ECG of the Inner Ear: Establishment of the Short-pulse DPOAE for the Detection of Ototoxicity

• Applicant: Dr. Katharina Bader
• Subject Area: Otolaryngology, Phoniatrics and Audiology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469837692

To date, there is no international consensus on how to measure ototoxicity in a standardized way. In 2009, the American Academy of Audiology rated the determination of pure-tone audiometry (PTA), especially in the high-frequency range (HFA), and the measurement of DPOAE as the most reliable methods. In 2019, the “International Late Effects of Childhood Cancer Guideline Harmonization Group” in collaboration with the European “PanCare Consortium” issued a recommendation that includes history-taking, PTA (1 - 8 kHz), DPOAE and tympanometry for the evaluation of ototoxicity in children and adolescents. Ideally, monitoring should be performed using various methods, as individual methods are not sufficiently informative. Based on studies of moderate evidence, DPOAE and HFA detect changes in hearing earlier and more sensitively than PTA. In conventional DPOAE stimulation and analysis procedures, continuous primary tones are used, which do not distinguish between the two DPOAE components and DPOAE detection can be erroneously influenced by interference. At the ENT Clinic in Tübingen, the separation of the DPOAE components was established and further developed by analyzing the DPOAE signal in the time domain and using pulsed primary tones. So-called short-pulse DPOAEs allow a precise, time-efficient, and thus clinically applicable estimation of hearing thresholds (EDPTs) using semi-logarithmic growth functions. Recent studies have shown that using short-pulse DPOAEs and taking into account individually optimized stimulus levels of the primary tones in DPOAE level maps not only improve the accuracy but also lower the variability of EDPTs. As part of the funded project, we have significantly advanced DPOAE level maps as an analysis tool for the cochlear amplifier. For this purpose, we have characterized high-frequency DPOAEs, established and validated a modern IPL calibration procedure and developed an “intelligent” adaptive measurement algorithm. It is now essential to evaluate and, if necessary, adjust EDPTs based on DPOAE level maps in a hearing-impaired patients before they are applied in patients receiving radiochemotherapy. The aim of the proposed project is to assess the sensitivity of EDPTs compared to PTA and conventional DPOAEs, to quantify differences in amplitude and latency of the individual DPOAE components and to investigate longitudinal changes in DPOAE level maps and their parameters. If this is successful, short-pulse DPOAEs can serve as a time-efficient, easy clinically applicable tool for the inner ear, enabling the early and sensitive detection of degeneration or regeneration of the cochlear amplifier.

• DFG Programme: Research Grants
• Co-Investigator: Dr.-Ing. Ernst Dalhoff