Pentoxifylline Maintains Cochlear Microcirculation and Attenuates Temporary Threshold Shifts Following Acoustic Overstimulation

Abstract

The etiology of noise-induced hearing loss is poorly understood despite years of clinical experience and experimental investigations. One potential mechanism which may contribute to noise-induced temporary threshold shifts (TTS) are vascular pathologies in the microcirculation of the cochlea. Several studies have demonstrated histologic evidence of reduced cochlear blood flow following noise exposure. Recent studies utilizing intravital microscopy (IVM) complement these histologic studies and furthermore demonstrate localized ischemia during noise exposure. the purpose of the current study was to attempt to maintain cochlear blood flow during noise exposure by treating with pentoxifylline, a xanthine derivative which promotes blood flow in capillary beds. the possibility that preserved cochlear microcirculation with pentoxifylline treatment attenuates noise-induced TTS was also examined in this study. the results show treatment with pentoxifylline maintains cochlear microcirculation as assessed by continuous red blood cell movement through capillaries. Pentoxifylline treatment did not prevent vasoconstriction or increased permeability often observed in the cochlear microvasculature during noise. Treatment with this drug reduced noise-induced TTS.

Key Words:

• inner ear blood flow
• pentoxifylline
• cochlear action potential
• intravital microscopy
• temporary threshold shift