Electrical Brainstem Response Research Articles

On the use of click-evoked electric brainstem responses in audiological diagnosis. IV. Interaural latency differences (wave V) in cochlear hearing loss.

Interaural latency differences (ILDs) of wave V of the brainstem electric response (BSER) were studied (1) in 20 normal-hearing subjects at 90, 80, 60 and 40 dB HL click level, (2) in 22 patients with symmetrical cochlear hearing loss at 90 dB HL, corresponding to 45-80 dB SL, and (3) in 45 patients with asymetrical cochlear hearing loss with interaural recruitment, at 90 dB HL on one hand and at a click sensation level corresponding to 90 dB HL in the poorer ear (range 10-75 dB SL) on the other hand. In the normal hearing group the ILDs did not exceed 0.2 ms except in one case at 40 dB HL (0.3 ms). In the symmetrical cochlear loss group the ILD did not exceed 0.2 ms in any patient. In the asymmetrical cochlear loss group the ILD at 90 dB HL exceeded 0.2 ms in 12 cases, but only in four cases after correction for pure tone hearing loss at 4 kHz by 0.1 for each 10 dB above 50 dB HL; at equal sensation levels the ILDs were all zero or negative meaning that the wave V latency was shorter on stimulation of the poorer ear. Assuming ILD to be a valid discriminator between cochlear and retrocochlear lesions, the corrected ILD at equal click hearing levels (90 dB HL), with the critical value set at 0.2 ms, thus gave a 9% false-positive rate whereas the ILS at equal sensation levels, with the critical value set at zero, gave no false-positives. It still remains to be shown that the latter criterion will not increase the number of false-negative results in retrocochlear lesions.

Electrocochleography and auditory brainstem electric responses in patients with pontine angle tumors.

In 45 patients with surgically proven pontine angle tumors, compound action potential (AP) and summating potential (SP) were recorded with transtympanic electrocochleography (ECochG) together with brainstem electric responses (BSER). The aims were to quantify the mechanism by which tumors cause hearing loss and evaluate the diagnostic potentials of ECochG and BSER for detecting eighth nerve and brainstem tumors. Except for AP latency and narrow band AP waveform, response parameters recorded by ECochG are uncorrelated. Four uncorrelated parameters were abnormal in only 10% of the cases, three in 25%, two in 40%, and one in 90%. The BSER criterion was the latency delay between waves I and IV and resulted in about 90% detection, improving to 95% when used in combination with ther interaural wave V delay criterion. ECochG results provide evidence that, for hearing losses up to 60 dB HL, the origin is cochlear, resembling that caused by Meniere's disease. Evidence is presented that the increase in I-V delay in the BSERs is caused by differential action of the tumor upon low and high frequency fibers in the auditory nerve and that desynchronization of the firings of the nerve fibers is of more importance than an increase in neural conduction time. ECochG as the sole test for detection of pontine angle tumors appears to be of limited value. Brainstem response on its own has great merits; however, it should be emphasized that no wave I was detected in about 30% of the cases. The 95% detection score obtained with BSER depends on specifying the latency of wave I. For these cases, we substituted the latency of the AP recorded by ECochG.

A workable approach to the identification of neonatal hearing impairment

The American Hearing Research Foundation has developed a regional Infant Screening Program in the state of Illinois, designed to meet the vital need for early identification of hearing impairment on a mass scale. The four major components of the program include: 1. Application of the High Risk Register to the general newborn population, 2. Hearing Screening in the Intensive Care Nursery, 3. Electrophysiologic confirmation with Brain Stem Electric Response testing and 4. Subsequent and immediate remediation and/or habilitation. Brain Stem Electric Response Audiometry (BERA) has been shown to be an accurate and sensitive clinical tool for obtaining auditory thresholds in infants from birth. At the Donald T. Forsythe Otologic Laboratory in Mercy Hospital, Chicago, IL, over 250 infants and young children have been tested in a controlled study with BERA to establish or rule-out the diagnosis of hearing impairment. The use of BERA preceded by screening of a refined neonatal population has proven to be an effective method of early identification. The goals of the program are: 1. To identify hearing impaired children prior to passage of the critical periods, 2. To medically or surgically classify and treat and/or auditorily habilitate, and 3. To ultimately improve the quality of life of the child born with hearing impairment.

Acoustic reflex latency test in the evaluation of nontumor patients with abnormal brainstem latencies.

The acoustic reflex latency test (ARLT), an indirect measure of neural conduction time utilizing the electroimpedance method, was used to evaluate 43 highly suspect, nontumor patients who demonstrated abnormal latency results on brainstem electric response audiometry (BERA), false-positive for tumor. Normative values and criteria for tumor-positive ARLT results were established on a control group using a second generation test unit, comprised of dual impedance bridges and a digital signal averager, designed especially to perform the ARLT. When cut-off criteria for both absolute reflex latency and interaural latency difference (ILD) values were applied to this BERA false positive population, the ARLT correctly identified 93% of patients as having end-organ lesions. Differences in ARLT and BERA test results are attributed to differences in 1) method of measurement, 2) characteristics of the eliciting signal, and 3) generation of the response. These factors are discussed as sources of variability. Both ARLT and BERA are recommended as tandem procedures when screening for acoustic or angle tumors.

Slow tremor and delayed brainstem auditory evoked responses in alcoholics.

Interpeak intervals of the auditory brainstem evoked electric response (ABR) were measured in 13 patients showing a characteristic slow rhythmic tremor and a more or less marked chronic cerebellar ataxia. Eleven of these patients were advanced alcoholics; two were less severe alcoholics. The tremor appeared primarily in the legs, and displayed distinctive features when examined in appropriate postures. Ten of the patients displayed a significant increase of the I-V interval of the ABR. The occurrence of the slow tremor with abnormal electric brainstem responses may provide objective evidence of lesions affecting extracerebellar regions of the CNS.

On the use of click-evoked electric brainstem responses in audiological diagnosis. II. The influence of sex and age upon the normal response.

Brain stem electric responses (BSER) to clicks at 80, 60 and 40 dB SL (rate 22.5/sec) were recorded from 62 normally hearing subjects grouped according to sex and age. There were four groups: young females (mean age 26.8 years), old females (56.1 years), young males (29.6 years), and old males (59.3 years). The BSERs were measured in respect to peak latencies (I, III, V) and interpeak intervals (I-III, III-V, I-V). Wave replicability was seen to deteriorate with age. Concerning peak, latencies, highly significant differences were established between the group of young females on the one hand, and the other three groups on the other, young females exhibiting shorter latencies (of the order of 0.2 msec); differences between the other three groups were less significant or not significant at all. Concerning interpeak intervals, the differences between groups showed little or no significance. Furthermore, in old subjects--but not in young ones--the individual III-V interval exhibited a significant increase with reduction of click intensity from 80 to 60 dB SL of the order of 0.1 msec. Variances of peak latency and interpeak interval measures were not seen to differ significantly between groups.

Latency of brainstem response in children.

Brainstem electric responses were obtained on a group of 70 normal hearing children, aged 5-11 years, matched by age and sex. The recordings were examined for differences in latencies between the sexes at each age. The results showed that males have a longer latency than females, but when broken down into age groups, the latency of children aged 5-7 years was the same, and the latency of children aged 8-11 years differed. The results for latency of wave V of the whole group showed the greatest difference. The reason why such a sex difference should occur in middle childhood is discussed, but no physical cause found.

Auditory brain-stem electric responses evoked with suprathreshold tone-bursts.

The brain-stem electric responses elicited by tone-bursts with central frequency at octave intervals from 0.5 to 4 kHz and at 80--100 dB HL stimulus levels have been studied in normally hearing subjects and patients with sensorineural hearing loss. Jewett V latencies were considerably prolonged in patients with retrocochlear or central pathology. Latencies from normal and cochlear hearing loss ears were largely independent of thresholds at both the stimulus and other frequencies. The interpretation of response latencies at suprathreshold stimulus levels is discussed. Stimulus frequency should be selected in accordance with the pure-tone audiogram, and ears with prolonged latencies investigated at more than one frequency.

Dorsal cochlear nucleus (DCN) and its contributions to the brain stem electric response (BSER)

This report focuses on the contributions of the DCN to the BSER as part of a larger study of the origins and clinical applications of the BSER. Since their initial description, the successive waves of the BSER were thought to be related to the successive nuclei of the brain stem auditory pathway. Although a strict correspondence appears not to be the case, the exact nature of the physiology and underlying anatomy of the BSER is very much in doubt. Restricted lesions of the cochlear nucleus were utilized to explore the role of various elements within the nucleus in the generation of the BSER, as well as to assess the sensitivity of the BSER to restricted lesions of the central auditory pathway. DCN was selected as the first independent variable because it is easily accessible for aspiration lesions. The results suggest that (1) an overall reduction of the BSER occurs as a result of general trauma; (2) waves I, II, and V are not otherwise affected by destruction of DCN; (3) waves III and IV are altered after DCN lesions. The nature of the changes, their clinical implications, and future directions of our research will be discussed. [Supported by the Research Service of the Veterans Administration.]

Brainstem Audiometry in Neurotologic Diagnosis

Brainstem electric response audiometry (BERA) has been found to be a valuable adjunct to the neurotologic diagnosis. Ninety-eight percent of patients with surgically confirmed acoustic neuromas has positive BERA findings. We report six cases that illustrate the value of this technique in examining patients with suspected retrocochlear lesions.

Reconstruction of the audiogram using brain stem responses and high-pass noise masking.

Contributions to the brain stem electrical responses (BSER) presumably initiated from specific frequency regions of the cochlea with center frequencies similar to the major audiometric frequencies (0.5, 1, 2, 4, and 8 kHz) are derived by the application of a high-pass noise masking technique utilizing click stimuli. In normal hearing subjects, these derived narrow-band responses from the midfrequency regions (4, 2, and 1 kHz) can be recognized at click levels as low as 10 dB HL. For the frequency regions around 8 kHz and 0.5 kHz, these derived responses can be discerned at click levels of 30 dB HL and higher. When one uses the lowest click level at which these derived responses can be obtained from a given frequency region, the differences between a patient with a hearing loss and a normal hearing subject correlate well with the amount of hearing loss (air conduction) recorded by conventional pure tone audiometry. Use of the high-pass noise masking technique to reconstruct the audiogram may be of great potential value in assessing young children and other individuals who cannot or will not respond to conventional audiometry.

Early Auditory-Evoked Responses in the Cat: Rate Effects

The brain-stem electric responses (BSER) of the cat have been evoked with a 4-kHz tone burst at three stimulus intensity levels, and at interstimulus intervals (ISI) varying fromm 500 to 20 ms. Response amplitude and latency have also been compared in different post-natal age groups, and in bilaterally hearing and unilaterally deaf animals. Increasing reptition rates produce greater latency changes in the youngest animals, whilst all age groups show amplitude decrement at shorter ISI, apart from wave III which increases in amplitude, particularly in bilaterally hearing cats at higher stimulus intensity levels. Wave I shows greater amplitude reduction than do the succeeding waves, which may indicate that the primary cochlear nuclei contribute to later waves of the BSER.

Brain stem electric response audiometry in the differential diagnosis of acoustic tumors

AbstractA brief history of the advances made in acoustic tumor diagnosis and treatment is presented indicating the benefits derived therefrom over the past 15 years. The recent application of brain stem electric response audiometry (BERA) as related to tumors affecting the auditory nerve is reviewed. Patients were considered to have a positive test result for tumor detection (abnormal BER) when their responses showed one of three characteristics: 1. wave V latencies were significantly different from the normal mean, 2. the interaural latency difference (ILD) was greater than .3 msec. (.4 msecs when the hearing loss was greater than 65 db HL), or 3. no response could be recognized at suprathreshold levels. An abnormal BER result was observed in 92.6% of 27 surgically proven tumors in this study. Two patients with surgically proven tumors had a false‐negative test. In a series of 115 nontumor patients with asymmetric sensorineural hearing losses of multiple etiology, one in three had an abnormal BER result. All conductive losses increased wave V latency values. The authors have concluded that an abnormal ILD is far from pathogmonic for a tumor affecting the auditory nerve; interpretive caution is recommended with even small conductive hearing losses. False‐negative responses are few, false‐positive responses are common (relative to tumor diagnosis). BERA is the most efficient audiometric test available today in our search for tumors affecting the auditory nerve. As such, this test probably heralds a new era in diagnostic audiology.

A slow brain stem response for low-frequency audiometry.

Proper choices of stimuli and of brain stem electric responses allow us to estimate peripheral auditory thresholds at 500, 1 000, 2 000 and 4 000 Hz with an accuracy of about +/- 10 dB. With the help of sedation (secobarbital), such audiograms may be obtained from each ear of a child of any age in a single session. Tone pips (filtered clicks) or very brief tone bursts give a frequency selectivity that is clinically adequate. The rise time must be adjusted to the center frequency. A rise time of two periods with a plateau from zero to one period gives a good compromise between frequency specificity and a synchronous neural discharge. The best threshold indicator for tone pips of 2 000 Hz or higher (or unfiltered clicks) is P6 (Jewett V). At 60 dB nHL its latency is 6.0-7.0 ms (for children of 1 year or older), but near threshold it is 8.0-9.5 ms. An input pass-band of 140-3 000 Hz is appropriate. The best threshold indicator at 500 or 1 000 Hz is a nearly neglected slower wave with a scalp-negative crest at about 10 ms following a 60-dB click. Latency is 15 ms following a 500-Hz tone pip at 15 dB SL. We call this wave "slow negative (ten)" or SN10. To see it well a wider input pass-band such as 40-3 000 Hz is needed. SN10 is usually obscured by P6 or by frequency-following response at stimulus levels above 35 dB SL. The details are given of a clinical routine that allows the determination (+/- 10 dB) of 8 threshold endpoints within about 80 min. Several precautions and limitations are discussed, and also the origin of the SN10 wave.

Brain stem electric response audiometry and middle ear effusion.

Brain stem electric response audiometry has been performed in a group of 41 difficult-to-test children under the age of 8 years. All ears were examined with the pneumatic otomicroscope prior to determination of response thresholds, and middle ear effusion found in 24 (29.3%). Seven of the 14 children requiring hearing aid amplification had fluid in 12 ears (42.9%). The importance of early recognition and treatment of middle ear pathology in children with sensori-neural hearing loss is stressed, and routine otomicroscopy by the attending otologist is recommended.

Brainstem electric responses (BERs) in rhesus monkeys and humans

Waveform and latency of BERs elicited by filtered, monaurally presented clicks (major energy, 2.4–7.4 kHz) were determined for Rhesus monkeys, N = 6 (M. mulata) and humans N = 46. Similar measurement conditions were maintained for the two species. BERs derived from monkeys consistently displayed a greater number of identifiable components then did those of humans, particularly at moderate and high click intensities. Values of absolute latency and intercomponent latency difference were foreshortened in Rhesus monkeys compared to these values in humans. The magnitude of this relative foreshortening was found to increase with later components. Possible anatomic bases for the interspecific response differences observed will be discussed. [Work supported by EPA and NIEHS.]

Bilateral recording of early auditory evoked responses in the cat

The brain-stem electric responses of the cat evoked by a short 4 kHz tone burst have been differentially recorded between vertex and both ipsilateral and contralateral ear electrodes. Six vertex-positive waves can be recognised in both recordings. Animals with hereditary unilateral anacusis were studied in order to avoid cross-stimulation of the opposite ear. The cochlear microphonic and summating potential can be readily recorded in young animals, occur simultaneously in both tracings, and show polarity inversion at the contralateral electrode. The later neural potentials have the same polarity and practically identical latencies in the ipsilateral and contralateral recordings, whilst the first three brain-stem waves show approximate polarity inversion and variable latency relationships in the two recording situations. It is concluded that none of the brain-stem waves represents electric activity from a discrete generator.

Analysis of the click-evoked brainstem potentials in man unsing high-pass noise masking.

Brainstem electrical responses (BSER) to 60-dB-SL click in noise high passed at various cutoff frequencies separated b 1/2-octave steps were recorded in normal-hearing adult subjects. By applying a derived response technique, narrow-band contributions to the BSER from specific portions of the basilar membrane were revealed. Latencies and amplitudes of the various waves in the derived BSER were recorded. Results indicate that nearly the whole cochlear partition can contribute to the brainstem response. The shifts in latency of waves I, III, and V and amplitude changes of waves I and III as a function of CF appear to be fully comparable to those of the AP. In contrast, the amplitude behavior of wave V as a function of CF is different from waves I and III depending upon frequency range. The discrepency in the behavior of wave V with respect to the earlier waves suggests some sort of neural reorganization at the level where was V is generated. The fact that there are contributions to the brainstem response from apical portions of the cochlea opens the possibility for extending the brainstem technique in assessing the higher cochlear turn function.

On the use of click-evoked electric brainstem responses in audiological diagnosis. I. The variability of the normal response.

The normal click-evoked BSER was studied in a total of 28 young (aged 12 to 40) normally hearing subjects in regard to wave latencies and amplitude ratios, considered to be (besides wave replicability) the characteristics of major interest from a clinical point of view. Latency means and standard deviations (S.D.), and peak-to-peak amplitude ratios between wave V on the one hand and wave I and III, respectively, on the other were determined in a sample of 20 subjects using unfiltered clicks at 20 to 90 dB SL. The latency averages were compared with those of other reports. Latency S.D.s were found to be generally less than 0.25 ms at levels above 50 dB SL. Medians of amplitude ratios (AV/AI and AV/AIII) were found to be significantly greater than unity. No significant latency differences concerning waves I, III, and V could be established on stimulation with condensation, rarefaction, and alternating clicks in 10 subjects at 80 and 60 dB SL, nor did the peak-to-peak amplitude predominance of wave V change with click polarity. With half-octave filtered clicks (2 and 4 kHz), latencies were found to increase significantly (and the responses to become less precise) at 80 and 60 dB SL in a sample of 12 subjects. Changing the interstimulus interval (ISI) from 80 to 60 to 40 ms (at 80 and 60 dB SL) hardly made any difference in regard to I, III, and V latencies, or wave V amplitude supremacy. Finally, a satisfactory test-retest reliability was established in a sample of 6 subjects, the intersession interval being 6 months.

Audiograms derived from the brain stem response

Nineteen normal and 22 hearing impaired subjects were used in this study. Thresholds were determined by the following methods: 1. behavioral continuous tone, 2. behavioral tone burst, and 3. the brain stem electric response (BER) with tone bursts. A comparison of the BER thresholds with the behavioral thresholds are made for each subject. The difference between these three measures of threshold suggests that audiograms can be derived from the brain stem response threshold. The derived audiogram compares favorably with conventional audiograms. However, it must be remembered that the brain stem response is not hearing.