Evoked otoacoustic emissions from normal newborns and babies admitted to an intensive care baby unit

Practicality, Validity, and Cost-Efficiency of Universal Newborn Hearing Screening Using Transient Evoked Otoacoustic Emissions

Although the importance of identifying significant hearing loss at an early age has long been recognized, it is generally acknowledged that newborn hearing screening programs in the United States have not been very successful. The problem has been that available techniques were impractical, too expensive, or invalid. This article summarizes the data regarding the use of transient evoked otoacoustic emissions (TEOAE) in a universal newborn hearing screening program and describes various facets of program implementation. It is concluded that available data provide clear evidence that TEOAE can be used to significantly reduce the average age of identification for hearing loss in the U.S.

Distortion evoked otoacoustic emission using GSI 70 analyzer for neonatal screening

OBJECTIVE

Following the recommendation of the United State National Institute of Health Consensus Conference in 1993, otoacoustic emissions (OAE) are now used internationally for hearing screening. The GSI 70 OAE screener provides the means for carrying out OAE recordings within a short period of time and includes an automatic evaluation of results. The aim of this study was to determine the reliability of recordings in comparison with available standards in brainstem audiometry.

METHOD

OAE recorded in 29 hearing-impaired suspected infants and young children (aged 1 months-7 years old) in order to compare the result of the GSI 70 screener with the result of ABR. This study was conducted in the outpatient clinic of the Tokyo University Hospital.

RESULT

Our study showed that the GSI 70 screener has higher false negative rate compared with ABR results (P<0.01). Consequently, an OAE measuring method, is also provides high sensitivity and easy to use. However, there was no trend toward increased refer rates with increased age.

CONCLUSION

Our findings show that the GSI 70 screener can meet the demands of systematic hearing screening in infants and young children, although there is a tendency to miss cochlear impaired cases.

A universal newborn hearing screening program in Taiwan

OBJECTIVE

Mackay Memorial Hospital and the Children's Hearing Foundation established a pilot universal newborn hearing screening program in November 1998. Our objective was to assess the feasibility, accuracy and cost effectiveness of implementing universal newborn hearing screening in Taiwan.

METHOD

Between November 1998 and October 2000 a total of 6765 newborns were screened for hearing loss prior to discharge from the wellborn nursery at Mackay Memorial Hospital. The average age of the subjects at the initial screening test was 52 h. The program employed a three stage hearing screening protocol using transient evoked otoacoustic emmisions (TEOAE) screening with referral for diagnostic auditory brainstem response assessment.

RESULTS

The mean TEOAE screening time per ear was 41.43 s. The overall pass rate at the time of hospital discharge was 93.6%. Thus achieving an acceptable referral rate of 6.4% for diagnostic audiological assessments. Nine newborns were identified with permanent bilateral hearing impairment. 26 newborns were identified with permanent unilateral hearing impairment. Infants identified with bilateral hearing loss were immediately referred to the Children's Hearing Foundation for hearing aid assessment and fitting. Infants as young as 5 weeks of age were successfully fitted with hearing instruments and enrolled in the family centered early intervention program at the Children's Hearing Foundation.

CONCLUSION

The frequency of bilateral congenital hearing loss requiring amplification in this population is shown to be approximately 1 in 752 newborns. This finding is consistent with previous research, which has indicated hearing loss to be the most frequently occurring birth defect. Universal newborn hearing screening using TEOAEs proved to be a cost effective and feasible method of identifying congenital hearing loss in Taiwan. The existence of many successful screening programs worldwide and the availability of fast, objective, reliable and inexpensive hearing screening procedures means that universal newborn hearing screening is becoming the standard of care.

Emissão otoacústica evocada transitória: instrumento para detecção precoce de alterações auditivas em recém-nascidos a termo e pré-termo

Introdução: O diagnóstico e a intervenção precoces nas alterações auditivas são de fundamental importância no desenvolvimento infantil. O registro das emissões otoacústicas tem sido largamente indicado, por ser um exame rápido, de fácil aplicação. Objetivo: Os objetivos do presente estudo foram avaliar a função auditiva periférica de recém-nascidos a termo e pré-termo adequados e pequenos para a idade gestacional, por meio da pesquisa das emissões otoacústicas transitórias, identificando a prevalência de alterações auditivas nesta população; verificar a influência das variáveis idade gestacional e peso ao nascimento, assim como de tipos de tratamento, ventilação mecânica, administração de medicamentos ototóxicos e permanência em incubadora e analisar os fatores que interferem nos programas de triagem auditiva neonatal. Forma de estudo: Clínico prospectivo. Material e método: Foram avaliadas 157 crianças, sendo 43 nascidas a termo, 79 pré-termo adequadas à idade gestacional e 35 pré-termo pequenas à idade gestacional. Resultado: Observou-se que recém-nascidos prematuros falham mais nas respostas das emissões otoacústicas. A prevalência de perda auditiva condutiva na população estudada foi de 29 orelhas para 1000 e para perda auditiva neurossensorial de 16 orelhas para 1000. As crianças de peso baixo ao nascimento foram as mais difíceis de serem avaliadas. As emissões otoacústicas transitórias foram observadas a partir de 27 semanas de idade gestacional. Os tipos de tratamentos utilizados foram fatores que influenciaram negativamente nas respostas das emissões otoacústicas nos grupos de prematuros. Conclusão: O trabalho de diagnóstico precoce da perda auditiva deve ser objetivo de equipe interdisciplinar -- neonatologista, pediatra, otorrinolaringologista, fonoaudiólogo, enfermeiro e familiares -- e deve ser seguido, imediatamente, por programas de intervenção precoce.

Identification of neonatal hearing impairment: transient evoked otoacoustic emissions during the perinatal period

OBJECTIVES

1) To describe transient evoked otoacoustic emission (TEOAE) levels, noise levels and signal to noise ratios (SNRs) for a range of frequency bands in three groups of neonates who were tested as a part of the Identification of Neonatal Hearing Impairment multi-center consortium project. 2) To describe the relations between these TEOAE measurements and age, test environment, baby state, and test time.

DESIGN

TEOAEs were measured in 4478 graduates of neonatal intensive care units (NICUs), 353 well babies with at least one risk indicator, and 2348 well babies without risk factors. TEOAE and noise levels were measured for frequency bands centered at 1.0, 1.5, 2.0, 3.0, and 4.0 kHz for a click stimulus level of 80 dB SPL. For those ears not meeting "passing" stopping criteria at 80 dB pSPL, a level of 86 dB pSPL was included. Measurement-based stopping rules were used such that a test did not terminate unless the response revealed a criterion SNR in four out of five frequency bands or no response occurred after a preset number of averages. Baby state, test environment, and other test factors were captured at the time of test.

RESULTS

TEOAE levels, noise levels and SNRs were similar for NICU graduates, well babies with risk factors and well babies without risk factors. There were no consistent differences in response quality as a function of test environment, i.e., private room, unit, open crib, nonworking isolette, or working isolette. Noise level varied little across risk group, test environment, or infant state other than crying, suggesting that the primary source of noise in TEOAE measurements is infant noise. The most significant effect on response quality was center frequency. Responses were difficult to measure in the half-octave band centered at 1.0 kHz, compared with higher frequencies. Reliable responses were measured routinely at frequencies of 1.5 kHz and higher.

CONCLUSIONS

TEOAEs are easily measured in both NICU graduates and well babies with and without risk factors for hearing loss in a wide variety of test environments. Given the difficulties encountered in making reliable measurements for a frequency band centered at 1.0 kHz, its inclusion in a screening program may not be justified.

Audiologic evaluation of neonates with severe hyperbilirubinemia using transiently evoked otoacoustic emissions and auditory brainstem responses

OBJECTIVES

To audiologically clarify the lesion site and to test the reliability of transiently evoked otoacoustic emissions (TEOAEs) in hearing screening of hyperbilirubinemic neonates.

STUDY DESIGN

Eleven neonates with severe hyperbilirubinemia who had exchange transfusion in the neonatal intensive care unit of an academic hospital over a 3-year period were included in this study. They were tested with auditory brainstem response (ABR) and TEOAEs after exchange transfusion during hospitalization or at an immediate follow-up visit after discharge. Follow-up ABR tests were performed when infants showed significant hearing loss.

METHODS

ABR and TEOAE tests were performed on the 11 neonates with severe hyperbilirubinemia after exchange transfusion. Follow-up ABR tests were carried out in 3-month intervals in the four neonates who showed abnormal or no response on initial ABR.

RESULTS

Four neonates showed abnormal or no response and the other seven demonstrated normal response in ABR. All 11 neonates passed TEOAEs. Two neonates showed improvement in auditory function at 3- or 6-month follow-up ABR.

CONCLUSION

The results of this study indicate that the site of lesion in hearing loss caused by hyperbilirubinemia may be at the retrocochlear location while the cochlea remains intact. TEOAEs may have limitations in evaluation of hearing in the neonates with hyperbilirubinemia.

Effects of middle ear effusion on transient evoked otoacoustic emissions in children

In order to assess the applicability of transient evoked otoacoustic emissions (TEOAEs) measurements on the sequential monitoring of children with middle ear effusion (MEE), the effects of MEE on TEOAEs response were investigated. TEOAEs responses were recorded on 56 ears of 33 patients before and after tympanostomy tube placement. In the 37 ears with MEE seen at myringotomy, the average band reproducibility below 2 kHz recovered significantly after tube placement, whereas the average band reproducibility at 5 kHz diminished. In the 19 ears without MEE, no significant changes in echo amplitude and band reproducibility were noted in the post-operative TEOAEs measurements compared with pre-operative ones. The results of this study suggest that an improvement in echo response and band reproducibility below 2 kHz in serial TEOAEs measurements may indicate resolution of MEE in children with otitis media with effusion.

Distortion-product otoacoustic emissions hearing screening in high-risk newborns

Universal infant hearing screening has recently been recommended by the National Institutes of Health. Otoacoustic emissions have been proposed as the first-level screening technique. Although transient evoked otoacoustic emissions have shown limited applications, distortion-product otoacoustic emissions hold promise as a screening technique but have not been fully investigated. The purpose of this study was to determine the validity of distortion-product otoacoustic emissions as a hearing screening technique. A total of 208 ears of 104 infants at risk for hearing loss were tested with both automated auditory brain stem response and distortion-product otoacoustic emission screening protocols. Acoustic brain stem response results were used as the standard for normal hearing. Distortion-product otoacoustic emission results were analyzed by means of calculation of the difference between the mean of the response levels and the mean of the noise floor levels from five frequency pairs between 2000 and 4000 Hz. Pass-fail rates for response above noise floor criteria of 5, 10, and 15 dB were examined. The sensitivity of distortion-product otoacoustic emissions was 50%, 67%, and 87%, and the specificity was 94%, 68%, and 38% at the 5, 10, and 15 dB levels, respectively. The pass-fail criterion of distortion-product otoacoustic emissions should be based on instrumentation calibration, infant status, and an acceptable false-positive, false-negative yield. The ability to test rapidly the hearing of all infants with distortion-product otoacoustic emissions points to the feasibility of using this test as a first-stage screen.

Evolution of transient evoked otoacoustic emissions in preterm newborns: a preliminary study

Transient evoked otoacoustic emissions (TEOEs) were recorded in a cohort study of preterm neonates in order to study their basic properties as a function of gestational age. Their main properties were: (1) TEOEs spectrum did not vary with age; it was analogous to those of full term; (2) there was no statistically significant variation of the TEOEs amplitude with age. The maturation of outer hair cell properties appears to be complete at a gestational age of 29 weeks. Because a number of infants at risk for hearing loss are preterm babies, screening for TEOEs has to be performed in the neonatal care unit. To improve the accuracy and efficiency of the test, screening should take place as close to hospital discharge as possible, with the optimum time at 35 gestational weeks.

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.

Universal screening for infant hearing impairment: simple, beneficial, and presently justified

In a recent article, Bess and Paradise (Pediatrics 93 (1994) 330-334) rejected the recommendation of the National Institutes of Health that all infants be screened for hearing loss on being released from their birthing hospital. This article responds to their objections with data from the literature and operational newborn hearing screening programs. These data show that universal newborn hearing screening is practicable, effective, cost-efficient, and safe, and concludes that such programs should be implemented without further delay.

Screening all newborns for hearing loss using transient evoked otoacoustic emissions

The importance of identifying hearing loss before 12 months of age is well established. Although recent research provides some evidence for the value of transient evoked otoacoustic emissions (TEOAEs) in newborn hearing screening, data are needed from large-scale clinical evaluations about the value of using TEOAE for screening high-risk and healthy babies. A cohort of 1850 infants from the well-baby nursery (WBN) and neonatal intensive care unit (NICU) were screened with TEOAE using a 2-stage process. Infants referred from the first stage prior to being discharged from the hospital were rescreened 4 to 6 weeks later. Those who did not pass the second-stage TEOAE screening were referred for diagnostic auditory brainstem response (ABR) and/or behavioral audiological evaluation for confirmation of hearing loss, fitting with amplification, and enrollment in early intervention programs. Eleven infants with unilateral or bilateral sensorineural hearing loss > 25 dB (a prevalence of 5.95 per 1000) and 37 with unilateral or bilateral recurrent conductive hearing loss > 25 dB (a prevalence of 20.0 per 1000) were identified from this cohort. These results suggest that TEOAE is a promising technique for screening newborns for hearing loss and should be evaluated further as a tool for universal newborn hearing screening.

The effects of noise in transient EOAE newborn hearing screening

The use of transient evoked otoacoustic emissions (TEOAEs) has been advocated as the first stage entry level technique for universal newborn hearing screening. To date, the majority of TEOAE infant testing has been conducted under controlled noise conditions; i.e., acoustically treated sound suites. As a result, previously reported TEOAE evaluations may not realistically represent test outcomes in actual hospital screening settings. The purpose of this study was to compare the results of TEOAEs with auditory brainstem response (ABR) hearing screening in a hospital environment where noise conditions do not meet the same ambient noise specifications as those found in sound rooms. A total of 119 stable newborns (67 high risk, 52 normal) ranging in post-conceptual age (PCA) from 33 to 41 weeks received both the ABR and TEOAE screening protocols. Testing was conducted at crib side in either the well baby nursery or the neonatal special care unit (NSCU). Newborn ABR screening failed 8 (3.8%) of 224 ears, whereas TEOAE testing failed 85 (38.4%) and could not test another 22 (9.8%) ears. That is, only 117 (52.2%) of the 224 ears passed the TEOAE test. Using the ABR as the reference test the specificity and sensitivity for TEOAE was 52% and 50%, respectively. Noise levels measured by the probe microphone within the ear canal exceeded those levels (30 dBA SPL) recommended for TEOAE newborn hearing screening. Results of this study suggest that under realistic hearing screening test conditions, TEOAE results may be influenced by the level of noise in the testing environment. Whereas significant advances have been attained in TEOAE measurement during the past decade, clinical evidence supports the need for continued research aimed at solving problems before this technique can be used efficiently for newborn screening.

Feasibility of otoacoustic emission detection followed by ABR as a universal neonatal screening test for hearing impairment

The feasibility of attempting a two-stage universal screening test for auditory impairment was assessed at a large district maternity hospital. The first stage was measurement of otoacoustic emissions using the Programmable Otoacoustic Emission Measurement System. Those failing the first stage proceeded to automated analysis of auditory brainsteam responses. A single tester working for 6 h on 6 days per week attempted to test all babies born between the hours of midday and midnight for 2 weeks and then all babies born between midnight and midday for a further 2 weeks. Of 217 babies born during the study periods, one infant died and three were still receiving intensive care at the end of the study. Of the remaining 213 infants, auditory testing was undertaken in 201 infants (94%). Eight infants (4%) who failed the first stage of the screening test did not undergo the second stage. Of those 193 infants completing the screen, one (0.5%) failed the screen unilaterally. There were no bilateral failures. Three testers, working two and a half whole-time equivalents, should be adequate to achieve a coverage of 90% and a specificity of 99% for this screen in this clinical setting.

Screening for hearing loss in an at-risk neonatal population using evoked otoacoustic emissions

The present study examines the performance of a transient evoked otoacoustic emissions hearing screening programme for neonates with risk factors for hearing loss. The programme has run for 5 years, and 772 babies with various risk factors have been screened using the Programmable Otoacoustic Emissions Measurement System (POEMS) designed by the Medical Research Council Institute of Hearing Research. Fourteen cases of significant hearing loss have been detected, with no false negative results. However, a very high false positive rate is reported, especially in babies with a birthweight of less than 1500 g.

Frequency analysis of transiently evoked otoacoustic emissions in sensorineural hearing disturbance

Transiently evoked otoacoustic emissions (TEOAE) are present in nearly all normal hearing ears and recognized as useful for objective auditory screening. In the spectral analysis of TEOAE with click stimuli, the normal power spectrum of TEOAE has yet to be obtained. In this study, the normal range of the power spectrum was determined for 42 adults with normal hearing and compared with sensorineural hearing disturbance data. The power spectrum of TEOAE in normal hearing adults sloped down at high frequencies and was the same for right and left ears in both males and females. For comparison with sensorineural hearing disturbance, a significant correlation between the audiogram and power spectrum of TEOAE was sought. Frequency specificity was noted in the power spectrum of TEOAE with click stimulation.

Otoacoustic emissions in the first year of life

Transient evoked otoacoustic emissions (TEOAEs) were successfully recorded in 192 ears of 100 consecutive full-term neonates tested on the third or fourth postnatal day. A follow-up study was performed in 35 of these infants at the ages of 3, 6 and 12 months. The number of infants presenting decreased linearly with postnatal age. TEOAE amplitudes were largest in the youngest age group. Both the time required for testing each infant and the number of ears in which TEOAEs could not be identified increased with age. Otomicroscopical changes indicating secretory otitis media were found in all the latter ears. Recording of TEOAEs is a suitable method for screening peripheral auditory function in infants, and can be most successfully performed at the age of 3 or 4 days.

Otoacoustic emissions: a new method to diagnose hearing impairment in children

Otoacoustic emissions (OAEs) are epiphenomena of sensitive, amplifying processes during hearing which can be detected in persons with normal inner ear function. They originate from the cochlea and are interpreted as an energy leakage of cochlear processes, perhaps resulting from active outer hair cell movements. OAEs travel from the cochlea through the middle ear to the external auditory canal where they can be detected using sensitive miniature microphones. Transient evoked (TEOAE) tests allow to otoacoustic emissions non-invasively check the integrity of the cochlea. In the neonatal period, registration of OAEs can be accomplished during natural sleep. In infants and neonates TEOAEs can be used as screening test with a screening level at 30 dB HL in paediatric audiology. They are less time consuming and elaborate than auditory brainstem responses (ABR) and they are more sensitive than behavioral tests. TEOAEs are constant over long periods of time and they are reduced or absent due to various adverse influences in the inner ear. These latter characteristics may allow monitoring of the inner ear function over time e.g. during disease and/or during ototoxic therapeutic interventions. Limitations of this new method are due to the fact that TEOAEs are absent in patients with a more than 30 dB HL hearing loss. Thus a hearing threshold cannot be determined. Diseases of the inner ear which are common in early childhood (like otitis media) reduce the transfer of TEOAEs and may wrongly indicate a cochlear hearing disorder. New methods for evaluation and interpretation of TEOAE test results are currently developed which may allow to circumvent this problem.(ABSTRACT TRUNCATED AT 250 WORDS)

Using transient evoked otoacoustic emissions for neonatal hearing screening

The Rhode Island Hearing Assessment Project was developed to determine the feasibility of establishing a valid cost-effective method of screening newborn hearing through a universal early identification programme. In a sample of 1850 infants, sensorineural hearing loss was identified in 11 infants using transient evoked otoacoustic emissions (TEOAEs). A second sample of 1451 infants showed similar trends in hearing loss identification. TEOAE was shown to have significant potential as a newborn screening tool when used in a carefully designed hospital-based early identification programme.

Development of neurosensory structures in the human cochlea

The present paper summarizes the main stages in the maturation of the cochlear neurosensory structures in humans. New trends in the field of the functional development of the cochlea, as well as some recent experimental data are also discussed.