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Acute Otitis Media
ALTERNATIVE NAMES: Acute ear infection; purulent otitis media.
DEFINITION: Acute inflammation in the middle ear space behind the eardrum.
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WHAT IS GOING ON IN MY BODY? The ear is divided into three components. There is the outer ear formed by the auricle and external canal. There is the middle ear, which is the air-filled space behind the eardrum that contains the three small bones for hearing, and then there is the inner ear, which contains the cochlea and vestibular labyrinth, the parts of the internal ear responsible for hearing and balance respectively. As the name implies, acute otitis media is acute inflammation of the middle ear space.
The middle ear is normally an air-containing space that has a communication to the air-filled mastoid cavity, which is a bony, honeycomb structure upon which the outer ear sits and is part of the temporal bone. The middle ear space communicates through the eustachian tube to the back part of the nasal cavity. The eustachian tube serves to maintain an equal ear pressure behind the eardrum to that in the environment. It also is the conduit for any secretions formed in the middle ear and mastoid to exit into the nasal cavity. Acute otitis media almost always begins with swelling of the eustachian tube. As the lining swells, the secretions formed in the middle ear and mastoid cannot clear into the nasopharynx, nor is there equilibration of air pressure behind the eardrum to that which is in the environment. As a result, the air behind the middle ear becomes absorbed, and a vacuum is created. The most common cause of eustachian tube inflammation is viral upper respiratory illness. The virus not only affects the lining within the sinus and nasal cavities but also the lining of the eustachian tube and middle ear. It also changes how well bacteria adhere to the mucous membrane lining in the back part of the nasal cavity where the tube opens. When the swollen eustachian tube does open because of the vacuum behind the eardrum, air from the bacteria-laden nasopharynx is aspirated up into the eustachian tube and the middle ear space. With the bacteria in the middle ear and the eustachian tube still poorly functioning, the bacteria proliferate, creating an acute infection. Allergic disease can also create eustachian tube swelling and thus can cause its obstruction, with subsequent development of acute otitis media. Individuals who have excessively small or poorly functioning eustachian tubes will also be at a heightened risk. This explains the propensity of children and infants who have small eustachian tubes to develop acute otitis media. Other children who have eustachian tube dysfunction, such as those with craniofacial anomalies, Down's syndrome, and cleft palate, are more prone to ear infections. Lastly, there are some individuals whose eustachian tubes fail to close and are constantly open and thus are a poor barrier between the bacteria containing nasopharynx and the middle ear. With the constantly open eustachian tube, bacteria have a constant access into the middle ear space, and thus these individuals are also more prone to acute otitis media.
WHAT ARE THE SIGNS AND SYMPTOMS? Most cases of acute otitis media often begin with a viral upper respiratory illness. Symptoms of a viral illness typically begin with clear nasal discharge, low- to mid-grade fever, brief sore throat, cough, and nasal congestion with a tendency to breathe more through the mouth. After the upper respiratory illness has been present for a few to several days is when the ear infection usually begins. The symptoms vary much, depending upon the age of the child. Obviously infants are unable to tell their parents or physicians that their ear is hurting, instead may become more restless, sleep more poorly, awaken frequently during the nighttime, cry inconsolably, and run a fever. Sometimes they may tug or bat at the ear, but this is a very non-specific symptom. The fact that they get worse when they lie down is a result of the increasing swelling of the inflamed ear tissues that naturally occurs when the head assumes a horizontal position relative to the heart. As children become verbal, they may complain of ear pain. Some children may actually tend to have some slight imbalance with acute ear infections. As an acute ear infection progresses, it may cause loss of blood supply to the tympanic membrane and result in infected, bloody material draining out of the external canal. They can cause local or intracranial complications. If there is an ear infection that perforates the tympanic membrane and continues to drain for 10 to 14 days, that is often a sign that it has progressed into the mastoid. Other findings of mastoiditis (refer to mastoid disease) are redness and swelling behind the ear with its forward displacement. An abscess can form behind the ear. The infection can also spread into the inner ear with consequent nerve hearing loss or imbalance (labyrinthitis). In the pre-antibiotic era, more severe complications of acute otitis media developed, such as meningitis, brain abscess, or epidural abscess, often with disastrous outcomes.
When a child is examined who has an acute ear infection, they often have fever, the eardrum is intensely red, and depending upon the stage of the infection, there may or may not be fluid present behind the eardrum. If it is very early, then only acute eardrum inflammation may be present (myringitis). If it is more fully developed, the eardrum may be bulging outward, and there may be purulent material behind it. If the drum has perforated, there is often clear to pus-like material in the ear canal. Because of the degree of inflammation behind the eardrum and the amount of blood coursing through the inflamed middle ear lining, the draining fluid often pulsates.
WHAT ARE THE CAUSES AND RISKS? As mentioned previously, there are a variety of causes and risks of acute otitis media. The main group that is affected is young children under the age of three to four years of age. Boys are more likely to be affected than girls. The fact that young children are more likely to develop infection is a result of the smaller bore of the eustachian tube, plus its position in the infant's and young child's base of skull is not optimum for its opening by the palate musculature. As the eustachian tube bore enlarges with age and its angulation in the base of skull changes, the palatal muscles are more effective in opening it. Young children are also more prone to upper respiratory illness, particularly after transferred maternal immunity during pregnancy wears off. Antibodies transferred during breastfeeding may explain the lessened propensity of breastfed infants to develop acute otitis media. Children with abnormal eustachian tube function either because of abnormal development of the cranium or palate will be more prone to have acute otitis. There are a number of other associated risk factors, such as daycare environments where there is greater transmission of upper respiratory viruses. Children whose parents themselves had childhood otitis media are more prone to develop otitis. Individuals of Mongoloid descent, such as American Indians and Eskimos, have a higher incidence of disease. Because children who live in smoking households have more respiratory disease, they too have a heightened incidence of otitis media. Other disorders of chronic nasal inflammation, such as chronic allergies or sinusitis, have an impact upon eustachian tube function and thus can predispose a child to the development of ear disease. There is also some suggestion that children who take bottles to bed by themselves and thus drink when they are lying flat are more prone to develop otitis media.
HOW TO PREVENT THE DISEASE: In the child with congenital or craniofacial abnormality, there is often no realistic means to prevent the disease. Very frequently these children need ventilation tubes placed in their eardrums to bypass the poorly functioning eustachian tube. Since viral upper respiratory illnesses are the most common inciting disease that leads to acute otitis, avoiding other sick children, high concentrations of sick children (such as daycare environments), and strict attention to hand washing can reduce the spread of viruses. It is sometimes necessary to remove children from a daycare environment and take care of them at home or place them into a home care situation with much fewer children. For those who must be fed before bedtime or who awaken at nighttime needing to be fed, they must be held with their head elevated above their stomach to prevent formula or juice from pooling around the eustachian tube openings. Because these fluids are excellent media for bacterial growth, it is thought that when fluid sits around the opening for the eustachian tube, bacterial movement into the middle ear space can occur and result in ear infection. If parents cannot stop smoking, then not smoking around the children is necessary. Children who already have a history of frequent episodes of otitis media, influenza A vaccination and for those over the age of two, pneumonia vaccine administration have been shown to diminish the incidence of acute ear infection. If allergies are a contributing factor, then these must be aggressively treated, and those patients who have chronic rhinosinusitis must be aggressively managed to try to reduce infection frequency. Lastly, for children whose ear infections are routinely triggered by viral upper respiratory illness, aggressive symptomatic management during a viral illness may diminish the risk of acute ear infection. Such measures as oral decongestants, avoidance of milk products, having the child sleep with their head elevated, using salt water rinses to clear the infected nasal secretions, and judicious use of spray decongestants can help keep the eustachian tube lining from getting so swollen that it causes the eustachian tube to dysfunction. There is no role for the use of over-the-counter antihistamines in the treatment of viral upper respiratory illness in that they tend to thicken secretion as one of their side effects. As it pools and is not cleared, then it increases the bacterial concentration.
Should recurrent acute infections continue in spite of preventive efforts, there are several different forms of medical or surgical approaches. If the ear infections are consequent to viral upper respiratory illness, starting an antibiotic at the same time the cold starts can be helpful. Antibiotics do not treat the viral infection but reduce the bacteria that adhere to the lining of the nasopharynx where the eustachian tubes drain. Another option would be a small dose of prophylactic antibiotic, typically Gantrisin or Amoxicillin. These preventive doses of antibiotics are usually given daily and are employed during the viral upper respiratory season. For those patients and their families who are leery about having their children on a constant daily dose of antibiotics or those children who have tried prophylactic antibiotics and yet have continued to have recurrent episodes of recurrent, acute otitis, then ventilation tube placement is a successful form of management.
HOW IS IT DIAGNOSED? The acute infection is diagnosed by the combination of symptoms and physical examination findings. If a hearing test is administered, then there will be a decline in hearing as a result of inflammation of the middle ear and/or fluid behind the eardrum.
WHAT ARE THE LONG-TERM EFFECTS? Fortunately, there are very few long-term effects of appropriately managed acute otitis media. It is possible in rare situations that these infections may cause damage to the nerve component of the inner ear and thus result in varying degrees of deafness. Recurrent acute ear infections can cause thickening and scarring of the tympanic membrane, but often this has no consequence. If an ear infection creates a perforation in the eardrum, a very small percentage of these do not heal and thus may require surgical repair. If an acute ear infection becomes complicated by meningitis or brain abscess, then a significant number of those children have residual neurologic deficits.
AM I PUTTING OTHERS AT RISK? No.
WHAT ARE THE TREATMENTS? Up to 60% of acute otitis cases will resolve without antibiotics. Antibiotics are primarily employed to reduce the symptom severity and thus make the child more comfortable and prevent serious complications. For those children with mild to moderate symptoms, careful repeat observation may be an effective non-antibiotic way to see if the infection will resolve. For children with more severe symptoms or whose mild to moderate symptoms are progressing or not improving, institution of antibiotics is indicated. Since most ear infections are a result of Streptococcus pneumonia, Hemophilus influenza, or Moraxella catarrhalis, first line therapy with Amoxicillin is appropriate, assuming that the patient is not allergic to Penicillin. If the child does not respond to the initial Amoxicillin therapy, then either doubling the Amoxicillin dose to cover a resistant strep pneumonia or changing to an antibiotic that will be effective against some of the hemophilus and moraxella that degrade Amoxicillin may be necessary. For those children who continue to not respond after several courses of appropriate antibiotic therapy, making an incision in the eardrum and removing the fluid for culture to identify the offending bacteria may be necessary. By culturing the bacteria, the antibiotics that the bacteria is sensitive to can also be determined.
WHAT ARE THE SIDE EFFECTS TO THE TREATMENTS? The side effects would be those specific to the antibiotics employed. Allergic reactions are typically characterized by rashes.
WHAT HAPPENS AFTER TREATMENT? If the acute infection has been adequately treated, then the fluid behind the eardrum usually resolves. In a variety of studies after two weeks of successful management, about 20% of children have the fluid go away. After a month, approximately 40% resolve. After two months, 60% of patients have had their middle ear fluid go away. By 90 days, approximately 90% of children have had their fluid clear. During this observation period, no further antibiotics are usually necessary, although it is common to try another round of antibiotics just to ensure complete eradication of any residual bacteria that might be present in the fluid. As long as the fluid is present, there will be a conductive hearing loss. Once the fluid goes away, the hearing returns to normal. If the fluid persists for more than three months, there is little statistical likelihood that it will resolve, and thus tube placement is usually recommended.
HOW DO I MONITOR THE DISEASE? The disease is mostly monitored by the child's symptoms. If the choice to observe a mild to moderately severe ear infection is made, this will require several physician visits to ensure that it is in fact improving spontaneously and not progressing. Anything unusual, such as ear drainage, facial weakness, vertigo, failure to respond to antibiotic management, or symptoms of meningitis (such as a stiff neck, severe vomiting, and worsening somnolence) require immediate medical attention.
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