Clinical application of otoacoustic emissions: what do we know about factors influencing measurement and analysis?

Exploring the effects and mechanisms of organophosphorus pesticide exposure and hearing loss

Many environmental factors, such as noise, chemicals, and heavy metals, are mostly produced by human activities and easily induce acquired hearing loss. Organophosphorus pesticides (OPs) constitute a large variety of chemicals and have high usage with potentiate damage to human health. Moreover, their metabolites also show a serious potential contamination of soil, water, and air, leading to a serious impact on people's health. Hearing loss affects 430 million people (5.5% of the global population), bringing a heavy burden to individual patients and their families and society. However, the potential risk of hearing damage by OPs has not been taken seriously. In this study, we summarized the effects of OPs on hearing loss from epidemiological population studies and animal experiments. Furthermore, the possible mechanisms of OP-induced hearing loss are elucidated from oxidative stress, DNA damage, and inflammatory response. Overall, this review provides an overview of OP exposure alone or with noise that leads to hearing loss in human and experimental animals.

Auditory function and prevalence of specific ear and hearing related pathologies in the general population at age 70

Objective: To describe the auditory function in early old age in detail based on both psychoacoustic and physiological measures, and to investigate the prevalence of specific audiological and otological pathologies.Design: An unscreened subsample from a population-based geriatric investigation was examined with otoscopy; tympanometry; pure-tone audiometry; word-recognition-in-noise test; distortion-product otoacoustic emissions; and auditory-evoked brainstem responses. Audiometric subtypes and diagnoses were established based on set criteria. The association between word scores and ABR was examined with linear regression analysis.Study Sample: 251 persons aged 70 (113 men, 138 women, born in 1944) that were representative of the inhabitants of the city of Gothenburg.Results: The prevalence of conductive pathology was 2% versus 49% for cochlear and 2% for auditory-neural pathology. Four percent had indeterminate type. Cochlear dysfunction was present in the majority of ears and around 20% performed worse-than-expected on speech testing. Poor performance on the speech in noise test was associated with prolonged interpeak latency interval of ABR waves I-V.Conclusion: Specific otological and audiological pathologies, other than cochlear hearing loss, are rare in the general population at age 70. Additionally, there is subtle evidence of age-related decline of the auditory nerve. Longitudinal follow-up would be of great interest.

An evaluation of hearing in infants administered with colistin in the premature neonatal intensive care unit

AIM

The aim of this study was to investigate the effects of colistin on hearing by evaluating the otoacoustic emission tests and clinical auditory brainstem responses in preterm infants treated with colistin in the neonatal intensive care unit.

METHOD

The study included 30 neonates (male: n = 16, female: n = 14) born before 37 weeks who were admitted to the Neonatal Intensive Care Unit at the Kahramanmaras Sutcu Imam Medical Faculty between January 2014 and January 2015 and who were treated with colistin during their time in intensive care because of infection. A control group was formed consisting of 30 preterm infants (male: n = 18, female: n = 12) with no additional disease born in the hospital during the same period. Following an ear, nose and throat examination the distortion product otoacoustic emission test, transient evoked otoacoustic emission and clinical auditory brainstem response tests were applied to all 60 patients.

RESULTS

The otoacoustic emission responses obtained from the control group were positive and clinical auditory brainstem responses up to 15 dB were obtained. In the colistin group negative otoacoustic emission responses were obtained in two patients unilaterally and in one patient bilaterally and loss was observed at the thresholds in the clinical auditory brainstem response test. Significantly prolonged fifth wave latency was observed in the colistin group compared to the control group for the clinical auditory brainstem response at 15 dB.

CONCLUSIONS

Given that the study results showed unilateral hearing loss in two patients and bilateral hearing loss in one as well as latency at 15 dB, hearing tests to check for ototoxicity are recommended for patients given colistin.

Possible Ototoxic Effects of Topical Rifamycin Application: An Electrophysiological and Ultrastructural Study

Objective

This study aimed to investigate possible ototoxicity associated with topical rifamycin application via electrophysiological tests and ultrastructural examinations.

Methods

Electrophysiological assessment was performed with tympanometry, auditory brainstem response (ABR), and distortion product otoacoustic emission (DPOAE) measurements. This study was conducted on 40 ears of 20 guinea pigs that were detected to have normal hearing thresholds. The animals were randomly assigned to three groups: Group 1 (n=12) received 0.1 mL rifamycin, Group 2 (n=8) received 0.1 ml gentamycin, and Group 3 (n=20) received 0.1 mL physiological saline. The antibiotics and saline solutions were administered via intratympanic injections. After five injections every other day, electrophysiological tests were performed again on the 15th day. After electrophysiological measurements, the temporal bones of all guinea pigs were prepared for ultrastructural examinations and the cochlear surface morphology was examined by scanning electron microscopy (SEM).

Results

The animals in group 3 did not show a statistically significant change in their DPOAE signal/noise ratio (SNR) or ABR thresholds (p>0.05). In groups 1 and 2, the reduction in the DPOAE SNR and the increase in the ABR threshold were statistically significant (p<0.05). Regarding SEM examination results, the animals in groups 1 and 2 showed statistically significant outer hair cell damage and cochlear degeneration due to the ototoxic effect of the drugs (p<0.05), whereas the animals in group 3 showed no significant damage (p>0.05).

Conclusion

The results indicate that rifamycin application to the middle ears of guinea pigs has mild ototoxic effects on their inner ears.

Transiently evoked otoacoustic emissions in children with otitis media with effusion

Introduction. Otitis media with effusion is a common pediatric disease whose diagnosis is based on pneumatic otoscopy, pure-tone audiometry, and tympanometry. The aim of this study was to evaluate transiently evoked otoacoustic emissions in the diagnosis of otitis media with effusion as compared to tympanometry. Patients and Methods. 38 children with bilateral otitis media with effusion were studied. 40 normal children of similar age and sex were used as controls. All subjects underwent pneumatic otoscopy, standard pure-tone audiometry, tympanometry, and transiently evoked otoacoustic emissions. Results. In the group of children with bilateral otitis media, transiently evoked otoacoustic emissions were absent in 51 ears (67%). In the remaining 25 ears (33%) the mean emission amplitude was reduced, as compared to the mean value of the control group. Conclusions. Transiently evoked otoacoustic emissions should be included in the diagnostic workup of otitis media with effusion because it is a fast, reliable, and objective test. Transiently evoked otoacoustic emissions should always be used in conjunction with tympanometry, because a more meaningful interpretation of transiently evoked otoacoustic emissions measures is possible.

Otoacoustic emissions and tympanometry in a general adult population in Sweden: Emisiones otoacústicas y timpanometría en la población general adulta de Suecia

The present study concerns a general adult population in Sweden, not exposed to hazardous occupational noise. Tympanometry and spontaneous (SOAE), transient evoked (TEOAE) and distortion-product (DPOAE) otoacoustic emissions were investigated in 493 randomly selected men and women aged from 20 to 79 years. Effects of gender, age, ear side and middle ear state were determined, with and without adjusting for hearing threshold level. No statistically significant effects on middle ear pressure or compliance were present. For TEOAEs and DPOAEs, the effect of gender and age was statistically significant (p < 0.01), with larger signal levels for female subjects and young subjects, even after adjusting for hearing threshold level. No effect of middle ear pressure on otoacoustic emissions was present, but high middle ear compliance was associated with low emission levels (p < 0.01). Reference data for middle ear compliance and pressure and prevalence data on SOAEs, TEOAEs and DPOAEs for male and female subjects in different age groups were determined. Mean signal levels of TEOAEs and DPOAEs are presented.

Occupational hearing loss: screening with distortion-product otoacoustic emissions

Hearing assessment of applicants for occupational hearing loss compensation can be a time-consuming process. An accurate screening procedure that is sensitive to occupational hearing loss may have application in many situations. The present study developed distortion-product otoacoustic emission (DPOAE) screening criteria to identify subjects likely to meet the Hong Kong requirements for occupational hearing loss compensation, namely a bilateral sensorineural loss > or = 40 dB HL (average of 1000, 2000 and 3000 Hz). The screening criteria of 1500 and/or 2000 Hz, with a signal-to-noise ratio of > 0 or 3 dB, yielded high sensitivity and specificity. DPOAE measures therefore have the potential to accurately indicate possible occupational hearing loss. However, DPOAEs should be used as a screening tool only, as conventional puretone audiometry remains the more comprehensive measure of hearing sensitivity.

Transient evoked otoacoustic emissions in the elderly

The purpose of this study was to analyse the changes in transient evoked otoacoustic emissions (TEOAEs) with age. We studied 232 subjects above 60 years of age with a battery of audiological tests, including TEOAEs Our criterion for the presence of TEOAEs was based on a cut-off at overall wave reproducibility 55% or overall response level 4 dB SPL. The prevalence of TEOAEs in left ears was 55.6%. No TEOAEs were found in subjects with a pure-tone average (PTA) above 40 dB HL. In the subgroup with TEOAEs, a significant decrease in overall wave reproducibility with age was found. We compared 45 normal-hearing elderly subjects with TEOAEs with a control group of 20 normal-hearing young adults The elderly had significantly lower mean overall response levels and mean overall wave reproducibility. Average hearing level was significantly higher in the elderly than in controls We conclude that the prevalence of TEOAEs decreases with age, and that the overall response level and overall reproducibility decrease with age. This decrease may not be seen in isolation from the increase in hearing threshold level.

Transient evoked otoacoustic emissions in patients with middle ear disorders

The aim of this study is to investigate the middle ear dynamic characteristics and their influence on TEOAEs in patients with middle ear disorders. The middle ear dynamic characteristics and TEOAE findings were investigated in 89 patients with middle ear disorders using the sweep frequency impedance (SFI) meter and the ILO88 system, respectively. These patients were divided into six subcategories: tympanic membrane aberrations, otitis media with effusion, chronic otitis media, tympanic membrane perforation, otosclerosis, and ossicular chain dislocation. Details of the TEOAE frequency characteristics were compared with the individual's middle ear dynamic characteristics. TEOAE status as a function of hearing threshold and middle ear dynamic characteristics was also examined. The results showed that the middle ear dynamic characteristics in patients with middle ear disorders correlated with the TEOAE frequency characteristics and amplitudes. The hearing level and middle ear mobility were the controlling factors affecting TEOAE status. Using both non-linear and linear stimulus modes, larger TEOAE responses were obtained when the hearing level was better than 20 dB HL, and there was moderately good middle ear mobility. Moreover, TEOAEs were absent using the non-linear mode when the hearing level was worse than 30 dB HL, whereas with the linear mode. TEOAEs were recordable even with hearing losses of up to 40 dB HL in patients with middle ear disorders. A higher incidence of recordable TEOAEs was found in the subgroups with tympanic membrane abnormalities and secretory otitis media when compared with the other subgroups. No TEOAEs were recordable in patients with chronic otitis media.

Otoacoustic emissions and tympanometry in children with otitis media

OBJECTIVE

To examine otoacoustic emission and tympanometric findings in children with surgically confirmed middle ear effusion (MEE).

DESIGN

A total of 102 children aged 0.7 to 11.4 yr undergoing surgery because of otitis media were included in the study. A tympanometric examination and transient evoked otoacoustic emission (TEOAE) measurement were performed on each ear before myringotomy. MEE was aspirated, weighed and classified as mucoid or nonmucoid. TEOAE measurements were compared with the quantity and quality of MEE and to the tympanometric findings.

RESULTS

Fifty (72%) ears out of the 65 ears containing effusion showed reduced TEOAE. The quantity of effusion was associated significantly (p < 0.001) with the TEOAE responses, and mucoid effusion reduced the emissions more than nonmucoid. The sensitivity of tympanometry in identifying the ears without recordable TEOAE was 73% and the specificity 81%.

CONCLUSION

MEE results in a significant reduction in TEOAEs even when the effusion is nonmucoid. This suggests that transmission of acoustic energy to and from the middle ear is altered in children experiencing any form of otitis media with effusion.

Influence of age and presbyacusis on DPOAE

The influence of presbyacusis on distortion-product otoacoustic emissions (DPOAEs) was studied on 180 ears of 96 normal-hearing subjects. The subjects' ages were distributed equally and ranged from 14 to 82 years. It was shown that there is a highly significant decrease in DPOAE amplitudes during the ageing process. By means of special statistical procedures, such as partial correlation and multiple regression, it was proved that the main reason for this is deterioration in pure-tone thresholds. However, other age-related effects were determined and were also found to lead to a further decrease in DPOAE amplitudes. The latter might be due to middle ear alterations in elderly people. Knowledge of the influence of presbyacusis on DPOAE is important if DPOAEs are to be used in expert assessment of inner ear disorders, for example, occupational noise-induced hearing loss.

Clinical applications of transiently evoked otoacoustic emissions in the pediatric population

Our objectives were 1) to determine whether transiently evoked otoacoustic emissions (TEOAEs) are affected by the status of the tympanic membrane (TM) and middle ear (ME) as determined by clinical examinations and tympanograms; 2) to determine the efficacy of TEOAEs in detecting hearing loss; and 3) to determine the relative effects of the ME status and hearing loss on TEOAEs. In a prospective observational study in a tertiary care children's hospital, 89 patients (169 ears; 9 ears eliminated from analyses) were examined by 2 attending pediatric otolaryngologists for otologic conditions and underwent audiologic evaluations including TEOAEs from August 1994 through May 1995. The main outcome measures were presence or absence of TEOAE whole reproducibility (WR) and reproducibility (R) at 2 kHz. Statistical analyses showed that of the 8 ME and TM conditions evaluated (normal, TM perforation, pressure equalization [PE] tube, TM retraction, tympanosclerosis, TM atrophy, ME effusion, surgery other than PE tube insertion), only the presence of ME effusion and normal examination findings had a significant effect on the results of WR and R at 2 kHz. Of the 6 different types of tympanograms evaluated (A, B, C, AD, As, B with large volume), type A, B, and C tympanograms had a significant effect on WR and types A and B had a significant effect on R at 2 kHz. Hearing losses > or = 25 dB hearing level (HL) at any of the 5 frequencies (0.25, 0.5, 1, 2, and 4 kHz) were well predicted by the absence of WR and R at 2 kHz. When clinical examination and impedance data were evaluated simultaneously with hearing status, hearing status had a greater effect on WR and R at 2 kHz. We conclude that type B and C tympanograms and the presence of ME effusion (which reflect abnormal ME status) have an adverse effect on TEOAEs. However, the presence of hearing loss is the most significant predictor of TEOAE results. The TEOAE WR and R at 2 kHz are effective in identifying patients with normal hearing and with hearing losses > or = 25 dB HL.

Transient evoked otoacoustic emissions: feasibility in the nursery

OBJECTIVE

To assess the feasibility of obtaining transient-evoked otoacoustic emissions (TEOAEs) directly in the nursery, to examine the nature of failures in this population, and to determine the time requirements for this test relative to the auditory brain stem response (ABR).

DESIGN

TEOAEs and ABRs were recorded from 149 ears, at bedside, in the recovery or intensive care nursery. Subjects were selected according to the risk criteria developed by the Joint Committee on Infant Hearing (1991). Parametric and nonparametric statistical procedures were conducted to describe demographics and test results, to evaluate TEOAE measures by subgroups, and to compare infants by pass/fail outcome. Multivariate techniques were applied to the data to test implicit hypotheses regarding the source of TEOAE failures. In addition, the time required to carry out each test was evaluated in an analysis of variance design.

RESULTS

63.5% of the ears studied passed both procedures, 5% failed both, and 31.5% passed the ABR but failed the TEOAE. Although infants who failed the TEOAE had lower birthweights, shorter gestational periods, and were younger at the time of testing, no statistical differences were found for nursery (intensive care nursery/recovery), bed type (isolette/open crib), ear (left/right), or gender. Infants < 38 wk postconceptional age had smaller TEOAE responses and lower noise levels than did those > 37 wk. There were no differences in environmental noise levels (at the microphone) for passed or failed ears or whether infants were in isolettes or open cribs. Statistically prolonged ABR wave I latencies (Z-scores) at 60 and 30 dB among infants who passed the ABR but failed the TEOAE indicated some obstruction to the acoustic stimulus, whereas TEOAE noise measures neither distinguished these groups nor identified this condition. Three summary times involved in the performance of these tests were obtained: (a) actual test time, measured from start to completion of data collection with a stopwatch; (b) total test time, defined by the actual test time plus the respective preparation, setup, and cleanup (ABR) time; and (c) time reported by the computer system during intrinsic sampling. There were no significant differences in actual or total test times, but these values were distinguished from the machine time, which represented an underestimate of the time required to effectively conduct each test.

CONCLUSIONS

These findings show that TEOAEs can be acquired in the nursery, but the high false-positive rate suggests that alternative or additional screening methods, for example, the ABR, must also be available. It must be recognized that TEOAE failures increase test time, thereby negating any savings relative to ABR screening alone.