Congenital and Acquired Atresia and Stenosis of the External Auditory Canal

CAA/CEACS

• A consult for a patient with microtia and CAA/CEACS is often requested shortly after birth. A history of airway, feeding, or other potentially life-threatening issues should be determined, as well as familial microtia/CAA or intrauterine teratogen exposure. A history of school and speech problems is important for older children.

AEACA

• AEACA usually involves soft tissue but occasionally bony obliteration of the EAC. The common pathway in AEACA is a history of exuberant fibroproliferative inflammation. Causes of AEACA include chronic otitis externa, chronic suppurative otitis media, fractures or burns of the EAC, tympanomastoid surgery, or chronic dermatitis.

CAA/CEACS

• A physical examination should be performed with special attention to the ears. CAA versus CEACS, syndromic appearance, and airway, feeding, and cardiac status are evaluated. Microtia is graded as follows: grade 1, nearly normal ear with some minor anomaly; grade 2, an ear with moderate structural deficiencies; grade 3, classic severe “peanut deformity” ( Fig. 208.1 ); and grade 4, anotia or no auricle and earlobe.

  

• CEACS should be débrided while restraining the child using a microscope, if possible, to examine the EAC and TM.

• Ongoing evaluations are important since otitis media occurs in higher frequency in the normal ear than in the general population. Tympanostomy is performed if indicated. The child is examined every 6 to 12 months or more frequently, if necessary.

AEACA

• The debris in the ear canal should be suctioned and cultured. The presence of ongoing inflammation versus mature scar in the EAC is determined.

CAA/CEACS

• For CAA/CEACS, high resolution CT of the temporal bones, in both axial and coronal planes, is obtained at 5 years to evaluate the anatomy for atresiaplasty and to rule out cholesteatoma. The incidence of congenital cholesteatoma in CAA/CEACS is 0% to 7%. Even if no surgery is planned, an initial CT should be obtained, as well as a later CT to rule out cholesteatoma not initially evident.

CAA/CEACS–—Grading Systems of Favorability for Atresiaplasty

• Candidacy for reconstruction of CAA/CEACS is dependent on the anatomy. Yeakley and Jahrsdoerfer devised a grading system to evaluate CT of the temporal bone and auricle to identify favorable candidates for atresiaplasty.

• Each favorable factor is awarded one point ( Table 208.1 ). A score of <6 indicates that the patient is not a candidate for atresiaplasty, while ≥6 indicates a favorable candidate. The higher the total number, the more likely a good hearing result after atresiaplasty.

  TABLE 208.1

  Jahrsdoerfer Grading System for Computed Tomography of Congenital Aural Atresia/Congenital External Auditory Canal Stenosis

  With permission from Yeakley J, Jahrsdoerfer RA: CT evaluation of congenital aural atresia: what the radiologist and surgeon need to know . J Comput Assist Tomogr 20:724-731, 1996 .

  Anatomic Structure	Points
  Stapes normal or abnormal but present	2 or 1
  Oval window open	1
  Middle ear well pneumatized	1
  Facial nerve favorable position	1
  Malleus/incus well formed	1
  Incudostapedial joint intact	1
  Mastoid well pneumatized	1
  Round window open	1
  Auricle normal	1
  Maximum total	10
  If total ≥6, favorable for atresiaplasty	—
  If total <6, unfavorable for atresiaplasty	—

• A normal stapes is the only factor awarded two points, while an anomalous stapes is awarded one point. An absent stapes receives no points. If no stapes or oval window (OW) can be identified on CT or intraoperatively, the procedure should be declined or aborted, respectively.

• A well-pneumatized middle ear space is associated with better hearing outcomes. The position of the facial nerve is critical. When favorable, the facial nerve lies superior to the OW in its horizontal portion and then courses inferiorly at the second genu to pass inferiorly through the mastoid cavity. When unfavorable, the facial nerve may totally or partially cover the OW/stapes, thus precluding a surgical approach to the window. A second possible anomaly in CAA is that the facial nerve may pass anterolaterally at the second genu, rather than inferiorly. Thus, the facial nerve crosses lateral to the middle ear and may be injured during an anterior (lateral) surgical approach.

• In CAA, it is very common to find a fused malleus–incus complex (MIC), which is fixed to the bony atretic plate ( Fig. 208.2 ). It is favorable when the MIC is well formed and not hypoplastic. A normal incudostapedial joint on CT is also favorable. The presence of a round window is favorable because obliteration impairs sound energy delivery into the cochlea. A normal auricle is awarded a point because it is formed earlier during embryogenesis than the middle ear, and this usually suggests less middle ear deformity.

  

• Dedhia et al. described useful modifications of the Jahrsdoerfer grading system for atresiaplasty ( Table 208.2 ). New and/or modified anatomic considerations and their respective incidences in CAA CTs included the presence of (1) moderately low-lying tegmen mastoideum (13%); (2) severely low-lying tegmen mastoideum (4%); (3) MIC large and positioned directly lateral to stapes rather than normal anterolateral position (24%); (4) facial nerve obstructing OW (41%); and (5) facial nerve turning anterolateral (21%).

  TABLE 208.2

  Modified Jahrsdoerfer Grading System for Computed Tomography of Congenital Aural Atresia/Congenital External Auditory Canal Stenosis

  With permission from Dedhia K, Yellon RF, Branstetter BF, et al.: Anatomic variants on computed tomography in congenital aural atresia . Otolaryngol Head Neck Surg 147(2):323-328, 2012 .

  Anatomic Structure	Points
  Stapes normal or abnormal but present	2 or 1
  Oval window open	1
  Middle ear well pneumatized	1
  Malleus/incus well formed	1
  Incudostapedial joint intact	1
  Mastoid well pneumatized	1
  Round window open	1
  Auricle normal	1
  Tegmen mastoideum normal or mildly low	2 or 1
  Malleus–incus versus stapes position normal	1
  Facial N. at oval window normal	1
  Facial N. posterior (not lateral) to middle ear	1
  Maximum total	14

• The anterior (lateral) approach to the middle/attic may be more difficult yet still possible if the tegmen mastoideum is mildly low; however, a severely low-lying tegmen precludes atresiaplasty. A large MIC that is directly lateral to the stapes will block access to the incudostapedial joint and stapes, making it difficult or impossible to assess incudostapedial joint discontinuity and/or stapes fixation, which may result in persistent CHL. Presence of these anomalies may make atresiaplasty impossible or more difficult.

• In the usual setting of bilateral chronic ear disease, the worse hearing ear is traditionally operated on first. In contrast, in bilateral CAA/CEACS, the ear with the most favorable anatomy is selected first to maximize chances for a good hearing outcome while minimizing risks.

AEACA

• CT imaging is helpful in differentiating bony from soft tissue atresia, detecting cholesteatoma, and assessing the mastoid, middle ear, and ossicles.

Unilateral Versus Bilateral CAA/CEACS

• With bilateral CAA/CEACS and CHL, there is greater need to provide hearing rehabilitation than for unilateral cases. The need for hearing rehabilitation for unilateral CAA/CEACS is more controversial, and some argue that there are risks and that gains are smaller than for bilateral cases.

• In the past, for unilateral CAA, no intervention was recommended other than preferential seating and close monitoring of the normal ear. Recently, up to 43% of children with unilateral CAA were shown to have school problems and require extra services, including speech therapy and educational intervention programs. Rehabilitation should be offered to children with language or school difficulties, but otherwise some wait for a decision by the child when older. For unilateral CAA/CEACS, binaural hearing, improved sound localization, and optimization of hearing in noise are desirable.

CEACS

• Schuknecht described the type A anomaly as isolated meatal stenosis, which is easiest to repair. Canal cholesteatoma may develop. Middle ear anatomy is fairly normal. The Lempert endaural approach (described later) is used for severe stenosis.

• The type B anomaly is more extensive CEACS affecting the entire EAC. Middle ear anomalies are more common. Canaloplasty/atresiaplasty is performed if narrowing is severe, or if there is canal cholesteatoma, or significant CHL (dependent on CT grading). The incidence of type A and B anomalies is approximately equal. Yellon observed that 50% of cases of CEACS will have a partial atretic plate, hypoplastic TM, and/or ossicular anomalies. Jahrsdoerfer and Chole reported a 50% incidence of canal cholesteatoma by age 20 with EAC diameter <4 mm. It is likely that some of these cases were untreated as children. A neonate with an EAC diameter of ≥2.5 mm who is examined and débrided in the office or operating room every 6 months will often outgrow the problem after 4 to 5 years. Canal cholesteatoma is much more likely when the EAC is ≤2 mm. Frequently cerumen occludes the CEACS causing CHL. Examination of the ear by a non-otolaryngologist will be difficult if not impossible, and pathology may go undetected.

AEACA

• CHL is the indication for repair of AEACA.

CAA/CEACS

• Any degree of SNHL that is more than mild will preclude atresiaplasty. Any anomaly of the inner ear precludes atresiaplasty because of an increased incidence of SNHL following surgery.

AEACA

• Inflammatory processes must be resolved prior to surgical repair.

Alternatives for Hearing Rehabilitation in CAA/CEACS

• Nonsurgical Devices

  • Children with bilateral CAA/CEACS or selected cases of unilateral CAA/CEACS may be fitted with a sound processor clipped to a Velcro headband (Softband) during the first year of life. Devices include the BAHA, Ponto, and Sophono sound processors with headbands. These devices may also be used as a trial prior to implantation.

  • The bone conduction hearing aid with metal headband is a less expensive option. A hearing aid is an option with a normal auricle.

• Timing and Sequence of Surgeries for Microtia/CAA/CEACS.

  • CAA usually occurs with microtia (see Fig. 208.1 ), although there are occasional cases without microtia. When associated with microtia, CAA reconstruction may be undertaken before, after, or in combination with microtia reconstruction. Most surgeons advocate for atresiaplasty after microtia reconstruction. Previous operations may compromise blood supply and decrease success of cartilage implantation.

  • In contrast, one group reported a series of early atresiaplasties followed by later microtia reconstruction using Medpor implants with temporoparietal flaps. Another group reported on 1460 ears that had canal wall-down atresiaplasty at the time of microtia reconstruction with rib graft, as a combined first stage of reconstruction.

  • Optimal age to begin microtia reconstruction is generally considered ≥7 years. Proponents for early reconstruction argue for minimizing psychologic trauma. Proponents for later reconstruction argue that better cosmetic results are obtained when rib cartilage is larger, and that older pediatric patients are more cooperative.

  • Proponents of early atresiaplasty contend that acquisition of binaural hearing, sound localization, and improved ability to hear sound in noise are beneficial. Proponents for late atresiaplasty believe the decision should be delayed until the patient understands risks.

  • For the occasional case of CAA without microtia and for isolated CEACS, atresiaplasty may be performed at ≥4 years if otitis media has resolved.

• AEACA

  • In the early phase, aggressive cleaning and ototopical corticosteroid-antimicrobial drops control infection and minimize granulation tissue. Wicks help in the delivery of ototopical drops and act as a stent. Cultures are helpful. Active dermatitis does not provide a good environment for successful reconstruction.

  • Once mature fibrosis is present, CHL is the concern. Amplification is offered. An osseointegrated implant is considered for patients who decline atresiaplasty or are unable to use a conventional hearing aid.