Otitis Media



Otitis Media


Heidi Schwarzwald

Mark W. Kline



Otitis media is a general term denoting inflammation of the middle ear. Acute otitis media refers to suppurative middle-ear infection of relatively sudden clinical onset. The term chronic otitis media encompasses several entities of insidious onset, the differentiation of which by clinical or pathologic criteria is difficult. Chronic suppurative conditions include tubotympanitis (e.g., permanent perforation syndrome), atticoantral disease (e.g., Shrapnell disease or cholesteatoma), and end-stage disease (e.g., atelectatic ear, adhesive otitis media, or tympano-sclerosis). Otitis media with effusion (secretory otitis media) is a chronic condition characterized by the persistence of fluid in the middle ear. Temporally, usually otitis media with effusion follows an episode of acute otitis media. Extension of inflammation beyond the mucoperiosteal lining of the middle ear constitutes a complication of otitis media (e.g., mastoiditis, epidural abscess).


OVERVIEW


Epidemiology

Otitis media is one of the most common infectious diseases of childhood. One large study revealed that 33% of pediatric office visits for illness of any kind were attributable to disease of the middle ear (acute otitis media or otitis media with effusion). Infants and young children are at highest risk for the development of otitis media, with a peak prevalence between 6 and 36 months of age. Two of every three children have at least one episode of otitis media before their first birthday. By age 3, 80% of children have had at least one episode of acute otitis media, and nearly 50% have had three or more episodes. After an initial episode of acute otitis media, 40% of children have
middle-ear effusion that persists for at least 4 weeks, and 10% have persistent effusion after 3 months. Children in whom otitis media with effusion develops early in life are at increased risk of recurrent acute or chronic middle-ear disease. The overall childhood prevalence of otitis media with effusion is estimated to be 15% to 20%. The incidence and prevalence of otitis media decline after approximately age 6.

Otitis media occurs more commonly in boys than in girls and is particularly prevalent among Inuit and Native Americans and among children with cleft palate or other craniofacial defects. A familial predisposition to otitis media may exist in some cases. Other implicated predisposing factors include lower socioeconomic status, bottle-feeding with the baby supine, bottle-feeding versus breast-feeding, day-care center attendance, and atopy. In general, the highest rates of otitis media are observed in the winter months, coinciding with the peak incidence of respiratory viral infections.


Pathogenesis

Abnormal eustachian tube function underlies most cases of otitis media. Normally, the eustachian tube permits equilibration of middle-ear pressure with atmospheric pressure, protects the middle ear from reflux of nasopharyngeal secretions, and drains secretions from the middle ear into the nasopharynx. Either obstruction or abnormal patency of the eustachian tube may lead to the development of otitis media. Intrinsic (e.g., inflammation secondary to infection or allergy) and extrinsic (e.g., tumor or adenoid enlargement) types of mechanical eustachian tube obstruction are recognized. Functional obstruction, caused by persistent collapse of an abnormally compliant eustachian tube, an abnormal active opening mechanism, or both, is common in young children and individuals with cleft palate. An abnormally patent, or patulous, eustachian tube, commonly found among Native American populations, permits reflux of nasopharyngeal secretions into the middle ear. Reflux, aspiration, or insufflation of nasopharyngeal bacteria into the middle ear on any basis leads to mucoperiosteal inflammation and otitis media.


Complications

Serious complications of otitis media are uncommon when appropriate medical therapy is initiated promptly. Extracranial complications include serous or purulent labyrinthitis, mastoiditis, osteomyelitis of the temporal bone, and facial nerve paralysis. Intracranial complications are subdivided into meningeal and extrameningeal complications. Epidural and subdural abscess, meningitis, lateral sinus thrombosis, and otitic hydrocephalus are reported as meningeal complications of otitis media. Lateral sinus thrombosis is characterized by high temperature, chills, signs and symptoms of increased intracranial pressure, and septicemia with embolization. The mortality is approximately 25%. Otitic hydrocephalus may follow acute otitis media by several weeks and usually is associated with impaired intracranial venous drainage. Commonly, hydrocephalus subsides spontaneously. Extrameningeal complications of otitis media include brain abscess and petrositis.


ACUTE OTITIS MEDIA


Clinical Manifestations

The classic description of acute otitis media is of children who have upper respiratory tract infection and suddenly develop fever, otalgia, and hearing loss. A classic presentation, however, may be the exception rather than the rule. Fever and hearing loss are inconstant features of the disease, and otalgia may be present but not be reported. In many young children in particular, otitis media must be inferred on the basis of nonspecific symptoms (e.g., fretfulness or irritability, anorexia, loose stools) and subtle findings suggestive of middle-ear disease (e.g., scratching or tugging at the ear). Otitis media must be excluded before children are labeled as having fever without localizing signs or having fever of undetermined origin. Unfortunately, overdiagnosis of acute otitis media is common, especially in uncooperative patients.

The appearance of the tympanic membrane is key to the diagnosis of acute otitis media. Evidence of middle-ear effusion and inflamation should be present. All wax and debris must be removed from the external canal before examination. Usually, otoscopy reveals a hyperemic, opaque tympanic membrane with distorted or absent light reflex and indistinct landmarks. A red appearance of the drum may be noted if affected children are agitated or if inadequate illumination is provided; this condition is not evidence of otitis media in the absence of other findings. Adequate assessment of tympanic membrane mobility requires pneumatic otoscopy, using an ear speculum large enough to occlude the external canal completely. Mobility may be further evaluated by tympanometry and/or acoustic reflectometry. Decreased mobility of the drum may result from either eustachian tube dysfunction or middle-ear effusion.

Usually, the diagnosis of acute otitis media is apparent, but if examination is difficult, diagnosis can be elusive as well. Referred otalgia may be associated with infections and other conditions of the tonsils, adenoids, teeth, or pharynx, however. The tympanic membrane should appear normal in these conditions. Purulent otorrhea may indicate otitis media with tympanic membrane perforation, but otitis externa must be excluded. In diseases of the external canal, frequently pain is elicited by manipulation of the pinna.


Diagnosis

Bacteria may be isolated from middle-ear fluid in approximately two-thirds of patients with acute otitis media. The approximate prevalence rates of various bacterial agents of otitis media beyond the neonatal period are shown in Table 251.1. Substantial percentages of Streptococcus pneumoniae isolates are resistant to penicillin and amoxicillin; resistance to other oral penicillins and cephalosporins also has been observed. With increased use of the heptavalent pneumococcal vaccine, the incidence of otitis media caused by S. pneumoniae has been decreasing. Many untypeable Haemophilus influenzae strains and almost all strains of Moraxella catarrhalis
produce beta-lactamase and therefore also are resistant to penicillin and amoxicillin. Bacterial cultures of middle-ear fluid are sterile in approximately one-third of patients with acute otitis media. Studies assessing the role of viruses have found a low rate of isolation from middle-ear fluid, with respiratory syncytial virus and influenza viruses being most common. Chlamydia trachomatis and Mycoplasma pneumoniae probably are infrequent causes of otitis media. These organisms are not necessarily associated with bullous myringities, as is commonly thought.

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Jul 24, 2016 | Posted by in ORTHOPEDIC | Comments Off on Otitis Media

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