CONGENITAL AURAL ATRESIA

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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

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The better developed the auricle the better the
middle earKountakis, 1995
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Atresia

• Epidemiology
• 1 in 10,000 to 15,000 births
• Up to 50 of the time associated with some
  craniofacial syndrome
• Unilateral Bilateral, about 31
• 30 are bilateral
• Atresia Microtia, 71
• Slightly more common on the right
• Male Female, 21

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Atresia

• Aural atresia associated with 22/71 known
  craniofacial syndromes
• Treacher Collins (Mandibulofacial Dysostosis)
• Nager Syndrome (Acrofacial Dysostosis)
• Cruzouns Craniofacial Dysostosis
• Goldenhars Syndrome
• Hemifacial Microsomia

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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

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Embryology

• 8 Week Stage

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Embryology

• 8 Week Stage

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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

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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

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Embryology

• First Branchial Arch-(Meckels)
• 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

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Embryology

• External ear (ectoderm) is derived from the 1st
  branchial cleft. A solid core of epithelium
  migrates inward toward the 1st branchial pouch
  (endoderm)

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Embryology

• Solid core of tissue migrates inward
• External canal re-canalizes by the 6th month

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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

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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

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Atresia

• Embryology 7th Month
• Canalization complete
• Mastoid separation from mandible

Normal posterior-inferior growth
No mastoid growth
Normal
Atresia
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Atresia

• Embryology
• Mastoid growth affects the facial nerve position

Normal 120o Curve
Acute Curve in Atresia
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Atresia
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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

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Atresia

• Classification-Severe Aplasia, no tympanic bone

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Atresia

• Complete Atresia

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Atresia

• Complete Atresia

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Atresia

• Moderate Aplasia
• The most common, solid mass of compact bone that
  has failed to recanalize

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Atresia

• Minor Aplasia-partial recanalization
• Middle space constricted, often with severe
  ossicular abnormalities

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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

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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

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Grading System
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 10

• 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

Kountakis, Helidonis and Jahrsdoerfer Arch. Oto
1995
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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
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Radiological Evaluation

• Good middle ear and mastoid aeration
• Prominent ossicular mass with incus and malleus
  fused
• Open oval window
• Score of 8

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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

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Radiological Evaluation

• Poor middle ear and mastoid development
• No definable ossicular mass
• Closed oval window
• Not a good candidate
• A score of 3

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Microtia
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Microtia Repair
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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)

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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

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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

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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

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Canal Cholesteatoma

• Usually in ears with minor aplasia
• Canal lt4mm, 50 incidence

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Surgical Technique

• Minor aplasia- canal widening and middle ear
  ossicular work with tympanoplasty
• Moderate Aplasia
• Mastoid or posterior approach
• Anterior approach

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Surgical Technique

• Anterior Approach
• Middle ear approached through the atretic bone
  with a limited mastoid opening

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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

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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

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Surgical Technique

• The Meatoplasty must be aligned with the newly
  created bony canal

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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

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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 _at_ 2 years
• Schuknect similar results at 1.3 years
• De La Cruz 56 patients 53 _at_ 20 dB at 6 mo.
• Lambert early 60 _at_25 dB, 46 gt1 yr.

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Alternatives to Surgery

• Bone anchored hearing aid (BAHA)

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BAHA

• Hearing results better than with BC aids

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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

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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