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

Hearing screening using auditory steady state responses obtained by simultaneous air- and bone-conduction stimuli

INTRODUCTION AND OBJECTIVES

Minimising false positives rates is an important goal of universal newborn hearing screening programmes. An adequate way for reaching that goal could be differentiating between transient conductive hearing losses (false positives) and permanent sensorineural hearing impairments (true positives) by means of a methodology that studies electrophysiological responses obtained using both air- and bone-conduction stimuli. Our objective was to evaluate the efficiency of an automated hearing screening test based on auditory steady state responses obtained using simultaneous air- and bone-conduction stimuli.

METHODS

A sample of 80 high risk babies lees than 2 months of born were screened using the automatic screening test. A confirmatory clinical and electrophysiological evaluation was used as the gold standard.

RESULTS

The estimated diagnostic efficiency of this screening test was equivalent (100% sensitivity and 97.7% specificity) to the efficiency reported for otoacoustic emissions and automated auditory brainstem responses. The introduction of bone conduction in the screening reduced the false positive rate from 13.3% to 2.2%. The test duration was 5.3 (± 1.9)min. In 34% of babies only one repetition of the test was needed to raising the result.

CONCLUSIONS

The screening test performed quite well in this initial clinical trial, differentiating transient conductive hearing losses from permanent neurosensory impairments and improving the diagnostic efficiency of auditory steady state responses.

Predictive value of hearing assessment by the auditory brainstem response following universal newborn hearing screening

OBJECTIVE

This study set out to determine the accuracy with which tone pip ABR and click ABR, carried out in babies referred from universal newborn hearing screening, is able to predict the hearing outcome as determined by follow-up hearing tests.

STUDY SAMPLE

The cohort of babies studied were all babies referred for hearing assessment from the universal newborn hearing screen in Sheffield, UK for the period January 2002 to September 2007, who were found to have a significant hearing impairment.

DESIGN

The results of hearing assessment following referral from the newborn hearing screen were collected together with those of follow-up tests carried out up to an age when behavioural testing had established ear- and frequency-specific thresholds at 0.5, 1, 2 and 4 kHz.

RESULTS

The standard deviation of the difference between the follow up and the tone pip ABR thresholds was 10.5 dB for the 4-kHz tone pip, 16.8 dB for the 1-kHz tone pip, and ranged between 21.7 and 24.7 dB for click ABR.

CONCLUSIONS

The results of the study show that tone pip ABR following referral from newborn hearing screening has a similar accuracy to that reported in older subjects, and is a much better predictor compared to click ABR.

Effect of hearing aids on auditory function in infants with perinatal brain injury and severe hearing loss

BACKGROUND

Approximately 2-4% of newborns with perinatal risk factors present with hearing loss. Our aim was to analyze the effect of hearing aid use on auditory function evaluated based on otoacoustic emissions (OAEs), auditory brain responses (ABRs) and auditory steady state responses (ASSRs) in infants with perinatal brain injury and profound hearing loss.

METHODOLOGY/PRINCIPAL FINDINGS

A prospective, longitudinal study of auditory function in infants with profound hearing loss. Right side hearing before and after hearing aid use was compared with left side hearing (not stimulated and used as control). All infants were subjected to OAE, ABR and ASSR evaluations before and after hearing aid use. The average ABR threshold decreased from 90.0 to 80.0 dB (p = 0.003) after six months of hearing aid use. In the left ear, which was used as a control, the ABR threshold decreased from 94.6 to 87.6 dB, which was not significant (p>0.05). In addition, the ASSR threshold in the 4000-Hz frequency decreased from 89 dB to 72 dB (p = 0.013) after six months of right ear hearing aid use; the other frequencies in the right ear and all frequencies in the left ear did not show significant differences in any of the measured parameters (p>0.05). OAEs were absent in the baseline test and showed no changes after hearing aid use in the right ear (p>0.05).

CONCLUSIONS/SIGNIFICANCE

This study provides evidence that early hearing aid use decreases the hearing threshold in ABR and ASSR assessments with no functional modifications in the auditory receptor, as evaluated by OAEs.

Prognostic validity of dichotic multiple frequencies auditory steady-state responses versus distortion product otoacoustic emissions in hearing screening of high risk neonates

OBJECTIVE

To determine the validity of dichotic multiple frequencies auditory steady-state responses (ASSR) as a hearing screening technique versus using distortion product otoacoustic emissions (DPOAEs) among high-risk neonates.

METHODS

A cross sectional study was performed on 118 high-risk neonates by means of dichotic multiple frequencies ASSR and DPOAE for hearing screening. DPOAE results were used as the standard for hearing screening in parallel with ASSR. Dichotic multiple frequencies ASSR results were analyzed by means of F-value of less or greater than 0.05 criteria as a pass-fail for the responses. Dichotic multiple ASSR hearing screening technique was considered in two intensity levels at 40 and 70 dB HL. The ASSRs thresholds were measured in high risk neonates with and without hearing deficits as determined by DPOAES. The results of ASSR and DPOAE were compared to be gathered by contingency table in order to obtain sensitivity, specificity and other different statistical values. Average performing times for the tests were analyzed.

RESULTS

The specificity of dichotic multiple ASSR was 92.6%, 93.8% and the sensitivity was 71.6%, 62.2% at the 70 and 40 dB hearing levels, respectively. Mean ASSR thresholds for normal-hearing infants at an average corrected age of 6 days were 32.2 ± 12.2, 29.8 ± 10.2, 26.2 ± 11.4 and 30.4 ± 10.8 dB HL for 0.5, 1, 2 and 4 kHz, respectively. The average times for performing the tests were 18.7 and 32.9 min respectively.

CONCLUSIONS

ASSR with this special paradigm is a fairly desirable method for hearing screening of high-risk neonates. There is good concordance between ASSRs and DOPAEs results among high risk neonates referred for hearing screening. The sensitivity and specificity of this test is sufficient for hearing screening in high risk neonates. This test could be valuable for rapid confirmation of normal thresholds. As long as further research have not been conducted on ASSR, great caution should be made to interpret the results of ASSR as a hearing screening technique in young infants and also additional techniques such as the tone-evoked ABRs should be used to cross-check results. It's still too soon to recommend ASSRs as a standalone electrophysiologic measure of hearing thresholds in infants.

Potencial Evocado Auditivo de Estado Estável com estímulo de ruído branco modulado em amplitude em triagem auditiva neonatal

OBJETIVO: verificar a utilização do estímulo ruído branco, modulado em amplitude, no exame de Potencial Evocado Auditivo de Estado Estável (PEAEE). MÉTODO: foram avaliados 30 neonatos e lactentes, na Maternidade do Hospital das Clínicas da UFPE, que realizaram os exames de Emissões Otoacústicas Transientes (EOAT) e PEAEE, com ruído branco de amplitude modulada. RESULTADOS: para o exame de PEAEE, sugere-se que a intensidade ideal para o ponto de corte seja 50 dB NPS, para os casos com passa na triagem auditiva, com o exame de EOAT. CONCLUSÃO: o exame de PEAEE, realizado com ruído branco, modulado em amplitude, parece ser promissor como ferramenta de triagem auditiva. Entretanto, estudos são necessários para observar a relação entre os limiares das respostas auditivas de estado estável utilizando-se tons puros e ruído branco, a fim de melhor elucidar e definir parâmetros e protocolos de sua utilização.

[Newborn hearing screening test with multiple auditory steady-state responses]

INTRODUCTION

The techniques most frequently used within a screening context (otoacoustic emissions and click auditory brainstem response) have well-known limitations in hearing loss detection.

OBJECTIVE

This study examines the feasibility of a semi-automated multiple auditory steady-state responses (MSSR) system designed for neonatal hearing screening.

METHODS

A sample of 50 newborns without risk factors (well-babies) was tested within two weeks of birth. All had detectable auditory brainstem responses to clicks down to 40dB nHL in both ears. Two amplitude modulated carrier tones of 500 and 2,000Hz were mixed together and presented simultaneously. Each infant (and ear) was screened with the MSSR system; to simulate a hearing loss, a recording without stimulation was also obtained.

RESULTS

Mean auditory thresholds were 42.5±7dB HL at 500Hz and 35.5±6dB HL at 2,000Hz. The average duration of the MSSR recording was 2.6±1.6 minutes for each tested ear and the overall duration of the screening procedure (including electrode fitting and infant preparation) was 17.8±3.7 minutes. The diagnostic sensibility and the positive predictive values of the MSSR semi-automatic screening system was 100% and 96% respectively, with specificity of 96% and negative predictive values of 100%.

CONCLUSIONS

Although the diagnostic efficiency of the semi-automated MSSR system was found adequate, further technological improvements are still necessary to facilitate its use in the context of universal newborn hearing screening program.

[Audiometric thresholds estimated by auditory steady-state responses. Influence of EEG amplitude and test duration on accuracy]

OBJECTIVE

To examine the influence of electroencephalogram (EEG) amplitude, test duration, and residual noise on the definition of threshold criteria for auditory steady-state responses (ASSR) in three representative populations.

METHODS

EEG recordings from 61 patients, 11 sedated babies, and 53 relaxed volunteers were used in an offline analysis that calculated the mean EEG amplitude and the time course of residual noise. Additionally, the time course of residual noise and the test duration for a fixed level of residual noise were estimated from the mean EEG amplitude using the "square root of N" law of averaging.

RESULTS

A strong correlation between measured and predicted residual noise was found in all three groups. The mean EEG amplitude as well as the predicted test duration for a fixed residual noise level differed significantly among the three groups, with EEG amplitudes in clinical patients being four times greater than in relaxed volunteers.

CONCLUSIONS

The strong correlation between EEG amplitude, test duration, and residual noise in ASSR recordings allows for the prediction of individual test duration or residual noise levels in advanced testing algorithms. This study found that high mean EEG amplitudes in awake patients considerably reduce the accuracy of hearing thresholds estimated by ASSR.

The effect of brief-tone stimulus duration on the brain stem auditory steady-state response

OBJECTIVE

To investigate the effect of brief-tone stimulus duration on the amplitude of the brain stem auditory steady-state response (ASSR), both in single- and multiple-stimulus conditions.

DESIGN

In Experiment 1, the primary stimuli were Blackman-windowed 500- and 2000-Hz brief tones presented using repetition rates of 79 and 83 Hz, respectively. Stimuli had durations ranging from 0.5 to 12 msec. In the single-stimulus condition, these two stimuli were presented dichotically, whereas in the four-stimulus multiple-stimulus condition, instead of being presented alone, each stimulus was combined with three interfering stimuli, which were also Blackman-windowed brief tones spaced one octave apart, and presented at rates of 77 to 96 Hz. In Experiment 2, the effect of brief-tone duration and the effect of interfering stimuli were further studied by systematically removing interfering stimuli from the multiple stimuli, with the goal of determining which specific stimuli in the multiple stimuli were responsible for the interference. In both experiments, stimuli were presented at 75 ppe dB SPL. The subjects were normal-hearing adults, who relaxed or slept during the recording sessions.

RESULTS

Experiment 1: ASSR amplitudes increased as stimulus duration decreased in the single-stimulus condition, for both 500 and 2000 Hz. However, amplitudes did not significantly increase until stimuli were quite brief (2 msec for 2000 Hz; 6 msec for 500 Hz). In the four-stimulus multiple-stimulus condition, the pattern of amplitude increase with decreasing stimulus duration at 2000 Hz was similar to that in the single-stimulus condition, although amplitudes at all durations were reduced. However, for 500-Hz stimuli in the four-stimulus multiple-stimulus condition, ASSR amplitudes showed no change as stimulus duration decreased. Experiment 2: for 2000-Hz stimuli, the 4000-Hz interfering stimuli resulted in the largest change in amplitude, the 1000-Hz interfering stimuli had a small effect, and the 500-Hz interfering stimuli had no effect. For 500-Hz stimuli, the 1000-Hz interfering stimuli had the greatest effect, the 2000-Hz interfering stimuli the next largest, and the 4000-Hz interfering stimuli a small effect. The interference effects for 500-Hz stimuli occurred only for brief (< or =6 msec) stimuli, with no effects of the interfering stimuli when the 500-Hz stimuli were 8 or 12 msec in duration.

CONCLUSION

Although brief tones may result in larger-amplitude ASSRs, their duration must be quite brief (not more than three to four cycles) to show a significant amplitude increase. Moreover, when presented together with other stimuli in the multiple-stimulus technique, response interference reduces the amplitudes of ASSRs, and for 500 Hz removes the amplitude gain normally seen with decreasing duration. Brief-tone stimuli, therefore, may not be optimal for ASSR threshold estimation, especially because of the compromise in frequency specificity accompanying the use of very brief tones.