Phenotyping Noise Induced Hearing Loss with Audiometry and DPOAEs - PowerPoint Presentation

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Phenotyping Noise Induced Hearing Loss with Audiometry and DPOAEs

Ishan Bhatt, Ph.D., NAUSusan L. Phillips, Ph.D., UNCGMohsin Ahmed Shaikh, Ph.D. candidate, UNCG

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Disclosure

Dr. Susan Phillips, Mr. Mohsin Ahmed Shaikh and I have no relevant financial or nonfinancial relationships to disclose.The material presented today is based on audiometric and otoacoustic emissions (OAEs) data collected from the School of Music, University of North Carolina at Greensboro. The study was approved by the Institutional Review Board, UNCG (11-0335).

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Key Factors in Noise-induced Hearing Loss

Globally growing hearing health concernNIHL is a complex disorderSome individuals are more susceptible than others

Gene

Environment

Gene-environment

interaction

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Importance of Phenotyping NIHL

Success of gene mapping lies on the ability to define the target phenotype (i.e. trait of a disease) with accuracy and precision

(

Schulze & McMahon, 2004)

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Early Efforts: Phenotyping NIHL

Definition: Absolute audiometric thresholds at high frequencies (3 to 8 kHz)Industrial populationConfounding variables

(Sliwinska-Kowalska & Pawelczyk, 2013; Van Laer et al., 2006)

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Recent Efforts: Phenotyping NIHL

Definition: Bilateral audiometric notch within 4 to 6 kHzCollage-aged student musiciansBetter control over confounding variables

(Phillips et al., 2012

)

Potential NIHL Phenotypes

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Purpose of the Study

To evaluate the 4-6 kHz audiometric notch using a test battery of Distortion-Product Otoacoustic Emissions (DPOAEs) Hypothesis: Musicians with 4-6 kHz audiometric notch will exhibit reduced DPOAEs compared to musicians without the notch

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Method

Sample77 musicians 18-31 yearsNormal otoscopic examination and tympanometric findingsDPOAE measured in the left earOnline SurveyPrimary instrumentsParticipation in ensembles Exposure to music

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DPOAE Test Battery

DPOAE I/O function (ILO 292-II V6): 2 f1 - f2 DP frequency at 2, 3, 4 and 6 kHz L2 ranging from 75 to 30 dB SPL in 5 dB stepsFormula-based approach: L1 = (0.4)L2+392f1 - f2 DPgram was measured from 2 to 8 kHz in 9 data points/octave with L1 and L2 were 60 and 40 dB SPL respectively

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Statistical Analysis

Repeated measure ANOVAWithin subject factors: 10 DP data points, Between subject factors: Audiometric groups and music exposureCovariate: Gender

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Results

55/77(23 females and 32 males) participants completed survey18/55 showed 4-6 kHz audiometric notch5/55 showed high frequency drop

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Results continue…

DPOAE I/O function:Main effect of exposure to music was statistically significant (p= 0.029)Main effect of audiometric groups was not statistically significant (p>0.05)

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Main effect of music exposure: DPgramFrequency range (2-4 kHz): F (3, 44) = 4.78, p= 0.006Frequency range (4-8 kHz): F (3, 44) = 2.884, p= 0.046Main effect of audiometric groups: No statistically significant effect found

Results continue…

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DPgram

: 2-8 kHz (9 data points/octave)

DPOAEs in 3 Audiometric Configurations

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Discussion

No effect of audiometric configurations on DPOAEsObservation can be attributed to: DPOAE recording limitations and/or Physiological basis

Standing Waves in the Ear Canal

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Damage to

Stria

Vascularis

Elevated audiometric thresholds and comparatively better DPOAEs

Damage to OHCs

Elevated audiometric thresholds and comparatively poor DPOAEs

(Mills, Norton, &

Rubel

, 

1993; Gates

et al., 2002)

(

Bhagat

et al., 2010; Hofstetter, Ding, Powers, & Salvi, 1997; Ozturan, Jerger, Lew, & Lynch, 1996)

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Conclusion

Musicians with higher music exposure are likely to show reduction in DPOAE amplitudeFurther research in required to investigate DPOAEs in musicians with the 4-6 kHz audiometric notch

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Future Research

DPOAE recording using advance calibration techniqueA well-defined control group of non-musicians may improve sensitivity of the future studiesAnimal study to validate potential sub-phenotypesValidate the music exposure survey

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References

Bhagat, S. P., Bass, J. K., White, S. T., Qaddoumi, I., Wilson, M. W., Wu, J., & Rodriguez-Galindo, C. (2010). Monitoring carboplatin ototoxicity with distortion-product otoacoustic emissions in children with retinoblastoma. International Journal of Pediatric Otorhinolaryngology, 74(10), 1156-1163.Gates, G. A., Mills, D., Nam, B. H., D'Agostino, R., & Rubel, E. W. (2002). Effects of age on the distortion product otoacoustic emission growth functions. Hearing Research, 163(1-2), 53-60.Hofstetter, P., Ding, D., Powers, N., & Salvi, R. (1997). Quantitative relationship of carboplatin dose to magnitude of inner and outer hair cell loss and the reduction in distortion product otoacoustic emission amplitude in chinchillas. Hearing Research,112(1-2), 199-215.Mills, D. M., Norton, S. J., & Rubel, E. W. (1993). Vulnerability and adaptation of distortion product otoacoustic emissions to endocochlear potential variation. Journal of The Acoustical Society of America, 94(4), 2108-2122. Ozturan, O., Jerger, J., Lew, H., & Lynch, G. R. (1996). Monitoring of cisplatin ototoxicity by distortion-product otoacoustic emissions. Auris Nasus Larynx, 23, 147-151.Phillips, S. L., Mace, S. T., Richter, S. J., Morehouse, R., Henrich, V. C. (2012). Genetic Bases of Noise Induced Hearing Loss. Podium presentation at the American Auditory Society conference, Scottsdale, Arizona, March.Schulze, T.G., McMahon, F.J. 2004. Defining the phenotype in human genetic studies: Forward genetics and reverse phenotyping. Hum. Hered., 58, 131-138.Sliwinska-Kowalska, M., & Pawelczyk, M. (2013). Contribution of genetic factors to noise-induced hearing loss: a human studies review. Mutation Research, 752(1), 61-65.Van Laer, L., Carlsson, P., Ottschytsch, N., Bondeson, M., Konings, A., Vandevelde, A., & Dieltjens, N. (2006). The contribution of genes involved in potassium-recycling in the inner ear to noise-induced hearing loss. Human Mutation, 27(8), 786-795.

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