Congenital Anomalies of External Ear: Symptoms, Progress, Treatment

Congenital anomalies of the external ear refer to developmental abnormalities of the auricle or the external acoustic meatus (EAM), also known as the external auditory canal (EAC). This group of pathologies may give rise to a range of dysfunctions and esthetic concerns.

Definition and Classification of Congenital External Ear Anomalies

Malformations of the Auricle:

• Microtia (grades I–IV) — hypoplasia of the auricle;
• Anotia (or grade IV microtia) — complete absence of the auricle;
• Macrotia — enlargement of the auricle;
• Prominent ears — an auriculocephalic angle greater than 30°;
• Darwin’s tubercle — a rudimentary prominence of the auricle.

Malformations of the External Auditory Canal:

• Complete EAC atresia — absence of the EAC;
• Partial EAC atresia, or stenosis — narrowing of the EAC lumen to less than 4 mm in diameter.

Periauricular formations:

• Preauricular fistulas — blind-ending tracts with external openings located anterior to the auricle or on the helix;
• Preauricular skin tags, or accessory auricles — small nodular lesions located anterior to the auricle. They consist of skin outgrowths and may contain cartilage.

Embryology

Auricular development begins in the fifth week of gestation from the first and second branchial arches. During fetal development, three hillocks of His form from each of these arches. These hillocks subsequently fuse and, by week 22, form a complete auricle with its characteristic anatomical structures: the tragus, antitragus, crus of the helix, helix, scaphoid fossa, and antihelix. By 5–6 years of age, the auricle has almost reached its final size.

The EAC develops between weeks 12 and 28 of gestation. The ectodermal epithelium of the first branchial cleft, located between the first and second branchial arches, invaginates and forms the canal of the external auditory meatus.

Epidemiology

Congenital auricular anomalies occur in approximately 1 in 7,000–15,000 newborns. Of these cases, 85% are unilateral, and the right ear is affected in 60% of cases. The condition is 2–2.5 times more common in boys than in girls. There are also some ethnic variations: the prevalence of auricular deformities is higher among populations of Latin American, Asian, and Navajo ancestry.

Microtia is observed in 1 in 7000 live births, with type 3 microtia accounting for 75 % of cases. Grade III microtia is the most common form and accounts for 75% of cases. EACA develops in 1 in 10,000–20,000 neonates, with the condition being twice as common in males as in females. Additionally, atresia can be associated with microtia.

Prominent ears occur with a reported frequency of 0.5–15%. Among Europeans, the prevalence is approximately 5%. In 66% of cases, the condition is inherited in an autosomal dominant pattern with incomplete penetrance.

Preauricular fistulas occur at a rate of 15–43 cases per 100,000 people. In 27% of cases, they are inherited in an autosomal recessive pattern. Periauricular skin appendages are the most common external ear anomaly, with a prevalence of 5–10 : 1000 newborns.

Most congenital ear malformations are manifestations of genetic syndromes, including Konigsmark syndrome, Moebius syndrome, Treacher Collins syndrome, Down syndrome, and others.

Etiology and pathogenesis

Congenital anomalies of the external ear may result from genetic mutations, which account for approximately 15% of cases, or from exposure to teratogenic factors. In most cases, however, they are idiopathic. Teratogenic factors include substances that can affect the auricle include isotretinoin, thalidomide, and ethanol. As a result, atresia develops. Various etiological factors can lead to impaired epithelium invagination of the ectoderm of the first branchial cleft. Bony atresia of the canal is always secondary and is associated with malformations of the temporal bone. Microtia develops when fusion of the hillocks of His and formation of the auricle are impaired. Preauricular fistulas arise due to delayed migration of epithelial and cartilaginous tissue or excessive tissue proliferation. Preauricular skin tags develop when migration of one of the three hillocks of the first branchial arch is disrupted. They are typically located on the skin within a triangle formed by the angle of the mouth and the base of the auricle (between the helix and the lobule of the auricle).

Clinical Manifestations

Congenital anomalies of the external ear typically raise esthetic concerns and/or may affect an individual’s hearing. Changes in the size or position of the auricles, as well as periauricular lesions, may cause distress related to appearance. This is particularly common at 5–6 years of age, when peers begin to notice visible differences. All of this may trigger self-esteem issues and hinder social adjustment.

Grade III–IV microtia and EAC atresia are associated with varying degrees of hearing loss on the affected side. In unilateral disease, however, the condition may remain undetected for a long time because hearing is compensated by the unaffected ear. In unilateral EAC stenosis, hearing may be preserved, and external changes may be minimal or absent. These patients more often present to an ENT specialist because of cerumen impaction. This occurs because the anatomically narrow canal has impaired self-cleaning. In addition to cosmetic concerns, periauricular fistulas may become inflamed. When this occurs, pathologic discharge may be present, along with local tenderness and erythema.

Periauricular skin appendages may be located in the buccal region or anterior to the ear. They may vary in shape and can be spherical, lobulated, nodular, or ovoid. They do not cause functional impairment and are primarily an aesthetic concern.

Diagnosis of Congenital Anomalies of External Ear

Physical examination and instrumental assessment are used to establish the diagnosis. They provide extensive data on the location and extent of tissue damage, the nature and severity of hearing impairment, and the middle and internal ear structures affected (if any).

Physical Examination

The size and shape of the auricles are assessed, along with their position relative to the skull and the presence of additional periauricular lesions, such as fistulas or skin tags. Both auricles should be examined and compared with the contralateral side.

In grade I microtia, the auricle is reduced in size, but anatomical landmarks are preserved.

Grade II microtia is characterized by reduced size and deformity of the auricle, with some anatomical structures preserved.

In grade III microtia, the auricle consists of small rudimentary projections of cartilage and skin, often described as having a “peanut” shape.

In grade IV microtia, or anotia, the auricle is absent together with the external auditory canal. In rare cases, the canal may be preserved.

Protruding ears are characterized by an increased auriculocephalic angle (more than 30 °).

In macrotia, the vertical height of the auricle exceeds 6 cm.

The tubercle of Darwin is a rudimentary enlargement of the cartilage in the superior part of the helix.

Otoscopy

Otoscopy is used to determine whether the external auditory canal is present. Absence of the canal indicates complete external auditory canal atresia. If the canal is present, its size, shape, and the visibility of the tympanic membrane are assessed. Stenosis is diagnosed when the diameter of the widest part of the canal is less than 4 mm. The tympanic membrane is also assessed by its identifying edges, color, and transparency. In grade II–IV microtia, the external auditory canal may be atretic.

Physical Examination

Audiologic assessment includes pure-tone audiometry, tuning fork tests, auditory brainstem response testing, and otoacoustic emissions (OAE). These tests are used to determine the type and severity of hearing loss. In isolated EAC atresia, conductive hearing loss ranging from mild to severe is identified. Both ears should be evaluated.

CT of the Temporal Bones

This examination helps determine the severity of EACA, assess the condition of the middle and internal ear, and identify any additional abnormalities. CT findings are used to determine whether surgical correction is feasible using the Jahrsdoerfer grading system (see “Treatment of Congenital Anomalies of External Ear”). In unilateral disease, this examination is not recommended in children younger than 6 years because of the relatively high radiation exposure and the fact that surgical treatment is usually deferred.

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Treatment of Congenital Anomalies of External Ear

Regarding the severity of the condition, external ear anomalies may be addressed through the use of a prosthetic ear (external prosthesis), hearing aids, or surgery.

External Auditory Canal Atresia

Hearing Aids

EAC stenosis combined with conductive hearing loss may be corrected with behind-the-ear (BTE) or in-the-ear (ITE) devices. These aids amplify the audible signal and transmit it to the middle ear structures. Bone-anchored hearing aids (BAHA) are implanted in cases of complete EACA and conductive hearing loss.

Such devices consist of two parts. The first part is a titanium implant placed into the temporal bone. Over time, the bone integrates with the implant in a process known as osseointegration. The second component is a removable sound processor, which attaches to the implant and detects sound. The device transmits sound waves from the external environment directly to the cochlea receptors through the skull bone.

Children typically wear their BAHA with an elastic head band. In complete bilateral atresia, early hearing rehabilitation within the first 3–4 months of life is essential to support normal speech development and prevent speech delay.

Surgical Therapy

Surgical treatment of EAC atresia aims to restore normal anatomy. Meatal reconstruction, or canalplasty, is performed with tympanoplasty when necessary, either as a single-stage or staged procedure. When the condition is combined with malformations of the middle ear, the management strategy should be at physician’s discretion.

Indications:

• bilateral EACA (either complete or partial)
• Preserved cochlear function, with conductive hearing loss;
• Jahrsdoerfer score of at least 7 points. This is associated with the most favorable postoperative outcome; a score of 6 is considered borderline. The Jahrsdoerfer grading system is based on temporal bone CT findings on the affected side, with a maximum score of 10.

Jahrsdoerfer Grading System

Contraindications:

• unilateral atresia;
• age under 5–6 years

Step-by-Step Technique

The temporal bone is exposed through a postauricular or anterior approach. The temporal fascia is dissected and preserved. Facial nerve monitoring is recommended throughout the procedure. In complete EACA, a new pathway toward the tympanic cavity is created using a burr. Drilling continues until the canal reaches a diameter of 12 mm. Next, the preserved auditory ossicles are exposed. A thin layer donor cartilage and temporal fascia are laid over the malleus. At the same time, a full-thickness skin graft is harvested from the anterior thigh. After the new EAC has been created, the skin graft is placed circumferentially within the canal. It covers all exposed bone and the neotympanic membrane formed by the temporal fascia.

In a stenotic EAC, the canal is widened to the required diameter. The skin is harvested in advance to later cover the walls of the newly formed canal. Firm packing of the external auditory canal is applied for 10–14 days.

Outcomes

The procedure recreates the anatomical sound-conduction pathway and improves hearing.

Complications and Limitations

Restenosis may occur. In some cases, there is no meaningful improvement in hearing.

Microtia

In grade III–IV microtia, ectoprostheses are widely used as a nonsurgical treatment option. With this method, a silicone prosthesis is created using impressions of the unaffected ear and then placed at the site of the defect. The ectoprosthesis is matched as closely as possible to the patient’s skin color and texture. It may be attached with adhesive, clips, or magnets; the latter are implanted into the bone. This option is not age-limited, with material intolerance being the only contraindication. Its advantages include technical simplicity and a short treatment time.

Surgical correction of microtia involves auriculoplasty, or auricular reconstruction. During the procedure, a person’s own cartilage (autografting) or an artificial ear model is used to restore the auricle.

Indications

Grade III–IV microtia.

Contraindications

The minimum age for surgery is 5–6 years. By this age, the unaffected ear has nearly reached its final size, approximately 85%, making it possible to create a similar graft. The rib cartilage has also developed sufficiently by this stage.

Step-by-Step Technique

For autologous reconstruction, the first step is to create an impression of the unaffected ear. This will be used as a model for reconstructing the absent auricle. A 7–9 cm segment of the sixth, seventh, and eighth costal cartilages is harvested together with the perichondrium. The cartilage is shaped with sutures placed in different directions to create an auricular framework with anatomical curves, including the helix and antihelix. The skin in the temporal region, where the new auricle will be positioned, is carefully separated from the underlying tissues. The transplant is inserted into the pocket formed by the skin to reapproximate it.

The second stage happens 3–4 months later. The skin is incised along the posterior edge of the helix, and the auricle as well as the skin is separated along the medial surface, The structure is then positioned as needed. A full-thickness skin graft, harvested from the thigh region, is placed onto the posterior surface of the newly formed auricle and the resulting defect in the temporal region. A pressure dressing is applied to the postauricular area and should be changed regularly until full recovery. If needed, the tragus and external auditory canal are formed in subsequent stages.

When medical implants are used, they are placed at the intended site of the auricle and covered with a skin graft.

Outcomes

Auricular reconstruction creates a formed auricle and eliminates the visible cosmetic defect.

Complications and Limitations

Hypertrophic scarring and graft deformity may occur. Cellulitis or chondritis, though extremely rare. Another limitation is the difficulty of creating an exact replica of the unaffected ear.

Macrotia and Prominent Ears

Otoplasty is performed for macrotia and prominent ears.

Indications

Macrotia; prominent ears.

Contraindications

Significant concomitant medical condition; age younger than 6 years.

Step-by-Step Technique

The skin is dissected from the posterior surface of the auricle. Depending on the condition of the auricle, the cartilage is excised and/or sutured in different directions to create the required contours and shape. The skin is closed with a cosmetic suture. A pressure dressing is applied. If necessary, the procedure is repeated on the contralateral ear.

Outcomes

The procedure creates the desired auricular shape and eliminates the visible cosmetic defect.

Complications and Limitations

Hypertrophic scarring and auricular deformity may occur. Cellulitis or chondritis, though extremely rare.

Periauricular formations

Preauricular lesions, including fistulas and skin tags, are treated surgically by excision.

Indications

Concern about appearance; Recurrent inflammation of the fistulous tract.

Contraindications

Significant concomitant medical condition; Acute inflammation of the fistula.

Step-by-Step Technique

If a fistula is present, an elliptical skin incision is made around the external opening. The fistulous tract is excised along its entire length within healthy tissue. In some cases, a dye such as methylene blue may be injected to delineate the tract more clearly. The wound edges are closed with sutures. Skin tags are removed with a scalpel or laser.

Outcomes

The anatomical defect is eliminated.

Complications and Limitations

Incomplete removal of the fistulous tract may occur, followed by subsequent infection.