Congenital anomalies of the inner ear may be considered in 2 broad categories: malformations with pathologic changes limited to the membranous labyrinth, and malformations that involve both the osseous labyrinth and the membranous labyrinth.
Development of the inner ear begins early during embryogenesis. By the end of the eighth week, the membranous labyrinth has reached its characteristic convoluted shape. Gradual ossification of the otic capsule develops around the membranous labyrinth and is essentially complete by birth.1 Maturation of the sensory epithelium occurs long after formation of the membranous labyrinth, during the late second and early third trimester. By the end of the 26th to 28th week of gestation, hair, cell, and auditory neural development are largely complete.
Imaging Quiz Case 3. Arch Otolaryngol Head Neck Surg. 2000;126(6):797-798. doi: