title: Temporal bone histopathologic abnormalities associated with mitochondrial mutation T7511C.
abstract: OBJECTIVE
  We previously reported a mitochondrial T7511C mutation in the tRNA gene in a Japanese family with nonsyndromic hearing loss (HL). However, the temporal bone histopathology associated with T7511C has not been reported. The aim of the present study is to report histopathologic findings of a temporal bone from a patient in the Japanese family with this mutation.
  
  
  METHODS
  Single case study.
  
  
  METHODS
  A temporal bone was obtained from the right ear of a male subject with progressive HL from 5 years of age and who died at 60 years of age from cerebral infarction. The bone was embedded, sectioned, and stained with hematoxylin-eosin for light microscopic study. Graphic reconstruction of the cochlea was performed using the method described by Schuknecht to determine loss of the stria vascularis and neurosensory elements including hair cells and spiral ganglion neurons.
  
  
  RESULTS
  The most significant histopathologic finding was severe loss of spiral ganglion cells in all turns of the cochlea. Severe loss of neuronal filaments in Rosenthal's canal was also observed. The organ of Corti showed scattered loss of inner and outer hair cells in the basal turn. Partial atrophy of the stria vascularis was observed in all turns of the cochlea.
  
  
  CONCLUSIONS
  Our results suggest that severe loss of spiral ganglion cells was the main cause of sensorineural HL associated with the T7511C mutation.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Jichi Medical University School of Medicine, Shimotsuke, Tochigi, Japan. ishikawak@nidcd.nih.gov
authors.forename: Kotaro
authors.initials: K
authors.lastname: Ishikawa
authors.forename: Yuya
authors.initials: Y
authors.lastname: Tamagawa
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Takahashi
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Iino
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Murakami
authors.forename: Keiko
authors.initials: K
authors.lastname: Kakizaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kimura
authors.forename: Jun
authors.initials: J
authors.lastname: Kusakari
authors.forename: Akira
authors.initials: A
authors.lastname: Hara
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ichimura
mesh_terms: D001284:Atrophy; D006319:Hearing Loss, Sensorineural / Q000235:genetics / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000235:genetics; D009154:Mutation; D009925:Organ of Corti / Q000473:pathology; D013136:Spiral Ganglion / Q000166:cytology / Q000473:pathology; D013316:Stria Vascularis / Q000473:pathology; D013701:Temporal Bone / Q000473:pathology*; D014722:Vestibule, Labyrinth / Q000473:pathology