Evaluation and Management of Congenital Aural Atresia

Key Points

Microtia/congenital aural atresia (CAA) can occur in conjunction with ocular, cervical, cardiac, renal, and other congenital anomalies that must be evaluated and treated if present.
The vast majority of patients with CAA have a maximal (60 dB) conductive hearing loss and normal cochlear function. Hearing evaluation by auditory brainstem response (ABR) testing with air and bone conduction thresholds early in infancy (6 months and younger) and behavioral testing with air and bone conduction thresholds in older children are critical to counseling families on appropriate and best interventions for hearing habilitation.
Hearing habilitation with a bone conduction hearing device is paramount for normal speech and language development in children with bilateral CAA and should be placed early in infancy or as soon as possible once normal bone conduction thresholds (ABR testing) are confirmed.
The timing and type of surgery for hearing habilitation, if any, 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.
If a child is a candidate for atresiaplasty, atresia surgery precedes MedPor microtia repair; atresiaplasty follow s autologous rib graft microtia reconstruction.
Candidacy for atresiaplasty relies on normal bone conduction thresholds on behavioral audiometry and favorable middle and inner ear anatomy as interpreted on the high-resolution temporal bone computed tomography (CT) scan.
Because atresia surgery is generally not contemplated until the child is 6 to 10 years old, CT scanning is not recommended before that age unless there is a suspicion for canal cholesteatoma (otorrhea, canal stenosis with odor).

The Jahrsdoerfer grading system for evaluating CT scans of the temporal bone helps determine which patients are potential candidates for atresiaplasty ( Table 19.1 ).

TABLE 19.1

Grading Systems for Computed Tomography of Congenital Aural Atresia

From Yeakley J, Jahrsdoerfer RA: CT evaluation of congenital aural atresia: what the radiologist and surgeon need to know, J Comput Assist Tomogr . 1996;20:724.

Jahrsdoerfer Grading Scale for the Evaluation of Candidacy for Congenital Aural Atresia Repair ∗
Anatomic Structure	Points Awarded
Stapes favorable	2
Oval window open	1
Middle ear well pneumatized ^†	1
Facial nerve favorable	1
Incus/malleus favorable	1
Incus/stapes connected	1
Mastoid well pneumatized	1
Round window open	1
Auricle normal	1
Total score	10

∗ If total ≥7, favorable for atresiaplasty. If total <6, unfavorable for atresiaplasty.

† Middle ear volume has been shown to be a predictor of hearing outcomes in congenital aural atresia surgery—volume greater than 305 mm ³ is predictive of better hearing outcomes.

Careful patient selection, advanced training and skills, and meticulous technique at every step of the operation are required for safe and successful atresia surgery.
Preservation of sensorineural hearing and the seventh cranial nerve must always take precedence over the desire to correct conductive hearing loss through atresiaplasty in patients with CAA and congenital external auditory canal stenosis (CEACS).
Complications of atresiaplasty include external auditory canal stenosis, infections or otorrhea, lateralization of the tympanic membrane, persistent or delayed conductive hearing loss, and, rarely, facial nerve injury and sensorineural hearing loss.
CEACS is a milder congenital ear anomaly that must be followed closely by examination and CT. Even if no surgery was initially planned, the development of canal cholesteatoma will require surgery. The incidence of cholesteatoma in ear canal stenosis is significantly higher (approximately 1 in 5) than that in complete CAA.
For patients who are not surgical candidates for atresiaplasty or for those who decline atresiaplasty, hearing options include no treatment if the CAA is unilateral, a bone-conduction hearing device (BCHD) either on a hard or soft band, or a conventional hearing aid if an auricle is present.
Osseointegrated bone conduction hearing devices (OIBCDs), either percutaneous systems (BAHA Connect, Cochlear Corp., Sydney, Australia; or Ponto, Oticon Medical, Askim, Sweden) or transcutaneous systems (BAHA Attract, Cochlear Corp., Sydney, Australia; or Sophono, Medtronic, Jacksonville, Florida) are also hearing options for patients 5 years or older (not U.S. Food and Drug Administration [FDA] approved for patients younger than 5 years, although some overseas centers are implanting at earlier ages).
OIBCD (BAHA and Ponto) surgery is performed in a single stage in patients with thick skulls (≥3 mm; usually teenagers and older) and in two stages in patients with thin skulls (<3 mm; younger than 10 years). Some centers are implanting pediatric patients in a single stage and loading the sound processor 6 to 12 months after the single-stage surgery.
Complications of open-skin OIBCDs include site infection, scalp thickening or skin overgrowth requiring revision surgery, and loss of the implant because of failure of osseointegration.
The Vibrant Soundbridge (Med-El Corp., Vienna, Austria), an active middle ear implant, is not FDA-approved for CAA, although it has been used in Europe.
The choice of hearing habilitation option ultimately depends on the child’s hearing status, middle and inner ear anatomy, and surgeon, in close consultation and discussion, respectful of the family’s wishes.

Demographics And Associated Deformities

The incidence of microtia/congenital aural atresia (CAA) is 0.83 to 17.4 per 10,000. In a report by Brent on 1200 patients with microtia, 58% of patients had right-sided CAA, 32% left-sided, and 9% bilateral ( Fig. 19.1 ). Of the patients, 63% 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 rate of microtia was 4.9% in the immediate family and 10.3% when including the extended family.

Fig. 19.1, Right congenital aural atresia and grade 3 microtia.

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. Known teratogens for microtia include retinoic acid, thalidomide, cadmium, vincristine, and colchicine.

Genetic studies of CAA have revealed chromosomal aberrations, multifactorial etiology, and both autosomal dominant and recessive inheritance. Haploinsufficiency for the HOXA2 gene has been associated with autosomal-dominant bilateral microtia and hearing loss. 18q deletion, either isolated or as part of de Grouchy or 18q deletion syndrome, is associated with bilateral aural atresia, and in some patients, atresia or stenosis in the absence of microtia. Genetic syndromes associated with microtia/CAA, such as hemifacial microsomia (also known as oculoauriculovertebral spectrum or Goldenhar syndrome when accompanied by dermoids or vertebral abnormalities) or Treacher Collins syndrome, should also be noted. Hemifacial microsomia may be an isolated finding or include cardiac, cervical spine, auricular, ocular, and renal anomalies (Goldenhar). Branchio-oto-renal syndrome is associated with ear anomalies, preauricular sinuses, branchial cleft anomalies, and renal anomalies. As noted above, microtia and CAA (as well as the very rare CAA in the absence of microtia ) have been associated with deletions of chromosome 18q, which may also be accompanied by foot deformities, palatal abnormalities, dysmyelination, developmental delay, and nystagmus. ^,

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. Although the most common phenotype is isolated—unilateral microtia/CAA—other physical examination findings should be sought and, if found, genetics consultation pursued.

Initial Evaluation

History and Physical Examination

The ideal time to evaluate a patient born with microtia/CAA is within a few weeks after birth. During the initial consultation, prenatal, perinatal, postnatal, and family histories should be obtained. A careful head and neck physical examination should be performed with special attention to the auricles, the presence of ear pits, tags, or canal stenosis, and other associated anomalies that might suggest hemifacial microsomia or Treacher Collins syndrome. A careful facial nerve examination should be performed.

The surgeon should reassure the parent(s), outline future management options, and discuss a plan for hearing evaluation, especially if the patient has bilateral CAA. Caretakers are advised that the top priority is to maximize the opportunity for good hearing and second, to achieve optimal cosmesis.

Hearing Evaluation

Auditory brainstem response (ABR) testing with air and bone conduction thresholds should be performed within the first 2 to 3 months of life to document hearing function in the normal ear (if unilateral) and the degree and type of hearing loss in the atretic ear (and cochlear function if bilateral CAA). Bone conduction thresholds are 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. Congenital external auditory canal stenosis (CEACS) may be associated with a lesser degree of conductive hearing loss. Children 0 to 2 years old should be followed in the office for hearing evaluation every 6 months, and if the hearing is stable, yearly thereafter.

In the past, for unilateral CAA patients, no intervention was considered necessary other than preferential seating and close monitoring of the normal ear as long as the normal appearing ear showed normal hearing. Normal hearing in one ear is sufficient for normal speech and language development in most typically developing children. However, there is increasing evidence that unilateral sensorineural or conductive hearing loss is associated with a decrease in academic performance in a subset of children. Unilateral hearing loss contributes to lack of sound localization and significantly increased difficulties in noisy environments such as the typical classroom. 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 chronic otitis media with effusion to preserve hearing in the normal ear, given that the anomalous ear has a large conductive hearing loss.

The infant with bilateral CAA should be fitted with a bone-conduction hearing device (BCHD) as soon as possible once the child is determined to have normal bone conduction thresholds (at least for the better-hearing ear). These devices can be fitted with a soft or hard band, with the bone oscillator on the mastoid bone. Although some families choose to have their child with bilateral CAA wear BCHDs bilaterally, the benefits of bilateral BCHDs in these children is unknown. Hearing rehabilitation in children with unilateral CAA is discussed later (see “Implantable Hearing Devices” section).

Imaging

CT scanning of the temporal bones is not necessary until the child is old enough for consideration of canal reconstruction, around the age of 4 to 5 years, or even later if the canal reconstruction will follow microtia reconstruction with autologous costal cartilage. Scanning earlier exposes the child to an unnecessary (albeit small) dose of radiation and the probable need for sedation. The incidence of congenital cholesteatoma in CAA is extremely low, and CT is not necessary if parents are not considering atresiaplasty. In contrast, strong consideration should be given to a CT for children with CEACS at age 4 to 5 years because of the real possibility of an ear canal cholesteatoma (see “Congenital External Auditory Canal Stenosis” section). ^,

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here