Congenital Microtia - microtia (micro = small, otia = ear), a birth defect, is an abnormal condition that involves the growth of the external ear. The deformity can vary from minor abnormalities of the helical ear folds to a marked absence of ear development. The presence of a small remnant tag of skin and cartilage may be the only indication of the presence of an external ear. It can be unilateral (occurring on one side only in 90% of patients) or bilateral (occurring on both sides in the other 10%). They occur more in males and are more frequent on the right side.

Typically, a classic microtia deformity has only a vestige of ear remnant present with an earlobe that is malpositioned with external ear canal present. In some patients, however, the ear deformity occurs together with other facial deformities. The most common syndrome where microtia occurs with other anomalies is called hemifacial microsomia which is a variable deformity that can involve the ear, the bones of the face, the fullness of the cheek tissue and the function of the facial nerve. Other syndromes where microtia may be present are Treacher Collins and Goldenhar syndromes.

Most children with severely microtic ears also have atresia of the external ear canal. Aural atresia refers to the absence or incomplete formation of an external ear canal. In most patients, microtia and aural atresia occur as an isolated condition. Patients with microtia and aural atresia do not have normal hearing on that side but may have completely normal hearing in the other ear. Atresia of the external ear canal may also occur in children with normal auricles. The overall incidence of atresia varies in different countries. Atresias may be unilateral or bilateral. Frequently there may be associated middle ear deformities but usually the inner ear anatomy is normal due to separate embryologic development.

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