Osteogenesis imperfecta of the temporal bone and its relation to otosclerosis

Osteogenesis imperfecta (OI) designates a heterogeneous group of heritable disorders of connective tissue that in addition to bone may affect tendons, ligaments, fascia, skin, sclerae, blood vessels, teeth, and hearing. The current classification identifies at least four major syndrome groups or types. It also recognizes a considerable number of additional syndromes that may represent supplementary types or subgroups. Loss of hearing is the least constant of the prominent features of OI. Its incidence varies between 26% and 60%. In OI, formation and remodelling of bone are variously affected. In the temporal bone the development of the inner ear capsule may be involved severely. In the stapes the disturbance in lamellar bone formation can lead to extreme thinness, dehiscence, and nonunion of the stapedial superstructure with the footplate. Osteogenesis imperfecta can be associated with otosclerosis, another bone dysplasia with a different morphology. Otosclerosis, in turn, may interfere with sound conduction and perception. Thus, the hearing loss encountered in OI may be the result of OI, otosclerosis, or a combination of both.