Clinical assessment of auditory dysfunction.

Abstract

Many drugs, chemical substances and agents are potentially toxic to the human auditory system. The extent of toxicity depends on numerous factors. With few exceptions, toxicity in the auditory system affects various organs or cells within the cochlea or vestibular system, with brain stem and other central nervous system involvement reported with some chemicals and agents. This ototoxicity usually presents as a decrease in auditory sensitivity, tinnitus and/or vertigo or loss of balance. Classical and newer audiological techniques used in clinical assessment are beneficial in specifying the site of lesion in the cochlea, although auditory test results, themselves, give little information regarding possible pathology or etiology within the cochlea. Typically,, ototoxicity results in high frequency hearing loss, progressive as a function of frequency, usually accompanied by tinnitus and occasionally by vertigo or loss of balance. Auditory testing protocols are necessary to document this loss in auditory function.

Ototoxicity: An Argument for Evaluation of the Cochlea in Safety Testing in Animals

“…In contrast, albino and hooded rats are responsive to sounds of up to 70 kHz (11), and dogs are responsive up to 60 kHz (20). To compound this issue further, ototoxicants typically have a degree of frequency specificity, often affecting the higher frequencies before progressing to the lower frequencies (24). This high-frequency sensitivity has motivated development of highfrequency audiometry in human clinical medicine (4,7,9).…”