Microtia is a congenital deformity where the auricle (external ear) is underdeveloped. A completely undeveloped pinna is referred to as anotia. Because microtia and anotia have the same origin, it can be referred to as microtia-anotia. Microtia can be unilateral (one side only in most cases, usually the right ear) or bilateral (affecting both sides). Microtia occurs in 1 out of about 8,000–10,000 births.
Classification
According to the Altman-classification, there are four grades of microtia:
- Grade I: A less than complete development of the external ear with identifiable structures and a small but present external ear canal
- Grade II: A partially developed ear (usually the top portion is underdeveloped) with a closed stenotic external ear canal producing a conductive hearing loss.
- Grade III: Absence of the external ear with a small peanut-like vestige structure and an absence of the external ear canal and ear drum. Grade III microtia is the most common form of microtia.
- Grade IV: Absence of the total ear or anotia.
