 middle ear effusion (MEE) develops. Chronic MEE may lead to hearing deficits and speech delay.
* After an episode of acute otitis media (AOM), as many as 45% of children have persistent effusion at 1 month, but this number decreases to 10% after 3 months.
* Most spontaneous perforations eventually heal, but some persist. Cholesteatoma formation with destruction of the ossicles is a serious but infrequent complication.
* Frequent recurrences of AOM are relatively common.
* AOM is not considered a major source of bacteremia or meningeal seeding, but local brain abscess and mastoiditis are potential sequela, demonstrating that it is possible for AOM to extend.

Race

Otitis media is more frequent in certain racial groups (eg, Inuit and American Indians); this is likely due to anatomic differences in the eustachian tube.

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 infections occur in all age groups, but they are considerably more common in children, particularly those between ages 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, Down syndrome) 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.

Clinical
History

Patients who can communicate usually describe feelings of pain or discomfort in the affected ear. However, most cases occur in children who are unable to communicate specific complaints. History alone is a poor predictor of acute otitis media, especially in young children.

* Accompanying or precedent upper respiratory infection (URI) symptoms (very common)
* Earache/fullness
* Decreased hearing
* Fever (not required for the diagnosis)
* Otorrhea
* Infants may be asymptomatic or irritable.
* Infants may present with pulling/tugging of the ear.

Physical

If the ear canal is clean and if the patient is cooperative, physical examination is generally easy. If the ear canal is occluded with cerumen or debris, if the canal is anatomically small, or if the patient is unable to cooperate, examination may be difficult.

* Remove cerumen and other debris from the ear canal, as necessary, to allow clear visualization of the entire tympanic membrane.
* Irrigation is useful, as it may soften and dislodge cerumen or any foreign bodies so that they may be removed more easily.
* A curette or suction may also be used.
* Patients may require referral to an otolaryngologist if sufficient time and resources are not available for the proper and safe removal of cerumen.
* Care should be taken to avoid perforation of the tympanic membrane or injury to the canal.

Visualization of the tympanic membrane with identification of a middle ear effusion (MEE) and inflammatory changes is necessary to establish the diagnosis of acute otitis media (AOM).

Drawing of a normal right tympanic membrane. Note...
Drawing of a normal right tympanic membrane. Note the outward curvature of the pars tens (*) of the eardrum. The tympanic annulus is indicated anteriorly (a), inferiorly (i), and posteriorly (P). M = long process of the malleus; I = incus; L = lateral (short) process of the malleus.

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Drawing of a normal right tympanic membrane. Note...

Drawing of a normal right tympanic membrane. Note the outward curvature of the pars tens (*) of the eardrum. The tympanic annulus is indicated anteriorly (a), inferiorly (i), and posteriorly (P). M = long process of the malleus; I = incus; L = lateral (short) process of the malleus.

Tympanic membrane of a person with 12 hours of ea...
Tympanic membrane of a person with 12 hours of ear pain, slight tympanic membrane bulge, and slight meniscus of purulent effusion at bottom of tympanic membrane. Reproduced with permission from Isaacson G: The natural history of a treated episode of acute otitis media. Pediatrics. 1996; 98(5): 968-7. See also Media file 3.

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Tympanic membrane of a person with 12 hours of ea...

Tympanic membrane of a person with 12 hours of ear pain, slight tympanic membrane bulge, and slight meniscus of purulent effusion at bottom of tympanic membrane. Reproduced with permission from Isaacson G: The natural history of a treated episode of acute otitis media. Pediatrics. 1996; 98(5): 968-7. See also Media file 3.

* Bulging of the tympanic membrane is the most sensitive sign 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. If difficult to determine, acoustic reflectometry or tympanometry may be helpful.
* Injection of the tympanic membrane is common in crying infants and with fever, this must be distinguished from the injection due to inflammation associated with AOM.
* A history suggestive of AOM and an ear canal full of purulent exudate is generally considered sufficient to diagnosis AOM with perforation.
* Blisters on the tympanic membrane may be present (bullous myringitis).
* Movement of the tragus should be painless in AOM. If pain is present, suspect that a foreign body is in the ear canal or that the patient has otitis externa.
* The association between bacterial conjunctivitis and AOM is well described, thus any patient with purulent conjunctival exudate should receive thorough examination of the tympanic membranes.
* Sinusitis and purulent rhinitis frequently accompany AOM in children and infants.

Causes

* Anatomic and immunologic factors in the presence of acute URI are the main causes of acute otitis media (AOM).
* Pneumococcus species, Haemophilus influenzae (untypeable), and Moraxella species are the bacteria most commonly involved in AOM.
* Various viruses, of which the most frequent are Rhinovirus and respiratory syncytial virus (RSV), are often involved in AOM.
* Bullous myringitis was initially believed to be associated with Mycoplasma pneumoniae but now is described as merely an acute otitis media with blisters within the substance of the eardrum.
* Sterile effusions occur in approximately 20% of cases studied.
* Risk factors for acute otitis media have been identified and can generally be divided into those associated with the host and those associated with the environment.
o Host risk factors:
+ Age
+ Race
+ History of seasonal allergies
+ Craniofacial abnormalities
+ Gastroesophageal reflux
+ Presence of adenoids
+ Genetic predisposition
o Environmental risk factors:
+ Frequent upper airway infections
+ Incidence is increased in the autumn and winter months.
+ Daycare center attendance increases risk of development of AOM.
+ Bottle-feeding increases the incidence compared with breastfeeding.
+ Pacifier use increases risk for AOM.
+ Smoking in the household clearly increases the incidence of all forms of respiratory problems in childhood.
+ Helicobacter pylori has recently been studied and found in middle ear, tonsillar, and adenoid tissues in patients with otitis media with effusion (OME), indicating a possible role in pathogenesis of OME.5

http://emedicine.medscape.com/article/764006-overview