eMedicine Specialties > Pediatrics: Surgery > Otolaryngology

External Auditory Canal Atresia

Author: Rahul K Shah, MD, FAAP, Assistant Professor of Otolaryngology and Pediatrics, George Washington University, Children's National Medical Center; Attending Physician, Department of Otolaryngologoy, Children's National Medical Center
Coauthor(s): Udayan K Shah, MD, Attending Surgeon, Division of Otolaryngology, Alfred I duPont Hospital for Children
Contributor Information and Disclosures

Updated: Jul 18, 2008

Introduction

Background

External auditory canal atresia (EACA) is a rare congenital disorder. Accurate counseling and referral for these children and their families demands an appreciation of the range of management options and indications for intervention. This article reviews the history, etiology, and epidemiology of EACA, as well as the clinical care of children with this condition.

EACA was first described in Western medicine by Paulus of Aegina in the seventh century AD. Paulus recommended simple incision for opening the atresia. Later, physicians used a hot iron probe to maintain canal patency after incising the atresia. The first operation to correct an atresia of the external auditory canal (EAC) was performed in 1882 by Kiesselbach. Unfortunately, the operation left the child with a facial nerve paralysis. In 1914, Page reported on a series of 8 patients who underwent operation. Of these 8 patients, 5 had a subjective improvement in their hearing after surgery.

In the early 20th century, techniques for correction of the atretic external canal have involved opening the antrum and aditus of the ear and lining the cavities with a skin graft. In these surgeries, the atretic bony plate was untouched, and the resulting hearing improvement was poor. In the past 50 years, improved radiologic and audiologic assessments coupled with improvements in surgical technology, such as the operating microscope and facial nerve monitoring, have resulted in good surgical success rates for properly chosen patients with EACA.

The future of medical and surgical interventions for patients with EACA is exciting and includes such novel approaches as computer-aided surgery as well as critical reviews of past surgical results, with further attempts to increase success rates and minimize morbidity.

Pathophysiology

The EAC is comprised of medial bony and lateral cartilaginous portions. The bony component changes from half of the length of the tubular EAC in children to two thirds of the length of the tubular EAC in adults.

The lateral soft tissue portion of the EAC begins to form at 26-28 weeks' gestation, when the epithelial plug arising from the first branchial cleft begins to canalize. During the sixth month of development, the medial bony portion is created out of the temporal bone's mesenchymal condensation. As canalization occurs, the mastoid separates from the mandible and grows posteriorly and inferiorly. The posteroinferior growth of the mastoid brings the facial nerve from the middle ear and brings the facial nerve and middle ear into its position at birth (ie, posterior and inferior to the EAC).

Congential atresia of the EAC is caused by a failure of canalization of the epithelial plug portion of the first branchial cleft. Persistence of the tympanic ring results in a bony atresia plate at the level of the tympanic membrane. Ossicular malformations may be seen as they arise from the first branchial cartilage (ie, Meckel cartilage).

Failure of the EAC to canalize means that sound cannot reach the tympanic membrane; thus, a conductive hearing loss results (see Media files 2-3). Concomitant ossicular malformations may result in additional conductive hearing loss. In addition, 11-47% of patients also have a sensorineural hearing loss in the affected ear.

EACA may be seen with microtia (ie, maldevelopment of the external ear). The auricle develops from ectodermal condensations and mesodermal condensations (referred to as the hillocks of His) at 5 weeks' gestation.

Case reports have detailed duplication anomalies of the first branchial cleft occurring in conjunction with a congenital aural atresia. The implication for the evaluating physician is to keep in mind that EACA and duplication anomalies can be present in the same patient, and both may need to be simultaneously addressed (surgically).

Frequency

United States

According to Jahrsdoerfer, the incidence of ear malformations in New York City from 1952-1962 was 1 in 5800 births.¹ In one year of this study, the incidence of EACA was 1 in 8000 births.

International

EACA is rare in persons with a normal pinna. The incidence of EACA with concurrent microtia is 1 in 10,000-20,000 live births. Unilateral EACA is 3-6 times more likely to occur than bilateral atresia. The right ear is more often involved than the left ear. Family histories positive for EACA are noted in 14% of patients.

Mortality/Morbidity

Intervention to treat bilateral EACA is important for hearing and language development. Social stigma may be experienced because of cosmetic or developmental issues, especially as grade school begins.

• Otitis media (OM) is a common pediatric diagnosis that is difficult to identify and manage in children with EACA. EACA complicates the diagnosis of OM. Symptoms of pain, fever, irritability, and worsening hearing loss or imbalance warrant evaluation. The contralateral ear may also show otitis. Oral antibiotics may be started presumptively. Although CT scanning is not a routine screening test for these children, it reveals soft tissue density in the middle ear cleft. Clinical management of OM is not significantly different, and complications of mastoiditis, facial nerve palsy, and intracranial complications must be monitored.
• Once complications have been encountered, CT scanning to examine the interrelationships of the otologic structures is certainly warranted. OM refractory to oral antibiotics may require insertion of tympanostomy tubes. However, these ventilation tubes should only be inserted in the normal ear and not the affected contralateral ear. The need for middle-ear ventilation to treat OM may prompt earlier correction of EACA as the diagnosis is made earlier. Recurrent OM is an age-limited problem that resolves with time.
• Canal cholesteatoma (epithelial inclusion cyst) may occur medial to the atretic ear canal. Canal cholesteatomas may be identified radiographically before symptoms begin because of widening of the EAC. Patients with infection of the cholesteatoma present with pain and fever. Treatment is primarily surgical with adjunctive use of oral or systemic antibiotics.
• Traditionally, unilateral EACA was not believed to limit children's language. Recently, therapies for hearing loss have appreciated the importance of bilateral hearing for optimal speech and language development. In addition to long-term development, bilateral hearing is important for hearing in a noisy environment (eg, in groups, with background noise) and for sound localization (eg, knowing from which side a car is approaching).

Sex

EACA occurs more often in males than in females.

Age

EACA occurs with a normal pinna or with an abnormal pinna (ie, concomitant microtia). When the atresia occurs in the setting of a normal pinna, the average age of diagnosis is 2.5 years. However, when EACA occurs with abnormal development of the pinna, the average age of diagnosis is 3.5 years.

Clinical

History

Diagnosis of a congenital ear malformation is usually made at birth, when a malformed pinna or atretic canal is noticed during the secondary survey of the newborn. Some cases may not be noticed at birth, such as those with a normal pinna and a blunted or partially patent canal. Some of these patients are detected during a screening examination performed in school.

• When soliciting information regarding the history of the present illness, determine how and when the problem was discovered and ask about the child's language and social development and associated problems.
• Survey the family for history of hearing loss and syndromic conditions and for genetic information.
• Inquire into maternal and neonatal health.
• Identify the state of patient's social and language development.
  • The child's interactions with other children, caregivers, and family are important.
  • The patient's language development, with age of babbling and first words or number of words, is a useful measure.
  • Children with unilateral external auditory canal atresia (EACA) usually have normal speech and language development. Hearing and learning may be impeded in noisy environments, such as group discussions or large lectures, and sound localization may be a problem at play and when outdoors.
• Rarely, an adult presents with a report of a hearing loss, and the physical examination reveals EACA.
• Reports of vertigo may require a formal assessment of the vestibular system.
• Pain, fever, or drainage from the atretic ear may indicate cholesteatoma or infection of the ear canal.
• History of facial nerve problems must be identified, particularly before surgical repair. Problems with eye closure may manifest as dry, itchy, or sandy eyes and rarely as exposure keratitis. Problems drinking liquids or drinking with a straw may also indicate facial nerve dysfunction.

Physical

The global level of functioning of the child should be addressed first. Complete head and neck examination then follows with attention to craniofacial anomalies. Then, otologic structures are assessed. For complete care of patients with EACA, physical examination must be combined with radiographic evaluation.

Examine the remainder of the body so as not to overlook other abnormalities, especially cardiac, renal, or ophthalmologic malformations.

• Pinna: Assess for microtia.
• Concha: A thumbprint concha is a classic sign for EACA (see Media file 1). The meatus of the EAC may simply be a pinpoint, indicating severe canal stenosis rather than complete atresia. Care of these patients is similar to that of patients with EACA.
• Congential ear malformations
  • These can be divided into major and minor forms.
  • Major ear malformations consist of an absence of the external canal and tympanic membrane, a small middle-ear cavity, and malformations of the malleus and incus. Microtia and a hypoplastic mandible are concomitant findings in patients with major ear malformations.
  • Minor ear malformations consist of abnormal ossicles with a patent EAC and tympanic membrane, although the latter 2 structures may be smaller than normal.
• Lateral skull
  • The relationship of the temporomandibular joint in relation to the mastoid tip and middle ear is documented.
  • Mastoid tip development should be assessed and especially compared to the contralateral side. Poor mastoid tip development portends abnormal facial nerve anatomy.
• Facial nerve
  • Evaluation should be performed using scoring or grading according to established systems, such as those by Fisch or House and Brackmann.
  • An objective assessment may be indicated in cases of palsy (see Lab Studies).
• Documentation
  • Photographic records of anomalies aid referrals, teaching, and objective analysis of surgical results.
  • Images should be standardized with respect to lighting and dimensions.
  • Appropriate consents from the family and patient should be obtained for teaching and publication purposes, ideally at the time of such documentation.

Causes

Precise etiology of the failure of EAC canalization is not known. Associations have been postulated between EACA and low birth weight, intrauterine trauma, toxins, or infection. Genetic defects are being identified for several craniofacial anomalies. Because of the importance of future genetic studies, serum needs to be obtained and banked for eventual genetic testing.

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