Auditory Brainstem Response Peak Research Articles

Automated auditory brainstem response interpretation

The authors report a complete automated system for auditory brainstem response (ABR) identification and waveform recognition. The goal was to develop an automated analysis methodology that would facilitate the clinical use of auditory brainstem responses by reducing the time required to manually label and measure absolute and interpeak latencies. The system presented here accomplished this goal, supplying not only threshold information, but also additional diagnostically significant information. In addition, such an automated system will standardize the labeling process, which can vary depending on the labeling preference of individual clinicians. There are currently no commercially available systems capable of labeling ABR peaks or interpreting results originating from a wide range of stimulation intensities. The system developed in this study performs both peak labeling and assessment functions. >

Pure-tone masking profiles for human auditory brainstem and middle latency responses

Several studies have compared the frequency selectivity of waves I and V of the auditory brainstem response (ABR) in humans, however little is known about the frequency selectivity of the middle latency response (MLR). Simultaneous recordings of ABRs and MLRs to 60 dB peSPL 2000-Hz probe tones were obtained in the presence of 0.5, 1.0, 1.41, 2.0, 2.83 and 4.0 kHz maskers presented at 40, 60, and 80 dB SPL. ABR/MLR iso-intensity masking profiles showing the percentage of the unmasked amplitudes as a function of frequency were constructed for ABR peak V-Vn and MLR peaks Na-Pa and Nb-Pb at each masker intensity. No significant differences were found between the frequency selectivity of the ABR and MLR, and the effects of masking on the amplitudes of these responses were similar. These results are consistent with the suggestion that frequency tuning is similar up to the level of the primary auditory cortex.

Effects of tone burst frequency and intensity on the auditory brainstem response (ABR) from albino and pigmented rats

Young adult male Sprague-Dawley (SC) and Long-Evans (LE) rats were evaluated using the auditory brainstem response (ABR). ABRs were evoked by stimuli with intensities ranging from 15 to 100 dB peSPL. Stimuli were tone bursts of 2000, 4000 and 8000 Hz. As stimulus intensity decreased from 100 to 15 dB, the ABR peak latencies prolonged, interpeak latencies (IPLs) shortened and amplitudes decreased. As stimulus frequency decreased from 8000 to 2000 Hz, ABR latencies prolonged, amplitudes decreased and ABR thresholds increased. The longest IPLs were in response to the 4000 Hz tone bursts. SD rats had ABRs with shorter peak latencies, larger amplitudes and lower thresholds than LE rats. The IPLs usually did not show significant strain-dependent differences. Our observations on stimulus intensity and frequency are consistent with previous reports. Our observations also suggest that the SD (albino) rat has better auditory acuity than the LE (pigmented) rat over the frequency range of 2000 to 8000 Hz. This implies that previous concerns about the use of albino animals in audiological research are somewhat overstated.

The effect of click rate on ABR stability measured with the REPs/ABR protocol.

Previous studies reported to this Society regarding our repeated evoked potentials (REPs) protocol for auditory brainstem responses (ABRs) have used a click rate of approximately 11 per s. Revisions in the REPs/ABR protocol requiring collection of as many as 16 waveforms in a single session encourage test streamlining, such as increasing click rate. The ABR literature suggests that while click rates of 30/s and above may affect 11/s-based absolute ABR parameters such as peak latency and peak amplitude, fewer changes will be seen with rates lower than 30/s. There are no data on the effect of click rate on ABR peak stability, the dependent variable targeted by the REPs procedure. Eight young adults with normal hearing (four women and four men) were tested in a within-subjects five-session design. Each session involved collection of 4 left ear, 4 right ear, and 8 binaural ABR waveforms; in sessions 1 and 5 a click rate of 11.1 per s was used; for sessions 2, 3, and 4, responses were evoked at click rates of 22.2, 33.3, and 44.4 per s, respectively. Results indicate that click rates faster than 30/s do create the most changes in 11/s-based peak latency and amplitude, though the effects for all increases are differentially distributed by peak, ear condition, and individual subject. Changes in click rate also have marked effects on ABR stability, both latency and amplitude, with details highly specific to individuals. In general, however, changes in stability as a function of click rate occur in the context of replication of the overall shape of the ‘‘stability profile’’ for each subject, providing further evidence of the ‘‘fingerprint’’ nature of this means of characterizing individual auditory brainstems.

Dependence of auditory brainstem response on click polarity and high-frequency sensorineural hearing loss.

An investigation is presented on the effect of click polarity upon the auditory brainstem response (ABR) in cases of simulated high-frequency hearing loss. A high-frequency hearing loss was stimulated in 12 normal subjects by applying a high-pass noise masker, the noise cutoff frequency being varied in half-octave steps through the range of audiometric frequencies. With this paradigm, the effects of click polarity on the ABR are similar to those reported in patients with high-frequency hearing loss, including changes in waveform morphology and substantial peak latency shifts. To evaluate the role of individual cochlear frequency channels in a more direct way, half-octave narrow-band responses were determined by pair-wise subtraction of the high-pass-noise-masked responses. As far as ABR peak latencies are concerned, stimulus polarity effects tend to increase towards the lower frequency bands. Thus, the selective elimination of the contribution to the ABR of cochlear high-frequency channels can be held responsible for the increased dependence of ABR on click polarity observed in high-frequency hearing loss. However, statistical evaluation of peak I, III and V latencies, both in high-pass-noise-masked and in narrow-band ABRs, reveals that the latency effects are not systematic between subjects. Mechanisms producing the observed rarefaction-condensation differences, possible explanations for the large intersubject variability and the consequences for clinical interpretation of ABR are discussed.

Latency stability of auditory brainstem responses in children aged 10–12 years compared with younger children and adults

Previous articles have reported the results of using standard clinical procedures in our laboratory for testing auditory brainstem responses (ABR) in a repeated-measures design, in order to quantify ABR latency and amplitude stability in normal young adults. In a subsequent paper, these findings were extended to include the results of similar procedures in a group of seven children ranging in age from 5 to 7 years. The current experiment involves repeated-measures ABRs in a group of nine children ranging in age from 10 to 12 years. Results indicate that while these older children show the expected similarities with adults in terms of ABR peak latencies, their latency stability values are in some cases significantly lower than adults. At the same time, ABR stabilities measured in the older children show some differences compared to data from the younger children studied previously. For all groups, the same types of patterns are observed: (1) significant differences contrasting the degree of between-subject v. within-subject latency stability; (2) clear individual differences characterizing subjects; (3) within-subject distinctions according to ear of stimulation; and (4) instances of good replicability of the 'latency-stability profiles' calculated for one set of repeated waveforms v. a second set collected later in testing.

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.

Individual Differences in Auditory Electric Responses: Comparisons of Between-Subject and Within-Subject Variability. V. Amplitude-variability Comparisons in Early, Middle, and Late Responses

Each of two groups of adult subjects was tested under a repeated-measures design (Lauter & Loomis, 1986, 1988; Lauter & Karzon, 1990a, b) for ABRs and one other set of responses: middle-latency responses (MLRs: 10 to 50 ms post-stimulus) from Group II (four females and four males), and late responses (50 to 300 ms post-stimulus) from Group I (four females and three males). A companion paper (Lauter & Karzon, 1990b) presents data comparing and contrasting the patterns of relative variability of waveform-peak latency observed in middle-latency, late responses, and the ABR data previously reported. This paper presents amplitude results for the same data sets. Our findings indicate that, as we have reported previously, with regard to between-subject vs. within-subject variability of peak parameters of auditory EP waveforms, normal adult subjects are more consistent when compared with themselves than when compared with each other. This is true at all auditory EP levels tested, from brainstem to cortex, and is observed in both amplitude and latency data, in spite of the fact that the actual values of amplitude-stability measures are an order of magnitude smaller than for latency stability.

Individual Differences in Auditory Electric Responses: Comparisons of Between-Subject and Within-Subject Variability IV.Latency-variability Comparisons in Early, Middle, and Late Responses

In this series of reports to date (Lauter & Loomis, 1986, 1988; Lauter & Karzon, 1990 a & b) we have described patterns of relative variability observed in latency and amplitude of auditory brainstem responses (ABRs) collected in a repeated-measures within-subjects design testing two groups of neurologically normal adults. Each of the two groups of subjects was additionally tested for one other type of auditory evoked potential, according to the same schedule of eight weekly sessions: middle-latency responses (MLRs: 10 to 50 ms post-stimulus) were collected from Group II (four females and four males), and late responses (50 to 300 ms post-stimulus) from Group I (four females and three males). This paper presents data comparing and contrasting the patterns of relative variability of waveform-peak latency observed in middle-latency, late responses, and the ABR data previously reported. Results document a trimodal distribution of response latency variability, with ABR peak V in one category, characterized by high within-subject stability and low between-subject stability, ABR peaks II, III, and IV, together with MLR peak No in a second category, of intermediate within-subject stability, and a third category consisting of ABR peak I together with all auditory-evoked-potential (AEP) peaks subsequent to MLR peak No, in which consistency of peak latency calculated within subjects approaches the low level of consistency calculated across subjects.

Auditory Brainstem Response in Hyperbilirubinemic Rat: Part I

The effect of hyperbilirubinemia on the auditory brainstem response (ABR) of rats and its change by hyperosmolality were examined. The ABR wave I did not change significantly. In bilirubin-loaded rats, the latencies of wave II and IV were prolonged and the amplitudes decreased. Bilirubin injection damaged the central auditory pathway but the peripheral auditory pathway was spared. These ABR changes were reversible in the acute phase of hyperbilirubinemia. Mannitol administration hastened the appearance of the ABR peaks and the recovery of the changed ABR. This tendency was more remarkable in latency changes than in amplitude changes.

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.

The 3-channel Lissajous' trajectory of the auditory brain-stem response. VII. Planar segments in humans

Auditory brain-stem response (ABR) recorded from 3 orthogonally placed electrode pairs reveals a voltage-voltage-voltage plot of activity known as the 3-channel Lissajous' trajectory (3-CLT). ABR 3-CLT responses have been recorded from 9 human subjects in response to monaural, 70 dB nHL clicks. Responses were simultaneously recorded from 3 electrode channels in the vertical, horizontal and anterior-posterior plane. These 3 channels were combined to form human ABR 3-CLTs. Analysis of data included inspection of single-channel data, determination of segments along the trajectory which fall into distinct planes, and derivation of overall amplitude by time measures known as vector amplitude plots. Depending upon definition, 9 or 10 sequential, overlapping planar segments are found in the ABR 3-CLT of human subjects. Measures of planar apex latency and duration of planar segments were found to be reasonably consistent between subjects as were the orientations of planar segments. Vector amplitude plots (absolute amplitude of 3-channel recordings over time) derived from the human 3-CLT demonstrate 8 fast peaks which appear to be superimposed upon slow wave activity. These plots are shown to be potentially useful in determining optimal electrode orientations for single-channel recording of various ABR peaks. It was concluded that planar-segment formation in the ABR 3-CLT is a consistent finding in human subjects and that this technique is a promising clinical and research tool.

The 3-channel Lissajous' trajectory of the auditory brain-stem response. IV. Effects of electrode position in the cat

Three-channel Lissajous' trajectories (3-CLTs) of the auditory brain-stem response (ABR) were recorded from anesthetized adult cats with 2 different orthogonal and 3 different non-orthogonal recording configurations. Click stimuli were presented monaurally at 70 dB impulse SPL. Planar analysis identified 12 planar segments regardless of electrode configurations. Boundaries, apex latencies, and durations of the planar segments were relatively unchanged by changes in recording locations, in contrast to changes in single-channel ABR peak latencies and amplitudes. The 3-CLT orientation and shape were maintained in voltage-space despite changes in electrode positions, provided that the recording axes remained orthogonal and a simple cosine correction was applied. Non-orthogonal recording axes resulted in 3-CLTs which differed in shape from 3-CLTs recorded from orthogonal recording axes, but had similar planar-segment boundaries and durations. We conclude that the 3-CLT has characteristics which are generator-dependent and unaffected by electrode position if appropriate spatial corrections are applied.