Reference ranges and stability of auditory and vestibular measures in a comprehensive assessment battery for traumatic brain injury.

BACKGROUND: Audiology clinics have many tools available to evaluate auditory and vestibular complaints. However, many tools lack established normative ranges across the life span. We conducted this study to establish reference ranges across the life span for audiology/vestibular measures commonly used to evaluate patients with traumatic brain injury. MATERIALS AND METHODS: In this repeated measures study, 75 adults, ages 18-65 years, without a history of traumatic brain injury, underwent robust auditory/vestibular evaluations three times over six months, including rotational chair, videonystagmography, computerized dynamic posturography, vestibular evoked myogenic potentials, and retinal fundoscopy. RESULTS: Age effect was notable for transient evoked otoacoustic emissions, pure-tone audiometry, auditory brainstem response, auditory middle latency response, and auditory-steady state response at 4000 hertz (Hz). Older participants (50-65 years) were more likely to have delayed latency horizontal saccades, positional nystagmus, slowed lower-extremity motor control responses, and delayed latency ocular vestibular evoked myogenic potentials. Low to mid-frequency horizontal (0.003-4 Hz) and mid-frequency vertical (1-3 Hz) vestibulo-ocular reflex, otolith-mediated reflexes, dynamic visual acuity and balance measures were generally not influenced by age. Females had larger static subjective visual testing offset angles, longer cervical vestibular evoked myogenic potential P1 latency, faster velocity horizontal saccades, and quicker motor control latency for large backward translations than age-matched males. CONCLUSION: These reference ranges can be used to discern impairment within the auditory and vestibular pathway following traumatic brain injury in young to middle-aged adults. ID: TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT01925963.

Electrocochleography: New Uses for an Old Test and Normative Values.

Purpose This article combines the results of 3 studies that were presented at the HeAL 2018 Conference in Lake Como, Italy, in June 2018. Each study involved electrocochleography (ECochG), a neurodiagnostic evaluation that has been used clinically for over 80 years but whose applications continue to expand. The 1st study describes recent research wherein ECochG was recorded from asymptomatic subjects who were siblings or offspring of patients with a confirmed diagnosis of Ménière's disease (MD). Our results provide evidence that ECochG may be helpful in not only diagnosing MD but also predicting it as well. Second, case studies are described where ECochG was important in both diagnosing superior semicircular canal dehiscence and monitoring the repair of this condition during surgery. Finally, although ECochG has been practiced clinically for over 8 decades, the protocols for recording, measuring, and interpreting the electrocochleogram continue to lack standardization among clinicians and scientists. We thus present normative data for some of these features based on noninvasive recordings made from the tympanic membrane from 100 normal hearing subjects. Conclusions Although the primary use of ECochG continues to be in the diagnosis of MD, we report on 2 additional clinical applications for this important test of inner ear/auditory nerve function. First, a preliminary study on a small sample of subjects indicates that ECochG may also be useful in predicting MD prior to the onset of symptoms in individuals who may be genetically predisposed to developing it. Second, through a series of case studies, we demonstrate how ECochG is used to help diagnose superior semicircular canal dehiscence and monitor the status of the inner ear during the surgical repair of this condition. Finally, normative values for clinically important components of the electrocochleogram based on tympanic membrane recordings have been established from a large sample of subjects.

Unraveling the Mystery of Auditory Brainstem Response Corrections: The Need for Universal Standards.

BACKGROUND: The auditory brainstem response (ABR) is used to estimate behavioral hearing thresholds in infants and difficult-to-test populations. Differences between the toneburst ABR and behavioral thresholds exist making the correspondence between the two measures less than perfect. Some authors have suggested that corrections be applied to ABR thresholds to account for these differences. However, because there is no agreed upon universal standard, confusion regarding the use of corrections exists. PURPOSE: The primary purpose of this article is to review the reasoning behind and use of corrections when the toneburst ABR is employed to estimate behavioral hearing thresholds. We also discuss other considerations that all audiologists should be aware of when obtaining and reporting ABR test results. RESULTS: A review of the purpose and use of corrections reveals no consensus as to whether they should be applied or which should be used. Additionally, when ABR results are adjusted, there is no agreement as to whether additional corrections for hearing loss or the age of the client are necessary. This lack of consensus can be confusing for all individuals working with hearing-impaired children and their families. CONCLUSIONS: Toneburst ABR thresholds do not perfectly align with behavioral hearing thresholds. Universal protocols for the use of corrections are needed. Additionally, evidence-based procedures must be employed to obtain valid ABRs that will accurately estimate hearing thresholds.

Sensitivity of the Automated Auditory Brainstem Response in Neonatal Hearing Screening.

BACKGROUND: In a 2-stage neonatal hearing screening protocol, if an infant fails the first-stage abstract screening with an otoacoustic emissions test, an automated auditory brainstem response (ABR)test is performed. The purpose of this study was to estimate the rate of hearing loss detected byfirst-stage otoacoustic emissions test but missed by second-stage automated ABR testing. METHODS: The data of 17 078 infants who were born at Lis Maternity Hospital between January 2013 and June 2014 were reviewed. Infants who failed screening with a transient evoked otoacoustic emissions (TEOAE) test and infants admitted to the NICU for more than 5 days underwent screening with an automated ABR test at 45 decibel hearing level (dB HL). All infants who failed screening with TEOAE were referred to a follow-up evaluation at the hearing clinic. RESULTS: Twenty-four percent of the infants who failed the TEOAE and passed the automated ABR hearing screening tests were eventually diagnosed with hearing loss by diagnostic ABR testing (22/90). They comprised 52% of all of the infants in the birth cohort who were diagnosed with permanent or persistent hearing loss .25 dB HL in 1 or both ears (22/42).Hearing loss .45 dB HL, which is considered to be in the range of moderate to profound severity, was diagnosed in 36% of the infants in this group (8/22), comprising 42% of the infants with hearing loss of this degree (8/19). CONCLUSIONS: The sensitivity of the diverse response detection methods of automated ABR devices needs to be further empirically evaluated.

[Compliance with current standards for the early detection of neonatal hearing loss]. / Cumplimiento de la normatividad vigente para la detección temprana de la hipoacusia neonatal.

OBJECTIVE: Assessing compliance with the section "Assessment of hearing" stipulated in the Technical Standard to Detect Alteration in children aged less than 10 years-old in Bogota. METHODS: This was a cross-sectional study which involved reviewing the medical records of all children born between July 1st and December 31st 2010 in two healthcare institutions in Bogota. Records were selected in which any of the following risk factors appeared: neonatal hyperbilirubinaemia involving phototherapy, neonatal exposure to ototoxic substances and/or <1.500 gr low birth weight. It was also ascertained whether children had been referred to an auditory evoked potential test as the prescribed screening test for neonatal hearing, as stipulated in mandatory Colombian technical standards for detecting abnormal growth and developmental in children aged less than ten years-old. RESULTS: Neither of the two institutions was making the aforementioned referral test. DISCUSSION: The results indicated significant difficulties in adherence to the protocol for the early detection of hearing loss regarding pertinent/current neonatal Colombian regulations.

Factors influencing tests of auditory processing: a perspective on current issues and relevant concerns.

BACKGROUND: Tests of auditory perception, such as those used in the assessment of central auditory processing disorders ([C]APDs), represent a domain in audiological assessment where measurement of this theoretical construct is often confounded by nonauditory abilities due to methodological shortcomings. These confounds include the effects of cognitive variables such as memory and attention and suboptimal testing paradigms, including the use of verbal reproduction as a form of response selection. We argue that these factors need to be controlled more carefully and/or modified so that their impact on tests of auditory and visual perception is only minimal. PURPOSE: To advocate for a stronger theoretical framework than currently exists and to suggest better methodological strategies to improve assessment of auditory processing disorders (APDs). Emphasis is placed on adaptive forced-choice psychophysical methods and the use of matched tasks in multiple sensory modalities to achieve these goals. Together, this approach has potential to improve the construct validity of the diagnosis, enhance and develop theory, and evolve into a preferred method of testing. RESEARCH DESIGN: Examination of methods commonly used in studies of APDs. Where possible, currently used methodology is compared to contemporary psychophysical methods that emphasize computer-controlled forced-choice paradigms. RESULTS: In many cases, the procedures used in studies of APD introduce confounding factors that could be minimized if computer-controlled forced-choice psychophysical methods were utilized. CONCLUSIONS: Ambiguities of interpretation, indeterminate diagnoses, and unwanted confounds can be avoided by minimizing memory and attentional demands on the input end and precluding the use of response-selection strategies that use complex motor processes on the output end. Advocated are the use of computer-controlled forced-choice psychophysical paradigms in combination with matched tasks in multiple sensory modalities to enhance the prospect of obtaining a valid diagnosis.

Auditory steady state responses in normal-hearing and hearing-impaired adults: an analysis of between-session amplitude and latency repeatability, test time, and F ratio detection paradigms.

OBJECTIVES: The aim of this study was to assess the between-session repeatability of auditory steady state response (ASSR) amplitudes and to examine F ratio response detection parameters. DESIGN: Suprathreshold ASSRs were recorded from 20 normal-hearing and 10 hearing-impaired subjects. Amplitudes and latencies were recorded in two test sessions conducted on separate days. ANALYSIS: The repeatability coefficients (limits of expected variation in repeat measurements) for amplitude and latency of ASSRs were calculated. The test time required for the responses to reach significance at 1%, 2%, and 5% F ratios was analyzed. The percentage false response detection rate was calculated to determine the suitability of current ASSR threshold estimation protocols for use in audiology clinics. RESULTS: The repeatability coefficients for the amplitude of ASSRs were 29 nV for the normal-hearing subjects and 57 nV for the hearing-impaired subjects. The repeatability coefficients for the latency of ASSR were 1.10 msec for the normal-hearing subjects and 1.19 msec for the hearing-impaired subjects. High false-positive detection rates were found for detection procedures that used variable test time ("stop when significance reached" methods). CONCLUSIONS: The results of this study showed that ASSR amplitudes are highly variable between test sessions with an average estimated variability in response amplitude of ± 40% for normal-hearing participants and ± 97% for hearing-impaired participants. This could be a possible cause of test-retest differences in ASSR threshold measurements, as it could potentially lead to thresholds that were above the EEG noise level and significant in one test session subsequently falling below the EEG noise level in the repeat test session leading to insignificant response and thus poorer ASSR threshold.

Cumplimiento de la normatividad vigente para la detección temprana de la hipoacusia neonatal / Compliance with current standards for the early detection of neonatal hearing loss

Objetivo Evaluar el cumplimiento del apartado de "Valoración de la Capacidad Auditiva" estipulado en la Norma Técnica para la Detección de las Alteraciones en el menor de 10 años en la ciudad de Bogotá, Colombia. Método Se realizó un estudio transversal. Se revisaron las historias clínicas de todos los niños nacidos entre el 01 de julio y el 31 de diciembre de 2010, en dos instituciones de salud de la ciudad de Bogotá. Se seleccionaron aquellas en las que se presentaba cualquiera de los siguientes factores de riesgo: hiperbilirrubinemia neonatal con requerimiento de fototerapia, exposición neonatal a ototóxicos, bajo peso al nacer (<1 500 gramos) y se verificó la remisión a Potenciales Auditivos Evocados como prueba de detección de la hipoacusia neonatal de acuerdo a lo estipulado de manera obligatoria en la Norma Técnica para la Detección de las Alteraciones de Crecimiento y Desarrollo en el Menor de Diez Años. Resultados En ninguna de las dos instituciones se realizó la remisión a la prueba mencionada. Discusión Los resultados del estudioindican graves dificultades en la adherencia al protocolo de detección temprana de la hipoacusia neonatal vigente en la normatividad Colombiana.

Objective Assessing compliance with the section "Assessment of hearing" stipulated in the Technical Standard to Detect Alteration in children aged less than 10 years-old in Bogota. Methods This was a cross-sectional study which involved reviewing the medical records of all children born between July 1st and December 31st 2010 in two healthcare institutions in Bogota. Records were selected in which any of the following risk factors appeared: neonatal hyperbilirubinaemia involving phototherapy, neonatal exposure to ototoxic substances and/or <1.500 gr low birth weight. It was also ascertained whether children had been referred to an auditory evoked potential test as the prescribed screening test for neonatal hearing, as stipulated in mandatory Colombian technical standards for detecting abnormal growth and developmental in children aged less than ten years-old. Results Neither of the two institutions was making the aforementioned referral test. Discussion The results indicated significant difficulties in adherence to the protocol for the early detection of hearing loss regarding pertinent/current neonatal Colombian regulations.

[Auditory steady-state responses--the state of art]. / Wywolane sluchowe potencjaly stanu ustalonego (ASSR--auditory steady-state responses), dotychczasowy stan wiedzy.

The auditory steady-state responses (ASSR) is quite a new method of electrophysiological threshold estimation with no clinical standards. It was the aim of this study to review practical and theoretical thesis of ASSR and mention recent recommendations and achievements of this technique. The most common application of ASSR is diagnosis of hearing loss in children together with ABR test. In this paper we mentioned information about influence of physiological factors (age, sex, state of arousal, handedness) and type of recording technique (electrodes placement, air and bone stimulation, occlusion effect, amplitude and frequency stimulation, multiple or single frequency stimulation, dichotic and monotic recording technique and type of hearing loss) on ASSR. We conclude that putting ASSR in clinical use as an standardized method it is necessary to do research with numerous groups of patients using the same equipment and parameters of tests.

Padronização do potencial evocado auditivo de tronco encefálico utilizando um novo equipamento / Standardization of brainstem auditory evoked potential using a new device

TEMA: padronização do Potencial Evocado Auditivo de Tronco Encefálico (PEATE) utilizando um novo equipamento. OBJETIVO: padronizar as respostas do PEATE utilizando de um novo equipamento desenvolvido (NED) no Brasil. MÉTODOS: análise das latências absolutas, interpicos e das amplitudes das ondas do PEATE, por meio de um novo equipamento desenvolvido para estudar grupos de ouvintes normais (91 adultos) e outro com perda neurossensorial (15 adultos) com perda auditiva neurossensorial bilateral entre o equipamento EP15 / Interacoustis e o NED. Utilizando o clique não filtrado, com duração de 100 microssegundo (µs), totalizando 2.000 estímulos, na polaridade rarefeita, frequência de estimulação de 13,1 cliques/s, intensidade de 80 decibels de nível de audição normalizado (dB NAn), com janela de 10 milissegundos e filtro passa-banda entre 100 e 3000 Hertz (Hz). Nível de significância de 0,05. RESULTADOS: as médias das latências absolutas e interpicos em 76 ouvintes normais no NED foram: onda I=1,50, III=3,57, V=5,53, I-III=2,06, III-V=1,96 e I-V=4,02. Ao separar por gênero houve diferença estatisticamente significante para as latências absolutas das ondas III e V e nos interpicos I-III e I-V. Valor médio da amplitude da onda I=0,384 microvolt (μV) e da onda V=0,825 μV. Não existiu diferença estatisticamente significante ao comparar as latências absolutas e interpicos entre dois equipamentos no mesmo indivíduo. CONCLUSÃO: os componentes do PEATE com o NED em ouvintes normais foram similares quanto às orelhas, com latências menores estatisticamente significantes nas mulheres. As latências do PEATE no mesmo indivíduo com o NED foram semelhantes às obtidas com o EP15 / Interacoustis. Foram obtidos os valores de normalidade para o PEATE em adultos ouvintes normais.

BACKGROUND: standardization of Brainstem Auditory Evoked Potential (BAEP) using a new device. AIM: to standardize BAEP responses using a new device developed (NDD) in Brazil. METHOD: analysis of absolute latencies, interpeaks and wave amplitudes of BAEP, using a new device developed to study normal-hearing groups (91 adults) and individuals (15 adults) with bilateral neurosensory hearing loss. Responses obtained in the EP15 hearing device/Interacoustics and the NDD were compared. For this, the following paramenters were used: non-filtered click of 100 microsecond (µs), totaling 2000 stimuli in rarefied polarity, stimulation frequency of 13.1 clicks/s, intensity of 80 decibels normalized hearing level (dB nHL), with a window of 10 milliseconds and bandpass filter between 100 and 3000 Hertz (Hz). Significance level was set at 0.05. RESULTS: absolute latency and interpeak means for 76 normal-hearing individuals with the NDD were: wave I=1.50, III=3.57, V=5.53, I-III=2.06, III-V=1.96 and I-V=4.02. When analyzing results according to gender, there was a statistically significant difference for the absolute latencies of waves III and V and in interpeaks I-III and I-V. Mean amplitude value of wave I=0.384 microvolt (µV) and of wave V=0.825 µV. There was no statistically significant difference between the absolute latencies and interpeaks of the two devices in the same individual. CONCLUSION: the components of BAEP with the NDD in normal-hearing subjects were similar regarding the tested ears, with statistically lower latencies in women. The BAEP latencies in the same individual with NDD were similar to those obtained with the EP15 / Interacoustics. Normal values of BAEP were obtained in normal-hearing adults.

Standardization of brainstem auditory evoked potential using a new device.

BACKGROUND: Standardization of Brainstem Auditory Evoked Potential (BAEP) using a new device. AIM: To standardize BAEP responses using a new device developed (NDD) in Brazil. METHOD: Analysis of absolute latencies, interpeaks and wave amplitudes of BAEP, using a new device developed to study normal-hearing groups (91 adults) and individuals (15 adults) with bilateral neurosensory hearing loss. Responses obtained in the EP15 hearing device/Interacoustics and the NDD were compared. For this, the following paramenters were used: non-filtered click of 100 microsecond (µs), totaling 2000 stimuli in rarefied polarity, stimulation frequency of 13.1 clicks/s, intensity of 80 decibels normalized hearing level (dB nHL), with a window of 10 milliseconds and bandpass filter between 100 and 3000 Hertz (Hz). Significance level was set at 0.05. RESULTS: Absolute latency and interpeak means for 76 normal-hearing individuals with the NDD were: wave I=1.50, III=3.57, V=5.53, I-III=2.06, III-V=1.96 and I-V=4.02. When analyzing results according to gender, there was a statistically significant difference for the absolute latencies of waves III and V and in interpeaks I-III and I-V. Mean amplitude value of wave I=0.384 microvolt (µV) and of wave V=0.825 µV. There was no statistically significant difference between the absolute latencies and interpeaks of the two devices in the same individual. CONCLUSION: The components of BAEP with the NDD in normal-hearing subjects were similar regarding the tested ears, with statistically lower latencies in women. The BAEP latencies in the same individual with NDD were similar to those obtained with the EP15 / Interacoustics. Normal values of BAEP were obtained in normal-hearing adults.

The influence of the detection paradigm in recording auditory steady-state responses.

OBJECTIVES: The purpose of this study was to evaluate the risks of uncontrolled use of an objective detection criterion in recording auditory steady-state responses (ASSRs). The influence of decisions such as when to accept a response and stop the recording was assessed by analyzing the number of false- and true-detected responses. DESIGN: A large sample of 500 multiple-stimulus ASSR recordings of normal-hearing and hearing-impaired adults and babies was processed offline. Three types of detection paradigms were evaluated. A first type had a fixed recording length with significance testing after the last sweep. A second type allowed a variable recording length and implied sequential application of the statistical decision criterion. The recording was stopped after significance was reached for y consecutive sweeps. The third type was analogous to the second, with the additional requirement of a minimum of eight recorded sweeps. Furthermore, the effect of significance level and averaging procedure were assessed. Error rates were calculated for the different detection paradigms at eight control frequencies. At the signal frequencies, detection rates and recording times were determined, keeping the error rates fixed. Moreover, ASSR thresholds were compared for a selection of detection paradigms. RESULTS: When a variable recording length was allowed and a significance level of p = 0.05 was applied, the error rate increased to unacceptable levels because of the effect of repeated testing. The error rate decreased as the required number of consecutive significant sweeps increased and approximated 5% only when eight consecutive significant sweeps were required (with a maximum of 32 recorded sweeps). With an error rate of 5%, the highest detection rate was associated with a fixed recording length of 32 sweeps combined with weighted averaging. A substantial decrease in detection rate was noted when less than 24 sweeps were recorded per intensity. All paradigms with a variable recording length had rather comparable detection rates and recording times. With an error rate of only 1%, small responses could not be distinguished from the noise. The reduction in recording time using a variable instead of a fixed recording length was very limited when a conventional multiple-stimulus approach was used. Test duration would be reduced considerably when the test set-up would allow an independent presentation and recording of the eight signals and responses. Differences in overall detection rate had a small effect on the ASSR thresholds. CONCLUSIONS: The error rate, detection rate, and recording time can improve or deteriorate significantly, even with small adaptations of the detection protocol. When a variable recording length is allowed, the acceptance criterion of the statistical test needs to be adjusted to ensure a tolerable error rate. However, most commercial devices do not offer this option. Then, it is advisable to use a fixed recording length and to judge the significance of the responses at the end of the recording. Although response detection is objective, the measurement protocol has to be well-considered and a critical approach is required when interpreting the responses.

Call for calibration standard for newborn screening using auditory brainstem responses.

The mode of stimulation employed in newborn screening of the auditory brainstem response has evolved from the clinically standardized supraaural earphone to the tubal insert earphone, to most recently a circumaural earphone developed for this test. Considered here is the need to develop a standard for calibration of such devices for newborn screening applications, in particular. At risk is the prospect of missing the milder degrees of hearing loss, assuming a goal of detecting all clinically-significant congenital hearing losses. Two commercially manufactured test instruments for automated newborn screening were scrutinized via bench testing of sound output from their respective transducers, using a variety of measurements. By convention or design, none of the measurement approaches involved a model of the newborn ear, per se. While it was concluded that the manufacturers' method shows promise, namely as a relatively simple and potentially reliable method of calibration, concerns arose regarding output levels when measured according to both the manufacturers' and the authors' methods. Further work is needed to critically assess calibration methods and to establish, to the extent possible, appropriate norms and validation studies in newborns to provide a better understanding of the actual sound pressure level of the screening stimulus.

Meta-analysis of variables that affect accuracy of threshold estimation via measurement of the auditory steady-state response (ASSR).

Reported are the results of meta-analyses of data derived collectively from a sample of 56 published research studies on electric response audiometry (ERA) using auditory steady-state responses (ASSRs). Several specific methodological issues were examined and hypotheses were posited to rigorously test common conclusions drawn from the ASSR literature on the accuracy of ASSR-ERA. Explanatory variables for analyses were type of population (normally hearing and hearing-impaired), type of modulation, number of sweeps acquired during response analysis, electrode montage, and modulation rate (80 vs. 40 Hz). No explanatory variables were found to be significantly related to the degree of disparity between thresholds obtained by ASSR-ERA versus behavioral audiometry in the normally hearing population. Conversely, all but one explanatory variable (i.e. electrode montage) was found to be significantly related to mean threshold differences in the hearing-impaired and combined populations. Results both substantiate some of common conclusions drawn from the literature but call others into question, helping to identify those methodological issues which appear to, or not to, significantly affect the accuracy of estimating threshold using ASSR measurement. In addition to these findings, another practical outcome of this study was the development of various summary tables of the data analysed from the literature sampled.

Effects of maturation on parameters used for pass/fail criteria in neonatal hearing screening programmes using evoked otoacoustic emissions.

We aimed to investigate the incidence of false alarms that occurred with the pass/fail criteria used in a published series of neonatal hearing screening programmes, as a function of age. We analysed the database of 19137 normally hearing babies (38274 ears) tested in the Wessex Universal Neonatal Hearing Screening Project. Otoacoustic emissions were recorded prior to discharge from maternity units, using IL088 equipment. We assessed the pass/fail rate using the Wessex criteria and 10 other pass/fail criteria published in the literature. Using Pearson's correlation coefficient, a statistically significant correlation between signal-to-noise ratio at each of the frequency bands 1, 2, 3, 4 and 5 kHz and babies' age in hours at the 0.01 level was identified. The correlation was also significant (0.01 level) between age and frequency reproducibility in each of the bands at 1, 2, 3, 4 and 5 kHz as well as the whole reproducibility. The number of false alarms reduced significantly after the first 24 h of life with all the criteria examined. We conclude that in the first hours after birth due to insufficient maturation of the otoacoustic emission, there is a high rate of false alarms. This increase in the false alarm rate, whilst dependent on the criteria used, occurs with all criteria. This leads to the consideration of whether the establishment of age-dependent pass/fail criteria could reduce the false alarm rate and the subsequent strain on diagnostic centres.

Hearing threshold assessment post grommet insertion. Is it reliable?

We aimed to investigate whether auditory brainstem response (ABR), assessed immediately after grommet insertion, was an accurate measure of hearing threshold. Ten children were recruited (20 ears). Patients underwent transient evoked otoacoustic emission (TEOAE) and ABR tests before and after grommet insertion under general anaesthetic. A third assessment was conducted at a six-week review, without anaesthetic or sedation. The hearing threshold in dB and the presence of TEOAE were recorded by senior audiologists. The results of each investigation were compared. At review, only 15 ABR and 17 TEOAE tests, of a possible 20, were recorded. Transient evoked otoacoustic emissions were recorded in 30 per cent of ears pre-operatively, 20 per cent of ears post-operatively and 82 per cent of ears at six-week review. The average ABR thresholds were 23.75 dB (range 10-45 dB) pre-operatively, 27.25 (range 15-40 dB) post-operatively and 15 dB (range 5-25 dB) at six-week review. Comparing pre- and post-operative assessment, decreased thresholds were seen in six ears and elevated thresholds in 11. Comparing the six-week review ABR with the post-operative ABR, 13 ears had decreased thresholds, by as much as 20 dB. Thresholds of 35 dB or greater were measured in six ears immediately after grommet insertion (maximum 40 dB). Threshold shifts of 15 dB or greater was observed in seven ears. The intra-subject variation was shown to be significant (p<0.001) when repeated measures analysis of variance was applied. We conclude that there is evidence that ABR can be inaccurate after grommet insertion, overestimating hearing thresholds. We believe that the mechanism by which the error is realised is temporary threshold shift.

Initial audiologic assessment of infants referred from well baby, special care, and neonatal intensive care unit nurseries.

PURPOSE: The purpose of the study was to evaluate the effectiveness of a 2-hr initial audiologic assessment appointment for infants referred from area universal newborn hearing screening (UNHS) programs to a clinical audiology department in an urban hospital. METHOD: A prospective auditory brainstem response (ABR)-based protocol, including clicks, frequency-specific tone bursts, and bone-conducted stimuli, was administered by 10 audiologists to 375 infants. Depending on the ABR findings, additional test options included distortion product otoacoustic emissions (DPOAEs), high-frequency tympanometry, and/or otologic examination. RESULTS: In 88% of the 2-hr test sessions, at least 4 ABR threshold estimates were obtained (i.e., bilateral clicks and either a 500- or 1000-Hz tone burst and a 4000-Hz frequency tone burst for the better ear). The incidence of hearing loss was significantly different across nursery levels: 18% for Level I (well baby), 29% for Level II (special care), and 52% for Level III (neonatal intensive care unit). Hearing loss type was defined at the initial assessment for 35 of the 51 infants with bilateral hearing loss based on bone-conduction ABR, latency measures, DPOAEs, high-frequency tympanometry, and/or otologic examination. CONCLUSIONS: Our findings indicate that a 2-hr test appointment is appropriate for all nursery levels to diagnose severity and type of hearing loss in the majority of infants referred from UNHS. Examination by an otolaryngologist within 24-48 hr further defines the hearing loss and facilitates treatment plans.

Validity and accuracy of electric response audiometry using the auditory steady-state response: evaluation in an empirical design.

The validity and accuracy of the application of the auditory steady-state response (ASSR) to electric response audiometry (ERA) was tested further in a study permitting subjects to be their own controls for hearing loss. Simulated sensorineural hearing loss (SSHL) of complex configuration and varying degrees was effected using filtered masking noise. Thresholds estimated via ASSR-ERA were compared to those measured via conventional pure-tone audiometry. Further, the slow vertex potential N1-P2 was recorded to permit a comparison with an evoked-response test of common content validity and known accuracy. Results in a homogeneous subject sample demonstrated strong interest correlation and agreement within 10 dB at 1000 to 4000 Hz (on average), but not at 500 Hz. The configurations determined by ASSR-ERA followed behavioral audiometric patterns well, except for the mildest degree of SSHL tested. Consequently, limitations of ERA remain, although ASSR-ERA appears to be quite valid overall and promises (justifiably) broad clinical applicability.

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.