Air and bone conduction brain stem responses in adults and infants

Contribution of bone conduction click-evoked auditory brainstem responses to diagnosis of hearing loss in infants in France

INTRODUCTION

Neonatal hearing screening in France involves confirmation by a childhood hearing expert centre in case of suspected hearing loss. Although click-evoked air-conduction auditory brainstem responses (AC-ABR) are the gold standard in France, there are no guidelines for bone-conduction ABRs (BC-ABR). The present study assessed the interest of associating click-evoked BC- and AC-ABRs for diagnostic confirmation in neonatal hearing screening.

MATERIALS AND METHODS

A retrospective study included 59 infant ears with conductive hearing loss referred to the centre of Lyon, France. Objective hearing thresholds were compared between click-evoked BC- and AC-ABRs on a method previously validated in a normal-hearing population.

RESULTS

There was a significant difference in mean threshold between AC-ABR (53.27±1.189 dBnHL) and BC-ABR (28.1±0.935 dBnHL) (P<0.001). AC thresholds ranged from 40 to 60 dBnHL while BC thresholds exceeded 40 dBnHL in only 9 ears.

CONCLUSION

Using BC-ABRs could reduce the false-positive rate in neonatal bilateral permanent hearing loss screening, in complement to AC-ABRs using the same stimulus. Click-evoked BC-ABR could be contributive whenever conductive hearing loss is suspected, in complement to AC-ABR, without unreasonably increasing examination time.

Update on Bone-Conduction Auditory Brainstem Responses: A Review

Auditory brainstem responses (ABR) have been used as a powerful and the most common objective tool to evaluate hearing sensitivity and to diagnose the types of hearing loss and neurological disorders, through the auditory peripheral pathway to a central level of the brainstem, since 1971. Although bone-conduction (BC) ABR could be an alternative to air-conduction (AC) ABR, as the former overcomes some limitations of the latter, the majority of clinicians rarely utilize it due to a lack of knowledge and no routine test administration. This review presents the weaknesses of AC ABR that apply to all clinical population, and discusses the development of BC ABR. The optimal placements of bone oscillators to obtain favorable clinical outcomes in infants, children, and adults, and the appropriate stimuli for BC ABR are examined. While providing absolute thresholds and latencies of BC ABR based on previous studies compared to AC ABR, this review includes clinical data of infants and young children with both normal hearing in terms of maturation, and with pathology such as congenital external auditory canal atresia. We recommend the future clinical application of BC ABR for candidacy as well as for patients with BC hearing implants.

Potencial evocado auditivo de tronco encefálico por condução óssea: uma revisão integrativa

O objetivo deste estudo foi de realizar uma revisão de forma integrativa sobre os procedimentos utilizados nos critérios de aquisição do exame de Potenciais Evocados Auditivos de Tronco Encefálico por condução óssea com fins ao auxílio no diagnóstico de problemas auditivos. Foi realizada uma busca nas seguintes bases de dados: Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs), Medical Literature Analysis and Retrieval System Online (Medline) e Scientific Eletronic Library Online (SciELO). Utilizaram-se as seguintes palavras-chave: Potencial Evocado Auditivo, Eletrofisiologia e Condução Óssea, encontrados por meio de Descritores em Ciências da Saúde (DeCS). Os resultados apresentados são referentes aos 35 estudos selecionados. A maioria dos estudos optou pelo uso do estímulo clique, com transdutores por condução aérea os fones supra-aurais, como o TDH-39, para o estímulo por condução óssea, o vibrador Radioear B-71, com pressão de 425+/-25g. Observou-se que a mastoide foi à região onde mais se posicionou mais o vibrador ósseo. A maioria dos estudos refere usar polaridade alternada, com taxa de apresentação diversificada, sendo 57,7/s a mais utilizada e filtro de 30-3000 Hz, com uma janela de 15 ms de duração. Para taxa do estímulo a maioria dos estudos utilizou de 2048, e um total de estímulos de 2 registros. O Potencial Evocado Auditivo de Tronco Encefálico é um exame que vem sendo pesquisado há muitos anos e muito se tem descrito na literatura sobre seus aspectos de aquisição e analise, além de destacar a importância da sua utilização na população neonatal.

Potencial evocado auditivo de tronco encefálico por via óssea em indivíduos com perda auditiva sensorioneural

OBJETIVO: caracterizar os resultados do PEATE por via óssea em indivíduos com perda auditiva sensorioneural leve, comparando esses dados com o grupo controle, formado por indivíduos audiologicamente normais. MÉTODO: a amostra foi constituída por 40 adultos, de ambos os sexos, com faixa etária de 18 a 55 anos, distribuídos em um grupo controle de 30 indivíduos com audição normal e um grupo estudo composto de 10 indivíduos com perda auditiva sensorioneural de grau leve. O PEATE foi realizado com equipamento EP15, da marca Interacoustics. O estímulo utilizado foi o clique com taxa de apresentação de 27,7/s, em um total de 2000 estímulos, com polaridade de rarefação por VA e alternada para VO e filtro passa-banda de 50Hz e 3000Hz. RESULTADOS: em indivíduos com perda sensorioneural de grau leve, não houve diferenças estatisticamente significantes entre o limiar do PEATE por via aérea e óssea, estando esses limiares equivalentes, com GAP aéreo-ósseo menor que 10dB. A latência da onda V no limiar eletrofisiológico e a 50 dBnNA foram menores que as referidas latências observadas em indivíduos com audição normal. CONCLUSÃO: foram encontrados limiares eletrofisiológicos por via óssea equivalente aos limiares obtidos por via aérea, com presença de GAP aéreo-ósseo menor que 10dBnNA. Assim a utilização do PEATE por VO fornece dados para uma caracterização mais detalhada do tipo da perda auditiva.

Estudo dos limiares eletrofisiológicos das vias aérea e óssea em crianças com até 2 meses de idade

O diagnóstico diferencial de perdas auditivas com potencial evocado auditivo de tronco encefálico por via aérea e por via óssea em crianças pequenas tem sido pouco estudado no Brasil. OBJETIVO: Comparar as respostas do potencial evocado auditivo de tronco encefálico por vias aérea e óssea em crianças de até 2 meses de idade sem perdas auditivas. FORMA DE ESTUDO: Clínico prospectivo com coorte transversal. MATERIAL E MÉTODO: Foram avaliadas 12 crianças que passaram na triagem auditiva, por meio do potencial evocado auditivo de tronco encefálico por via aérea e via óssea. A via óssea foi realizada sem mascaramento contralateral. As respostas foram comparadas e analisadas por meio do teste de McNemar e pela análise de variância com medidas repetidas. RESULTADOS: Não houve diferença estatística no limiar eletrofisiológico por via aérea e via óssea (p>0,05). O tempo de latência por via óssea foi estatisticamente maior do que o tempo de latência por via aérea (p=0,000). CONCLUSÃO: Houve concordância no registro do Potencial Evocado Auditivo de Tronco Encefálico captado por vias aérea e óssea nas intensidades próximas ao limiar auditivo; a latência da onda V registrada por via óssea foi estatisticamente maior que a registrada por via aérea.

Electrophysiologic threshold study in air and bone conduction in children with 2 months or less age

The differential diagnosis of hearing loss with air and bone Auditory Brainstem Response in small children has not been enough studied in Brazil.

AIM

To compare air and bone Auditory Brainstem Response results in children under 2 months of age with normal hearing.

STUDY DESIGN

clinical with transversal cohort.

MATERIALS AND METHODS

12 children who passed the hearing screening were evaluated using air and bone Auditory Brainstem Response. No contralateral masking was used in the bone conduction test. The responses were compared and analyzed by the McNemar test and repetitive measurements of the variance test.

RESULTS

There were no statistic differences between air and bone conduction Auditory Brainstem Response thresholds (p>0.05). The bone conduction latency for wave V was statistically higher than air conduction latency (p=0.000).

CONCLUSION

There was agreement on the results recorded for air and bone conduction Auditory Brainstem Response for threshold intensities; latency for bone conduction wave V was statistically higher than the air conduction latency.

[Bone conduction auditory brainstem responses in normal hearing individuals]

BACKGROUND

bone conduction auditory brainstem responses (ABR) in normal hearing individuals.

AIM

to evaluate the clinical applicability of bone conduction ABR, characterizing normality and determining an assessment protocol.

METHOD

participants of this study were 22 individuals with normal hearing (20dB NA), with ages between 20 and 30 years, 14 female and 8 male. All individuals were assessed using air and bone (vibrator positioned on the forehead and mastoid) conduction ABR. EP25 equipment, Interacoustic; 3A insertion phone; B-71 bone vibrator; click stimulus.

RESULTS

it was possible to evaluate the bone conduction ABR in all individuals. The results demonstrate that the electrophysiological threshold obtained when the vibrator was positioned on the forehead (32.69+/-5.63 and 32.5+/-7.07dB nHL) was higher than that obtained when the vibrator was positioned on the mastoid (25.00+/-7.33 and 30.00+/-5.34dB nHL) for both genders respectively. For this reason the vibrator was positioned on the mastoid. The electrophysiological threshold obtained by bone conduction was higher than that obtained by air conduction for both genders and also when all individuals were grouped together. Thus it is necessary to use a correction factor, according to the results, of 10dB nHL. The latency-intensity values of the V wave in the ipsilateral and contralateral recordings differed statistically according to gender, and should be considered separately. The value of 26.81+/-6.99dB nHL was adopted as being the normal threshold for bone conduction ABR.

CONCLUSION

it is possible to evaluate bone conduction ABR in the clinical environment. These results, when considered along with the air conduction ABR, increase the chances of a more precise diagnosis regarding the type of hearing loss.

The latency of auditory nerve brainstem evoked responses to air- and bone-conducted stimuli

The auditory nerve brainstem evoked responses (ABRs) to bone conduction (BC) stimuli are longer in latency than those to air conduction (AC). In order to study the mechanism of this difference, ABR wave I was recorded in experimental animals in response to low intensity (0-20 dB above their threshold) logon stimuli delivered by BC and by using the same bone vibrator to generate the air-conducted stimulus. The BC stimuli were delivered to skull bone, and directly to the contents of the cranial cavity (brain and cerebrospinal fluid) through a craniotomy. ABR wave I in response to BC stimuli delivered to skull bone was significantly longer in latency than that to BC delivered on the brain, while there was no latency difference between AC stimuli and BC to the brain. Furthermore, the vibration (measured with an accelerometer) recorded on the brain during BC stimulation of skull bone was always delayed compared to that measured on the skull. Thus there is a delay in the transfer of vibratory energy from the skull bone to the underlying contents of the cranial cavity. From there, the delayed vibrations of the contents of the cranial cavity are transmitted to the inner ear. This is probably the mechanism of the longer latency BC response compared to the AC response.

Comparison of air- and bone-conducted brain stem auditory evoked responses in young dogs and dogs with bilateral ear canal obstruction

Brain stem responses to air- and bone-conducted stimuli were analyzed in 11 young dogs, using an in-the-ear transducer and a vibrator designed for human hearing tests, respectively. The mean thresholds were 0 to 10 dB for air-conducted stimuli and 50 to 60 dB for bone-conducted stimuli. The wave forms and inter-peak latencies of the waves of the auditory evoked responses elicited by air-conducted and bone-conducted stimuli were similar. This indicated that the signals had the same origin and thus both the air-conducted and the bone-conducted responses could be considered to be auditory responses. Measurement of air-conducted and bone-conducted brain stem-evoked responses in five dogs with bilateral chronic obstructive ear disease revealed thresholds of 50 to 60 dB for air-conducted stimuli and 60 to 70 dB for bone-conducted stimuli. By comparison of these results with those in the 11 young dogs, it could be concluded that there was hearing loss other than that caused by obstruction of the ear canals.

Frequency-specific brainstem responses to bone-conducted tone pulses masked by notched noise

As in the case of auditory brainstem responses (ABRs) to air-conducted stimuli, recording of frequency-specific ABRs to bone-conducted stimuli needs adequate masking of those parts of the basilar membrane that are not to contribute to the ABR. The present study shows that tone-pulse stimulation with notched noise-masking can be realized via a bone vibrator after its frequency response has been flattened. The latency-intensity curves for 4, 2, 1, and 0.5 kHz run approximately parallel, indicating the ABR to be indeed frequency-specific. As adequate air-conducted masking of the nontest ear can produce cross-masking, the use of an insert earphone is proposed. Because of its higher interaural attenuation, a higher masking level can be applied to the nontest ear.

Auditory air and bone conduction brainstem responses and damped rotation test for young children with bilateral congenital atresia of the ears

This paper describes our assessment of auditory and vestibular functions at a very early age using the auditory air and bone conduction brainstem responses and the damped rotation test for infants and children with bilateral congenital atresia of the ear. Twelve infants and children with congenital microtia and occlusion of bilateral auditory canals were evaluated by this assessment to determine their function of hearing and balance and their suitability for fitting and surgical improvement.

Auditory brainstem response to bone-conducted clicks in adults and infants with normal hearing and conductive hearing loss

Knowledge concerning auditory brainstem response (ABR) by bone conduction (BC) is limited, and occasionally controversial. The present study was aimed at further elaboration of this issue. The research population consisted of 107 subjects. Four groups were investigated: group 1, normal-hearing adults aged 20-37 years; group 2, 10 children aged 5.6-8.4 years, with confirmed middle ear effusion (MEE); groups 3 and 4, 22 infants, matched by pairs, aged 5-18 months, 11 with normal otoscopy and 11 with suspected MEE. Comparison between ABR by AC and BC for all four groups is discussed. We observed that the AC-ABR threshold of group 2 was statistically significantly elevated compared to group 1. The same tendency was observed for group 4 compared to group 3. In AC ABR, the mean latency of wave V was significantly prolonged, compared to that of BC ABR in children with confirmed MEE, and infants with suspected MEE. We strongly suggest that by combining AC and BC ABR, more information concerning cochlear reserve status can be obtained in infants and young children who are difficult to test, or wherever a behavioral audiogram cannot be achieved.

Development of hearing in neonatal rats: air and bone conducted ABR thresholds

While the human full-term neonate can hear at birth, in the rat the onset of auditory function as monitored by recording auditory nerve-brainstem evoked responses (ABR) has been reported to begin on post-natal day (PND) 12-14 and reaches adult thresholds at about 22 days. In order to determine the factors involved in this late onset and then rapid threshold improvement in rats, the ABR to both air conducted (AC) and bone-conducted (BC) auditory stimulation was determined in neonatal rats. ABR to maximal intensity BC stimuli (55 dB above adult rat ABR threshold--55 dB HL*) could be recorded from PND 7-8 while AC responses to 80 dB HL* stimuli, only from PND 11. The air-bone gap (a measure of conductive immaturities only) disappeared on PND 15. This shows that there are both conductive (external and middle ear--Air-bone gap) and sensori-neural (inner ear--BC threshold) immaturities in the neonatal rat; the conductive factors are resolved by PND 15 while the sensori-neural continue after that. With respect to conductive factors, it seems that the state of the ear canal is not important while the chief conductive factors involved probably include mesenchyme resorption and/or ossicular ossification. The chief sensori-neural factor may be the development of the endocochlear potential. It is likely that the human fetus in-utero undergoes similar stages of development.

Relative effective frequency response of bone versus air conduction stimulation examined via masking

An adaptation of the sensorineural acuity level procedure was employed to obtain thresholds under bone- (BC) vs. air-conducted (AC) white noise masking. For the BC masking condition, a Radioear B71 was placed on one mastoid. An Etymotic ER3 with a foam tip placed in the ear on the same side was used to deliver the pure-tone probe stimulus. This transducer was chosen to approximate the Telephonics TDH-39 earphone response characteristic while reducing occlusion effect. For the AC masking condition, the masker and probe were mixed electrically and delivered to the earphone. Masked threshold data, transformed into frequency response curves, demonstrated greater variance of BC vs. AC response across frequency but less high-frequency roll-off than expected from coupler measurements obtained using an artificial mastoid and 6-cm3 cavity, respectively.

Test-retest variability of the auditory brainstem response to bone-conducted clicks in newborn infants

The variability of the auditory brainstem response (ABR) to bone- and air-conducted clicks was investigated utilizing a test-retest paradigm with 20 normal full-term newborn infants. ABRs to bone-conducted clicks at 15 and 30 dB nHL and air-conducted clicks at 30 dB nHL were obtained. The delivery of the bone-conducted signal was controlled. ABR wave V latencies were measured from each test-retest stimulus condition. The results indicated no statistically significant difference in test-retest variability of ABR wave V latencies or amplitudes between bone- and air-conducted clicks. ABRs to bone-conducted clicks, under controlled clinical conditions, are as reproducible and reliable as ABRs to air-conducted clicks in newborn infants.

Normal infant and adult auditory brainstem responses to bone-conducted tones

Auditory brainstem responses (ABRs) were recorded to 500- and 2000-Hz bone-conducted (BC) tones from normal infants and adults. Infant ABR thresholds for the 500-Hz BC tones are significantly lower than their thresholds to 2000-Hz BC tones. Infant wave V latencies to 500-Hz BC tones are significantly shorter than those of adults, whereas infant and adult responses to 2000-Hz BC tones are similar in latency, suggesting that the effective intensity of the BC tones may be 9-17 dB greater for infants than for adults. A marked asymmetry between the ipsilaterally and contralaterally recorded wave V is seen for infant responses to 500- and 2000-Hz tones at all intensities; this asymmetry is not as evident in adults, except near threshold.

Frequency-specific auditory brainstem responses to bone-conducted stimuli

The feasibility of recording bone-conducted auditory brainstem responses (ABRs) to 500-Hz and 2000-Hz tone bursts and clicks was investigated in normal-hearing adults. For all 3 stimuli, responses were detectable in all subjects at 30 dB nHL. At 20 dB nHL, the tone burst responses were detectable in 80-87% of the subjects, demonstrating that even the responses to 500-Hz tone bursts were relatively robust. Latencies and amplitudes of the responses were related to the stimuli. The cochlear locations contributing to the responses were investigated using high-pass masking. Derived-band analysis indicated reasonably good frequency specificity for the tone burst responses and a broad representation for the bone-conducted click, despite its lower frequency spectrum. The results of this study support the use of bone-conducted tone burst ABR for demonstrating frequency-specific normal cochlear sensitivity.

Validity of bone conduction stimulated ABR, MLR and otoacoustic emissions

The present study considers the validity of objective auditory investigation via bone conduction. Auditory Brainstem Responses (ABR) and Middle Latency Responses (MLR) were recorded in response to a bone vibrator stimulation with or without continuous bilateral air white noise masking. In all cases, such masking was found to result in an absence of recorded evoked potentials. It shows that under bone-conducted stimulation the evoked potential recorded is purely auditory, with no additional mechanical somatosensory component. In a further study, the feasibility of oto-acoustic emissions (OAEs) via bone conduction is demonstrated. These OAEs are, for a given subject, comparable to those found for air-transmission stimulation.