Porth's Essentials of Pathophysiology, 4e

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Nervous System

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to reduce the risk of developing OM include minimal exposure to group settings and avoidance of expo- sure to passive tobacco smoke. 51 Prevention of OM during the respiratory illness season has been demon- strated by immunoprophylaxis with influenza vaccines. Immunization with pneumococcal vaccine has also been reported to reduce the incidence of OM, but the reported overall effect has been small. 51,52 Etiology. Most cases of AOM follow an uncomplicated upper respiratory tract infection that has been present for several days. The most common bacteria in AOM are S. pneumoniae, nontypeable H. influenzae, and Moraxella catarrhalis. 51 The overall incidence of these pathogens has changed with widespread use of the conjugate pneumococcal vaccine, with nontypeable H. influenzae replacing S. pneumoniae as the most common pathogen. 51 Evidence of respiratory viruses is also found in the middle ear exudates in children with AOM, either alone or, more commonly, in association with pathogenic bacteria. Of these viruses, rhinovirus and respiratory syncytial virus (RSV) are found most often. 51 It remains unclear whether viruses alone can cause AOM or whether their role is limited to setting the stage for bacterial invasion and, perhaps, amplifying the inflammatory response. The etiologies of AOM and OME are interrelated. Acute infection is usually followed by residual inflammation and effusion that, in turn, predisposes to recurrent infection. Middle ear effusion, which is a component of both AOM and OME, is an expression of underlying mucosal inflammation. Clinical Manifestations. Acute otitis media is characterized by an acute onset of otalgia (ear pain), fever, and hearing loss. Children older than 3 years of age may have rhinorrhea or a runny nose, vomiting, and diarrhea. In contrast, younger children often have nonspecific signs and symptoms that manifest as ear tugging, irritability, nighttime awakening, and poor feeding. Key diagnostic criteria include ear pain that interferes with activity or sleep, tympanic membrane erythema (redness), andmiddle ear effusion. 50–52 Perforation of the tympanic membrane may occur acutely, allowing purulent material from the middle ear to drain into the external auditory canal. This may prevent spread of the infection into the temporal bone or intracranial cavity. Healing of the tympanic membrane usually follows resolution of the infection. Otitis media with effusion is often an asymptomatic condition. 51,53 There may be mild intermittent ear pain, complaints of ear fullness, and “popping.” Secondary manifestations in infants may include ear rubbing, excessive irritability, and sleep disturbances. Hearing loss, evenwhen not suggested by the child, is evidenced by a seeming lack of attentiveness, behavioral changes, and failure to respond to conversation-level speech. There may be problems related to school performance, balance problems and unexplained clumsiness, or delayed speech and language development. 52 The duration of the effusion may range from less than 3 weeks to more than 3 months. Many cases of OME resolve spontaneously, but 30% to 40% of children have recurrent OME, and 5% to 10% of episodes last 1 year or longer. 52

Diagnosis. The diagnosis of OM is based on recent and usually acute onset of symptoms, presence of middle ear effusion, and signs and symptoms of middle ear inflammation, including erythema or redness with mild bulging of the tympanic membrane and otalgia or ear pain. Younger, nonverbal children with OMmay present with holding, tugging, or rubbing of the ear. Nonspecific symptoms may include excessive crying, fever, or changes in sleep or behavior patterns. 54 Other evidence of infection includes mild bulging of the tympanic membrane, onset of ear pain of less than 48 hours, or intense redness of the tympanic membrane. Both AOM without otorrhea (drainage from the ear) and OME are accompanied by otoscopic signs of middle ear effusion—namely, the presence of at least two of three tympanic membrane abnormalities: white, yellow, amber, or occasionally blue discoloration; opacification other than scarring; and decreased or absent motility. With OME the tympanic membrane is often cloudy with distinct impairment of mobility, and an air–fluid level or bubble may be visible in the middle ear. The overall importance of distinguishing normal ear status from AOM versus OME is avoidance of unnecessary use of antibiotics along with the potential of adverse effects and antimicrobial resistance. The diagnosis of AOM can also be confirmed using tympanometry or acoustic reflectometry. A tympano- gram is obtained by using a small probe that is placed snugly into the external ear canal. A sound stimulus gen- erator then transmits acoustic energy into the canal, while a vacuum pump introduces positive and negative pres- sures into the ear canal. A microphone in the instrument detects returning sound energy. The tympanogram pro- vides a determination of the degree of negative pressure present in the middle ear. It detects disease when present but is less reliable when disease is absent. Acoustic reflec- tometry detects reflected sound waves from the middle ear and provides information on whether an effusion is absent or present. Increased reflected sound correlates with an increased likelihood of effusion. This technique is most useful in children older than 3 months, and its success depends on user technique. Tympanocentesis (puncture of the tympanic membrane with a needle) may be done to relieve pain from an effusion or to obtain a specimen of middle ear fluid for culture and sensitivity testing. In instances where the tympanic membrane has perforated with resultant drainage into the external ear, a specimen can be obtained and microbiologic studies can be done to identify the organism. Treatment. The treatment of AOM focuses on symptom control and management of the underlying pathologic process. A number of options for pain management are available, including the local application of heat and use of analgesic drugs such as acetaminophen and ibuprofen. 51 Myringotomy (incision in the tympanic membrane) can be used for relief of pressure in the child with severe pain, providing almost immediate relief. The extensive use of antimicrobial agents contributes to the development of bacterial resistance. Observation without antimicrobial agents is an option in a child