Otitis media

• Otitis media, or inflammation of the middle ear, is defined 
  • by the presence of fluid in the middle ear 
  • accompanied by signs or symptoms of acute illness. 
• The peak incidence occurs in the first 3 years of life. 
• The disease is less common in the school-aged child, adolescents, and adults but the bacteriology and therapy are similar to those in children.  
• In addition, adults suffer from the sequelae of otitis media of childhood: 
  • hearing loss
  • cholesteatoma
  • adhesive otitis media
  • chronic perforation of the tympanic membrane

Predisposing factors

• The vast majority of children have no obvious defect responsible for severe and recurrent otitis media
• Otitis media is most common in the younger age groups. 
  • The eustachian tube wall lacks stiffness in infants and young children. 
• Older individuals have eustachian tubes with stiffer walls which are less likely to collapse.
  •  In addition, as the eustachian tube grows with an individual, a small amount of swelling due to an upper respiratory infection is less likely to occlude the tube or cause significant tube dysfunction.
• A small number have 
  • Eustachian tube dysfunction include anatomic abnormalities (Down's syndrome,cleft palate, cleft uvula, submucous cleft)
  • alteration of normal physiologic defenses (patulous eustachian tube)
  • congenital or acquired immunologic deficiencies. 
•  Breast-feeding for 3 or more months is associated with a decreased risk of  acute otitis media in the first year of life. 
•  Race and ethnicity provide additional data suggesting a genetic basis for recurrent middle ear infections; Native Americans, Alaskan and Canadian Eskimos, and Australian aborigines have an extraordinary incidence and severity of otitis media.
• The introduction of infants into large day care groups increases the incidence of respiratory infections, including otitis media. 
• Passive smoking documented by a biochemical marker, the serum nicotine level, increased the incidence of new episodes of otitis media with effusion and the duration of effusion. 

Classification

• Episodes of otitis media should be classified as acute otitis media (AOM) or otitis media with effusion (OME). 

Etiologic agents 

The most common causes of otitis media are

• Streptococcus pneumoniae (40 %)
• Hemophilus influenzae (30%)
• Moraxella catarrhalis (15%)

Group A streptococcus and Staphylococcus aureus are rare causes of otitis media

Viruses

• Virologic and epidemiologic data suggest that viral infection is frequently associated with acute otitis media. 
• Respiratory syncytial virus, influenza virus, enteroviruses, and rhinoviruses were the most common viruses found in middle ear fluids.
• Many patients with virus in middle ear fluid have a mixed viral-bacterial infection.

Mycoplasma, Chlamydia, and Unusual Organisms rarely.

Pathogenesis

• The middle ear is part of a continuous system that includes the nares, nasopharynx, and eustachian tube medially and anteriorly, and the mastoid air cells posteriorly. 
• These structures are lined with a respiratory epithelium that contains ciliated cells, mucus-secreting goblet cells, and cells capable of secreting local immunoglobulins.
• The eustachian tube is the structure which plays a major role in the development of acute otitis media. 
  • The eustachian tube has at least three physiologic functions with respect to the middle ear: 
    • protection of the ear from nasopharyngeal secretions
    • drainage into the nasopharynx of secretions produced within the middle ear
    • ventilation of the middle ear to equilibrate air pressure with that in the external ear canal
  • When one or more of these functions is compromised, the results may be the development of fluid and infection in the middle ear. 
• Viral or allergy
  • Viral upper respiratory infection or allergy causes inflammation and edema in the eustachian tube, impairing its normal functions. 
  • When ventilation of the middle ear is lost, oxygen is absorbed from the air in the middle ear and negative pressure results.
  • This negative pressure draws bacteria into the middle ear. 

Clinical manifestations

• Symptoms 
  • ear pain
  • ear drainage
  • hearing loss
  • nonspecific, such as fever, lethargy, or irritability
  • Vertigo, nystagmus, and tinnitus may occur

Physical findings

• Redness of the tympanic membrane is an early sign of otitis media, but erythema alone is not diagnostic of middle ear infection since it may be caused by inflammation of the mucosa throughout the upper respiratory tract. 
• The presence of fluid in the middle ear is determined by the use of pneumatic otoscopy, a technique that permits an assessment of the mobility of the tympanic membrane. 
  • Fluid persists in the middle ear for prolonged periods after the onset of acute otitis media even though symptoms usually resolve within a few days after the initiation of antimicrobial therapy. 
• The motion of the tympanic membrane is proportional to the pressure applied by gently squeezing and then releasing the rubber bulb attached to the head of the otoscope. 
  • Normal mobility is apparent when positive pressure is applied and the tympanic membrane moves rapidly inward; with release of the bulb and the resulting negative pressure, the membrane moves outward.
  • Fluid or high negative pressure in the middle ear dampens the mobility of the tympanic membrane.
  • Tympanometry uses an electroacoustic impedance bridge to record compliance of the tympanic membrane and
    middle ear pressure. 
  • This technique presents objective evidence of the status of the middle ear and the presence or absence of fluid.
•   hearing loss of variable severity. 
•  lower in tests of speech, language, and cognitive abilities than do their disease-free peers. 

Complications and long-term consequences   .

• Mastoiditis was a very common infection in the pre-antibiotic era, and results from spread of infection from the middle ear to the mastoid air cells of the temporal bone
• A bulging tympanic membrane will occasionally spontaneously perforate, with purulent discharge seen from the ear canal. 
  • These perforations spontaneously heal and cause no long-term damage. 
• Persistent middle ear effusion may follow an acute otitis media, and result in hearing loss and language delay in young children. Intracranial infections such as meningitis can occasionally occur. 
• Chronic otitis media may result in formation of a cholesteatoma, an overgrowth of squamous epithelium in the middle ear which must be removed by resection to restore proper hearing.

 Diagnosis

The only way to determine the specific pathogen in the middle ear is to perform  tympanocentesis . It is not commonly performed, and antibiotic therapy is generally used empirically. Tympanocentesis should be considered in selected patients:  

• the patient who is critically ill at the onset
• for patients who fail to respond to therapy, in 48 to 72 hours and is toxic
• for neonates in whom the bacteria causing, otitis media may be different (group B streptococcus and gram-negatives)
• for immunocompromised patients 

• Amoxicillin remains the drug of choice for the treatment of acute otitis media. 
  • It will cover non-penicillin resistant Streptococcus pneumoniae, and beta-lactamase negative strains of Hemophilus influenzae and Moraxella catarrhalis.
  • With appropriate antimicrobial therapy, most children with acute otitis media are significantly improved within 48 to 72 hours. If there is no improvement, the patient should be reexamined. 
• Penicillin resistant Streptococcus pneumoniae. 
  • If a patient fails to respond, he may require treatment with a second-line agent for presumed beta-lactamase positive organisms.
  • In these patients, tympanocentesis to establish a bacteriologic diagnosis is helpful. 
  • Optimal treatment of penicillin-resistant S. pneumoniae otitis media is currently unclear, but may include drugs such as IM ceftriaxone or oral clindamycin.
• Antimicrobial agents are indicated for treatment of AOM
• Acute otitis media can be treated with a 5- to 7-day course of antimicrobial agents in certain children 2 years of age or older.
• Younger children and children with underlying medical conditions, craniofacial abnormalities, chronic or recurrent otitis media, or perforation of the tympanic membrane, should be treated with a standard 10-day course.
• Persistent middle ear effusion (OME) for 2 to 3 months after therapy for AOMis expected and does not require retreatment.

Antimicrobial agents are not indicated for initial treatment of OME; treatment may be indicated if effusions persist for 3 months or more. 

Decongestants, Antihistamines, and Corticosteroids.: no significant evidence of efficacy of any of these preparations.

Chronic Otitis Media

• The term chronic otitis media includes recurrent episodes of acute infection and a prolonged duration of middle ear effusion usually resulting from a previous episode of acute infection. 
• For the prevention of recurrent episodes of acute otitis media, management includes the consideration of
  • chemoprophylaxis (the use of antimicrobial agents). 
    • A reduction of episodes of acute febrile illnesses due to otitis media occurred. 
    •  Children should be considered for prophylaxis if they have had two episodes of acute otitis media in the first 6 months of life or, in older children, three episodes in 6 months or four episodes in 1 year. 
    • Amoxicillin, 20 mg/kg, or sulfisoxazole, 50 mg/kg, may be administered once a day.
    • The physician who chooses to use chemoprophylaxis to prevent acute recurrent disease must examine the patient at approximately 1-month intervals for middle ear effusion. 
  • immunoprophylaxis (the use of vaccines or immunoglobulin)
    • Pneumococcal vaccines have been evaluated for the prevention of recurrences of acute otitis media in children. 
    •  As in previous studies, children younger than 2 years had unsatisfactory responses to single-dose regimens. 
    • The vaccine reduced the number of episodes of acute otitis media due to types of S. pneumoniae present in the vaccine, but the reduction was not sufficient to alter the experience of the children with middle ear infections. 
    • The basis for failure of the vaccine was due to the poor immunologic response to the polysaccharide antigens in the young infants enrolled in the trials.
    •  The data suggested that the vaccine was likely to be more effective in children older than 2 years.
    •  Vaccines composed of pneumococcal capsular polysaccharides conjugated to proteins increased immunogenicity in young infants and are currently undergoing clinical evaluation.
    • Because of the importance of respiratory viruses in the pathogenesis of acute otitis media, viral vaccines could be of preventive value.
    •  Influenza virus vaccine has been documented to decrease the incidence of acute otitis media in children in day care in Finland and North Carolina. 
•  For the management of persistent middle ear effusions, three surgical methods are considered: 
  • myringotomy
    • Myringotomy, or incision of the tympanic membrane, is a method of draining middle ear fluid. 
    • Myringotomy offers quick pain relief when a patient is in severe pain from otitis media. 
    • Today, the use of myringotomy is limited to the relief of intractable ear pain, hastening resolution of mastoid infection, and drainage of persistent middle ear effusion that is unresponsive to medical therapy.
  • adenoidectomy
    • Enlarged adenoids may obstruct the orifice of the eustachian tube in the posterior portion of the nasopharynx and interfere with adequate ventilation and drainage of the middle ear. 
  • Tympanostomy tubes resemble small collar buttons.
    • They are placed through an incision in the tympanic membrane to provide drainage of fluid and ventilation of the middle ear. 
    • The criteria for the placement of tubes include persistent middle ear effusions unresponsive to adequate medical treatment over a period of 3 months and persistent negative pressure. 
    • Hearing improves dramatically after placement of the ventilating tubes.
    • The tubes have also been of value in patients who have difficulty maintaining ambient pressure in the middle ear such as would occur due to barotrauma in airline personnel.
    • The liabilities of the placement of tubes include those of anesthesia associated with the procedure, persistent perforation, scarring of the tympanic membrane, the development of cholesteatoma, and otitis media caused by swimming with ventilating tubes in place, but these occur infrequently.

Prevention 

•  Recurrences may be prevented in patients with recurrent otitis media by either placement of tympanostomy tubes (which provide continuous ventilation of the middle ear by means of a plastic ventilation tube which has one end in the middle ear and the other end in the external ear canal) or prophylactic antibiotic therapy. 
• Both pneumococcal vaccine and influenza vaccine have been shown to be effective in reducing the number of episodes of otitis media in otitis-prone patients. 
  • Unfortunately, currently available pneumococcal vaccine is not effective in children less than 2 years of age, the group at greatest risk of developing recurrent otitis media. 
• Otitis media due to H. influenzae is associated with nontypable strains in the vast majority of patients. 
• Antimicrobial prophylaxis should be reserved for control of recurrent AOM, defined as 3 or more distinct and well-documented episodes per 6 months or 4 or more episodes per 12 months.