Use Of Auditory Brainstem Response Research Articles

The outcomes of an audiological management programme for neonates with hyperbilirubinaemia.

Hyperbilirubinaemia is a contributing condition to the prevalence of neonatal hearing loss. Because of its pathophysiology, the use of Otoacoustic Emissions (OAE) and Automated Auditory Brainstem Response (AABR) testing is essential in diagnosing hearing loss. Two-tier screening models are typically used in developing world contexts; however, a combined approach to testing (using both tests) should be used for early detection. Blood serum levels should also be monitored to determine how they impact audiological test results. To determine the outcomes of using a combined testing approach of both OAE and Auditory Brainstem Response (ABR) for both screening and diagnostic testing of neonates with hyperbilirubinaemia and studying the relationship between the test results and the serum bilirubin levels. A cross-sectional, comparative design was utilised. Forty neonates were tested (80 ears). Neonates underwent hearing screening and diagnostic testing (ABR and/or AABR and DPOAE tests). The study was conducted at a hospital in South Africa. One-third (32.5%) of the neonates had comorbidities. Screening results indicated that the AABR test could identify more cases of abnormalities than DPOAEs (p= 0.001). Participants with a serum level greater than 10 mg/dL presented with abnormal diagnostic ABR test results while passing the DPOAE test (p 0.001). Combined use of ABR and DPOAE testing yielded a greater identification of auditory pathology than using either test alone. Serum bilirubin levels can be used as an indicator for combination testing.Contribution:Combined use of ABR and DPOAE testing leads to greater identification of auditory pathology.

Pathophysiological and Clinical Aspects of Hearing Loss Among 85-Year-Olds.

This study aimed to identify the prevalence of conductive/mixed and sensorineural hearing loss, with an attempt to differentiate between sensory and neural components in 85-year-olds. A comprehensive auditory test protocol, including pure-tone audiometry, speech audiometry, auditory brainstem response (ABR), and distortion product otoacoustic emission (DPOAE), was used to identify different types of hearing loss in 85-year-olds. This study comprised a subsample (n = 125) selected from an unscreened cohort of 85-year-olds born in 1930, within the Gothenburg H70 Birth Cohort Studies in Sweden. Test results were reported descriptively. Sensorineural hearing loss was present in one or both ears in almost all participants (98%), and the majority had absent DPOAEs. Only approximately 6% had additional conductive hearing loss, that is, mixed hearing loss. Approximately 20% of the participants with a pure-tone average at 0.5-4 kHz < 60 dB HL had worse word recognition scores compared with predicted scores by the Speech Intelligibility Index (SII), whereas only two participants were classified with neural dysfunction with the use of ABR. Sensorineural hearing loss, likely related to outer hair cell loss, was present in the vast majority of 85-year-olds. Conductive/mixed hearing loss appears to be relatively rare in advanced age. Poor word recognition scores in relation to SII-predicted scores were relatively common (20%) in 85-year-olds, whereas auditory neuropathy was only rarely identified (1.6%) by the use of ABR latencies. To explain abnormal word recognition and to identify the neural component of hearing loss among the older-old population, future research should consider factors such as listening effort and cognition among the older-old population.

Neuroaudiological Considerations for the Auditory Brainstem Response and Middle Latency Response Revisited: Back to the Future.

The auditory brainstem response (ABR) and middle latency response (MLR) are two sets of evoked potentials that have made major contributions to the field of diagnostic audiology. Many of these contributions were guided by clinical research audiologists. Though many of these auditory evoked potentials (AEPs) are still being used diagnostically by audiologists, there has been a steep decline in their popularity both clinically and in the research laboratory. This is indeed most unfortunate because these AEPs could and should be advancing our field and benefitting many patients. In this article, some critical research is overviewed that addresses some of the reasons why these AEPs (ABR and MLR) are not being utilized as frequently as they should be for neuroauditory assessments. Reflecting on our past when ABR and MLR were more commonly used can serve as a model for our future. Multiple applications and the diagnostic value of these AEPs are presented in an effort to convince audiologists that these electrophysiologic procedures should be revisited and reapplied in the clinic and research settings. It is argued that the dwindling use of ABR and MLR (and AEPs in general) in the field of audiology is not only remarkably premature but also lacks good scientific grounding. While on the other hand, if applied clinically, the value of these AEPs is both substantial and promising.

Usefulness of auditory brainstem response in Cornelia de Lange Syndrome

Usefulness of auditory brainstem response in Cornelia de Lange Syndrome

Evaluation of Auditory Brainstem Response in Chicken Hatchlings.

The auditory brainstem response (ABR) is an invaluable assay in clinical audiology, non-human animals, and human research. Despite the widespread use of ABRs in measuring auditory neural synchrony and estimating hearing sensitivity in other vertebrate model systems, methods for recording ABRs in the chicken have not been reported in nearly four decades. Chickens provide a robust animal research model because their auditory system is near functional maturation during late embryonic and early hatchling stages. We have demonstrated methods used to elicit one or two-channel ABR recordings using subdermal needle electrode arrays in chicken hatchlings. Regardless of electrode recording configuration (i.e., montage), ABR recordings included 3-4 positive-going peak waveforms within the first 6 ms of a suprathreshold click stimulus. Peak-to-trough waveform amplitudes ranged from 2-11 µV at high-intensity levels, with positive peaks exhibiting expected latency-intensity functions (i.e., increase in latency as a function of decreased intensity). Standardized earphone position was critical for optimal recordings as loose skin can occlude the ear canal, and animal movement can dislodge the stimulus transducer. Peak amplitudes were smaller, and latencies were longer as animal body temperature lowered, supporting the need for maintaining physiological body temperature. For young hatchlings (<3 h post-hatch day 1), thresholds were elevated by ~5 dB, peak latencies increased ~1-2 ms, and peak to trough amplitudes were decreased ~1 µV compared to older hatchlings. This suggests a potential conductive-related issue (i.e., fluid in the middle ear cavity) and should be considered for young hatchlings. Overall, the ABR methods outlined here permit accurate and reproducible recording of in-vivo auditory function in chicken hatchlings that could be applied to different stages of development. Such findings are easily compared to human and mammalian models of hearing loss, aging, or other auditory-related manipulations.

Evaluation of Auditory Brainstem Response in Chicken Hatchlings

The auditory brainstem response (ABR) is an invaluable assay in clinical audiology, non-human animals, and human research. Despite the widespread use of ABRs in measuring auditory neural synchrony and estimating hearing sensitivity in other vertebrate model systems, methods for recording ABRs in the chicken have not been reported in nearly four decades. Chickens provide a robust animal research model because their auditory system is near functional maturation during late embryonic and early hatchling stages. We have demonstrated methods used to elicit one or two-channel ABR recordings using subdermal needle electrode arrays in chicken hatchlings. Regardless of electrode recording configuration (i.e., montage), ABR recordings included 3-4 positive-going peak waveforms within the first 6 ms of a suprathreshold click stimulus. Peak-to-trough waveform amplitudes ranged from 2-11 µV at high-intensity levels, with positive peaks exhibiting expected latency-intensity functions (i.e., increase in latency as a function of decreased intensity). Standardized earphone position was critical for optimal recordings as loose skin can occlude the ear canal, and animal movement can dislodge the stimulus transducer. Peak amplitudes were smaller, and latencies were longer as animal body temperature lowered, supporting the need for maintaining physiological body temperature. For young hatchlings (<3 h post-hatch day 1), thresholds were elevated by ~5 dB, peak latencies increased ~1-2 ms, and peak to trough amplitudes were decreased ~1 µV compared to older hatchlings. This suggests a potential conductive-related issue (i.e., fluid in the middle ear cavity) and should be considered for young hatchlings. Overall, the ABR methods outlined here permit accurate and reproducible recording of in-vivo auditory function in chicken hatchlings that could be applied to different stages of development. Such findings are easily compared to human and mammalian models of hearing loss, aging, or other auditory-related manipulations.

The Use of Auditory Brainstem Response (ABR) as Indicator of Neural Integrity in Newborn and Infants Submitted to High Complexity Cardiac Surgery

The Use of Auditory Brainstem Response (ABR) as Indicator of Neural Integrity in Newborn and Infants Submitted to High Complexity Cardiac Surgery

Neurophysiologic measures of auditory function in fish consumers: Associations with long chain polyunsaturated fatty acids and methylmercury

BackgroundDetermining if associations exist between child neurodevelopment and environmental exposures, especially low level or background ones, is challenging and dependent upon being able to measure specific and sensitive endpoints. Psychometric or behavioral measures of CNS function have traditionally been used in such studies, but do have some limitations. Auditory neurophysiologic measures examine different nervous system structures and mechanisms, have fewer limitations, can more easily be quantified, and might be helpful additions to testing. To date, their use in human epidemiological studies has been limited. We reviewed the use of auditory brainstem responses (ABR) and otoacoustic emissions (OAE) in studies designed to determine the relationship of exposures to methyl mercury (MeHg) and nutrients from fish consumption with neurological development. We included studies of experimental animals and humans in an effort to better understand the possible benefits and risks of fish consumption. ObjectivesWe reviewed the literature on the use of ABR and OAE to measure associations with environmental exposures that result from consuming a diet high in fish. We focused specifically on long chain polyunsaturated fatty acids (LCPUFA) and MeHg. MethodsWe performed a comprehensive review of relevant studies using web-based search tools and appropriate search terms. ResultsGestational exposure to both LCPUFA and MeHg has been reported to influence the developing auditory system. In experimental studies supplemental LCPUFA is reported to prolong ABR latencies and human studies also suggest an association. Experimental studies of acute and gestational MeHg exposure are reported to prolong ABR latencies and impair hair cell function. In humans, MeHg exposure is reported to prolong ABR latencies, but the impact on hair cell function is unknown. ConclusionThe auditory system can provide objective measures and may be useful in studying exposures to nutrients and toxicants and whether they are associated with children's neurodevelopment.

Temporary reduction of distortion product otoacoustic emissions (DPOAEs) immediately following auditory brainstem response (ABR)

The hearing status of an experimental animal is typically assessed in the laboratory setting by the combined use of auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs), carried out in succession, with the former assay preceding the latter. This study reports a cautionary finding that the use of this accepted regimen yields a reduced DPOAE response. When the DPOAEs were performed after ABR testing, transient reduction of the DPOAE amplitudes was observed at all frequencies in both the inbred, C57/B6 and FVB/N, and the outbred, SW mouse strains. DPOAEs were reduced post-ABR in multiple mouse strains which suggests that this finding is not strain-specific but a general consequence of the preceding ABR analysis. The reduction in DPOAE was temporary: when re-tested at one hour, DPOAE amplitudes recovered to pre-ABR levels. In contrast to the ABR’s impact on DPOAE response, ABR thresholds were not altered or reduced when preceded immediately by DPOAE measurements. The molecular alterations underlying the ABR-induced transient reduction of DPOAE remain to be determined. To investigate the potential role of reactive oxygen species in post-ABR DPOAE reduction, transgenic mice over-expressing SOD1, the cytoplasmic enzyme critical for removal of superoxide radicals were subjected to the same auditory testing regimen. Similar to their wild type littermates, the SOD1 transgenic mice also demonstrated post-ABR DPOAE reduction, and thus do not support a role for superoxide radicals in transient reduction of DPOAE. While toxic noise exposure is known to negatively impact OAE, transient decrease in DPOAE levels following standard ABR assay has not been previously described. A practical outcome from this study is a recommendation for reversal of the traditional order for carrying out auditory tests, with the OAE measurements preceding ABR assessment, thus ensuring that the DPOAE response is unaffected.

Auditory brainstem responses in birds: How well do they compare to behavioral techniques for assessing hearing

Behavioral methods are the gold standard for assessing hearing sensitivity in birds. In many cases, however, behavioral techniques are simply impractical. The non-invasive auditory brainstem response (ABR) represents perhaps the next best approach, and researchers are increasingly turning to the ABR to obtain estimates of hearing sensitivity, auditory system function and development. Our lab has evaluated hearing sensitivity in over 11 species of birds using the ABR, and for six of these species, we have also obtained auditory thresholds by behavioral conditioning methods. These data, along with other results from the literature on bird hearing, now allow general conclusions about the use of ABR as a tool for measuring auditory sensitivity in birds. Waveform morphology is highly conserved across orders of birds. Regardless of how threshold is defined, the ABR audiogram reliably reflects the frequency range of hearing and the shape of the behavioral audiogram. However, ABR thresholds are higher than behavioral thresholds by 20-30 dB but with some variation across species. Aside from audiograms based on simple detection thresholds for tone bursts, ABR methods in birds have also been useful in assessing auditory development, hearing impairment, recovery of function with hair cell regeneration, masked thresholds and aspects of spectral and temporal processing.

Stimulus Repetition Rate and the Reference Levels for Clicks and Short Tone Bursts: A Warning to Audiologists, Researchers, Calibration Laboratories, and Equipment Manufacturers

To make the audiologic community aware of a technical issue with potential for misunderstanding that could affect the design, calibration, and use of auditory brainstem response (ABR) systems. Two international standards published in 2007 relating to the stimuli commonly used in ABR tests were studied and the behavior of a commercially available ABR system examined with regard to the relationship between stimulus level and repetition rate. There is potential for misunderstanding of the need to compensate for the effect of stimulus rate on stimulus level. Although rapidly presented stimuli appear louder as the rate is increased, it is inappropriate to compensate for this when calibrating the stimulus level of ABR systems. Users of ABR systems should, if possible, use the stimulus reference levels now available in an international standard rather than establish local values. No adjustment of level should be made to account for different stimulus repetition rates. Users of ABR systems should check their systems to ensure that no automatic level adjustment is made; if necessary, equipment manufacturers should be consulted.

Stimulus Repetition Rate and the Reference Levels for Clicks and Short Tone Bursts: A Warning to Audiologists, Researchers, Calibration Laboratories and Equipment Manufacturers

Purpose To make the audiologic community aware of a technical issue with potential for misunderstanding that could affect the design, calibration, and use of auditory brainstem response (ABR) syste...

Usefulness of auditory brainstem response as early predictor of kernicterus in early breast-feeding jaundice

Purpose : The present study examined the etiology and risk factors of the early breast-feeding jaundice and the usefulness of auditory brainstem response test as early predictor of kernicterus. Methods : Medical records of neonatal jaundice in newborn admitted to Daegu Fatima Hospital between September 2005 and May 2006 were analyzed prospectively. Infants were grouped according to feeding method : breast feeding group (breast feeding only, n=23), mixed feeding group (breast feeding mainly plus addition of fomula feeding, n=13). Results : There were no significant differences in gestational age, birth weight, sex, duration of phototherapy, serum bilirubin and hemolytic evidence between the two study groups. First visiting day of life at out patient department was significantly delayed in breast feeding group (8.7±3.6 day) compared to mixed feeding group (6.0±1.9) (P=0.009). Weight loss was significantly severe in breast feeding group compared to mixed feeding group (P

Auditory Brainstem Responses in Dyslexia: Comparison between Acoustic Click and Verbal Stimulus Events

This study examined the use of auditory brainstem response (ABR) by classic clicks and verbal stimuli in young dyslexic adults to identify latency abnormalities. Subjects included 10 dyslexic adults and 10 age-, sex-, IQ-, education-, and hearing sensitivity-matched normal subjects. Both groups had normal auditory status. Measurements included the absolute latencies of waves I through V; the interpeak latencies I-III, III-V, and I-V elicited by acoustic click; and the negative peak latencies of A and B waves, as well as the interpeak latencies of A-B elicited by the verbal stimulus "ma," created on a digital speech synthesizer. The measured latencies and interpeak latencies in response to both clicks and verbal stimuli were found delayed in eight dyslexic subjects, although they did not reach the level of significant difference. However, two dyslexic subjects had significantly delayed peak and interpeak latencies elicited by verbal stimuli. There are dyslexic subjects who may have abnormalities in acoustic representation of a speech sound as low as the auditory brainstem, as elicited by the verbal stimulus "ma."

Use of auditory brainstem responses for the early detection of ototoxicity from aminoglycosides or chemotherapeutic drugs

Effective objective HF (high-frequency) testing methodology provides for the early detection of ototoxic hearing loss because it typically progresses from high to low frequencies. Such early detection is considered necessary to prevent hearing loss from progressing into the frequency range important for understanding speech. Objective tests must be reliable, sensitive to hearing change, and time efficient. Auditory brainstem responses (ABRs) appear well suited to this task; however, current ABR techniques have limitations. Conventional clicks stimulate middle (1-4 kHz) rather than high frequencies (>8 kHz). Responses to HF tone bursts require considerable recording time. We hypothesized that using HF band-limited clicks (HF clicks) could overcome these limitations. Two different HF clicks, with bandwidths of 8-14 kHz were used to elicit ABRs. The current study compared responses among these stimuli. The results demonstrate the reliability of HF-click responses and of tone bursts presented in trains.

Avaliação dos achados ao exame dos potenciais evocados do tronco cerebral em indivíduos com síndrome de West

A síndrome de West é um tipo de espasmo infantil caracterizado por encefalopatia epiléptica associado a espasmos em flexão e deficiência mental de instalação no primeiro ano de vida e de etiologia incerta. Acredita-se ser determinada por diferentes fatores etiológicos como infeção intrauterina, esclerose tuberosa, asfixia perinatal ou afecções pós-natais. FORMA DE ESTUDO: Observacional coorte com corte transversal. MATERIAL E MÉTODO: No presente estudo dez pacientes com Síndrome de West foram submetidos ao exame de Potencial Evocado de Tronco Cerebral (BERA) para avaliar o envolvimento do tronco cerebral e das vias auditivas a este nível. RESULTADO: Os achados anormais ao BERA incluem alteração na morfologia das curvas com reprodutibilidade apenas de onda I e II, (caso 7), aumento do intervalo interpico da onda I-V (casos 1, 2 e 9), aumento da proporção de amplitude da onda I/V (caso 8) e alteração do limiar eletrofisiológico (caso 7). Tais achados ao BERA sugerem que a disfunção do sistema nervoso resulte principalmente da hipogênese ou degeneração das células nervosas, em parte como resultado da dismielinização. CONCLUSÃO: Os autores recomendam o uso de estudos eletrofisiológicos para avaliar a disfunção do sistema nervoso central no paciente com suspeita de espasmo infantil.

Experimental model of cisplatin ototoxicity in chinchillas

Cisplatin is an important antineoplastic agent. Its ototoxicity has been well defined, both in human and animal studies. However, animal models of systemic cisplatin administration have been complicated by multiple toxic effects. We studied cisplatin ototoxicity in an animal model involving topical application of cisplatin to the round-window membrane. Adult chinchillas were anesthetized with ketamine and pentobarbital, and auditory function was tested with the use of auditory brain-stem responses to various stimuli (clicks and 8-and 16-kHz tone bursts). Each animal was used as its own control. The middle-ear cavity was exposed through the bulla. In the experimental ear, a 25-μl solution of 0.25 mg cisplatin/1.0 ml normal saline solution was applied to the round-window membrane. In the control ear, 25 μl normal saline solution was applied to the round-window membrane. Follow-up auditory brain-stem response testing was conducted 7 days after treatment. A significant increase in threshold in the experimental ears was seen on comparison with the control ears. This finding suggests that application of cisplatin to the round-window membrane is a useful animal model in which to study cisplatin ototoxicity. (Otolaryngol Head Neck Surg 1998;119:574-80.)

Is auditory brainstem response a bilirubin neurotoxicity marker?

Purpose: To find a correlation between increasing levels of serum bilirubin and auditory brainstem responses (ABR) and to find the use of ABR as a bilirubin neurotoxicity marker. Material and Methods: A prospective study of 60 neonates in which ABR of hyperbilirubinemic neonates was compared with the normal neonates. All cases with abnormal ABR were studied for 6 months and after 1 month and 6 months a repeat ABR was performed. Results: Brainstem conduction time was found to be prolonged from 5.12 ± 0.26 to 5.83 ± 0.14 in neonates with a mean serum bilirubin level of 16.6 mg/dL (12 mg/dL to 18 mg/dL), which was found to be additionally prolonged to 6.0 ± 1.0 with an increase in mean serum bilirubin level to 21.98 mg/dL (P < .01). At first retest after 1 month, 33.33% of cases with a mean serum bilirubin level of 19.46 mg/dL and 80.00% with a mean serum bilirubin level of 15.97 mg/dL showed total recovery. After 6 months, three cases with mean serum bilirubin levels of 26.3 mg/dL and one case with a mean serum bilirubin level of 17.7 mg/dL failed to show any improvement. Conclusion: A positive correlation was found between increasing levels of serum bilirubin and brainstem conduction time (P < .01). ABR was found to be a very sensitive tool in picking up the earliest signs of neurotoxicity. Neonates with distortion of normal wave patterns on ABR were found to have poorer prognosis compared with those with delayed inter-peak (I-P) latencies.

Rethinking the use of auditory brainstem response in acoustic neuroma screening.

The ability of magnetic resonance imaging (MRI) to detect very small acoustic tumors has triggered many to rethink the use of auditory brainstem response (ABR) in the screening of acoustic tumors. To assess ABR accuracy, we conducted a retrospective study of 388 surgically treated patients. Of these patients, 111 had complete databases including both preoperative MRIs and ABRs. The ABR was abnormal by wave V interaural latency difference in 106 (95%) of the cases. Although our overall sensitivity was 95%, sensitivity varied according to tumor size. ABR was abnormal or absent for all tumors (100%) larger than 2 cm in diameter, for 98% of tumors 1.1 to 2 cm in diameter, and for only 89% of tumors less than or equal to 1 cm in diameter. Ramifications of this in the decision-making process are presented. Criteria for cut-off values are also discussed.

The diagnostic use of auditory brainstem response and evoked otoacoustic emissions in the era of magnetic resonance imaging

The diagnostic use of auditory brainstem response and evoked otoacoustic emissions in the era of magnetic resonance imaging