title: Cochlear nucleus neuron analysis in individuals with presbycusis.
abstract: OBJECTIVE
  The aim of this study was to analyze the cochlear nucleus neuron population in individuals with normal hearing and presbycusis.
  
  
  METHODS
  Retrospective study of archival human temporal bone and brain stem tissues.
  
  
  METHODS
  Using strict inclusion criteria, the temporal bones and cochlear nuclei from six normal hearing individuals and four individuals with presbycusis were selected for analysis. The spiral ganglion cell population, the cochlear nucleus neuron population, and the cell body size of the neurons were quantified in these cases.
  
  
  RESULTS
  A relationship was not observed between age and the spiral ganglion cell population in the normal hearing group. Presbycusis subjects exhibited a reduced spiral ganglion cell population. The mean cochlear nucleus neuron population was observed to be significantly higher in the presbycusis group (mean ± standard deviation: 114,170 ± 10,570) compared to the normal hearing group (91,470 ± 9,510) (P = .019). This difference was predominantly the result of greater multipolar and granule cell neuron populations. Only the fusiform neuron type exhibited a significantly different mean cell body cross-sectional area between the normal hearing group (242 ± 27) and the presbycusis group (300 ± 37) (P = .033).
  
  
  CONCLUSIONS
  This investigation is the first time, to our knowledge, that the populations of the eight neuron types in the cochlear nucleus have been quantified in both normal hearing individuals and individuals with presbycusis. The data support the concept that presbycusis is not an effect of aging alone but instead may be a condition that predisposes one to hearing loss with advancing age and is characterized by a congenitally elevated cochlear nucleus neuron population.
authors: Section of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Chicago, Chicago, Illinois 60637-1447, USA.
authors: Raul
authors: R
authors: Hinojosa
authors: Erik G
authors: EG
authors: Nelson
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001299:Audiometry / Q000379:methods; D001344:Autopsy; D016022:Case-Control Studies; D016923:Cell Death / Q000502:physiology; D016922:Cellular Senescence / Q000502:physiology*; D017626:Cochlear Nucleus / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000473:pathology; D011304:Presbycusis / Q000473:pathology* / Q000503:physiopathology; D012016:Reference Values; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013136:Spiral Ganglion / Q000473:pathology*; D055815:Young Adult