Atresia and microtia
This lack of development of the external ear canal is called congenital atresia. It is a birth defect and is often accompanied by abnormalities of both the middle ear bones as well as the external ear.
Another birth defect is microtia, which is an abnormal growth or under-development of the external ear. Microtia can vary from a minor abnormality to a small tag of skin or cartilage being the only indication of the ear being there. Microtia often occurs along with atresia, but atresia can also appear isolated and in this case the external ear looks normal except for lacking the ear canal.
In most cases of atresia, a bony plate separates the external ear from the rest of the ear, which results in hearing loss. In cases of complete atresia there is no external ear canal present, but a complete obstruction of the external opening by skin. Other cases of atresia may demonstrate a small, undeveloped external ear canal which is narrower and much thinner than normal.
In some cases, surgery may be an option. This depends on a range of different aspects and normally the operation does not take place until the child is about four years old. An alternative to surgery is a bone implantable hearing aid, which bypasses the obstruction in the ear canal.