Effect of neonatal test environment on recording transient-evoked otoacoustic emissions

Transient Otoacoustic Emissions and Auditory Brainstem Responses in Low-Risk Cohort of Newborn and One-Month-Old Infants: Assessment of Infant Auditory System Physiology in the Prenatal Alcohol in SIDS and Stillbirth Network Safe Passage Study

BACKGROUND

The Prenatal Alcohol and Sudden Infant Death Syndrome and Stillbirth Network, known as the "Safe Passage Study," enrolled approximately 12,000 pregnant women from the United States and South Africa and followed the development of their babies through pregnancy and the infant's first year of life to investigate the role of prenatal alcohol exposure in the risk for sudden infant death syndrome (SIDS) and adverse pregnancy outcomes, such as stillbirth and fetal alcohol spectrum disorders.

PURPOSE

Auditory system tests were included in the physiologic test battery used to study the effects of prenatal alcohol exposure on neurophysiology and neurodevelopment, as well as potential causal relationships between neurodevelopmental disorders and SIDS and/or stillbirth. The purpose of this manuscript is to describe normative results when using the auditory test battery applied.

RESEARCH DESIGN

The test battery included the auditory brainstem response (ABR) and transient-evoked otoacoustic emissions (TEOAEs). Data were collected on individual ears of newborns and 1-month-old infants.

STUDY SAMPLE

From a cohort of 6,070 with auditory system exams, a normative subsample of 325 infants were selected who were not exposed prenatally to alcohol, cigarette smoke, or drugs nor were they preterm or low birthweight. The subsample is small relative to the overall study because of strict criteria for no exposure to substances known to be associated with SIDS or stillbirth and the exclusion of preterm and low birthweight infants. Expectant mothers were recruited from general maternity at two comprehensive clinical sites, in the northern plains in the United States and in Cape Town, South Africa. These populations were selected for study because both were known to be at high-risk for SIDS and stillbirth.

DATA COLLECTION AND ANALYSIS

ABR and TEOAE recordings were stored electronically. Peak latency and amplitude analysis of ABRs were determined by study personnel, and results were evaluated for differences by age, sex, test site, race, and ear (left versus right).

RESULTS

TEOAE findings were consistent with existing literature including the increase in signal-to-noise (SNR) over the first month of life. The SNR increase is due to an increase in amplitude of the emission. TEOAE amplitude asymmetry favoring the right ear was found, whereas SNR asymmetry was not, perhaps because of the small sample size. A nonsignificant trend toward larger responses in female babies was found; a result that is generally statistically significant in studies with larger samples. Latencies were found to be shorter in ABRs elicited in the right ear with amplitudes that were slightly bigger on average. An expected decrease in wave V latency was observed from birth to 1-month of age, but the finding was of borderline significance (p = 0.058).

CONCLUSIONS

One month is a short time to judge development of the auditory system; however, the ABR and TEOAE findings were consistent with current literature. We conclude that the auditory system data acquired for the Safe Passage Study, as reflected in the data obtained from this cohort of "unexposed" infants, is consistent with published reports of these auditory system measures in the general population.

Identifying the Optimal Age to Perform Newborn Screening for Hearing Loss in Uganda

Background:

Permanent congenital hearing loss affects up to 6/1000 births in developing countries. Currently, in Uganda there is no newborn screening for hearing loss (NSHL) program and no published work on this topic. Within the existing healthcare system there are two opportunities to deliver screening, at birth or 6 weeks of age when infants receive their immunizations.

Aim:

This study explored the outcomes of otoacoustic emission (OAE) testing in infants at birth and 6 weeks of age, to identify the optimal age for screening.

Subjects and Methods:

This cross-sectional pilot study recruited 60 consecutive infants from two health centres in Kampala, Uganda. Thirty infants were newborns recruited from the postnatal ward and 30 were aged 4–8 weeks from the immunization clinic, we performed OAE testing on all infants.

Results:

The results showed 56.7% (17/30) of newborn infants passed OAE testing compared with 90.0% (27/30) of the immunization infants, P < 0.01. Furthermore, of the 11 newborn infants aged ≥24 h of age 90.9% (10/11) passed, compared with the 19 infants <24 h of age where 37% (7/19) passed, P < 0.01.

Conclusions:

This study demonstrates a higher pass rate for OAE testing for infants ≥24 h of age compared to those <24 h of age. The overall lower pass rate of the newborn infants could be due to external ear debris and middle ear fluid compromising the OAE testing. These findings would support a NSHL programme in Uganda that offers screening to infants ≥24 h of age, to maximize the cost-effectiveness of the program.

Otoacoustic emissions in newborn hearing screening: a systematic review of the effects of different protocols on test outcomes

BACKGROUND AND OBJECTIVES

Otoacoustic emission (OAE) tests are currently used to screen newborns for congenital hearing loss in many Universal Newborn Hearing Screening programs. However, there are concerns about high referral and false-positive rates. Various protocols have been used to address this problem. The main objective of this review is to determine the effects of different screening protocols on the referral rates and positive predictive values (PPV) of the OAE newborn screening test.

METHODS

Eligible studies published in English from January 1990 until August 2012 were identified through searches of MEDLINE, Medline In-Process, Embase, PubMed (NCBI), ISI Web of Science, and the Cochrane Central Register of clinical controlled trials. Two reviewers independently screened the data sources, using pre-defined inclusion criteria to generate a list of eligible articles. Data extracted included the number of newborns screened, age at screening, OAE pass criteria, frequencies screened, number of retests, referral rates, and the number of newborns identified with permanent congenital hearing loss.

RESULTS

Ten articles met the inclusion criteria, with a total of 119,714 newborn participants. The pooled referral rate was 5.5%. Individual referral rates ranged from 1.3% to 39%; the PPV from 2 to 40%. Increasing the age at initial screening and performing retests reduced the referral rate. Likewise, screenings involving higher frequencies had lower referral rates.

CONCLUSION

Delaying newborn hearing screening improves test results but may not be practical in all contexts. The use of higher frequencies and more sophisticated OAE devices may be useful approaches to ensure better performance of the OAE test in newborn hearing screening.

Effects of background noise on recording of portable transient-evoked otoacoustic emission in newborn hearing screening

Transient-evoked otoacoustic emission (TEOAE) is a well-established screening tool for universal newborn hearing screening. The aims of this study are to measure the effects of background noise on recording of TEOAE and the duration required to complete the test at various noise levels. This study is a prospective study from June 2006 until May 2007. The study population were newborns from postnatal wards who were delivered at term pregnancy. Newborns who were more than 8-h old and passed a hearing screening testing using screening auditory brainstem response (SABRe) were further tested with TEOAE in four different test environments [isolation room in the ward during non-peak hour (E1), isolation room in the ward during peak hour (E2), maternal bedside in the ward during non-peak hour (E3) and maternal bedside in the ward during peak hour (E4)]. This study showed that test environment significantly influenced the time required to complete testing in both ears with F [534.23] = 0.945; P < 0.001 on the right ear and F [636.54] = 0.954; P < 0.001 on the left. Our study revealed that TEOAE testing was efficient in defining the presence of normal hearing in our postnatal wards at maternal bedside during non-peak hour with a specificity of 96.8%. Our study concludes that background noise levels for acceptable and accurate TEOAE recording in newborns should not exceed 65 dB A. In addition, when using TEOAE assessment in noisy environments, the time taken to obtain accurate results will greatly increase.

Hospital-based universal newborn hearing screening for early detection of permanent congenital hearing loss in Lagos, Nigeria

OBJECTIVE

To determine the feasibility and effectiveness of hospital-based universal newborn hearing screening programme for the early detection of permanent congenital or early-onset hearing loss (PCEHL) in Lagos, Nigeria.

METHODS

A cross-sectional pilot study based on a two-stage universal newborn hearing screening by non-specialist health workers using transient evoked otoacoustic emissions (TEOAE) and automated auditory brainstem-response (AABR) in an inner-city maternity hospital over a consecutive period of 40 weeks. The main outcome measures were the practicality of screening by non-specialist staff with minimal training, functionality of screening instruments in an inner-city environment, screening coverage, referral rate, return rate for diagnosis, yield of PCEHL and average age of PCEHL confirmation.

RESULTS

Universal hearing screening of newborns by non-specialist staff without prior audiological experience is feasible in an inner-city environment in Lagos after a training period of two-weeks. Notwithstanding excessive ambient noise within and outside the wards, it was possible to identify a test site for TEOAE screening within the hospital. The screening coverage was 98.7% (1330/1347) of all eligible newborns and the mean age of screening was 2.6 days. Forty-four babies out of the 1274 who completed the two-stage screening were referred yielding a referral rate of 3.5%. Only 16% (7/44) of babies scheduled for diagnostic evaluation returned and all were confirmed with hearing loss resulting in an incidence of 5.5 (7/1274) per 1000 live births or a programme yield of 5.3 (7/1330) per 1000. Six infants had bilateral hearing loss and the degree was severe (> or =70 dB nHL) in three infants, moderate (40 dB nHL) in one infant and mild (<40 dB nHL) in two infants. The age at diagnosis ranged from 46 days to 360 days and only two infants were diagnosed within 90 days.

CONCLUSIONS

Hospital-based universal hearing screening of newborns before discharge is feasible in Nigeria. Non-specialist staff are valuable in achieving a satisfactory referral rate with a two-stage screening protocol. However, a more efficient tracking and follow-up system is needed to improve the return rate for diagnosis and age of confirmation of hearing loss.

Feasibility of neonatal hearing screening program with two-stage transient otoacoustic emissions in Turkey

BACKGROUND

The objective of this study was to investigate the incidence of hearing loss in neonates and evaluate the feasibility of a two-stage Transient Evoked Otoacoustic Emission (TEOAE) screening test. Maternal concerns about hearing screening were also studied.

METHODS

Neonatal intensive care patients and well babies were screened using a two-stage TEOAE test, which was followed by an Auditory Brainstem Response (ABR) test for those babies who failed the first test twice.

RESULTS

In total, 711 neonates were screened. At the end of the two TEOAE tests, the cumulative pass rate was 99.3% and false-positive rate was 0.3%. Five neonates (0.7%) were referred for the ABR test. Sensorineural hearing loss was found in three of them (0.4%). Of these three neonates, one was from the well baby nursery and two were from the NICU population. Families generally welcomed the screening program, with no refusals. Positive test results have not caused important maternal concerns.

CONCLUSIONS

Congenital hearing impairment is a prevalent disease in Turkey. The two-stage TEOAE program is suitable for the neonatal hearing screening program. In general, hearing screening tests do not cause notable maternal concerns.

Neonatal screening for hearing impairment--The Oman experience

BACKGROUND

Oman introduced universal hearing screening at a national level in 2002 after piloting it in limited regions. Authors present their experiences.

METHODS

The screening had three phases. In Phase I, trained health staff of the delivery suits screened newborns by transient evoked otoacoustic emissions (TEOAE) test. In Phase II, otologists examined ears and repeated hearing tests after 6 weeks. Those who failed the repeat test were referred to a tertiary unit for the Phase III. Audiometrists tested their hearing by an Automated Auditory Brainstem Response (AABR). The rates of hearing disabled, false positive, yield and cost of screening were estimated.

RESULTS

The coverage of Phase I was 66.6% (21,387/32,125) and it had significant regional variation. Two thousand two hundred and eighty-seven (10.7%) newborns were suspected with hearing impairment. We detected 262 (1.2%) children with hearing impairment. In Phase II, 55 (0.26%) neonates failed the test. In Phase III, 36 neonates were tested with ABR. Eleven were lost to follow up and eight children were advised to undergo further investigations. Ten children were found normal and 26 had hearing impairment. Six neonates had sensory-neuronal hearing loss, 17 children had otitis media with effusion and three children had atresia of the middle ear. The yield of hearing screening was 1.2/1000. The cost of screening was US$7.1/newborn.

CONCLUSION

Universal hearing screening in Oman was useful but had teething problems. Proper planning, advocacy to the health staff and parents, commitment of the staff and care of the equipment are important. Such screening should be complimented with a defaulter retrieval and rehabilitation facilities for the hearing disabled.

A Multisite Study to Examine the Efficacy of the Otoacoustic Emission/Automated Auditory Brainstem Response Newborn Hearing Screening Protocol

Purpose: This article examines whether changes in hearing screening practices are warranted based on the results of the recent series of studies by J. L. Johnson, K. R. White, J. E. Widen, J. S. Gravel, B. R. Vohr, M. James, T. Kennalley, A. B. Maxon, L. Spivak, M. Sullivan-Mahoney, Y. Weirather, and S. Meyer (Johnson, White, Widen, Gravel, James, et al., 2005; Johnson, White, Widen, Gravel, Vohr, et al., 2005; White et al., 2005; Widen et al., 2005) that found a significant number of infants who passed an automated auditory brainstem response (A-ABR) screening after failing an initial otoacoustic emission (OAE) screening later were found to have permanent hearing loss in one or both ears.

Method: Similar to the approach used by F. H. Bess and J. Paradise (1994), this article addresses the public health tenets that need to be in place before screening programs, or in this case, a change in screening practice (use of a 2-step screening protocol) can be justified.

Results: There are no data to suggest that a 2-step OAE/A-ABR screening protocol should be avoided.

Conclusion: Research is needed before any change in public policy and practice surrounding current early hearing detection and intervention programs could be supported.

Decreasing test time in newborn hearing screening

This study examined the effect of reducing the number of accepted responses in transiently evoked otoacoustic emissions based on the results of a universal neonatal hearing screening program. Our intention was to decrease the test time of newborns. A total of 464 ears were examined by using a universal newborn hearing-screening program implemented in a private maternity hospital. ILO88 Otodynamics Analyzer Quickscreen program was used for all testing and a two-stage procedure was adopted. In the first stage, the results were continuously evaluated for the 'pass' criteria, during the test, after at least 20 low-noise sweeps had been presented. As soon as the criteria were met, the test was interrupted and the results were recorded. In the second stage of the procedure, the test was continued and finally terminated after 260 quiet samples had been recorded. The results of each stage of this procedure were compared and evaluated. A total of 402 ears had normal otoacoustic emissions and only 62 ears had absent emissions. It was concluded that after a minimum of 20 averaged quiet responses, which we consider necessary in order to record reliable emissions and as soon as the 'pass' criteria were fulfilled the test could be terminated without affecting the 'pass-fail' rates which were similar in both stages. However, we believe that for diagnostic and clinical purposes, all 260 quiet samples must be used, because the results after the second stage indicated statistically better scores in response and reproducibility measures.