1. CONGENITAL AURAL ATRESIA
Dennis R. Maceri, M.D., F.A.C.S.
Associate Professor
Otolaryngology- Head and Neck Surgery
Keck School of Medicine

2. “ The better developed the auricle the better the middle ear” Kountakis, 1995

3. 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

4. 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

5. 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

6. Embryology
8 Week Stage

7. Embryology
8 Week Stage

8. 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

9. 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

10. 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

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

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

13. 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

14. 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

15. Atresia Embryology – 7th Month Canalization complete
Mastoid separation from mandible
Normal posterior-inferior growth
No mastoid growth
Normal
Atresia

16. Atresia Embryology Mastoid growth affects the facial nerve position
Normal 120o Curve
Acute Curve in Atresia

17. Atresia

18. 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

19. Atresia
Classification-Severe Aplasia, no tympanic bone

20. Atresia
Complete Atresia

21. Atresia
Complete Atresia

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

23. Atresia Minor Aplasia-partial recanalization
Middle space constricted, often with severe ossicular abnormalities

24. 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

25. 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

26. Grading System Based on high resolution CT scan
Variable
Points
Stapes Present 2
Oval Window Open 1
Facial Nerve
Middle Ear Space
Mastoid Pneumatization
Malleus/Incus Complex
Incudostapedial Joint
Round Window
External Ear Appearance
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

27. Grade of Microtia as an Indicator of ME Development
Atresia
Grade of Microtia as an Indicator of ME Development
Microtia Grade Radiological Score I II
III
Kountakis Arch Otolaryngol 1995

28. Radiological Evaluation
Good middle ear and mastoid aeration
Prominent ossicular mass with incus and malleus fused
Open oval window
Score of 8

29. 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

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

31. Microtia

32. Microtia Repair

33. 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)

34. 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

35. 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

36. 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

37. Canal Cholesteatoma Usually in ears with minor aplasia
Canal <4mm, 50% incidence

38. Surgical Technique
Minor aplasia- canal widening and middle ear ossicular work with tympanoplasty
Moderate Aplasia
Mastoid or posterior approach
Anterior approach

39. Surgical Technique Anterior Approach
Middle ear approached through the atretic bone with a limited mastoid opening

40. 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

41. 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 ( inches) lines the canal

42. Surgical Technique
The Meatoplasty must be aligned with the newly created bony canal

43. 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

44. 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 2 years
Schuknect similar results at 1.3 years
De La Cruz 56 patients 20 dB at 6 mo.
Lambert early dB, 46% >1 yr.

45. Alternatives to Surgery
Bone anchored hearing aid (BAHA)

46. BAHA
Hearing results better than with BC aids

47. 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

48. 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