Duplication anomaly of the external auditory canal involving the middle ear

According to the embryology of external auditory canal .（EAC）, Karmodyl classified the anomalies of the first cleft inio four categories, depending on the degree of the development of the EAC, which are aplasia, atresia, stenosis, and duplication. Traditionally, the term ＂first cleft anomaly＂ has been limited to duplication anomaly of the EAC in most of the literatures. In the duplication anomaly, the EAC is present and is usually well formed.