Congenital Abnormalities of the Ear
Your child may be born with an abnormality involving the ear. This may include an underdeveloped outer ear MICROTIA, a narrowing of the ear canal CANAL STENOSIS, or complete absence of the ear canal AURAL ATRESIA.
Because the inner ear and ear bones form early (first trimester), most patients with outer ear deformities do not have inner ear deformities or nerve deafness. Creation of the outer ear canal begins about 7 months (in utero) and takes place from the inside out. Therefore, any interruption in this process can create a problem on the outside with normal hearing on the inside.
Microtia is a term used to describe underdevelopment of the outer ear. There are four grades of Microtia. Grade 1 looks like a normal ear with some mild changes. (Figure 1)
Grade 2 usually consists of a curved mass of tissue (Figure 2). Grade 3 involves only a small amount of bumps of tissue (Figure 3). Grade 4 is anotia or lack of any tissue.
Microtia can be surgically repaired by a plastic surgeon and is done prior to any surgical repair of canal stenosis or atresia. This is usually a multi-stage repair and may involve using rib cartilage and skin grafts. This repair is performed about 5 years of age.
When the ear canal fails to completely develop during the 7th month in utero, the result is a very narrow ear canal. This leads to difficulty in examining the ear, collection of wax and debris in the canal and hearing loss. Canal stenosis is repaired by widening the canal by CANALPLASTY.
Aural atresia occurs in about 1:10,000 to 20,000 live births. It occurs on one side almost 2:1 and is more common in males. The appearance in sporadic although in may occur in association with a known syndrome. Some of the more common syndromes include: Hemifacial microsomia, Treacher-Collins, Goldenhar, Trisomy 22, Fanconi’s, Klippel-Feil, Crouzon’s, DiGeorge, and others.
Because aural atresia occurs after inner ear development, most ( ›80%), patients have normal nerve hearing but have a maximum conductive hearing loss because bone separates the inner ear from the outside sound.
Repair of aural atresia should take place after the outer ear is repaired if this is necessary.
This usually occurs about age 5 since the outer ear is close to full size. Surgery for repair of aural atresia is outlined in Surgeries We Perform.
Thomas M. Andrews
Dr. Andrews specializes in the medical and surgical treatment of ear, nose and throat disorders of children and adolescents. His accreditations include Florida State Medical License and Ohio State Medical License. He is also a board member of the National Board of Medical Examiners and American Board of Otolaryngology, Head and Neck Surgery