CONGENITAL AURAL ATRESIA Dennis R Maceri M D

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 n 1 in 10, 000 to 15, 000 births n Up to 50% of the time associated with some craniofacial syndrome n Unilateral : Bilateral, about 3: 1 n 30% are bilateral n Atresia : Microtia, 7: 1 n Slightly more common on the right n 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 n First attempt to surgically correct aural atresia was by Thomson in 1843 n Shambaugh, 1967, recommended unilateral surgery only if the cochlear reserve allowed hearing to improve by 25 d. B n Jahrsdoerfer, 1978, first large series using the anterior approach

Embryology 8 Week Stage

Embryology 8 Week Stage

Embryology n The external ear forms earlier than the middle ear n Microtia and Atresia imply an arrest in development at any stage n The earlier the arrest, the less developed the middle ear

Embryology n Inner ear and labyrinth develop at 3 weeks from an invagination of ectoderm called the ottic placode n Middle ear space, mastoid, eustachian tube and part of the drum develop from the first pharyngeal pouch at 30 weeks n Mastoid air cells continue to develop up to age 5

Embryology n First Branchial Arch-(Meckel’s) – Malleus head, body, tensor tympani (V 3) – Short process of the Incus n Second Arch (Hyoid) (Reicherts) – – – n Manubrium of the malleus Stapes superstructure VIIth nerve Foot plate from the otic capsule and 2 nd arch

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

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

Embryology n The external canal starts to hollow out (recanalize) during the 6 th month and progresses from medial to lateral n Arrest of recanalization process leads to the various deformities seen in atresia n Formed tympanic membrane and bony canal with a stenotic membranous canal leads to canal cholesteatoma

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

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

Atresia

Classification of Deformities After Colman-3 types n Minor Aplasia-incomplete recanalization n Moderate Aplasia- the tympanic bone has developed but has failed to recanalize n Severe Aplasia-complete absence of the external canal

Atresia Classification-Severe Aplasia, no tympanic bone

Atresia Complete Atresia

Atresia Complete Atresia

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

Atresia Minor Aplasia-partial recanalization n 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 n High resolution CT in coronal and axial planes n Axial to delineate malleus, incus and I-S joint and round window n Coronal to delineate stapes, oval window and vestibule n 3 -D CT of little help n Timing indicated by timing of surgery

Grading System Based on high resolution CT scan n A score of 5 or less denotes a poor candidate n Microtia indicates an arrest in development and abnormalities of the middle ear n 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 Kountakis, Helidonis and Jahrsdoerfer Arch. Oto 1995

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 n Prominent ossicular mass with incus and malleus fused n Open oval window n Score of 8 n

Radiological Evaluation n 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 n n 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 n n n 50 -60 d. B 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 n Most consider repair in bilateral atresia n 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 d. B speech-hearing level

Surgical Considerations n Most surgeons choose the anterior approach to avoid the mastoid cavity n 40% of patients with unilateral atresia are not surgical candidates such as those with severe aplasia as in Treacher Collins syndrome n Bilateral atresia- best ear by CT done as child approaches school age

Surgical Considerations Timing of surgery n Usually performed after age 6 or 7 years n This allows for microtia repair to be done first (If Medpor used, canalplasty done first) n Canal cholesteatoma in the stenotic ear usually develops in canals less than 2 mm in diameter. If ear unfavorable, canalplasty alone is offered

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

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

Surgical Technique Anterior Approach n 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 n The epitympanum is the first part of the middle ear encountered n Fused ossicles identified n

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

Surgical Technique n 4 cm X 6 cm split thickness skin graft n The graft is positioned in the canal and sewn to the meatal margin n Graft stabilized with Merocel wicks and hydrated with ear drops

Hearing Results n Post-op hearing level of 30 d. B or better In 50 -75% of patients with moderate or severe aplasia n 20 d. B or better in 15 -20% – Bellucci 20 d. B in 50% @ 2 years – Schuknect similar results at 1. 3 years – De La Cruz 56 patients 53% @ 20 d. B at 6 mo. – Lambert early 60% @25 d. B, 46% >1 yr.

Alternatives to Surgery n Bone anchored hearing aid (BAHA)

BAHA Hearing results better than with BC aids

Surgical Complications n Persistent or recurrent conductive hearing loss – Lateralization of graft – Scar tissue SNHL n VIIth Nerve injury n 30 % revision rate n – Re-stenosis – Graft migration – Inadequate hearing n Chronic cavity infection

Summary n Choose your patients carefully n Realize your potential v. patient expectations n Appropriate radiographic studies n Accurate audiological analysis n Facial nerve monitoring n Know when NOT to operate