Acute Otitis Media

2 Otology

2.2 Otitis Media

2.2.1 Acute Otitis Media

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Key Features

● The presence of middle ear fluid along with a bulging or an inflamed tympanic membrane and pain are features of acute otitis media.

● It may also be accompanied by hearing loss, nausea, vomiting, or otorrhea.

● It is one of the most common childhood illnesses, contributing greatly to healthcare costs.

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Epidemiology

AOM is common in children: 60% of all children under the age of 1 will suffer at least one bout, and that percentage increases to 80% by age 3. It can ac- count for up to 20% of all clinic visits for pediatric patients 10 years old and younger. Specific risk factors other than age include male sex, attendance in daycare, exposure to cigarette smoke, and history of previous infection.

There also appears to be a seasonal fluctuation, with more cases occurring in autumn or winter.

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Clinical

Signs

Specific signs include an opaque, bulging, and erythematous tympanic membrane (TM) demonstrating poor mobility. If mastoiditis is suspected, the postauricular region may also be erythematous and edematous.

Symptoms

The Agency of Healthcare Research and Quality (Rockville, MD) defines acute otitis media as the presence of a middle ear effusion or the presence of fluid in the ear canal as a result of a ruptured TM with or without TM opacification, erythema, bulging, and hearing loss, and the rapid onset of one or more of the following: otalgia, otorrhea, irritability, and fever with or without anorexia, nausea, or vomiting.

Differential Diagnosis

The differential diagnosis of AOM is really a differential diagnosis for ear pain. Temporomandibular joint disease is probably the most common cause of ear pain that adult patients initially believe may be an ear infection.

Another condition that can mimic AOM in adults is herpes zoster oticus. In that case the pain is from reactivation of the herpes virus, and vesicles will be seen in the canal and/or the periauricular region. The otolaryngologist should always consider the possibility of an occult malignant lesion of the upper aerodigestive tract, particularly the larynx, as a source of referred otalgia, especially in an adult patient with a normal ear exam and a history of tobacco abuse. Unilateral otitis media in the adult (more commonly chronic serous effusion) may arise secondary to a nasopharyngeal neoplasm causing obstruction of the eustachian tube orifice.

The most likely cause of ear pain in children is AOM, whether bacterial or viral. Other causes of ear pain are otitis externa, external canal trauma, and an external canal foreign body. Otitis externa can spread from the ear canal out to the auricle as a cellulitis. The auricle may then protrude from the skull with an increased auriculocephalic angle, and closely resemble AOM that has progressed to acute coalescent mastoiditis. AOM must also be distinguished from OME, which can be diagnosed as middle ear fluid with or without hearing loss, but without evidence of acute infection.

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Evaluation

Physical Exam

The most important portion of the physical exam is inspecting the TM. The auricle and the external canal remain normal in appearance and are not tender to palpation. The appearance of the TM will change as the disease process follows its usual course. Initially, the TM is engorged and hyperemic.

The hyperemia is most prominent along the manubrium of the malleus and the periphery of the drum. The TM is sluggish to pneumatic otoscopy, but all normal topographic landmarks are visible. As the infection progresses and the middle ear fills with pus, the TM thickens, bulges, and loses normal landmarks. There may be erythema, tenderness, and edema in the postauricular region, especially in small children.

If the infection progresses untreated, the TM perforates in the pars tensa, and the patient experiences a resolution of pain and fever. If pu- rulence is seen in the external canal, then cultures should be obtained. If the perforation heals, and pus reaccumulates untreated, the infection may spread through the antrum into the mastoid, and the mastoid trabeculae may begin to decalcify, leading to coalescent mastoiditis along with other complications. At this stage, the auricle becomes more prominent from the skull as postauricular edema increases. It is important to differentiate this from a severe otitis externa with painful cellulitis and swelling of the auricle.

Imaging

Imaging is usually not indicated unless coalescent mastoiditis or another complication of otitis media is suspected. If such a complication is suspected, a fine-cut temporal bone CT with contrast is indicated. If the patient is an adult with a persistent unilateral otitis media, and the nasopharyngeal exam is equivocal, then an MRI of the head with atten- tion to the nasopharynx may be considered to evaluate for a mass lesion obstructing the eustachian tube.

Labs

Labs are rarely needed to treat routine AOM. One would expect to see leuko- cytosis on CBC. Routine cultures can be obtained if the ear is draining, and is absolutely indicated in an infant less than 6 weeks of age. Tympanocentesis is rarely indicated to obtain cultures, unless suspicion is high for a resistant pathogen and empiric therapy might not be indicated. Tympanocentesis may be helpful in the immunocompromised patient, especially the patient with chemotherapy neutropenia or acquired immunodeficiency syndrome (AIDS).

Other Tests

An audiogram is not needed in the acute phase, but can be helpful in evalu- ating children with recurrent AOM, especially in light of other cognitive delays. In cases where the presence of an effusion is in question, tympano- grams may be helpful. Occasionally, the combination of a good pneumatic

exam and an accurate tympanogram are needed to determine the presence of an effusion, even for an experienced otologist.

Pathology

Most commonly, the bacteria that cause AOM will gain entry to the middle ear cleft by way of the eustachian tube. The eustachian tubes of infants are short and horizontally aligned. Infants are also likely to eat in a reclined position. These factors put them at high risk for penetration of nasopharyngeal secretions into the middle ears via the eustachian tubes.

Once they grow into early childhood, they continue to suffer from mul- tiple upper respiratory infections each year, and each bout of nasopharyngeal mucosal congestion can close a eustachian tube, leading to negative pressure behind the eardrum, exudate formation, and infection once the exudate becomes contaminated. An allergy can also lead to AOM secondary to eustachian tube dysfunction.

AOM in adults, especially if unilateral, may be ominous. The nasopharynx must be fully evaluated to identify the cause of the eustachian tube blockage or dysfunction. A nasopharyngeal mass must be ruled out prior to ascribing the cause to either an upper respiratory infection or a recent airline flight.

An allergy may also contribute to AOM in adults.

Historically, the most common bacterial pathogens causing AOM have been Staphylococcus pneumoniae (40–50%), nontypeable Haemophilus influ- enzae (20–30%), and Moraxella catarrhalis (10–15%). Over time, strains of Pneumococcus have become penicillin-resistant due to an alteration of the penicillin binding site, and strains of H. influenzae have become -lactamase positive. Also, recently, children vaccinated with a 7-valent pneumococcal vaccine may have a decreased rate of S. pneumoniae and a subsequent increase in H. influenzae.

Histologically, middle ears display signs of inflammation and edema. The TM and middle ear mucosa are thickened and engorged with an inflamma- tory infiltrate. There is often frank pus in the middle ear space.

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Treatment Options

Medical

There has been a trend toward treating children with uncomplicated AOM symptomatically with pain control and no antibiotics for the first 24 to 48 hours, but this should only be done in children where close follow-up can be performed. Otherwise, uncomplicated AOM is a medical disease, and if persisting more than 24 to 48 hours requires antibiotic therapy.

Traditional empiric therapy has been appropriately dosed amoxicillin as a first-line antibiotic because it is effective, well tolerated, and inexpensive.

With emerging resistance, the dose of amoxicillin has been doubled to 80 to 90 mg/kg/day. If patients fail to improve at 48 to 72 hours, they can be switched to high-dose amoxicillin-clavulanate. If patients are penicillin allergic, second- or third-generation cephalosporins, macrolides, or clin- damycin are all options.

Surgical

AOM is not a surgical disease. In patients failing to respond to empiric therapy, diagnostic tympanocentesis may be done for culture. Removing the fluid from the middle ear may also relieve pain.

Patients evaluated for recurrent AOM may be candidates for tympanostomy tubes. Standard criteria for tube placement include more than three episodes of AOM in the preceding 6 months or more than four episodes of AOM in the preceding 12 months.

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Complications

See Chapter 2.2.3 for complications of AOM. Complications of tube placement include otorrhea, retained tubes, and postextrusion perforations. Otorrhea may occur in upwards of 10%, and is treated with appropriate ototopical drops, currently fluoroquinolones as they are not ototoxic. Tubes are watched yearly, and if they have not extruded after 3 years, many otolaryngologists plan removal under general anesthesia. Postoperative perforations are estimated to occur 3 to 5% of the time, and are followed conservatively. If they persist or cause considerable hearing loss, tympanoplasty may be recommended.

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Outcome and Follow-Up

Children with tympanostomy tubes require little postoperative care, and physician preference is usually the driving force determining postoperative recommendations. Many otolaryngologists advocate the use of 5 days of antibiotic topical drops twice daily [i.e., Ciprodex (Alcon Laboratories, Fort Worth, TX) or Floxin Otic (Daiichi Pharmaceutical Corporation, Montvale, NJ)] postoperatively only to children with mucoid or purulent effusions found at the time of tube placement. Many otolaryngologists also recom- mend ear plugs only for children swimming in fresh water, and not during bath or shower time.

The children are otherwise followed with a postoperative audiogram and interval visits at 6 to 12 months until the tubes extrude.

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ICD-9 Code

382.9 Acute otitis media