In the literature, the term Mondini's deformity describes virtually any malformation of the bony labyrinth short of complete aplasia. Mondini described this anomaly in cases of congenital deafness in which the cochlea was dilated and contained only one to one and a half turns. [1,2] Should inner ear development be interrupted between the fourth and fifth weeks of gestation---after differentiation of the auditory placode into the otocyst, but before division of the latter into the primordium of the cochlea, vestibule, and semicircular canals--a "common cavity" forms that has no internal architecture (figure). [2] In these cases, hearing loss is usually profound.
References
(1.) Jackler RK, Luxford WM, House WF. Congenital malformations of the inner ear: A classification based on embryogenesis. Laryngoscope 1987;97(Suppl 40):2-14.
(2.) Swartz JD, Harnsberger HR. The otic capsule and otodystrophies. In: Swartz JD, Harnsberger HR. Imaging of the Temporal Bone. 2nd ed. New York: Thieme Medical Publishers, 1992:192-246.
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