Auditory screening in high-risk pre-term and full-term neonates using transient evoked otoacoustic emissions and brainstem auditory evoked potentials

Diffusion tensor imaging of the inferior colliculus and brainstem auditory-evoked potentials in preterm infants

BACKGROUND

Preterm and low-birth-weight infants have an increased risk of sensorineural hearing loss. Brainstem auditory-evoked potentials (BAEP) are an effective method to detect subtle deficits in impulse conduction in the auditory pathway. Abnormalities on diffusion tensor imaging (DTI) have been shown to be associated with perinatal white-matter injury and reduced fractional anisotropy (FA) has been reported in patients with sensorineural hearing loss.

OBJECTIVES

To evaluate the possibility of a correlation between BAEP and DTI of the inferior colliculus in preterm infants.

MATERIALS AND METHODS

DTI at term age and BAEP measurements were performed on all very-low-birth-weight or very preterm study infants (n=56). FA and apparent diffusion coefficient (ADC) of the inferior colliculus were measured from the DTI.

RESULTS

Shorter BAEP wave I, III, and V latencies and I-III and I-V intervals and higher wave V amplitude correlated with higher FA of the inferior colliculus.

CONCLUSION

The association between the DTI findings of the inferior colliculus and BAEP responses suggests that DTI can be used to assess the integrity of the auditory pathway in preterm infants.

Test accuracy and prognostic validity of multiple auditory steady state responses for targeted hearing screening

The test accuracy and prognostic validity of Multiple Auditory Steady State Responses (MSSR) and click Auditory Brainstem Responses (cABR) was compared within the context of a targeted screening protocol. A sample of 508 high-risk babies was first screened using cABR and MSSR (500 and 2000 Hz). All children (failed/ pass) were called back at three to four years of age to determine their hearing status (pure-tone audiometry). Although both methods showed an equally good test performance in the first screen (sensitivity: 100% and specificity: 92-95%), the MSSR may have some potential advantage to identify low-frequency hearing loss. Furthermore, the confirmatory audiometry with MSSR predicted the child hearing status more accurately than the cABR. In conclusion, the MSSR can provide valuable information for the diagnosis and management of infants earlier detected by a screening protocol and further developed might be also useful as a screening test.

From hearing screening to cochlear implantation: cochlear implants in children under 3 years of age

CONCLUSIONS

Universal hearing screening gives a deaf child earlier diagnosis and intervention with a better chance for successful management of hearing and speech development.

OBJECTIVES

Universal newborn hearing screening has a major impact on early identification of deafness in children. This study evaluated the outcome of cochlear implantation in screened and non-screened deaf children.

SUBJECTS AND METHODS

Group 1 comprised 9 deaf children diagnosed by screening; group 2 comprised 21 children diagnosed by traditional methods. The following parameters were evaluated: age at the time of diagnosis, age at the time of the first hearing aid fitting, age at the time of cochlear implantation. In children who had been using a cochlear implant for more than 2 years the results of audiological tests, category of auditory performance (CAP), and development and quality of speech were also evaluated.

RESULTS

Hearing screening significantly reduced the age at the time of diagnosis (6.9 months vs 15.4 months) as well as the age at the time of the first hearing aid fitting (9.3 months vs 17 months) and age at the time of cochlear implantation (26 months vs 32 months). Children from the screening program had better results in speech audiometry (95% discrimination vs 84%), monosyllabic tests (62% vs 34%), CAP (level 6 vs level 5), evaluation of spontaneous speech (level 6 vs level 5), and intelligibility of speech (level 5 vs level 3.5). According to the statistical evaluation (Fisher's test) the functional results did not show significant difference.

Tone-evoked ABR in full-term and preterm neonates with normal hearing

This study was designed to investigate the feasibility of applying tone-ABRs in the nursery and neonatal intensive care unit (NICU), and to provide normative tone-ABR data from neonates. Normative tone-ABR latency data were determined. The study obtained intensity series of tone-ABRs from thirty preterm neonates and twenty full-term neonates who had confirmed normal peripheral auditory function after passing both an OAE and ABR screening examination. ABRs were collected in response to 500, 1500, and 4000 Hz tone bursts at 70, 50, 30, and 20 dB nHL. Mean wave V latencies were compared between groups, ears, and by gender. Responses to tone bursts of 20 and 30 dB nHL were detected in 97% and 100% of all ears respectively, in addition to responses to the higher-intensity stimuli. Preterm neonates' ABRs showed significantly longer latencies than those of the full-term infants. Tone-ABR evaluation was found to be both feasible and reliable as a measure of auditory function in neonates.

Low prevalence of hearing impairment among very low birthweight infants as detected by universal neonatal hearing screening

OBJECTIVES

To (a) study the prevalence of hearing impairment in a cohort of very low birthweight (VLBW) infants and (b) evaluate the effectiveness of transient evoked otoacoustic emissions (TEOAE) as a first stage in-hospital hearing screening tool in this population.

STUDY DESIGN

The study group was a cohort of 346 VLBW infants born in 1998-2000 at The Sheba Medical Center. The prevalence of hearing impairment in the study group was compared with that of all other newborn infants participating in a universal newborn hearing screening programme during the same period. To evaluate the effectiveness of TEOAE, a control group of 1205 healthy newborns who had no known risk factors for hearing impairment was selected. The results and follow up of hearing screening for these infants were examined retrospectively.

RESULTS

Only one VLBW infant (0.3%) was diagnosed with bilateral sensory-neural hearing loss. In addition, nine infants (2.7%) were diagnosed with conductive hearing loss. Bronchopulmonary dysplasia and low Apgar score were the most significant factors for predicting the occurrence of conductive hearing loss. The percentage of VLBW infants who successfully passed the in-hospital TEOAE screening was 87.2, compared with 92.2% in the full term control group. No false negative cases were detected on follow up.

CONCLUSIONS

The study shows a low incidence of sensory-neural hearing loss in a cohort of VLBW infants and a relatively high incidence of conductive hearing loss. TEOAE screening was found to be an effective first stage in-hospital hearing screening tool in this population.

Otoacoustic Emissions in Universal Hearing Screening: Which Day after Birth Should We Examine the Newborns?

Transiently evoked otoacoustic emissions (TEOAEs) have been widely used in universal newborn hearing screening programs. Although there is consensus with regard to the avoidance of early screening, especially during the first hours after birth, the optimum testing day is not yet unanimously accepted. The aim of the present study was to compare the 'pass-refer' results between 4 groups of newborns tested during the 4 postbirth days and determine the most appropriate day for assessing newborn hearing. Our results suggest that, although TEOAEs can be recorded in very high rates from the first 24 h of life, 'refer' scores are lower on the third and fourth days after birth. It may be thus concluded that the optimum time of assessing newborn hearing in universal hearing screening programs seems to be the third or fourth postbirth day, provided that other social or financial reasons do not suggest an earlier discharge from the hospital.

Comparison of two methods of TEOAE recording in newborn hearing screening

This paper summarizes the results of trials performed in two hospitals, comparing the scoring of transient evoked otoacoustic emissions (TEOAEs) on the same neonates and within the same test session, recorded by the fully automatic device EchoScreen (Madsen Electronics/Fischer-Zoth GmbH) and ILO Otodynamics Ltd system. These trials form part of a larger project (Project Sentinel), whose primary aim is to stimulate the creation of new neonatal hearing screening programmes. Four thousand two hundred and forty-eight neonates were tested with both devices (8494 ears), in randomized order. The response scores obtained with the two devices are in full agreement in 98.72% of the tested ears. Considering the recording time, the fully automatic Echo Screen was, on average, about 3.6 times faster than the ILO88, bearing in mind, however, that when using ILO88, the end of the recording is decided by the operator on the basis of some mandatory decision rules.

[Systematic screening of deafness at a maternity ward using evoked otoacoustic emissions: practical aspects and parental attitudes]

OBJECTIVE

Evaluation of the feasibility and parental attitudes towards a hearing screening programme using evoked otoacoustic emissions, implemented in a maternity ward in France.

METHODS

A hearing screening test using transiently evoked otoacoustic emissions (TEOAE) was proposed to each baby, and an anonymous questionnaire was given to parents to assess their attitudes towards the screening procedure.

RESULTS

Although the refusal of the test reached 16% (mainly during the first two weeks of the program), more than 92% of parents judged the test as being useful, and 65% wished it to be systematically done. However, nearly 35% of parents admitted to have a low level anxiety about being unnecessarily worried by the test results. One hundred and twenty-four babies were screened. Fifty three per cent of the tests have been performed in less than ten minutes, with an average of 12.2 minutes. This duration does not include delays due to programme and babies management. False positive rate (uni or bilateral fail) was 10.5% at the first stage. Repeating the test before discharge decreased the false positive rate to 6.5%.

CONCLUSION

Although limited in time, this study shows that a systematic hearing screening programme using TEOAE is possible and should be done in France. False positive rate was below 7%, and the test was considered as useful by more than 90% of parents, although knowledge about deafness in childhood and its consequences were clearly insufficient.

Data processing options and response scoring for OAE-based newborn hearing screening

Scoring of click-evoked otoacoustic emissions (CEOAEs) is typically achieved by the evaluation of the reproducibility of the whole emission and/or within narrow bands. Screening outcomes are influenced not only by the specific combination of the subdivision scheme (i.e., the number, position, and bandwidth of the narrow bands) and the threshold used to determine pass and refer, but also by the accuracy with which the reproducibility is estimated. This study was designed to examine what factors affect the accuracy of the reproducibility estimate and how the accuracy of the reproducibility estimate together with the choice of the subdivision scheme/thresholds affect CEOAE scoring. Simulations with real CEOAEs corrupted with synthesized noise indicated that the reproducibility estimate is influenced by time-windowing and band-pass filtering: the longer the time-window or the broader the bandwidth of the filter, the more accurate the estimate. Quantitative figures on numerical scoring were given in terms of the referral rate and were derived from CEOAEs recorded in a clinical environment from more than 3400 newborns. The narrow bands were extracted according to 12 different subdivision schemes covering the 1.5-4-kHz range. The referral rate was found to depend on the subdivision scheme being used: (i) the worst results were obtained considering four narrow bands at 1.6-2.4-3.2-4 kHz; (ii) the best results were obtained considering two narrow bands at 2.25 and 3.75 kHz; (iii) bandwidths greater than 1 kHz resulted in the lowest referral rates. Also, scoring based on the extraction of four narrow bands produced the most unstable results, i.e., a small change in the threshold might cause even a great change in the referral rate.

Ototoxicity: an argument for evaluation of the cochlea in safety testing in animals

The cochlea is one of the more common targets for toxic effects, yet current toxicologic screening in animals does not routinely evaluate the cochlea as a potential target organ. Although histopathologic sections are routinely taken from the eye and the optic nerve and tract and most studies include at least 1 section through the nasal cavity and olfactory mucosa, the cochlea is not histopathologically examined in routine toxicity studies. Unfortunately, routine clinical examinations frequently miss ototoxicity because rodents and other species can lose most of their high-frequency hearing and still respond to most ambient noises. Ototoxicity as a deficiency in toxicologic screening can be remedied by using well-established histopathologic and behavioral methods or electrophysiologic methods, such as brain stem auditory evoked responses (BAERs). Once the equipment is in place, BAERs can be obtained quickly and easily for ototoxicity screening (approximately 15 minutes for paired testing of 2 rats and 30 minutes each for dogs). BAERs also can be used in virtually all mammalian species. Three or 4 probe frequencies (eg, 4, 8, 16, and 32 kHz), representing different areas of the cochlea, can be tested in a few minutes with subcutaneous electrodes under short-acting chemorestraint. Given the availability of several approaches to screening for ototoxicity and the importance of the auditory function in human health, safety tests of chemicals and drugs should include an effective screening test for ototoxicity.