oto disorders of the middle ear Flashcards
What antibiotic is considered first-line therapy for
an otherwise healthy child with acute otitis media?
Amoxicillin, 90 mg/kg daily, divided into two doses each day
for 10 days
What predisposing factors may put young children
at risk for recurrent otitis media?
● Second-hand smoke exposure, group day care, nasal
allergy, immunodeficiency, craniofacial abnormalities, adenoid hypertrophy, gastroesophageal reflux, vaccina-
tion status, supine bottle feeding, and pacifier use
● Breastfeeding in the first 6 months of life is likely
protective against recurrent acute otitis media.
What factors impact a child’s candidacy for
surgery to treat otitis media with effusion?
Hearing status, associated symptoms, duration of effusion
(> 4 months), structural damage to the TM or middle ear,
developmental delays or risk factors for delay (syndromic
children, autism-spectrum disorders, uncorrectable visual
impairment, etc.), craniofacial abnormalities/cleft palate
What condition must be excluded in all adult
patients with a unilateral persistent middle ear
effusion?
● Nasopharyngeal carcinoma should be ruled out by
nasopharyngoscopy.
● Examination of the oropharynx, hypopharynx, and larynx
should also be performed if otalgia is present.
Define atticotomy, and describe the typical indi-
cations of this approach in the context of chronic ear disease.
Atticotomy involves removal of a portion of the scutum
(lateral epitympanic wall) to visualize and access the
epitympanum. This technique is often used in patients with
limited cholesteatoma or retraction pockets and small
contracted mastoids and can be performed in conjuction
with tympanoplasty and ossicular chain reconstruction.
Define congenital cholesteatoma.
Caused by a persistent embryonic rest of epithelial tissue within the middle ear space. Patients should have a normal-
appearing pars tensa and pars flaccida, no history of prior otorrhea, and no prior otologic surgery.
Differentiate primary acquired and secondary ac-
quired cholesteatoma.
Primary acquired cholesteatoma arises from a tympanic
membrane retraction pocket most commonly involving the
pars flaccida; secondary acquired cholesteatoma results
from an injury to the tympanic membrane (e.g., tympa-
nostomy tube, surgery, accidental trauma) with implanta-
tion of skin into the middle ear space.
Describe the invagination theory of primary
acquired cholesteatoma formation.
Infantile sterile otitis media develops shortly after birth.
Before resportion occurs, mucosal fibrosis occurs, resulting
in blocakage of the epitymanum and localized negative
pressure. This results in poor pneumatization of the
mastoid and retraction of the pars flaccida.
Describe the metaplasia theory of acquired cholesteatoma formation.
Columnar epithelium of the middle ear space undergoes squamous metaplasia, resulting from inflammation associated with recurrent otitis media.
Describe the proposed mechanisms of bony
erosion by cholesteatoma.
● Pressure erosion: Caused by mechanical pressure from
the growing cholesteatoma sac
● Biochemical erosion: Bacterial products, inflammation
from granulation tissue, and enzyme products of the
cholesteatoma itself
● Cellular-mediated erosion: Osteoclastic activity
Define Prussak space.
Prussak space is a recess, bordered laterally by the pars
flaccida, superiorly by the scutum and lateral malleolar
ligament, inferiorly by the short process of the malleus, and
medially by the neck of the malleus.
Describe the three most common sites of origin
for cholesteatoma.
Posterior and anterior epitympanum and the posterosupe-
rior mesotympanum
Describe the anatomical limits of the sinus
tympani.
Ponticulus superiorly, subiculum inferiorly, the mastoid
segment of the facial nerve laterally, and the posterior
semicircular canal medially
What is the most common site of labyrinthine
fistula formation secondary to chronic ear disease?
The horizontal semicircular canal
Describe the signs and symptoms of labyrinthine
fistula secondary to chronic otitis media.
Labyrinthine fistula most commonly involves the lateral
semicircular canal. Classically, patients show mixed hearing
loss, intermittent dizziness, and potentially sound-induced
vertigo (Tullio phenomenon), although in practice a large
number of patients may lack such findings.
Describe the likely mechanism of dizziness asso-
ciated pneumatic otoscopy in a patient with cholesteatoma.
Cholesteatoma eroding into the bony labyrinth has most likely led to an inner ear fistula. With the labyrinth exposed, increased middle ear pressure can be translated to perilymphatic fluid movement and subsequent vertigo.
How should a lateral semicircular canal fistula
associated with chronic ear disease be managed?
In an “only hearing ear” or “better hearing ear,” a canal wall–down procedure is often recommended, with exteriorization of the matrix overlying the erosion. If the other ear has good hearing, same-surgery repair with fascia or a
second-look procedure with matrix removal may be considered if an intact canal wall is desired. Large or
complex fistulae have a high risk of SNHL and are generally best managed with a canal wall–down procedure.
What is the difference between a radical and
modified radical mastoidectomy?
With a radical mastoidectomy, there is complete removal of
the malleus, incus, tympanic membrane, and middle ear
mucosa, and the cavity is left open.
With a modified radical mastoidectomy, the middle ear space
is reconstructed.
A Bondy modified radical mastoidectomy implies a canal wall–
down procedure where the middle ear space is not entered
or reconstructed.
Describe the Wullstein classification system for tympanoplasty.
● Type 1: All ossicles are present and mobile.
● Type 2: The tympanic membrane is grafted to an intact
incus and stapes.
● Type 3: The tympanic membrane is grafted to the stapes
superstructure.
● Type 4: The tympanic membrane is grafted to the stapes
footplate.
● Type 5: Semicircular canal fenestration procedure
What are common indications for canal wall–down mastoidectomy?
Advanced cholesteatoma with significant canal wall erosion,
labyrinthine fistula, cholesteatoma in an only hearing ear
What are the most common causes of persistent
otorrhea after a canal wall–down mastoidectomy?
Inadquate meatoplasty, failure to lower the facial ridge,
mucosalization, exposed eustachian tube
Describe the histologic appearance of cholestea-
toma.
A sac of keratinizing squamous epithelium with a central
core of keratinaceous debris
In a healthy patient with cholesteatoma and no
history of other otologic procedures, what are the
primary indications for surgery?
There is no effective medical therapy for cholesteatoma;
surgical removal and exteriorization are the only effective
treatments. The primary goal of surgery is to create a safe
and dry ear. Surgery is almost universally recommended for
healthy patients.
What are the advantages and disadvantages of
lateral graft tympanoplasty?
The choice to use a lateral graft technique is based largely
on the surgeon’s preference. It is commonly used for total,
near-total or anterior perforations. The main disadvantages
are technical difficulty and the possibility of blunting (loss
of the acute anterior canal angle) and lateralization
(separation of the graft from the malleus).
Why is the temporomandibular joint potentially at
risk for injury during lateral graft tympanoplasty?
Classically, lateral graft tympanoplasty involves temporary
removal of the anterior canal wall skin with canalplasty,
removing the bony overhang such that the entire drum can
be seen through the canal. Overly aggressive drilling risks
entry into the glenoid fossa.
Describe the mechanism of hearing loss in a
patient with a tympanic membrane perforation.
There is a decrease in the ratio of the tympanic membrane
to stapes footplate surface area (transformer ratio). In addition, sound striking the oval window and round window simultaneously (through the perforation) may result in phase cancellation.
What is the rate of persistent tympanic membrane
perforation after tympanostomy tube placement?
Approximately 2 to 5%
Describe the advantage of cartilage grafts when used in repair of tympanic membrane perfora-
tions.
Cartilage is more rigid than other graft materials, making it
more resistant to retraction and resorption. Long-term studies have demonstrated hearing results to be similar to
those obtained with fascia.
