Auditory Brainstem Response Waveforms Research Articles

Assessment of cisplatin-induced ototoxicity using derived-band ABRs

Ototoxicity is an adverse side effect of numerous therapeutic agents (aminoglycoside antibiotics, blood chelating agents, diuretics and oncologic drugs) used in treatment of both adult and pediatric patients. Recently, there has been increasing interest in using the auditory brainstem response (ABR) to detect both short-term effects of ototoxicity in adults and long-term effects of drug administration on neonates and children. Since click ABRs have relatively poor frequency selectivity they best approximate the pure-tone hearing threshold in the 2000–4000 Hz frequency range. Hearing loss above or below that frequency range can be present without producing significant abnormalities in the ABR waveform parameters. Frequency-specific ABRs can be obtained using the derived response technique. The purpose of this study was to investigate early cisplatin ototoxicity using both the broadband click and derived ABR and to monitor progressive hearing loss with repeated drug trials in 18 patients studied over a 2-year period. ABRs were obtained serially prior to and following intravenous administration of cisplatin. Derived ABRs were found to be more sensitive than broadband click ABR in detecting early high-frequency hearing loss. For click ABRs, the cumulative dosage of cisplatin at age of ABR examination was correlated with hearing loss in only those patients under 3 years of age. No significant correlation was found between cumulative cisplatin dosage when tested and degree of hearing loss in those patients over 3 years of age.

Relationship between Auditory Brainstem Response Waveform and Head Size

The relationship between the head size and the latency and amplitude of the auditory brainstem response (ABR) was investigated in 60 normal-hearing adults (30 males and 30 females). We found a strong positive correlation between the latency of ABR waves and the head size and a strong negative correlation surfaced between the ABR amplitude and head size. These results indicate that the head size is one of the most important factors influencing the waveform of the ABR.

Auditory Brain Stem Response in Newborn Infants—Masking Effect on Ipsi- and Contralateral Recording

Ipsilateral and contralateral auditory brain stem responses (ABR) were recorded in 10 full-term neonates. We investigated the effect of the masking level on the peak latency and amplitude on ipsi- and contralateral recordings. Clicks were presented at 85 dB HL to the ipsilateral ear and the masking white noise was presented at 75, 65, 55, 45 and 0 dB HL on the contralateral one, respectively. Masking had no significant effect on the ipsi- and contralateral recording in regard to latency and amplitude except for wave CVI (contralateral wave VI). In addition, ABR was recorded in an infant with total unilateral hearing loss. Crossover responses on both sides were observed with-out contralateral masking, but these responses were completely eliminated when 45 dB HL contralateral masking masked the 85 dB HL clicks to the dead ear. Therefore, it is suggested that such crossover responses will contribute to the ipsi- and contralaterally recorded ABR waveform when an ABR recording is carried out without contralateral masking. Our results indicate that contralateral masking is necessary and should be used in cases of unilateral hearing loss.

Audiogenic seizure severity and hearing deficits in the genetically epilepsy-prone rat

Hearing deficits have been observed in rodents that are susceptible to audiogenic seizures (AGS), including the genetically epilepsy-prone rat (GEPR). AGS sus-ceptibility can be induced in normal animals by treatments that damage the cochlea. In this study, we measured the relative degree of hearing loss in animals from the GEPR substrains that exhibit different degrees of AGS severity and examined the relationship between the deficit and the AGS severity. Auditory brain stem response (ABR) thresholds to clicks in the GEPR substrain that exhibits exclusively maximal AGS severity (GEPR-9) were significantly elevated, and latencies for ABR peaks I, III, and IV were significantly increased as compared to normal Sprague-Dawley rats. ABR thresholds for the substrain of GEPRs that exhibit exclusively submaximal AGS (GEPR-3) were even higher than those in the GERP-9, and ABR waveforms were distorted. ABR peak IV was significantly longer than normal in the GEPR-3 substrain, as were mean interpeak intervals and central conduction times. These data indicate that significant hearing deficits occur in the GEPR-3 substrain. In non-AGS-susceptible progeny of the GEPR-9 [GEPR-0(9)], ABR thresholds were not significantly different from normal. These data along with studies of ABR thresholds in thyroid-deficient rats suggest that an inverted Ushaped relationship exists between hearing deficit and AGS severity. That is, moderate threshold elevations are associated with increasing AGS severity, but when the hearing deficit exceeds a certain level, a decrement in AGS severity occurs.

Comparisons of between‐ and within‐subject variability in repeated‐measures auditory brain‐stem responses (ABRs) in 10‐ to 12‐year‐old children

In reports to this Society, and in various publications [J. L. Lauter and R. L. Loomis, Scand Audiol. 15, 167–172 (1986); 17, 87–92 (1988)], results of repeated‐measures ABR testing in young adults have been described, indicating that the variability of peak parameters, such as latency and amplitude, provides information that absolute values of these parameters do not: contrasts in between‐ versus within‐subject consistency, and by ear of stimulation. Nine 10‐ to 12‐year‐old boys were tested in four biweekly sessions, with five ABR waveforms collected in each session for monaural right, monaural left, and binaural clicks. Relative variability measures of ABR latencies reveal adultlike patterns based on nonadult values: (1) contrast in between‐ versus within‐subject consistency; (2) peak differences; and (3) ear differences. There are also differences in within‐ versus between‐session consistency. Preliminary comparisons with results of similar testing in 5‐ to 7‐year‐old children [J. M. Lord‐Maes and J. L. Lauter, J. Acoust. Soc. Am. Suppl. 1 85, S38 (1989)] and adults suggest that ABR variability may be sensitive to auditory‐system developmental changes that continue long after ABR absolute peak latencies have achieved adult values. [Work supported in part by AFOSR.]

Evaluation of a computer-automated program for clinical assessment of the auditory brain stem response.

An evaluation of an automatic auditory brain stem evaluation (AABE) for waves I, III, and V, of the auditory brain stem response (ABR) is presented. The on-line procedure performs a mathematical analysis of ABR waveforms using principles similar to those used by experienced clinicians to make threshold and latency decisions. It has been tested and applied to normal and pathologic traces at stimulus levels from 20 to 100 dB HL. Subject ages ranged from 6 months through adulthood. Latencies and thresholds determined by the analytic technique were examined and found to be indistinguishable from decisions of two "expert" observers and four practicing clinical audiologists experienced in ABR. Speed, practicality, and limitations of the software for routine ABR assessments are discussed.

相互相関関数法による聴性脳幹反応の解析 脊髄小脳変性症と多発性硬化症における検討

The diagnostic usefulness of cross correlation function in the analysis of auditory brain stem responses (ABR) in Spinocerebellar degeneration (SCD) and multiple sclerosis (MS) was evaluated. ABR recordings from 30 normal males and females were averaged to produce normative ABR waveforms serving as templates for each gender. The cross correlation function between the individual ABR recording and the corresponding template was calculated, yielding an objective measure of the ABR waveform and gross latency. Cross correlation indexes were: RU (Correlation Coefficient at time O), RM (Maximal Correlation Coefficient) and DL (Latency Delay in msec).In 22 patients with SCD with pontine atrophy diagnosed by CT scan, abnormalities of cross correlation function were detected more frequently (81.8%) than abnormalities of ABR peak latency (68.2% according to traditional criteria and 77.3% according to the criteria for each gender).The evaluation of ABR waveform characteristics with cross correlation function using normative ABRs of the same gender were demonstrated to contribute to the diagnosis of slight lesions in the brain stem auditory pathway.

Effects of cisplatin and thiosulfate upon auditory brainstem responses of guinea pigs.

Two side effects which limit the use of cisplatin in cancer chemotherapy are severe nephrotoxicity and ototoxicity. The concurrent administration of sodium thiosulfate with cisplatin reportedly protects from cisplatin nephrotoxicity, however, protection from ototoxicity has not been documented. The purpose of this study was to examine the efficacy of using thiosulfate to ameliorate the ototoxic effects of cisplatin. Toward this end, the effects of cisplatin alone, cisplatin administered concurrently with sodium thiosulfate (CIS/THIO), and sodium thiosulfate alone on the auditory brainstem response (ABR) of guinea pigs were compared. ABR waveforms, comparing latencies, amplitudes and response thresholds, were monitored before, immediately after, and 30 days post treatment. Sodium thiosulfate administered with cisplatin (CIS/THIO) consistently protected animals from hearing loss and surprisingly yielded significant increases in amplitude when compared to baseline and saline controls. However, ABRs of CIS/THIO animals returned toward baseline values after 30 days.

ＡＢＲの相互相関関数による解析

Cross correlation analysis of auditory brain stem response (ABR) by means of the fast Fourier transform (FFT) was performed in normal subjects and its clinical significance was discussed.Cross correlation functions were computed between individual ABRs and each of following three kinds of normative ABR templates (nABR): (1) mean of ABR recordings from 30 normal males (MnABR), (2) mean of recordings from 30 normal females (FnABR) and (3) mean of MnABR and FnABR (MFnABR), because significant difference in wave V latency between MnABR and FnABR was observed. It was, therefore, subsequent that three kinds of cross correlation functions were obtained for each individual ABR. As the cross correlation index, R0 (correlation coefficient at 0msec), RM (maximal correlation coefficient) and DL (latency delay in msec) were adopted.Means and standard deviations of the parameters in normal subjects were compared among three kinds of cross correlation functions. From the results, evaluation of ABR waveform characteristics with cross correlation analysis using nABR of the same gender seems to be more significant than the analysis using MFnABR or using nABR of the other gender.

Automated system for screening hearing using the auditory brainstem response.

Routine screening of hearing using the auditory brainstem response (ABR) in infants, such as neonates in the special care baby unit, requires a system which is quick, user-friendly and gives a simple outcome. A system which consists of a stimulator/amplifier unit for recording the ABR controlled by a standard Master Series BBC Microcomputer is described which fulfils these requirements. The test procedure is highly automated, and a pass or refer decision for the screen on each ear is given by a machine-scoring algorithm which detects the ABR waveform.

Validation of addition and subtraction of ABR waveforms.

Procedures that use the auditory brainstem response (ABR) to demonstrate binaural interaction, phasic differences, narrow-band derived responses, and adaptation rely on additions and subtractions of waveforms to demonstrate effects that are not evident in the raw waveforms. The purpose of this study was to validate these data manipulations by performing additions and subtractions of waveforms in cases in which the theoretical result should be no difference potential and in cases in which the theoretical result should be a difference potential. The results indicate that additions and subtractions of ABR waveforms are valid data manipulations.

Microprocessor-based auditory brainstem response (ABR) simulator.

A low-cost, microprocessor-based instrument is designed to simulate the human auditory brainstem response (ABR) to acoustic clicks. the device normally delivers a continuous simulated EEG signal in the absence of click input. When an acoustic click is sensed, its onset and intensity are recognised promptly and an appropriate ABR waveform is superimposed on the ongoing EEG. Fast recognition of onset and intensity are achieved by using analogue detector circuits which issue microprocessor interrupts. The output waveform is synthesised by a 16-bit D/A convertor to preserve realistic signal (ABR) to noise (EEG) ratios. As multiplication operations cannot be performed at speeds appropriate for ABR waveform simulation, superposition is accomplished by position-weighted loading operations in a 16-bit register. The instrument is tested using a microcomputer-based signal averager. it satisfactorily simulates the randomness of single sweeps. Upon averaging enough sweeps, an ABR waveform is obtained. The device, believed to be the first available of its kind, is used to test and calibrate clinical EP systems and is expected to prove useful as a clinical engineering tool in hospitals and medical centres.

Changes in the extracellular potential power spectra depending on the duration, asymmetry and conduction velocity of the intracellular potentials generated by an excitable fiber: [formula omitted], Z. Lateva and N. Dimitrova (CLBA, Center of Biology, Bulgarian Academy Sci., Sofia 1113, Bulgaria)

Simultaneous auditory brainstem responses (ABRs) to click stimuli at 30 and 60 dB nHL were recorded from 16 full term neonates with four electrode arrays: vertical (Cz-Nape of neck), ipsilateral (Cz-Mi), contralateral (Cz-Mc), and horizontal (Mc-Mi). Results indicated that ABR waveforms were morphologically similar to those recorded in adults: Waves I, III, and V were clearly identifiable and of the same polarity in 15 of 16 subjects 60 dB nHL and Wave V was clearly identifiable in 14 of 16 subjects at 30 dB nHL. Although ABR waves were identified in most cases, waveforms expression was variable with different electrode recording montages. It is suggested that if a clinician must choose one montage array for recording neonatal ABRs at high intensity levels for neurodiagnostic evaluations, the ipsilateral recording array is indicated since it displays the highest expression of wave components. For screening applications or threshold searching at lower stimulus levels, however, either the ipsilateral or vertical montage would be justified. Further, caution should be employed when interpreting ABR results in neonates recorded with unconventional montages due to the variable expression of wave components.

Analog and zero phase-shift digital filtering of the auditory brain stem response waveform.

Auditory brain stem response waveforms, derived from normal ears, were analyzed with a computer-based digital filtering program as a means of systematically evaluating the effects of phase-shift distortion. Off-line analysis involved the stimulated responses of a Butterworth-type filter at five high-pass and four low-pass frequencies, three filter slopes, and standard versus zero phase-shifting. Phase-shift, as seen with analog filters, proved to be a major cause of waveform distortion including significant latency and amplitude changes. A discussion on the need and use of digital filtering as well as suggested analog filter parameter settings is included.

Stimulus duration and waves of auditory brainstem response.

This study was conducted to investigate the effects of stimulus duration on auditory brainstem response (ABR) waveform. Stimuli were 3-kHz tone bursts with 1 ms rise/fall times and durations of 5, 10, 20 and 30 ms. They were delivered at interstimuli intervals ranging from 80 to 140 ms. Latency and amplitude increases were observed in waves V and VI as the stimulus duration increased, whereas wave III showed no increase in latency, but decreased in amplitude. Animal experiments showed that the slowly rising curve of the response with increasing stimulus duration results in an increase in the peak latency and in the amplitude of the slow component of the ABR. Thus the change in ABR waveform observed when the duration of the stimulus was increased is not explained by a recovery process of the nervous system, but is possibly mediated by the slow component of the ABR.

Auditory Brain Stem Response Test Battery for Multiple Sclerosis Patients: Evaluation of Test Findings and Assessment of Diagnostic Criteria: Bilan des examens électrophysiologiques (tronc cérébral) dans la sclérose en plaques: évaluation des résultats de différents tests et établissement de critères de diagnostic

A battery of auditory brain stem response (ABR) tests has been used to evaluate 39 multiple sclerosis (MS) subjects (9 with probable, 8 with possible, 6 with suspected and 16 with definite MS, according to conventional classification of the disease). Test battery included evaluation of ABR waveform, latencies and interpeak intervals, test-retest variability, rate-induced ABR changes, binaural increase of wave-V amplitude and effect of ipsilateral masking with broad-band noise. Test results allowed a measure of the sensitivity, specificity and efficiency of each test in the battery. The high efficiency values thus obtained validated each test in the battery when normals were compared with definite MS patients. No single test, however, proved to be sufficient--by itself--to reliably distinguish subjects with earlier stages of the disease, suggesting that a combined evaluation of tests is necessary to fit better the clinical classification. When compared with 'conventional' ABR analysis, 'sensitized' ABR tests--i.e. the measures of test-retest variability, binaural increase of wave-V amplitude and the effect of ipsilateral broad-band noise masking--showed higher percentages of positive results in subjects with no clinical signs of brainstem and midbrain involvement. Sensitized tests therefore appeared more suitable to reveal a brainstem subclinical involvement.

An improved technique for simultaneous recording of action potential and auditory brainstem responses.

A simple method for the assessment of central conduction time in auditory brainstem response (ABR) cases with distorted or absent wave I and the technical problems involved are discussed. New electrodes systems for extra/transtympanic recording, artifact-free acoustic stimulation and a combined recording of the large amplitude SP/AP complex and small ABR waveforms are described. The need for external adjustment of the AP/wave V amplitude ratio has been demonstrated in order to obtain the satisfactory recording.

Brainstem response audiometry as subjective and objective test for neurological diagnosis.

This investigation is a preliminary report in which the auditory brainstem response (ABR) cross-correlation evaluation method is applied to a group of patients with a definite diagnosis of multiple sclerosis. The analysis of the results shows that the cross-correlation procedure is able to detect the ABR abnormalities with at least the same degree of accuracy as the abnormality identification made by visual inspection. Furthermore, discriminant analysis of the cross-correlations results shows that by using the Z-maximum correlation from only two derivations it is possible to separate the multiple sclerosis group from the normal group with only two failures. Since the cross-correlation procedure allows the evaluation of the ABR waveform, avoiding the unsatisfactory limitations of subjective identification, this contribution supports the idea that the cross-correlation procedure can be a clinically promising method for objective evaluation of the ABR.

聴性脳幹反応と下丘

The role of the inferior colliculus (IC) to the auditory brainstem response (ABR) was investigated in rats by the following experiment consisting of; (1) observation of change in the ABRs and evoked potentials (EPs) of the IC before and after unilateral destruction of the cochlea. (2) observation of change in the wave form of EPs and ABRs before and after destruction of the IC. (3) recording of the EPs at various points in and around the IC. (4) search for the isopotential line in and around the IC. (5) recording of EPs to electrical stimulation of the IC. The EP of the central nucleus of the IC consists of one or two positive waves followed by a large negative wave. The wave form of the ABR seems to be a composite of a positive slow wave and several sequential fast wave-lets, and characteristics and origins of these two potentials are different to each other.The central nucleus of the IC is more important for generation of the positive slow component. A negative field is observed in the central nucleus of the IC, and a positive field surrounding this negative field is recorded as the positive slow wave of the ABR from the surface of the brain. A similar electrical potential field was also observed by the direct electrical stimulation of the IC, that is, a large negative potential was recorded at the central nucleus of the IC and a positive potential was observed at the surface of the brain, when the lateroventral part of the IC were stimulated electrically. Thus, the positive slow wave of the ABR is consisted mainly of this positive potential field, at least in latter part of the slow wave.The central nucleus of the IC might not be essential for generation of the several sequential fast waves of the ABR, because their latencies and amplitudes were not changed by destruction of the central nucleus of the IC. However, when the lesion was extended to or located in the lateroventral part of the IC, where the nerve fibers of the peripheral nuclei penetrate into the IC, potential V and VI were abolished whereas potential IV was remained unchanged. Thus, the structures peripheral to the IC play an important role for the generation of potential IV, and the lateoventral part of the IC is essential for generation of potential V and VI.

On-Line Computer Scoring of the Auditory Brainstem Response for Estimation of Hearing Threshold

Auditory brainstem responses (ABRs) to click stimuli have become established as a useful indicator of hearing thresholds in infants and young children. Although the investigation is objective in so far as the patient is concerned, a subjective element remains in the decision by the operator as to whether or not an ABR is present in an averaged waveform. A simple on-line computer detection technique is described which removes some of the reliance placed upon the operator. The technique employs a scanning window for correlation and amplitude analysis of pairs of averaged ABR waveforms. The reliability and accuracy of computer and operator scoring of 25 thresholds in normally hearing adults and 50 thresholds in infants and young children with suspected hearing impairment have been investigated. In the adult group, 96% of computer estimates of the threshold were within +/- 10 dB of the subjective hearing threshold, compared with 92% for operator scoring. There were 92% of computer and operator scores within +/- 10 dB of each other. In the patient group there was equally good agreement between computer and operator scoring with 90% of the thresholds within +/- 10 dB of each other; the incidence of possible false-positive thresholds was also lower with computer scoring. This on-line scoring technique, therefore, offers useful assistance to the operator; requires only limited computing power, and is suitable for use in a routine clinical environment.