Introduction:
Aural atresia is a common defect in the absence of patent ear canals. It can be acquired or is congenital (present since birth). It is sometimes associated with microtia (a child born with a small or missing ear). The external ear canal is recanalized (hollowed out) by the six months of child development. Disturbance in this process results in external ear deformities. During the seventh month of birth, the formation of ear canals is completed, and the mastoid bone (part of the temporal bone located behind the ears) grows posteriorly (back) to separate from the mandible (lower jaw). Failure to separate the mastoid bone (absence of mastoid growth) with the lower jaw leads to aural atresia.
What Is the Prevalence of Aural Atresia?
Aural atresia accounts for one among 15,000 births in the general population. Approximately 50 percent of cases are associated with birth (congenital) abnormalities. It can affect one or both ears, but in 30 percent of cases, it is mostly bilateral (both ears). Males are more affected than females. The right ear is more frequently affected than the left ear.
What Are the Causes of Aural Atresia?
Causes of aural atresia are:
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Associated With Congenital (Birth) Abnormalities: Like Treacher Collin syndrome (a genetic disorder affecting teeth, jaw, and bones) or hemifacial microsomia (structural defects in jaws, eye sockets, and ears).
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External Ear Trauma: Like trauma to the ear during road accidents, gunshot injuries, or during surgery.
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Genetic Abnormalities: Due to deletion of gene 18q22.3.
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Hereditary: Parents with aural atresia have a high chance of having children with similar defects.
What Are the Types of Congenital (Inborn) Aural Atresia?
There are three types of inborn aural atresia based on development:
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Type A: Stenosis (narrowing) of the external ear canal, with a slightly deformed or small but intact tympanic membrane.
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Type B: Partial aural atresia (partial formation of bony and fibrocartilage membrane ear canal). The tympanic membrane is usually absent.
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Type C: Total aural atresia (the absence of ear canals with middle ear deformities).
What Are the Signs and Symptoms Associated With Aural Atresia?
Signs and symptoms of aural atresia are:
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Abnormal-looking external ears.
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Impaired speech.
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Delayed language development.
How Is Aural Atresia Diagnosed?
Diagnostic criteria for aural atresia are:
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History: A detailed history of recent trauma to the ears, past ear surgery, frequent external ear infections, and any person in the family with a similar disorder is recorded.
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Clinical Examination: A complete physical examination of the external ear is done by an ENT (ear, nose, and throat) specialist. The presence of any hearing impairment is ruled out. A thorough physical examination of a newborn in the first few days of life is done for any abnormalities in the development of jaws, head, eyes, spine, ears, and facial nerve function.
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Computed Tomographic (CT) Scans: These scans help to detect any abnormalities present in the inner and middle ear, such as facial nerve involvement, otic (ear) capsule defects, and ear bone connections (incus -stapes bone).
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Audiometry (Hearing Test): This is done to check the severity of hearing impairments.
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Speech and Language Assessment: This is done by a speech-language pathologist to check for any disturbances in speech and delays in language development.
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Brainstem Auditory Evoked Response (BAER): This is done to assess a child's response to sounds.
What Is the Treatment of Aural Atresia?
Various management criteria for aural atresia are:
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Headband Hearing Device: This device helps to transfer sound waves from the skull bone to the inner ears and is called a bone conduction sound processor (BCSP). It is given to children in the early stages of hearing loss in the first month of their life till the age of five to prevent speech and language development delay.
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Bone Anchored Hearing Device: These are the titanium devices that are surgically implanted (placed) by the surgeon behind the child's skull (back of ears). It helps in hearing by transfer of sound from the skull bone to the auditory nerve (hearing nerve). It is done at five years of age.
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Surgical Repair: Surgical treatment is usually indicated at the age of six to seven years of age. If present, Microtia (small ear) is treated first by the surgeon. Atresia repair (atresiaplasty) is then performed by creating the ear canal by drilling the atretic plate (abnormal or closed-ear) and forming an eardrum to improve hearing. After surgery, cosmetic reconstruction uses graft material like skin grafts from the thighs' and ribs' cartilage.
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Ossiculoplasty: Surgical repair of bony ear ossicles (tiny bones present in the middle ear- malleus, incus, and stapes) is done to improve hearing efficiency.
After six weeks of surgery, an audiogram is recommended for the patient to check for hearing improvement.
What Are the Complications That Can Occur After the Aural Atresia Repair Surgery?
Complications related to the surgery are:
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Temporomandibular joint dysfunction.
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Loss of taste sensation.
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Damage to the facial nerve.
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Hearing loss.
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Infection at the surgical site.
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Loss of balance.
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Dizziness.
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Vertigo (spinning sensation in the head).
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Restenosis (narrowing) of ear canals.
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Scarring of the surgical site.
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Failure of the graft material.
What Are the Differential Diagnosis for Aural Atresia?
Narrowing of the external auditory canal or congenital aural stenosis.
Conclusion:
Auricular atresia is a common disorder, but it affects both parents and the child emotionally or mentally in life. Auricular atresia (absence of ear canal) is acquired by ear trauma or congenital (inborn) head and face abnormalities. A mandatory assessment of the newborn for the presence of any skull or face deformities and an auditory brainstem test (hearing test) should be performed by an ENT (ear, nose, and throat) specialist. Surgical repair of aural atresia is a standard gold technique for treating impaired hearing loss and the physical appearance of the ear. The golden period of surgical procedure is at six to seven years of age, so hearing devices like hearing headbands or bone-anchored titanium devices are given to the child in their first few months of life till the age of five years to prevent delay of speech and language development in the child.
