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CONGENITAL AURAL
ATRESIA
Dennis R. Maceri, M.D., F.A.C.S.
Associate Professor
Otolaryngology- Head and Neck Surgery
Keck School of Medicine
“ The better developed the
auricle the better the middle
ear”
Kountakis, 1995
Atresia
Epidemiology
 1 in 10,000 to 15,000 births
 Up to 50% of the time associated with some
craniofacial syndrome
 Unilateral : Bilateral, about 3:1
 30% are bilateral
 Atresia : Microtia, 7:1
 Slightly more common on the right
 Male : Female, 2:1
Atresia
Aural atresia associated with 22/71 known
craniofacial syndromes
– Treacher Collins (Mandibulofacial Dysostosis)
– Nager Syndrome (Acrofacial Dysostosis)
– Cruzoun’s Craniofacial Dysostosis
– Goldenhar’s Syndrome
– Hemifacial Microsomia
Aresia Surgery
First attempt to surgically correct aural
atresia was by Thomson in 1843
 Shambaugh, 1967, recommended
unilateral surgery only if the cochlear
reserve allowed hearing to improve by
25dB
 Jahrsdoerfer, 1978, first large series using
the anterior approach

Embryology
8 Week Stage
Embryology
8 Week Stage
Embryology
The external ear forms earlier than the
middle ear
 Microtia and Atresia imply an arrest in
development at any stage
 The earlier the arrest, the less developed
the middle ear

Embryology
Inner ear and labyrinth develop at 3
weeks from an invagination of ectoderm
called the ottic placode
 Middle ear space, mastoid, eustachian
tube and part of the drum develop from
the first pharyngeal pouch at 30 weeks
 Mastoid air cells continue to develop up to
age 5

Embryology

First Branchial Arch-(Meckel’s)
– Malleus head, body, tensor tympani (V3)
– Short process of the Incus

Second Arch (Hyoid) (Reicherts)
– Manubrium of the malleus
– Stapes superstructure
– VIIth nerve

Foot plate from the otic capsule and 2nd
arch
Embryology

External ear (ectoderm) is derived from the 1st
branchial cleft. A solid core of epithelium
migrates inward toward the 1st branchial pouch
(endoderm)
Embryology
Solid core of
tissue migrates
inward
External canal
re-canalizes by
the 6th month
Embryology
The external canal starts to hollow out
(recanalize) during the 6th month and
progresses from medial to lateral
 Arrest of recanalization process leads to
the various deformities seen in atresia
 Formed tympanic membrane and bony
canal with a stenotic membranous canal
leads to canal cholesteatoma

Embryology

Arrested growth of the ossicles leaves
them in various stages of formation
– Stapes often malformed but mobile
– The incus and malleus are fused
– Altered course of facial nerve
Atresia
Embryology – 7th Month
 Canalization complete
 Mastoid separation from mandible
Normal
posterior-inferior
growth
Normal
No mastoid
growth
Atresia
Atresia
Embryology
 Mastoid growth affects the facial nerve
position
Normal 120o
Curve
Acute Curve in
Atresia
Atresia
Classification of Deformities
After Colman-3 types
 Minor Aplasia-incomplete recanalization

Moderate Aplasia- the tympanic bone has
developed but has failed to recanalize

Severe Aplasia-complete absence of the
external canal
Atresia
Classification-Severe Aplasia, no tympanic
bone
Atresia
Complete Atresia
Atresia
Complete Atresia
Atresia
Moderate Aplasia
 The most common, solid mass of compact
bone that has failed to recanalize
Atresia
Minor Aplasia-partial recanalization
 Middle space constricted, often with severe
ossicular abnormalities
Microtia
Types of Microtia (Based on Marx 1926)
Class I Mild deformity, auricle smaller, all
parts of ear identifiable
Class II ½ to 2/3 normal size with partially
retained structures
Class III Severely malformed, peanut
shaped
Radiological Evaluation
High resolution CT in coronal and axial
planes
 Axial to delineate malleus, incus and I-S
joint and round window
 Coronal to delineate stapes, oval window
and vestibule
 3-D CT of little help
 Timing indicated by timing of surgery

Grading System
Based on high
resolution CT scan
 A score of 5 or less
denotes a poor
candidate
 Microtia indicates an
arrest in development
and abnormalities of
the middle ear

Variable
Points
Stapes Present
2
Oval Window Open
1
Facial Nerve
1
Middle Ear Space
1
Mastoid Pneumatization
1
Malleus/Incus Complex
1
Incudostapedial Joint
1
Round Window
1
External Ear Appearance
1
Total Points
Kountakis, Helidonis and Jahrsdoerfer Arch. Oto 1995
10
Atresia
Grade of Microtia as an Indicator of ME
Development
Microtia Grade
Radiological Score
I
8.5
II
7.2
III
5.9
Kountakis Arch Otolaryngol 1995
Radiological Evaluation




Good middle ear
and mastoid
aeration
Prominent
ossicular mass
with incus and
malleus fused
Open oval
window
Score of 8
Radiological Evaluation

Score of 8
2-stapes & OW
2-I-S joint, Incus
1-Aerated ME space
1-Bony cover on VII
1-Aerated mastoid
1-Pinna
Radiological Evaluation





Poor middle ear and
mastoid development
No definable ossicular
mass
Closed oval window
Not a good candidate
A score of 3
Microtia
Microtia Repair
Audiological Evaluation






50-60 dB conductive loss
Usually normal sensorineural function
Unilateral- behavioral audiometry
ABR for infants
Bilateral atresia presents a masking dilemma
Bone conduction ABR can help resolve the
masking problem (Wave I on stimulated ear)
Surgical Considerations
Most consider repair in bilateral atresia
 Many are reluctant to operate on unilateral
cases

– Not simply the hearing loss
– Expectations of hearing recovery
– Lifetime care of mastoid cavity
– Potential risks to facial nerve and labyrinth
– 55-65% achieve 25 dB speech-hearing level
Surgical Considerations
Most surgeons choose the anterior
approach to avoid the mastoid cavity
 40% of patients with unilateral atresia are
not surgical candidates such as those with
severe aplasia as in Treacher Collins
syndrome
 Bilateral atresia- best ear by CT done as
child approaches school age

Surgical Considerations
Timing of surgery
 Usually performed after age 6 or 7 years
 This allows for microtia repair to be done
first (If Medpor used,canalplasty done
first)
 Canal cholesteatoma in the stenotic ear
usually develops in canals less than 2mm
in diameter. If ear unfavorable, canalplasty
alone is offered
Canal Cholesteatoma
Usually in ears with minor aplasia
 Canal <4mm, 50% incidence

Surgical Technique
Minor aplasia- canal widening and middle
ear ossicular work with tympanoplasty
 Moderate Aplasia

– Mastoid or posterior approach
– Anterior approach
Surgical Technique
Anterior Approach
 Middle ear approached through the atretic
bone with a limited mastoid opening
Surgical Technique
The posterior wall of the
glenoid fossa becomes
the anterior wall of the
new ear canal
 The epitympanum is the
first part of the middle
ear encountered
 Fused ossicles identified

Surgical Technique







Atretic bone removed at times with a curette
Globular mass separated from the stapes to
avoid cochlear trauma
Course of facial nerve determined
Ossiculoplasty performed
Tympanic membrane grafted
Meatoplasty
Split thickness skin graft (.008-.010 inches)
lines the canal
Surgical Technique

The Meatoplasty must be aligned with the
newly created bony canal
Surgical Technique
4cm X 6cm split
thickness skin graft
 The graft is positioned
in the canal and sewn
to the meatal margin
 Graft stabilized with
Merocel wicks and
hydrated with ear
drops

Hearing Results
Post-op hearing level of 30 dB or better In
50-75% of patients with moderate or
severe aplasia
 20 dB or better in 15-20%

– Bellucci 20 dB in 50% @ 2 years
– Schuknect similar results at 1.3 years
– De La Cruz 56 patients 53% @ 20 dB at 6 mo.
– Lambert early 60% @25 dB, 46% >1 yr.
Alternatives to Surgery

Bone anchored hearing aid (BAHA)
BAHA
Hearing results better than with BC aids
Surgical Complications

Persistent or recurrent conductive hearing loss
– Lateralization of graft
– Scar tissue
SNHL
 VIIth Nerve injury
 30 % revision rate

– Re-stenosis
– Graft migration
– Inadequate hearing

Chronic cavity infection
Summary
Choose your patients carefully
 Realize your potential v. patient
expectations
 Appropriate radiographic studies
 Accurate audiological analysis
 Facial nerve monitoring
 Know when NOT to operate
