Incomplete partition of the cochlea type II Mondini defect The triad of incomplete partition of the cochlea type II, dilation of the vestibule, and an enlarged vestibular aqueduct was previously referred to as a Mondini malformation but this nomenclature is no longer recommended. It is important to note that while reading the related literature, it is often not easy to understand if the authors use the correct terminology, so even in recent studies, the term Mondini should be considered with caution. Mondini dysplasia With incomplete partition II, the cochlea consists of 1.5 turns; the apical and middle cochlea turns are undifferentiated and form a cystic apex. The vestibule is normal while the vestibular aqueduct is always enlarged. Developmental arrest occurs at the seventh week of gestation. Mondini malformation Cochlear malformation defect (Mondini dysplasia) UMLS:C1857078 HP:0000376 UMLS:C4025857 Incomplete partition of the cochlea