Key Points
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Preservation of hearing and the seventh cranial nerve must always take precedence over the desire to correct conductive hearing loss in congenital aural atresia and congenital external auditory canal stenosis.
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The vast majority of patients with congenital aural atresia have maximal (60 dB) conductive hearing loss and normal sensorineural hearing. Behavioral testing, otoacoustic emissions, and auditory brainstem response testing may be needed to determine hearing thresholds.
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Microtia/congenital aural atresia often occur in conjunction with ocular, cervical, cardiac, renal, and other inherited anomalies that must be evaluated and treated if present.
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Hearing rehabilitation is more important for patients with bilateral congenital aural atresia compared with those with unilateral cases that have milder deficits.
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Grading systems including the Jahrsdoerfer and modified Jahrsdoerfer systems for grading computed tomography scans of the temporal bone help determine which patients are possible candidates for atresiaplasty surgery to correct conductive hearing loss.
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For patients who are not surgical candidates for atresiaplasty or for those who decline atresiaplasty, nonsurgical options include no treatment, traditional bone-conduction metal headband hearing aids, newer soft headband hearing aids, and, if an auricle is present, standard hearing aids. Patients over 18 years old can also use the SoundBite dental hearing device.
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For patients who are not surgical candidates for atresiaplasty or for those who decline atresiaplasty, surgical implant options for hearing include the bone-anchored hearing aid (BAHA) and Ponto open-skin implants, and Sophono and Vibrant Soundbridge closed-skin implants.
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The timing and type of surgery for hearing should be coordinated with a microtia surgeon to develop an overall plan for each individual patient taking into consideration all hearing and cosmetic issues and options.
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Some surgeons advocate early microtia and congenital aural atresia reconstruction, whereas others argue for the patient to decide when older.
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Families should be educated about the options for microtia reconstruction, including no surgery, glue-on prosthetic ears, prosthetic ears that clip on to bone anchors, rib cartilage graft auricle reconstruction, and Medpor prosthetic implants.
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Some surgeons combine stages of microtia and atresiaplasty surgery.
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Atresiaplasty may be successful with canal-wall-up or canal-wall-down techniques.
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Careful patient selection and advanced training and skills are required for safe and successful atresiaplasty surgery.
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BAHA surgery is performed in a single stage in patients with thick skulls (≥3 mm) and in two stages in patients with thin skulls (≤2.5 mm).
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Complications of atresiaplasty surgery include external auditory canal stenosis, infections, lateralization of the tympanic membrane, conductive hearing loss, and, rarely, facial nerve injury and sensorineural hearing loss.
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Complications of open-skin BAHAs include site infections, scalp thickening requiring revision surgery, and loss of the implant.
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Congenital external auditory canal stenosis is a milder form of congenital ear anomaly that must be followed closely with computed tomography, even if no surgery was initially planned, to watch for development of canal cholesteatoma, which will require surgery.
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Several types of implantable hearing aids are now available for hearing rehabilitation of ear canal atresia in patients more than 5 years of age: bone-conduction devices clipped on a percutaneous abutment (BAHA, Ponto), closed-skin bone-conduction devices (Sophono Alpha), and the active middle ear implant Vibrant Soundbridge.
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The choice of device depends on the child’s age, the thickness of the cortical bone, the severity of the middle ear malformation, the surgeon’s experience, and finally the choice of the patient.
Management of microtia and congenital aural atresia (CAA) is a challenging yet rewarding process in reconstructive surgery and otology. For CAA, the challenge arises from the altered anatomy and the absence of the standard anatomic landmarks. Preservation of hearing and the seventh cranial nerve must always take precedence over the desire to correct conductive hearing loss. High-resolution computed tomography (CT) and seventh nerve monitoring increase the safety of CAA reconstruction. Even today, new and important pearls contributed by committed surgeons around the world continue to enrich the armamentarium of knowledge and experience of congenital ear surgeons.
Demographics and Associated Deformities
The incidence of microtia/CAA is 0.83 to 17.4 in 10,000. In a report by Brent on 1200 patients with microtia, 58% of cases were right sided, 32% left sided, and 9% bilateral ( Fig. 15-1 ). Sixty-three percent were male and 37% female. Associated deformities included facial asymmetry (36.5%), seventh nerve weakness (15.2%), cleft lip or palate or both (4.3%), urogenital defects (4%), cardiovascular malformations (2.5%), and macrostomia (2.5%). Familial recurrence of microtia was seen 4.9% of the time in the immediate family and 10.3% of the time when including the extended family. Haploinsufficiency for the HOXA2 gene has been associated with autosomal-dominant bilateral microtia and hearing loss.
Microtia may occur as a result of in utero tissue ischemia secondary to obliteration of the stapedial artery or hemorrhage into local tissues. Some studies have reported an increase in auricular anomalies with increasing maternal age. Genetic studies have revealed chromosomal aberrations, multifactorial inheritance, and both autosomal and recessive traits as possible etiologic factors. Known teratogens for microtia include thalidomide, isotretinoin, vincristine, colchicine, and cadmium. Genetic syndromes associated with microtia/CAA such as hemifacial microsomia (also known as oculoauriculovertebral spectrum or Goldenhar syndrome) or Treacher Collins syndrome should be noted. Hemifacial microsomia may include cardiac, cervical spine, auricular, ocular, and renal anomalies. Branchio-oto-renal syndrome is associated with ear anomalies, bilateral preauricular sinuses, bilateral branchial cleft anomalies in the neck, and renal anomalies. Microtia and CAA have been associated with deletions of chromosome 18q, manifested by foot deformities, CAA, microtia, palatal abnormalities, dysmyelination, developmental delay, and nystagmus. Syndromes associated with microtia and CAA are listed in Table 15-1 .
| Pathologic Name | Eponym |
|---|---|
| 4p-syndrome | Wolf-Hirschhorn syndrome |
| Acrocephalosyndactyly type I | Apert syndrome |
| Acrocephalosyndactyly type III | Saethre-Chotzen syndrome |
| Acrocephalosyndactyly type V | Pfeiffer syndrome |
| Anus imperforate with hand, foot, and ear anomalies | Townes-Brocks syndrome |
| Arteriohepatic dysplasia | Alagille syndrome |
| Branchio-oto-renal syndrome | Melnick Fraser syndrome |
| Brevicollis | Klippel-Feil syndrome |
| Cervico-oculoacoustic syndrome | Wildervanck syndrome |
| Cleft palate, microcephaly, large ears, and short stature | Say syndrome |
| Cleft palate, micrognathia, and glossoptosis | Pierre Robin sequence |
| Congenital contractural arachnodactyly | Beals syndrome |
| Congenital facial diplegia | Möbius syndrome |
| Constitutional aplastic pancytopenia with multiple anomalies | Fanconi syndrome |
| Craniofacial dysostosis | Crouzon disease |
| Craniometaphyseal dysplasia | Pyle disease |
| Dyschondrosteosis | Léri-Weill syndrome |
| Exomphalos-macroglossia-gigantism syndrome | Beckwith-Wiedemann syndrome |
| Faciodigitogenital syndrome | Aarskog syndrome |
| Gargoylism | Hurler syndrome |
| Gonadal aplasia | Turner syndrome |
| Hemifacial microsomia (oculoauriculovertebral dysplasia) | Goldenhar syndrome |
| Lacrimoauriculodentodigital syndrome | Levy-Hollister syndrome |
| Mandibulofacial dysostosis | Treacher Collins syndrome |
| Orofaciodigital syndrome type II | Mohr syndrome |
| Osteodysplasty | Melnick-Needles syndrome |
| Osteopetrosis | Albers-Schönberg disease |
| Renal agenesis, bilateral | Potter syndrome |
| Third and fourth pharyngeal pouch syndrome | DiGeorge syndrome |
| Trisomy 13-15 syndrome | Patau syndrome |
| Trisomy 18 syndrome | Edwards syndrome |
| Trisomy 21 syndrome | Down syndrome |
Keogh and colleagues reported that 40% of patients with a diagnosis of “isolated microtia/CAA” actually had hemifacial microsomia with additional orbital deformity, mandibular hypoplasia, seventh-nerve abnormalities, and soft tissue deficiency. Such patients should be referred for ophthalmologic and dental/craniofacial consultation. Cardiac, cervical spine, and renal anomalies may be present and should be identified. Genetics consultation is advised.
Initial Evaluation
The ideal time to consult on a patient born with microtia and CAA is within a few weeks after birth. During initial consultation, the ear reconstructive surgeon should reassure the parents and outline future management and options. Parents are advised that the two important factors are first to maximize the opportunity for good hearing and second to achieve optimal cosmesis. A thorough history and physical examination should be performed with special attention to the anomalous ear, the normal ear, and other possible associated anomalies. Any history of intrauterine exposure to teratogens should be determined.
Assuming that microtia and/or CAA are the only developmental anomalies, the evaluation of the child’s hearing status is mandatory. Otoacoustic emissions and/or auditory brainstem response testing should be performed within the first 2 or 3 months, to document hearing function in the normal ear and the degree and type of hearing loss in the atretic ear. The bone conduction is usually, but not always, normal in CAA. Conductive hearing loss is usually maximal at 60 dB secondary to the lack of the external auditory canal (EAC) as well as nearly universal ossicular fixation. With congenital external auditory canal stenosis (CEACS), which is part of the spectrum of congenital ear anomalies, there may be a lesser degree of conductive hearing loss.
In the past, for unilateral cases, no intervention was considered necessary other than preferential seating and close monitoring of the normal ear. Speech usually develops normally in unilateral microtia/CAA patients. Ongoing otologic evaluations are important to identify and treat other possible problems, such as otitis media in the normal ear. A slightly lower threshold for tympanostomy tube placement should be considered in patients with recurrent acute otitis media and persistent otitis media with effusion to preserve hearing in the normal ear, given that the anomalous ear has conductive loss.
CT scanning of the temporal bones, in both axial and coronal planes, may be obtained when the child is approximately 1 year old to evaluate the favorability of the anatomy for possible atresiaplasty reconstruction and to rule out possible cholesteatoma. Some would postpone the CT scan until the age of 5 to 7 to avoid early radiation exposure and possibly avoid sedation. The incidence of congenital cholesteatoma in CAA has been reported to be between 0% and 4% to 7% ; however, some of these series may have included CEACS and not only true CAA. Even if no surgery for the CAA is performed, an initial CT scan should be obtained as well as a possible repeat CT scan several years later. The repeat CT scan is important to rule out possible congenital cholesteatoma or canal cholesteatoma, which can grow and cause destruction that was not evident on the initial scan of CAA or CEACS. Parents should be counseled to look for the signs and symptoms of complications of cholesteatoma or chronic suppurative otitis media such as facial paralysis, twitching, vertigo, a mass near the microtic vestige, or drainage. Canal cholesteatomas in the setting of CEACS have been reported and may occur in conjunction with postauricular sinuses with drainage.
Parents should be counseled about realistic expectations for both hearing and cosmesis with the various surgical and nonsurgical options. If the anatomy is favorable for hearing reconstruction, the parents are instructed that hearing may improve, but the restoration of perfectly normal hearing may not be possible. Parents should be informed that the plan for reconstruction of both the auricle and the CAA will require staged surgeries and that revision surgery may be required. Parents should be educated about the options of prosthetic auricles, rib graft auricles, Medpor (Sonitus Medical, San Mateo, CA) auricles, prosthetic auricles clipped on to bone anchors, bone-anchored hearing aid (BAHA), Ponto, Sophono, Vibrant Soundbridge middle ear implants (Med-El, Innsbruck, Austria), Sound Bite (Sonitus Medical, San Mateo, CA) devices, and Softbands (see Chapter 14 ). Possible complications of surgery should be described. The child should be followed in the office at 12-month intervals or more frequently if there are active issues.
Timing and Sequence of Surgeries for Microtia and Congenital Aural Atresia
CAA is usually associated with microtia (see Fig. 15-1 ), although there are occasional cases of CAA with normal or near-normal auricles. When associated with microtia, CAA reconstruction may be undertaken before microtia reconstruction, after completion of all stages, or in combination with a stage of microtia repair. Historically, most authors advocate CAA repair to follow three stages of microtia reconstruction: cartilaginous auricular reconstruction, lobule rotation, and postauricular elevation and skin grafting. The best chances for auricle reconstruction occur when the tissues of the surgical site have not had previous surgery. Previous operations may create scarring and compromise blood supply that may decrease the chances of successful cartilage graft implantation.
The sequence of microtia reconstruction before atresiaplasty has recently been challenged in reported series of CAA repairs without microtia repairs. Roberson and colleagues reported a series of early atresiaplasties followed by later microtia reconstruction with Medpor implants and temporoparietal flaps. Zhao and associates reported a large series of 1460 ears in 1300 children with microtia/CAA who underwent canal-wall-down atresiaplasty at the same time as microtia reconstruction with rib graft, as the first stage of reconstruction.
Currently, the optimal age to begin auricular reconstruction is generally considered age 7 years, although various surgeons have recommended reconstruction at ages ranging from 2 to 9 years. Proponents for reconstruction in younger children argue that psychologic trauma is minimized and hearing function is improved. Proponents for reconstruction in older children argue that better cosmetic results are obtained when the rib cartilage is larger to allow more detail and projection of the graft. An older child will also be more cooperative with dressing changes and postoperative management.
For the occasional case of CAA without microtia and for CEACS, the atresiaplasty may be undertaken after the age of 4 years. However, the appropriate age for atresia repair is debated. Proponents of early atresiaplasty believe that acquisition of binaural hearing, sound localization, and improving the ability to hear sound in noise at as early an age as possible is beneficial for good surgical candidates. Proponents of late atresiaplasty believe that the decision for atresiaplasty should be delayed until the patient is old enough (teenage years or early adulthood) to take part in the decision. The rationale is that young children should not be subjected to the risks of surgery for CAA until they are able to understand and willing to accept the risks of potential facial nerve injury and sensorineural hearing loss (SNHL).
For unilateral cases of CAA, acquisition of binaural hearing, improved sound localization, and optimizing hearing in noise are also desirable. However, the need for surgical reconstruction for unilateral CAA is controversial, as some would argue that the risks of surgery are high and the gains for unilateral CAA are small.
Congenital Aural Atresia: Grading Systems of Favorability for Atresiaplasty
The most important factor in the decision for reconstruction of CAA and CEACS is proper patient selection based on individual anatomy. Yeakley and Jahrsdoerfer devised a grading system based on high-resolution CT of the temporal bone and auricle to determine which patients are candidates for atresiaplasty ( Table 15-2 ).
| Jahrsdoerfer System | Modified Jahrsdoerfer System | ||
|---|---|---|---|
| Anatomic Structure | Points Awarded | Anatomic Structure | Points Awarded |
| Stapes favorable | 2 | Stapes favorable | 1 or 2 |
| Oval window open | 1 | Oval window open | 1 |
| Middle ear well pneumatized | 1 | Middle ear well pneumatized | 1 |
| Facial nerve favorable | 1 | Incus/malleus favorable | 1 |
| Incus/malleus favorable | 1 | Incus/stapes connected | 1 |
| Incus/stapes connected | 1 | Mastoid well pneumatized | 1 |
| Mastoid well pneumatized | 1 | Round window open | 1 |
| Round window open | 1 | Auricle normal | 1 |
| Auricle normal | 1 | Tegmen mastoideum normal, mildly low, severely low | 1 or 2 |
| Maximum total * | 10 | Malleus-incus vs. stapes position | 1 |
| Facial nerve at oval window normal | 1 | ||
| Facial nerve posterior or lateral to middle ear | 1 | ||
| Maximum total | 14 | ||
* If total ≥6, favorable for atresiaplasty. If total <6, unfavorable for atresiaplasty.
Each favorable factor is awarded 1 point. A score of less than 6 indicates that the patient is not a favorable surgical candidate, whereas a score of 6 or greater indicates that the patient may be considered a candidate for atresiaplasty. The higher the total number on the grading scale, the more likely a good hearing outcome after surgery. The presence of a normal stapes is the only factor that is given 2 points (see Table 15-2 ; Fig. 15-2 ); an anomalous but present stapes is awarded 1 point. An absent stapes receives no points. Because a good hearing result requires conduction of sound to the inner ear via the oval window, the presence of an open oval window and mobile stapes is critical. If no stapes or oval window can be identified intraoperatively, the procedure should be aborted.
A well-pneumatized middle ear space is more favorable than a small one, as it is easier to find and provides more room to work in the middle ear. Similar to the presence of a functional stapes, the position of the facial nerve is critical. The facial nerve may lie in a normal position, an abnormal but favorable position, or various unfavorable positions. In a favorable case, the facial nerve will lie superior to the oval window in its horizontal portion. It will then turn inferiorly at the second genu to pass inferiorly through the mastoid cavity in the vertical portion. In unfavorable cases, the facial nerve may totally or partially cover the oval window and stapes, obscuring the view and thus precluding a surgical approach to the window ( Fig. 15-3 ). The stapes and facial nerve may be injured during surgery if one is not aware of this possible anomaly. A second possible anomaly in CAA is that the facial nerve may make a more acute turn at the second genu and pass anteriorly and laterally instead of inferiorly ( Fig. 15-4 ). In this situation, the facial nerve crosses lateral to the middle ear and will be vulnerable to injury during a lateral surgical approach. Patients with CAA may also have middle ear dehiscence of the bony canal of the facial nerve. Dissection and transposition of the unfavorably located facial nerve to allow successful atresiaplasty has been reported but is risky and rarely performed.
In CAA, it is very common to have a fused malleus-incus complex (MIC), and it is common to have the MIC fixed to the bony atretic plate. It is favorable when the MIC is well formed and the attachment to the atresia plate is limited. A well-formed incudostapedial joint identified on CT scan is also favorable. The lenticular process of the incus may be absent, creating ossicular discontinuity. The presence of a round window is favorable because obliteration of the window may impair energy transfer from the oval window into the cochlea. A normal auricle is awarded 1 point because, embryologically, it is formed earlier than the middle ear and usually indicates a lesser degree of deformity of the middle ear.
Yellon and Branstetter and Dedhia and colleagues recently reported modification of the Jahrsdoerfer CT scan grading system for CAA candidacy for atresiaplasty (see Table 15-2 ), describing several anatomic variants that are important to assess during the decision-making process and surgical approach to CAA. A total of 130 CT scans with CAA or CEACS were graded with the Jahrsdoerfer and new modified grading systems. The new and/or modified anatomic considerations with their respective incidences included the presence or absence of (1) moderately low-lying tegmen mastoideum (13%; Fig. 15-5 ), (2) severely low-lying tegmen mastoideum (4%; Fig. 15-6 ), (3) MIC large and positioned directly lateral to the stapes rather than the usual anterolateral position (24%; Fig. 15-7 ), (4) facial nerve obstructing oval window (41%; see Fig. 15-3 ), and (5) facial nerve turning anterolaterally and obstructing the lateral surgical approach to the attic or middle ear (21%; see Fig. 15-4 ). The lateral approach to the middle ear or attic may be more difficult yet still possible if the tegmen mastoideum is mildly low lying; however, a severely low-lying tegmen mastoideum may preclude surgical access to the middle ear or attic. A large MIC will block visualization and palpation of the incudostapedial joint and the stapes, making it difficult or impossible to rule out incudostapedial joint discontinuity and stapes fixation, which may be a cause of persistent conductive hearing loss. Grading the favorability of facial nerve anatomy at two sites (oval window/stapes and vertical portion) helps to systematically assess seventh-nerve anatomy. The presence of these anomalies may make atresiaplasty impossible or at least more difficult. Systematic review of CT scans for these anatomic variants may assist in selection of candidates for atresiaplasty, in surgical planning, and in teaching the anatomy of CAA.
