title: Modeling the measurements of cochlear microcirculation and hearing function after loud noise.
abstract: OBJECTIVE
  Recent findings support the crucial role of microcirculatory disturbance and ischemia for hearing impairment especially after noise-induced hearing loss (NIHL). The aim of this study was to establish an animal model for in vivo analysis of cochlear microcirculation and hearing function after a loud noise to allow precise measurements of both parameters in vivo.
  
  
  METHODS
  Randomized controlled trial. Setting. Animal study. Subjects and Methods. After assessment of normacusis (0 minutes) using evoked auditory brainstem responses (ABRs), noise (106-dB sound pressure level [SPL]) was applied to both ears in 6 guinea pigs for 30 minutes while unexposed animals served as controls. In vivo fluorescence microscopy of the stria vascularis capillaries was performed after surgical exposure of 1 cochlea. ABR measurements were derived from the contralateral ear.
  
  
  RESULTS
  After noise exposure, red blood cell velocity was reduced significantly by 24.3% (120 minutes) and further decreased to 44.5% at the end of the observation (210 minutes) in contrast to stable control measurements. Vessel diameters were not affected in both groups. A gradual decrease of segmental blood flow became significant (38.1%) after 150 minutes compared with controls. Hearing thresholds shifted significantly from 20.0 ± 5.5 dB SPL (0 minutes) to 32.5 ± 4.2 dB SPL (60 minutes) only in animals exposed to loud noise.
  
  
  CONCLUSIONS
  With regard to novel treatments targeting the stria vascularis in NIHL, this standardized model allows us to analyze in detail cochlear microcirculation and hearing function in vivo.
authors.affiliation: Walter Brendel Center for Experimental Medicine, University of Munich, Munich, Germany.
authors.forename: Warangkana
authors.initials: W
authors.lastname: Arpornchayanon
authors.forename: Martin
authors.initials: M
authors.lastname: Canis
authors.forename: Markus
authors.initials: M
authors.lastname: Suckfuell
authors.forename: Fritz
authors.initials: F
authors.lastname: Ihler
authors.forename: Bernhard
authors.initials: B
authors.lastname: Olzowy
authors.forename: Sebastian
authors.initials: S
authors.lastname: Strieth
mesh_terms: D000818:Animals; D001309:Auditory Threshold; D003051:Cochlea / Q000098:blood supply* / Q000503:physiopathology / Q000648:ultrastructure; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D006168:Guinea Pigs; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis*; D008144:Loudness Perception / Q000502:physiology; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008856:Microscopy, Fluorescence; D009622:Noise / Q000009:adverse effects*; D011897:Random Allocation; D018709:Statistics, Nonparametric