Arpornchayanon, Warangkana; Canis, Martin; Suckfuell, Markus; Ihler, Fritz; Olzowy, Bernhard; Strieth, Sebastian
Modeling the Measurements of Cochlear Microcirculation and Hearing Function after Loud Noise.
In: Otolaryngology -- Head and Neck Surgery, Vol. 145, Nr. 3: S. 463-469
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.
Study Design: 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 ± 4.2dB SPL (60 minutes) only in animals exposed to loud noise.
Conclusion: 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.