What is Microtia?
Children born with microtia have a congenitally small, malformed or absent external ear. Microtia is also associated with an absent or narrowed ear canal resulting in significantly decreased hearing. Microtia is seen on one side (unilateral) 90% of the time. Only 10% of children born with microtia have the condition on both sides. Microtia is an uncommon condition, and the frequency of microtia in newborns varies in different countries. Only one in 8,000 to 10,000 children is born with microtia in the United States every year. The incidence appears to be higher in Asia and certain Central and South American countries.
The Four Grades of Microtia
Grade 1: Small ear with mostly normal ear anatomy and often no canal or a narrow canal.
Grade 2: Characterized by some ear anatomy, including a developed tragus. The bottom 1/3 of the ear is usually normal, no ear canal or a narrow canal.
Grade 3: Most common form of microtia, characterized by small, undeveloped ear remnants and no canal.
Grade 4: Also referred to as anotia, no ear remnants or canal present.
Grade 1 Grade 2 grade 3
The cause of microtia is unknown. Because of the low incidence of microtia, it is usually not discovered on a prenatal ultrasound, and there is a family history of microtia in only a small percentage of families. It is important for parents to understand that there is nothing that you could have done differently during pregnancy to change your child’s condition. The good news is that, through medical technology, microtia can be successfully repaired, allowing you and your child to move forward and enjoy an excellent quality of life.
CONDITIONS ASSOCIATED WITH MICROTIA
All children with microtia have either Aural Atresia or Aural Stenosis. Atresia is the absence of an external ear canal and ear drum while stenosis refers to a narrowing of the canal and a small ear drum. With either atresia or stenosis, the ability to transmit sound to the inner ear is compromised and results in a significant hearing loss. While all children with microtia have aural atresia or stenosis, not all children with aural atresia or stenosis have microtia. When a child is born with microtia, it is usually an isolated finding. The great majority of children with microtia have no other abnormalities.
On rare occasions microtia occurs with other abnormalities as part of a syndrome. The most common condition associated with microtia is Hemifacial Microsomia, in which half the face does not grow in proportion to the other. The degree of hemifacial microsomia varies from barely perceptible (most common) to very noticeable (less common).
Treacher Collins Syndrome involves both ears and also affects the eyes, which appear to have a downward slant or “pulled down” appearance. The cheek bones are small and the eyelids and jaw are affected. Goldenhar Syndrome may involve one or both ears and is characterized by incomplete development of ear, nose, soft palate, lip and jaw. These children often have abnormalities of the neck bones as well as a benign tumor of the eye. There are also other less common syndromes where microtia may occur.