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Otitis Media
Mary Bennett, Amanda Buisman & Roline Campbell
Pertinent Anatomy
Ossicles
(malleus, incus, stapes)
OR
Auricle
External Ear Canal
OR
Tympanic Membrane
Pertinent Anatomy
(Cone of light)
Physiology of the Ear
External Ear
Consists of the pinna (auricle) and the auditory ear canal
• The pinna functions to both protect the tympanic
membrane, and to collect sound waves.
• The auditory ear canal distributes sounds in the form
of pressure waves to the tympanic membrane.
Physiology of the Ear
Middle Ear
Consists of the tympanic membrane, auditory ossicles (malleus, incus,
stapes) and the eustachian tube.
• The tympanic membrane receives sound waves (in the form of
pressure waves) from the auditory ear canal and converts the waves
into mechanical vibrations by way of the auditory ossicles. The
mechanical vibrations are then transmitted to the inner ear.
• The eustachian tube links the pharynx to the middle ear and while it is
normally closed, it can let a small amount of air though to equalize the
pressure between the middle ear and the atmosphere. It also drains
mucous from the middle ear.
Physiology of the Ear
Inner Ear
Consists of the semicircular canals, vestibule, acoustic nerve, and
the cochlea.
• Mechanical vibrations are received from the TM and are
transformed into fluid vibrations, which are then converted
into nerve impulses by nerve endings located in the cochlea.
These impulses are conducted via the auditory nerve to higher
levels and interpreted as sound by the brain.
• The semicircular canals and vestibule function to maintain
balance and equilibrium.
Pathophysiology
of Otitis Media (OM)
OM is defined as inflammation in the middle ear without
reference to etiology. OM is one of the most common reasons
for a child to visit the pediatrician.
OM can be classified into four categories;
• Acute Otitis Media (AOM)
• Otitis Media with Effusion (OME)
• Recurrent AOM
• Chronic OME
Pathophysiology
of Acute Otitis Media (AOM)
The most important factor in the pathogenesis of AOM is
abnormal function of the eustachian tube.
• Reflux, aspiration, or insufflation of nasopharyngeal
bacteria into the middle ear via the dysfunctional
eustachian tube may lead to infection.
• Eustachian tube dysfunction occurs due to either
abnormal patency, or obstruction (either functional or
mechanical).
Pathophysiology
of Acute Otitis Media (AOM)
Common causative microorganisms for AOM are:
• Streptococcus pnumoniae (30-50% of cases)
• Haemophilus influenzae (20-30% of cases)
• Moraxella catarrhalis (7-25% of cases)
Acute Otitis Media (AOM)
With and Without Perforation
When AOM is present and the TM is intact, it is
referred to as “AOM without perforation”.
When AOM is present and the TM is NOT intact, it
is referred to as “AOM with perforation”.
AOM with Perforation
AOM with perforation has two categories;
• AOM complicated by perforation of the tympanic membrane
presenting as otorrhea. (Left)
• AOM in a patient with tympanostomy tubes. (Right)
OM with Effusion (OME)
OME occurs when thick fluid accumulates behind
the TM. OME typically occurs immediately
following treatment of AOM due to the resolution
of acute inflammation, allowing visualization of the
middle ear fluid behind the TM.
Epidemiology
The overall prevalence of AOM is 15-20%, with the
highest peak at 6-36 months of age.
An additional smaller peak occurs at 4-6 years of age.
Between 60-80% of infants have had at least one
episode of AOM by one year of age.
AOM is uncommon in older children and adolescents.
Epidemiology
AOM is more common in boys, and the
prevalence is greatest in Alaskan natives and
Native Americans (Caucasian race is also
considered a risk factor however).
AOM is most common in the winter months and
in early spring, coinciding with peaks in the
incidence of URI’s.
Epidemiology
Risk factors for developing OM;
• Male gender
• Absence of breastfeeding
• White race
• Passive exposure to tobacco smoke
• Daycare attendance
• Low socioeconomic status
• Presence of siblings in the household
• Altered host defenses/underlying conditions
Patient Evaluation-History
Clinical presentation- children with AOM often have a
history of rapid onset of fever and ear pain (usually
within 48 hours). The patient may also have hearing loss,
otorrhea, and irritability. Nonverbal children present with
“ear pulling” and generalized fussiness.
Associated symptoms include URI, cough, diarrhea, and
nonspecific complaints such as decreased appetite,
waking at night, or irritability in infants.
Patient Evaluation- History
It is important in the history to differentiate
nonspecific symptoms of OM from those indicating
a more serious condition such as meningitis.
For infants or children with a history of persistent or
recurrent OM, it is important to find out when they
had their last documented infection and what
treatment they received.
Patient Evaluation- History
Helpful questions to ask when obtaining the
patient’s history;
• Does the infant have fever, ear pain, hearing loss, or
otorrhea?
• Is the infant/child inconsolable or lethargic?
• Has the infant/child had a previous ear infection? If so,
when?
• Did the child complete the course of prescribed
antibiotics?
Helpful Questions
• How many ear infections has the child had in the past
year?
• Is the child taking any medication to prevent recurrent
OM?
• Does the child attend daycare?
• Is the child exposed to passive smoke?
• Is the infant breast-fed?
• Does the child appear to hear?
• Is the child’s speech development normal?
Physical Exam Findings
To diagnose OM, the TM must be
visualized. The position, color, degree
of translucency, and mobility of the TM
must be evaluated.
Classically, in AOM the TM is full or
bulging, opaque, and has limited or no
mobility, or is retracted. The light reflex
is usually absent or distorted.
Physical Exam Findings
Associated physical exam findings may include;
• posterior auricular and/or cervical adenopathy
• pain on movement of the pinna
• anterior ear displacement
*The presence of these symptoms may also suggest a more serious condition such as
mastoiditis therefore thorough history taking and visualization of the TM is essential.
Normal (no AOM present) Exam
Findings
Position- process of the malleus should be visible
but not prominent through the membrane.
Color- pearly gray.
Translucency- middle ear or bony landmarks
should be visible through the TM.
Mobility- normal ear will move with pneumatic
otoscopy.
Physical Exam Findings
Here is a normal TM
Physical Exam Findings
Here is a picture of a
typical TM with AOM. The
TM is noted to appear
erythematous or injected
in color, the light reflex is
absent, landmarks are
poorly visualized, and
there is a poor degree of
translucency.
Physical Exam Findings
Here is an example of AOM
with a bulging TM. Note the
color, position, transparency,
lack of visible landmarks,
and distorted light reflex
Physical Exam Findings
Here is a retracted TM
Diagnosis of AOM
• Accuracy in diagnosis of utmost
importance
• Ensures appropriate treatment for AOM
• Avoids unnecessary use of antibiotics in
OME
• Prevents overuse of antibiotics –
considered a major factor in increased
drug-resistance
AOM in Infants & Children
• Challenges in establishing a diagnosis:
– Uncooperative
– TM obscured by cerumen
– Symptoms of AOM may overlap with other conditions (URI)
– Symptoms may be subtle or even absent
• Successful diagnosis facilitated by:
– Systematic assessment
– Stringent diagnostic criteria
– Training and experience
AAP & AAFP Diagnostic Criteria
Three diagnostic criteria
1. Recent, abrupt onset of ME inflammation & effusion
(ear pain, irritability, otorrhea, and/or fever)
2. MEE confirmed by:
–
–
–
–
bulging TM,
limited or absent mobility (pneumatic otoscopy),
air-fluid level behind TM, or
Otorrhea (with TM not intact)
3. Evidence of ME inflammation - confirmed by:
– distinct erythema of TM, or
– distinct otalgia interfering with normal sleep or activity
Diagnostic Techniques
• Pneumatic otoscopy
– Assess inflammation
– Assess effusion
– Assess perforation & character of otorrhea
• Tympanometry and/or acoustic reflectometry
– Assess/confirm effusion
• Tympanocentesis (by otolaryngologist)
– Identify infectious organism
– Use in special populations
Tympanometry
• Accurate & objective
assessment of effusion
• Requires an air-tight seal &
pressurization of the ear
canal
• Painful & uncomfortable for
children
• Limited use & costly
Acoustic
Reflectometry
• Analyzes sound reflected off
the TM to detect MEE
• No pressure seal required
• Small quantity of cerumen
does not affect this test
• Increased use in primary care
Pneumatic Otoscopy
• Allows direct visualization of TM & ear structures to
confirm presence of inflammation, effusion and assess
for perforation.
• Important to:
– Remove cerumen obscuring TM
– Ensure adequate lighting
– Appropriately restrain the child to allow examination & prevent
injury
– For pneumatic otoscopy – adequate airtight seal by choosing
correct size and shape speculum.
Assessment of the TM
• Locate border between external ear canal & TM
• Assess:
– Surface
– Opacity
– Color
– Mobility
– Other findings
The Surface of the TM
• Are the landmarks visible?
• Are the landmarks
obscured or unusually
prominent?
• Where is the cone of light?
• Is the TM intact?
Retracted & Bulging TM
Abnormally retracted TM
Bulging TM
Opacity of the TM
Normal Tympanic Membrane
- Usually translucent
Scarred Tympanic Membrane
- note loss of translucency
at area of scar
Color of the TM
Expected Findings
• Normal TM = Pearly grey
• Crying infant = Pink TM
• Classic AOM = red or
infused TM
• Atypical AOM = white or
yellow TM (from purulent
middle ear fluid)
AOM with infused erythema
Mobility of the TM
• Successful pneumatic otoscopy requires airtight seal of
external ear canal
• With normal mobility the TM will
– move inward when positive pressure is applied
– move outward when negative pressure is applied
• A retracted TM will show
– decreased or absent inward deflection
– but normal outward deflection with negative pressure
• Crying children have increased middle ear pressures during
exhalation which fleetingly normalize during inspiration
• Severely diminished or absent mobility is indicative of
effusion
Normal TM Movement
Decreased TM Movement
Other Findings
Cholesteatoma →
↖ Bleb / blister
Air-fluid level behind the TM
- Indicative of Middle Ear
Effusion (MEE)
Cholesteatoma – grey or white
mass behind the TM
Blebs / blisters on the surface
of the TM – Bullous Myringitis
Clinical Diagnosis of AOM
Requires:
Acute onset of symptoms AND
Middle Ear Effusion AND
Middle Ear Inflammation
OR
Acute purulent otorrhea
via perforated TM or tympanostomy tube
AND otitis externa has been excluded
Differential Diagnoses
Diff. Dx
S&S
Viral
Myringitis
OME
AOM
Otalgia
Present
Usually absent some reports Acute pain
"fullness“
Inflammation
Present
Absent
Bulging TM
No bulging
Normal position
Bulging
or retracted
TM Mobility
Normal
Decreased
Present
Decreased
AOM or OME?
Two year old Ron’s mom reports him rubbing and slapping at
his left ear since early this morning. He refused breakfast
and has been irritable all day. Pneumatic otoscopy reveals
a bulging, yellow tympanic membrane with marked
decrease in mobility.
Is this AOM or OME?
Summary: MEE
• MEE (Middle Ear Effusion) = fluid in middle
ear
• Occurs in both AOM and OME
• OME often precedes development of AOM
• OME mostly also follows resolution of AOM
OM with ruptured TM
AOM with TM intact
AOM with ruptured TM
(or with Tympanostomy tube)
• Acute onset otalgia
• Inflamed TM
• Middle Ear Effusion present
(Bulging and decreased
mobility)
• History of acute onset
otalgia which improved
when ear started draining
(relief of pressure when TM
ruptured)
• Inflamed TM
• TM ruptured & draining
purulent fluid into external
ear canal
Treatment of AOM
• Clinical course of 24 – 72 hours with
appropriate antimicrobial Rx
• Slightly slower resolve of acute symptoms
when not treated
• MEE may persist for weeks or months
Clinical Practice Guideline
• AAP and AAFP Clinical Practice Guidelines
(2004) state that the following aspects of
management should be considered:
1. Symptomatic therapy
2. Observation (“Watchful waiting”)
3. Appropriate antimicrobial therapy
1. Symptomatic Therapy - Pain
• Acetaminophen
– 10 -15mg/kg PO/PR every 4 – 6 hours as needed
– not to exceed 90mg/kg/day
• Ibuprofen
– 5 - 10mg/kg PO/PR every 6 – 8 hours as needed
– not to exceed 40mg/kg/day
• Topical agents
–
–
–
–
Antipyrine-benzocaine otic drops
4 – 5 drops into affected ear(s) every 2 hours as needed
not to be given in case of TM perforation
Aqueous lidocaine ear drops (30 minute efficacy – needs
further evaluation – not currently a recommendation)
Treatment of pain (cont.)
• Complementary treatments
– Herbal extracts:
• Otikon Otic solution
• Compared well to topical anesthetic
• Home remedies
– Distraction
– External application of heat or cold
– Instillation of oil into external auditory canal
– Clinical evidence still lacking
Symptomatic Therapy Congestion
• Decongestants and antihistamines
– Still commonly used in some populations
– No proof of efficacy in treatment of AOM
– Demonstrated:
• Increased medication side-effects
• Did not improve healing or reduce complications/surgery
• Prolonged duration of MEE
• AAP recommends OTC cough and cold
medications NOT used in infants & children < 2
years (danger of life-threatening side effects!)
2. “Watchful waiting”
• Objective is to reduce the unnecessary use of
antibiotics
• Limit development of drug-resistance
• Option only for selected children
• Certain criteria must be met to ensure safety
• “Watchful waiting” is NOT appropriate for any
infant < 6 months
– Infants < 6 months should be treated with antibiotics
REGARDLESS of the degree of diagnostic certainty.
Considerations for “Watchful
Waiting”
• Age of infant/child
• Certainty of diagnosis
• Severity of illness
• Can follow-up be ensured?
• Ability to acquire prescription medications if needed
• Parents must understand risks and benefits of
“watchful waiting” vs immediate treatment
3. Antimicrobial treatment
• Selection of drugs should be based on:
 Clinical & microbiologic efficacy
 Acceptability of the oral preparation (taste &
texture)
 Absence of side effects and toxicity
 Convenience of dosing schedule
 Cost
First-line antimicrobial therapy
Amoxicillin
• Controversy but still recommended as drug of choice (safe,
effective, affordable, narrow spectrum)
• Doubled dose increase concentration in ME
• Then active against most intermediate strains of S.
pneumoniae (including many resistant strains)
• 80 – 90 mg/kg per day (divided in 2 doses)
• Heavier children – max of 3g/day
When is Amoxicillin contraindicated?
• High risk for AOM caused by an amoxicillin-resistant
otopathogen
– Treated with antibiotics in previous 30 days (especially
beta-lactam antibiotics)
– Concurrent purulent conjunctivitis (non-typable H.
influenzae)
– Receiving amoxicillin chemoprophylaxis for recurrent
AOM or UTI
– Allergy
Alternative 1st Choice treatment
Amoxicillin-clavulanate
• Active against beta-lactamase-producing nontypeable H. influenzae
• Also active against S. pneumoniae
• Dosing:
< 3 months: 30mg/kg/day PO divided in 2 daily doses
≥ 3 months & < 40 kg: 90mg/kg/day PO divided in 2
daily doses x 10 days
Children weighing > 40 kg – 250-500mg every 8 hours
Secondary treatment options
• Choice of alternatives depend on type of previous
hypersensitivity reaction
HISTORY OF NON-TYPE 1 REACTIONS
Cefdinir
• 14 mg/kg/day in 1 or 2 doses (limit total 600mg/day)
Cefpodoxime
• 10 mg/kg /day once daily (limit 800 mg/day)
Cefuroxime (cefuroxime axetil suspension)
• 30 mg/kg/day in 2 divided doses (limit total 1 g/day)
Cefuroxime tablets
• 250 mg every 12 hours
Treating AOM due to
Penicillin-resistant S. pneumoniae
• Oral Cephalosporins are not effective against penicillinresistant S. pneumonia
• Consider :
Ceftriaxone
• 50mg/kg in single IM dose
• If clinical signs do not improve after 48 hours, a second dose may
be given. In some cases even a third dose may be necessary.
• Be mindful of the physical discomfort and psychological distress
caused in a young child when following this approach.
Secondary treatment options
HISTORY OF TYPE 1 REACTIONS
Erythromycin plus sulfisoxazole
• 50-150 mg/kg/day in 4 divided doses
• Limit total erythromycin to 2g/day
• Often rejected due to taste and high frequency of dosing
Azithromycin
• Single dose Rx: Give 30mg/kg in one single dose x1 day
• 3-day Rx: Give 20mg/kg/day – one dose daily x3 days
• 5-day Rx: Give 10mg/kg on day 1 & 5mg/kg/day on days 2 – 5
Secondary options cont.
HISTORY OF TYPE 1 REACTIONS
Clarithromycin
• 15mg/kg/day divided in 2 doses (limit to 1g/day) OR
• 30-40mg/kg/day divided in 4 doses (limit to 1g/day)
Clindamycin
• 30-40 mg/kg/day divided in 3 – 4 doses
Treatment of AOM in children
with Tympanostomy Tubes
• For some children, topical antibiotic therapy may
be an alternative to oral therapy.
• Requirements:
– Mild to moderate illness
– No immune compromise
– Must be older than 2 years
• Options:
Quinolone otic drops (Ofloxacin / Ciprofloxacin)
• Efficacy has not been studied in children with
AOM & acute perforation
• Oral therapy is always preferred
Complications of Otitis Media
Risks for complications associated with otitis media:
• Increase if an acute episode of otitis media persists
longer than 2 weeks.
• Increase if symptoms recur within a 2-3 week period.
• Decrease with early diagnosis and effective
antibiotic treatment.
Complications of Otitis Media
Intracranial complications are uncommon in developed
counties but are a concern where access to medical care is
limited. They develop and spread:
• Through vascular channels.
• By direct extension.
• Through preformed pathways such as the round window.
Extracranial complications are direct sequelae of:
• Localized acute inflammation, or
• Chronic inflammation.
Complications of Otitis Media
• Hearing loss:
Temporary: hearing loss of 25 to 30dB for several
months due to OME; risk of impaired language
development, vestibular, balance, and motor
dysfunctions.
Permanent: damage to the tympanic membrane or
other middle ear structures, resulting in vertigo or
facial weakness.
Complications of Otitis Media
• Adhesive otitis media: abnormal healing in inflamed middle ear.
Irreversible thickening of the mucus membranes causing
impaired movement of the ossicles and possible conductive
hearing loss (e.g., tympanosclerosis).
• Chronic suppurative otitis media: chronic otorrhea through a
perforated TM; the cycle of inflammation, ulceration, infection,
and granulation tissue formation may destroy surrounding bony
margins and ultimately lead to various complications.
Complications of Otitis Media
• Postauricular abscess: the most common extracranial complication.
• Tympanic membrane perforation due to increased middle ear pressure.
• Meningitis: AOM is the most common cause of this intracranial
complication.
• Cholesteatoma: cystlike lesions of the middle ear that may erode the
ossicles, labyrinth, adjacent mastoid bone, and surrounding soft
tissues.
• Mastoiditis: inflammation as an extension of acute or chronic OM,
causing necrosis of the mastoid process and destruction of the bony
intercellular matrix.
Complications of Otitis Media
• Facial nerve paresis
• Labyrinthitis: intratemporal complication
• Labyrinthine fistula
• Temporal abscess
• Petrositis: intratemporal complication
• Intracranial abscess
• Otitic hydrocephalus
• Sigmoid sinus thrombosis or thrombophlebitis
• Encephalocele
• CSF leak
Signs of possible impending
complication:
•
Sagging of the posterior canal wall
•
Puckering of the attic or epitympanic recess
•
Swelling of the postauricular areas with loss of the skin crease
•
Persistent headache and/or fever
•
Tinnitus
•
Stiff neck
•
Visual or other neurologic symptoms
•
Severe otalgia
•
Vertigo
•
Lethargy
•
Nausea and vomiting
•
Fetid otorrhea
Signs or Symptoms of complication:
Intracranial
• Fever associated with a chronic perforation
• Lethargy
• Focal neurologic signs (e.g., ataxia, oculomotor deficits,
seizure)
• Papilledema
• Meningismus
• Altered mental status
• Severe Headaches
Signs or Symptoms of complication:
Extracranial
• Fever associated with a chronic perforation.
• Postauricular edema or erythema.
Patient Education
• Explain the natural history of acute otitis media.
• Explain the benefits of using analgesics to treat ear pain.
Do not use longer than 3 days for pain without consulting
healthcare professional.
• Explain to parents topical analgesics must not be used if
the tympanic membrane ruptures.
• Explain the use of antibiotics in the management of otitis
media and implications of antibiotic-resistant bacteria in
AOM.
Patient Education
• Provide parent with extensive information about antibiotic
overuse.
• Explain signs and symptoms of allergic reaction to antibiotics
and to report to healthcare provider immediately.
• Explain that symptoms should decrease in 24-72 hours with
the use of analgesics and/or antibiotics.
• Explain that persistent otalgia, fever, and other systemic
symptoms past 72 hours should be reevaluated by healthcare
provider.
Patient Education
• Educate regarding the signs and symptoms of clinical
deterioration.
• Educate on preventable risk factors.
• Educate parents and patients regarding the problem
of drug-resistant bacteria and the need to avoid the
use of antibiotics unless absolutely necessary.
• Explain the entire course of the prescription of
antibiotics must be completed.
Patient Education
• Measure body temperature via oral, rectal, or axillary
methods. Transtympanic measurements of
temperature in children with middle ear effusions may
be inconsistent.
• Heat packs to affected ear may help relieve
discomfort.
• Saltwater nasal spray or rinses may decrease
congestion.
• Elevating head of crib may facilitate drainage.
Patient Education
• Do not use Q-tips in ears.
• Keep follow-up appointments until the tympanic
membrane is normal. Middle ear effusion may
persist for several weeks, affecting speech and
language development.
• AOM treatment failure requires referral to
otolaryngologist.
Prevention Measures
• Identify and treat underlying conditions that predispose
the child to AOM. This includes:
1. Immune deficiencies: e.g., IgG subclass
deficiency, hypogammaglobulinemia,
granulocyte defects.
2. Anatomic abnormalities: e.g., craniofacial
abnormalities, such as micrognathia, or palatal clefts.
Prevention Measures
• Breast feed infants: breastfeeding provides for the
transfer of protective maternal antibodies to the
infant; bottle-fed infants have a higher incidence of
AOM than breast-fed infants, probably due to feeding
position during bottle-feeding, which facilitates the
reflux of milk into the middle ear.
• Reduce or eliminate pacifier use, especially after 6
months of age.
Prevention Measures
• Minimal exposure to group settings or daycare setting
with few children.
• Avoid or eliminate bottle-propping.
• Avoid feeding infants in supine position.
• Infection can spread more easily through the
eustachian canal of infants who spend most of the day
in the supine position.
• Avoid exposure to passive tobacco smoke.
Prevention Measures
• Chewing at least 3-5 sticks a day of Xylitol chewing
gum may reduce recurrence rate (if age appropriate).
Xylitol is a sugar found in fruits and the bark of birch
trees that has bacteriostatic effects against S.
pneumonia and interferes with bacterial adhesion to
mucous membranes. Side effects include excessive
gas and diarrhea.
Prevention Measures
• Annual influenza vaccine, especially in high-risk children
who attend day care.
• Early treatment of influenza with the antiviral oseltamivir
may reduce OM.
• Immunization with heptavalent pneumococcal conjugate
vaccine (PCV7 or Prevnar) may reduce the incidence of
AOM caused by S. pneumoniae.
• Consider tympanostomy tube placement for prevention of
recurrent AOM.
References
• American Academy of Pediatrics and American Academy
of Family Physicians (2004). Diagnosis and management of
acute otitis media. Clinical practice guideline. Retrieved
from
http://aappolicy.aappublications.org/cgi/reprint/pediatrics
;113/5/1451.pdf
• Burns, C.E., Dunn, A.M., Brady, M.A., Starr, N.B. &
Blosser, C.G. (2009). Pediatric primary care . (4th ed.). St.
Louis, MO: Saunders/Elsevier
References
• Donaldson, J. (2010). Middle ear, acute otitis media,
medical treatment. Retrieved from
http://emedicine.medscape.com/article/859316-overview
• Eaton, D. (2009). Complications of otitis
media.
Retrieved from
http://emedicine.medscape.com/article/859316-overview
• Greydanus, D., Feinberg, A., Patel, D., & Homnick, D.
(2008). The pediatric diagnostic examination. NY:
McGraw-Hill.
References
• Klein, J. & Pelton, S. (2011). Acute otitis media in children:
Treatment. Retrieved from http://0-
www.uptodate.com.topekalibraries.info/contents/acuteotitis-media-in-childrentreatment?source=search_result&selectedTitle=1%7E150
• Klein, J. & Pelton, S. (2011). Acute otitis media in children:
Prevention of recurrence. Retrieved from http://0www.uptodate.com.topekalibraries.info/contents/acuteotitis-media-in-children-prevention-ofrecurrence?source=search_result&selectedTitle=1%7E150
References
• Leskinen, K. (2005). Complications of acute otitis
media in children. Current Allergy and Asthma
Reports, 4, 308-312. Retrieved from
http://www.ncbi.nlm.nih.gov/pubmed/15967073
• Porth, C. & Matfin, G. (2009). Pathophysiology:
Concepts of altered health states. (8th ed.).
Philadelphia, PA: Lippincott Williams & Wilkins.