An individualized, sensitive frequency range for early detection of ototoxicity

Objective: The aim of this study was to identify auditory frequencies at wh ich serial threshold testing would provide the greatest sensitivity for ear ly detection of ototoxicity. The overall objective is to develop a more tim e-efficient ototoxicity monitoring protocol. Design: Threshold data were analyzed from 370 hospitalized patients treated with aminoglycoside antibiotics (AMGs) or cisplatin (CDDP) who received se rial auditory monitoring before, during, and after treatment at conventiona l (0.25 to 8 kHz) and high (9 to 20 kHz) frequencies. Results: For patients showing hearing changes due to ototoxicity, a frequen cy range was identified for its apparent high sensitivity to initial ototox icity. This sensitive range is identified according to an individual's hear ing threshold configuration, and is, therefore, unique for each patient. Th e range consists of five frequencies, generally separated by 1/6 octave, e. g., 8, 9, 10, 11.2, and 12.5 kHz. To determine frequencies and combinations of frequencies that were most often involved in ototoxicity detection, thr eshold data in the sensitive range were analyzed in detail. This analysis s uggests that patients receiving treatment with AMG or CDDP can be monitored for hearing thresholds at only five frequencies, resulting in an 84% detec tion rate for AMG and 94% for CDDP compared with monitoring at all conventi onal and high frequencies. Conclusions: This comprehensive analysis supports earlier observations that a sensitive, limited frequency range exists in which serial threshold moni toring will provide early warning of ototoxicity before effects in the spee ch frequency range. This finding is now being evaluated in a prospective in vestigation.