Anotia / Microtia
Anotia (an-NO-she-uh) means absence of the external ear. Microtia (my-KRO-she-uh) is the term for an incompletely formed external ear. Aural atresia is the absence of the ear canal.
Early in fetal life (about the 5th week) the complex process of development causes cells to move to the correct position for ear formation. If this process is interrupted for any reason, then the ear will not form correctly.
There are 4 types of microtia. Type I microtia is the term for a smaller-than-normal ear that has most of the components of a non-affected ear. The ear canal may or may not be present and functional. Type II microtia describes an ear that has some of the features of the external ear (usually the top portion is underdeveloped) with a closed external ear canal producing a conductive hearing loss. Type III is the term for microtia involving a vertical skin appendage at the location of the ear, with a vestige of a lobule at the lower end and some amount of cartilage tissue at the upper end. No ear canal is present. Type III is the most common form of microtia. Type IV is anotia.
In most instances the children with microtia will have normal inner ears and sensory structures, causing conductive (rather than sensory) loss.
This is a relatively common group of disorders, occurring in 1 of every 6,000-12,000 live births. Our program has been tracking anotia/microtia among live births in select counties since 2005 and are gradually expanding statewide.
- Using data from births to Hennepin and Ramsey county residents 2007-2011, we found that 1.3 babies were born with anotia/microtia per 10,000 births.
- Using this data, we estimate about 10 babies are born with anotia/microtia every year in Minnesota.
Treatment may depend on the severity of the condition. Early intervention for hearing loss is important for maximizing communication outcomes.
Parental education and support are essential, and local, regional and national organizations may be very helpful.
Condition specific organizations
- Minnesota Department of Health - Hearing Loss
- CDC Hearing Loss in Infants and Children
- CDC Facts about Anotia/Microtia