title: Otopathology in Osteogenesis Imperfecta.
abstract: BACKGROUND
  Osteogenesis Imperfecta (OI) is a genetic disorder of connective tissue matrix. OI is caused by mutations that affect type I collagen. The hearing loss in OI is characterized by onset in early adulthood and can be conductive, sensorineural, or mixed.
  
  
  OBJECTIVE
  To describe the temporal bone histopathology in 9 individuals with OI.
  
  
  METHODS
  Four adult, 1 pediatric, and 4 infant specimens were identified. Temporal bones were removed at autopsy and studied using light microscopy.
  
  
  RESULTS
  All adults and 1 pediatric specimen showed otosclerotic lesions. The findings included examples of clinical, histologic, and cochlear otosclerosis. The temporal bones of infants showed delayed ossification of the endochondral layer of bone and of the ossicles. There were no infant specimens with otosclerotic lesions.
  
  
  CONCLUSIONS
  Hearing loss in OI may be the result of clinical or cochlear otosclerosis. Fracture or atrophy of the ossicles may also be present in OI. A third unidentified mechanism of hearing loss may lead to cochlear degeneration. The described findings of otosclerotic lesions have implications for the observed heterogeneity of hearing loss patterns and for the surgical management of hearing loss in OI.
authors.affiliation: Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA. felipe_santos@meei.harvard.edu
authors.forename: Felipe
authors.initials: F
authors.lastname: Santos
authors.forename: Andrew A
authors.initials: AA
authors.lastname: McCall
authors.forename: Wade
authors.initials: W
authors.lastname: Chien
authors.forename: Saumil
authors.initials: S
authors.lastname: Merchant
mesh_terms: D000328:Adult; D001284:Atrophy; D002648:Child; D002675:Child, Preschool; D003051:Cochlea / Q000473:pathology; D004429:Ear Ossicles / Q000473:pathology; D005260:Female; D050723:Fractures, Bone / Q000473:pathology; D034381:Hearing Loss / Q000209:etiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009925:Organ of Corti / Q000473:pathology; D010013:Osteogenesis Imperfecta / Q000150:complications* / Q000473:pathology*; D010040:Otosclerosis / Q000209:etiology* / Q000473:pathology*; D010046:Oval Window, Ear / Q000473:pathology; D012042:Registries; D012405:Round Window, Ear / Q000473:pathology; D012444:Saccule and Utricle / Q000601:surgery; D013136:Spiral Ganglion / Q000473:pathology; D013201:Stapes Surgery; D013701:Temporal Bone / Q000473:pathology*