An unique patient population for clinical trials against noise-induced hearing loss

AbstractNoise is the number one occupational and environmental hazardand noiseinduced hearing lossNIHLis one common form of sensorineural hearing deficitonly second to age related hearing lossCurrently no drug preventing NIHL is approved by the United States Food and Drug AdministrationFDAOne major challenge for the introduction of such interventions is the need to identify appropriate human populations available for evaluating the effectiveness of new otoprotective agentsIn this STTR Phase I projectwe propose to determine the extent of hearing loss in unoperated ears of patients after drilling during skull based surgeryBased on our preliminary studieswe have reduced the variability of electrocochleography for detecting hearing lossBy working with our collaborators at Washington University School of Medicine in StLouisin two out three patientswe have detected temporal hearing threshold shifts in unoperated ears after the skull based surgeryA recent seminal discovery in animals revealed thateven without permanent threshold shifta loss of synapses between inner hair cells and spiral ganglion neurons in the inner ear is the primary pathology for NIHLThis form loss of synapses is called cochlear synaptopathyor hidden hearing lossSo farno longitudinal studies have been reported to confirm the existence of hidden hearing loss in people although two human studies implicated possibility of cochlear synaptopathy by comparing groups with different risks for noise exposureHerewe will continue to recruit qualified patients scheduled for skull based surgeryFunctional assayssuch as audiometric testingelectrocochleographydistortion product otoacoustic emissionsand the Words in Noise test with multi talker babble will be repeated on their unoperated ears before the surgeryone day and one month postsurgeryBy the project s endwe expect to quantify the extent of both temporary and permanent threshold shift in patientsand confirm the existence of hidden hearing loss in a certain percentage of these volunteersThe main innovative aspect of this study is to identify a new population with unavoidable noise exposure under a laboratory like setting using improved functional assaysIf successfulIn the STTR or SBIR Phase II projectwe will carry our FDA approved clinical trialNCTbased on this populationThusthis project will not only identify a new population for future clinical studies of new otoprotective agentsbut also the first epidemiological study of hidden hearing loss in this populationOur long term goal is to develop an effective medical intervention for NIHL Public Health Relevance Narrative By identifying a new population with unavoidable noise exposure under a laboratory like settingwe can effectively test new otoprotective agents to prevent noise induced hearing lossa major health issue for factory workerswith hearing lossand military personnel$billion to cover the claims by U SVeterans Administration