Assessment of cisplatin-induced ototoxicity using derived-band ABRs

Ototoxicity is an adverse side effect of numerous therapeutic agents (amino-glycoside antibiotics, blood chelating agents, diuretics and oncologic drugs) used in treatment of both adult and pediatric patients. Recently, there has been increasing interest in using the auditory brainstem response (ABR) to detect both short-term effects of ototoxicity in adults and long-term effects of drug administration on neonates and children. Since click ABRs have relatively poor frequency selectivity they best approximate the pure-tone hearing threshold in the 2000-4000 Hz frequency range. Hearing loss above or below that frequency range can be present without producing significant abnormalities in the ABR waveform parameters. Frequency-specific ABRs can be obtained using the derived response technique. The purpose of this study was to investigate early cisplatin ototoxicity using both the broadband click and derived ABR and to monitor progressive hearing loss with repeated drug trials in 18 patients studied over a 2-year period. ABRs were obtained serially prior to and following intravenous administration of cisplatin. Derived ABRs were found to be more sensitive than broadband click ABR in detecting early high-frequency hearing loss. For click ABRs, the cumulative dosage of cisplatin at age of ABR examination was correlated with hearing loss in only those patients under 3 years of age. No significant correlation was found between cumulative cisplatin dosage when tested and degree of hearing loss in those patients over 3 years of age.