Clinical assessment of auditory dysfunction.

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.