Acute Otitis Media
Dr. T. Balasubramanian M.S. D.L.O.
suppurative otitis media is defined as suppurative infection involving
the mucosa of the middle ear cleft. By convention it is termed acute if
the infection is less than 3 weeks in duration.
Pathophysiology: Obstruction to the eustachean
tube seem to be the most important antecendent event in the
pathophysiology of acute suppurative otitis media. Majority of acute
suppurative otitis media is triggered by upper respiratory infections
which might find its way into the middle ear cavity through the
eustachean tube orifice. Infections involving the nasopharynx may find
its way into the middle ear through the pharyngeal end of eustachean
tube. The infection is initially commonly viral in origin, allergy
could also play an important role in the pathogenesis. Later the middle
ear mucosa becomes secondarily infected by pathogenic bacteria. The
bacteria commonly implicated in this disorder is S Pneumoniae, H.
Influenza, and M Catarrhalis.
The majority of otitis media prone children have
a patulous eustachean tube or an hypotonic eustachean tube. Children
with neuromuscular disorders or with abnormalities of the first or
second arch have a patulous eustachean tube leading on to this problem.
To become pathogenic the bacteria must become adherent to the mucosa
lining the middle ear cavity, this is made possible by prior infection
of the middle ear mucosa by viruses.
Flask model explaining the role of eustachean
tube in middle ear infections:
The eustachean tube, middle ear, and mastoid air
cell system can be likened to a flask with a long narrow neck. The
mouth of the flask represents the nasopharyngeal end, the narrow neck,
the isthumus of the eustachean tube, and the bulbous portion, the
middle ear and mastoid air chamber. The fluid flow through the neck of
the flask would be dependent on the pressure at either end, the radius
and length of the neck, and the viscosity of the liquid. When a small
amount of liquid is instilled into the mouth of the flask, liquid flow
stops somewhere in the narrow neck owing to capillarity within the neck
and the relative positive air pressure that develops in the chamber of
Fig explaining the flask model of normal eustachean tube function
The basic geometry is considered to be critical for
the protective function of the eustachean tube - middle ear system.
Reflux of liquid into the body of the flask occurs if the neck of the
flask is excessively wide, or the length of the neck of the flask is
too short as seen in children. Because infants have a shorter
eustachean tube than adults, reflux is more likely to occur in the
baby. The position of the flask in relation to the liquid is another
important factor. In humans, the supine position enhances flow of
liquid into the middle ear; thus infants might be at risk for
developing reflux otitis media because they are commonly supine. Reflux
of liquid into the vessel can also occur if a hole is made in the
bulbous portion of the flask, because this prevents the creation of
positive pressure in the bulbous portion. This positive pressure is
useful in the prevention of reflux of material from the neck of the
Fig showing the differences between eustachean tubes of adult and a
Fig showing various pathophysiological factors involved in middle ear
If negative pressure is applied to the
bulbous portion of the flask then this pressure is sufficient to cause
aspiration of contents from the neck of the flask. This scenario is
represented by high negative pressure in middle ear as it occurs in
nose blowing, crying, closed nose swallowing, diving or airplane
descent. The neck of the eustachean tube is supposed to be compliant
hence compliance plays a vital role in prevention of reflux of
Acute suppurative otitis media passes through 4 stages: 1. Stage of
2. Stage of exudation
3. Stage of suppuration
4. Stage of resolution.
The progression of these stages depend on the virulence of the
infecting organisms, resistance of the host, adequacy of antibiotic
therapy. If the infecting organism is virulent or if the antibiotic
treatment is not sufficient then the disease may progress to a stage of
coalescent mastoiditis with its attendant complications.
Stage of hyperemia: Initial infection by infection results in hyperemia
of the mucous membrane causing otalgia, fever and fullness in the
affected ear. This stage is characterised by oedema of the
mucoperiosteum due to vascular engorgement. Otoscopy show dilated
vessels along the handle of malleus and along the rim of the tympanic
membrane. Antibiotic therapy during this stage will help in resolution
of the disease. Amoxycillin is the drug of choice.
Stage of exudation: Absence of treatment during the stage of hyperemia
leads to the stage of exudation. In this stage there is outpouring of
fluid from the dialted vessels of the mucoperiosteum. This fluid is
serous in nature containing fibrin, red cells, and polymorphs. This
exudate fills the tympanomastoid compartment really fast, and the whole
middle ear cavity is under intense pressure due to this retained
secretion. Pain is the most prominent feature of this stage. The
patients may have fever and fullness in the ear. Otoscopy shows a
bulging ear drum with loss of all landmarks. The drum is reddish and
bulging in nature. These patients have also coexistant mastoid
tenderness due to mastoiditis.
Stage of suppuration: Failure of treatment during the stage of
exudation leads on to stage of suppuration. The exudate present in the
middle ear cavity is a very good culture medium and hence there is
secondary bacrterial infection leading on to suppuration.
Stage of resolution: is preceded by either rupture of the ear drum
leading on to a serous / serosanguinous / purulent disharge from the
ear. When the middle ear is free from the exudate / pus the stage of
resolution sets in. The patient has reduction in otalgia, fever
subsides. The patient has considerable clinical improvement.
Stage of complication: If the infection persists beyond a period of 2
weeks then there is associated thickening of the mucoperiosteum
especially in the air cells around the peri antral area leading to a
block in the drainage from the antral cells. The pent up secretions in
the mastoid air cell system causes intense pressure, venous stasis and
local acidosis. This acidosis cause dissolution of calcium from the
bone causing decalcification and coalescence of the mastoid air cell
system. This condition is known as coalescent mastoiditis. This stage
is characteristed by emergence of otalgia and low grade fever. Erosion
of the outer cortex in the mastoid lead to the formation of abscess
under the periosteum of the mastoid cortex. This condition is known as
Ear drum in acute otitis media
Acute suppurative otitis media is a self limiting condition. If
appropriate antibiotics is started early then it resolves. Amoxycillin
is the drug of choice. Cephalosporins may also be started in refractive
cases. Anti inflammatory drugs like ibuprofen is also prescribed in
order to alleviate pain. Patients who are refractory to medical
management may under go myringotomy in order to decompress the middle
ear cavity. This procedure is done using a myringotome.
Coalescent otitis media and subperiosteal abscess are surgical
complications. These patients must be taken up for surgery under
adequate antibiotic cover.
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