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At least 1,171 records · Page 65Linked to original sources
PubMed1991

Transient retrocochlear low-frequency sensorineural hearing loss: a new clinical entity.

Sensorineural hearing loss (SNHL) of varying types and extent developed in a number of the 963 patients who underwent microvascular decompression for hemifacial spasm. Fourteen of the patients with hearing loss had transient low-frequency SNHL. Low-frequency SNHL is seldom noted in patients with retrocochlear hearing loss, but five of these patients had Horner's syndrome or bulbar palsy. The results of Békésy audiometry, auditory brainstem response, and electrocochleography in the patients were also suggestive of brainstem pathology. Surgical records revealed that all of them had excessively short perforating arteries surrounding the entry zone of nerves VII and VIII, so that they had to be stretched during surgery. Occlusion of perforating arteries is suspected to have caused lateral brainstem infarction around the entry zone of nerves VII and VIII, and resulted in low-frequency SNHL.

Adult↗
PubMed1995

ABR interpeak latencies in rats are shorter at low click intensities.

There are conflicting findings concerning whether auditory nerve-brainstem evoked response (ABR) interpeak latencies (e.g. brainstem transmission time - BTT) are constant in response to different stimulus intensities. In order to study the effects of click intensity on the BTT, and to try to determine the mechanism of such an effect, ABR was recorded from 10 adult white Sabra rats in response to different click intensities. The stimulus intensity was reduced from the highest intensity generated by the equipment until no responses could be obtained. Band-reject (notched) noise was presented simultaneously with the clicks in order to restrict the region of basilar membrane activation. BTT decreased with decreasing click intensity and this was accompanied by a prolongation of the latency of wave I to a greater extent than that of wave IV. At high and intermediate intensities, wave I appeared as two split peaks. These effects were not abolished by the restricting notched noise. Possible mechanisms of these latency changes are considered.

Acoustic Stimulation↗
PubMed1997

Evidence for primary auditory cortex involvement in the echo suppression precedence effect: a 3CLT study.

An echo lagging shortly after a source and arising from another direction perceptually blends with the source, and the location of the fused 'source-echo' is dominated by the source location (the Precedence Effect). The neural substrates underlying the echo localization suppression are ambiguous. We recently suggested an auditory evoked potentials correlate of binaural echo lateralization suppression. A significant and specific reduction in binaural peak amplitude and area of the echo-evoked middle-latency component Pa was observed. The binaural echo-Pa suppression depended on echo lag and correlated with the psychophysical echo lateralization suppression. In this study, the echo-Pa generators were analyzed with 3CLT spatio-temporal analysis, in order to suggest the neural substrates involved in echo lateralization suppression. 3CLT enables reliable identification of components, based on rigid geometrical properties. The results suggest that the Pa1 subcomponent of Pa, associated with primary auditory cortex activity, fully accounts for the echo-Pa suppression. This physiological indication for primary auditory cortex involvement in the precedence effect is the first in humans.

Acoustic Stimulation↗
PubMed1991

Age-related loss of auditory sensitivity in two mouse genotypes.

Frequency-specific auditory brainstem responses (ABR) (frequency range 2-31.5 kHz) were used to describe age-dependent alterations in frequency sensitivity in CBA/ca (to 30 months) and C57BL/6J (to 16 months) mouse genotypes. The two strains displayed an age-related loss similar to that of humans, with a primary decline in high-frequency sensitivity. CBA mice showed a slow, yet gradual decrease in sensitivity to high- followed by low-frequency until 18 months of age and a rapid deterioration at all frequencies thereafter. C57 mice demonstrated precocious aging in auditory sensitivity in an unsteady rather than gradual manner. By testing the same individuals on repeated occasions it was shown that, for C57 mice, the degenerative process was more precipitous with three phases, and that the individual variability was larger than that of CBA mice. It is suggested that the two mouse genotypes can be used to express the different aspects of human presbycusis in individual variability and modes of gradual or staggered progression.

Aging↗
PubMed1991

Hypothermia differentially affects tuning curves generated by forward and by simultaneous masking.

In the gerbil maintained at euthermic (37.5 degrees C) conditions, forward masking produces a compound action potential tuning curve (CAP TC) which is less sensitive but more sharply tuned than that which is generated by simultaneous masking. These differences between forward- and simultaneously-masked CAP TCs are minimized at hypothermic (30 degrees C) conditions. The unmasking effect occurs at both temperatures, suggesting that hypothermia does not exert these changes by eliminating two-tone suppression.

Adaptation, Physiological↗
PubMed1994

Postoperative changes in the contralateral auditory brainstem response after microvascular decompression in cases of trigeminal neuralgia.

Postoperative changes in auditory brainstem response (ABR) in 40 patients with trigeminal neuralgia (TN) who underwent microvascular decompression (MVD) were analyzed. A high proportion (60%) were found to have a decrease in the latency of wave V in the contralateral (unaffected) ABR in the postoperative period. In some cases, a decrease in the latency of wave V was found on the unaffected side postoperatively while an increase was found on the affected side. Furthermore, in one case it was found that an improvement of the shortened latency of wave V on the unaffected side occurred in parallel with a recovery of prolonged latency on the affected side. This indicates that the decrease in the latency of wave V on the unaffected side corresponds to some retrocochlear lesion produced by MVD on the affected side, and shortened latency is considered to be a result of damage to the efferent system of the auditory pathway.

Adult↗
PubMed1988

Toward a strategy for analyzing the auditory middle-latency response waveform.

The present paper describes for the auditory middle latency response (MLR) an analysis strategy which includes measures of latency, amplitude, waveform width, and area under the waveform. This combination of parameters can adequately describe the MLR and allow reliable and comprehensible comparisons of experimental conditions within and across studies. MLRs were recorded from normal-hearing adults utilizing a variety of recording filter settings, stimulus frequencies and stimulus envelopes. A filter window narrower than 3-300 Hz caused marked distortions in the MLR and significantly affected all parameters. Lower stimulus frequencies yielded significantly larger MLR amplitude, width, and area compared to higher frequencies. Stimulus envelope had no effect on any parameter.

Acoustic Stimulation↗
PubMed1990

Influence of menopause on the auditory brainstem response.

Auditory brainstem response (ABR) wave latency, interpeak interval and amplitude as a function of intensity were measured in 40 subjects divided into equal groups of postmenopausal females, age-matched males and young adults of both sexes. The results illustrate that age and gender play a significant role in ABR wave latency and amplitude. A larger age effect occurred for the female subjects. While this does not dispute an anatomical explanation for the gender effect in ABR, hormonal changes accompanying menopause may also account for some of the gender differences noted in ABR.

Adult↗
PubMedDate not supplied

Normal brainstem auditory evoked potentials in Pax5-deficient mice despite morphologic alterations in the auditory midbrain region.

The inferior colliculus in the auditory midbrain region is underdeveloped near the midline in mice lacking the transcription factor Pax5. We have now tested whether hearing deficiencies occur in these mice by measuring auditory evoked brainstem responses. However, the responses and audiograms obtained in homozygous Pax5 mutants did not differ from those of control mice, suggesting that the observed morphologic alterations of the inferior colliculus do not affect hearing, as judged by auditory evoked potential recordings. The only detectable effect of the Pax5 mutation was a delay in the development of the auditory sensitivity and response latency that correlates with the general growth retardation observed in these mice.

Age Factors↗
PubMedDate not supplied

Effects of click polarity on the auditory brainstem responses of older men.

This study was designed to evaluate the effects of stimulus polarity on the auditory brainstem responses (ABRs) in the older population. Nine men between the ages of 40 and 69 years participated in the study. Rarefaction and condensation clicks were delivered at 70 and 80 dB nHL to elicit the ABRs. The latencies were significantly earlier for rarefaction clicks for components II and V. The inter-peak interval I-II was significantly shorter for rarefaction clicks than for condensation clicks. The amplitudes of the IV-V complex did not change with stimulus polarity at 80 dB nHL, but at 70 dB nHL larger amplitudes were observed with rarefaction clicks yielding a significant polarity-intensity interaction. The IV-V/I ratio elicited by rarefaction clicks was larger than that produced by condensation clicks at 80 dB nHL, but it was much larger for rarefaction clicks at 70 dB nHL resulting in a significant polarity-intensity interaction. The waveform morphology also changed with click polarity, with the most prominent effects apparent on components II and IV. A new hypothesis suggesting separate generators for ABRs recorded in response to the two click polarities is proposed. Use of both condensation and rarefaction clicks is recommended in recording ABRs for clinical use.

Adult↗
PubMed1992

Phase coherence of the middle-latency response in the elderly.

We compared phase coherence of the auditory-evoked, middle-latency response (MLR) and the 40-Hz steady-state evoked potential (SSEP) in two groups of elderly listeners, matched for degree of audiometric hearing sensitivity loss. In group A, speech understanding was appropriate to the degree of audiometric sensitivity loss. In group B, speech understanding was disproportionately poor in relation to the degree of loss. In both modes of measurement (MLR and SSEP) phase coherence was significantly poorer in group B than in group A. In the case of MLR, maximum phase coherence was observed at the expected 40 Hz in group A, but at 30 Hz in group B. In the case of SSEP, maximum phase coherence was observed at 40 Hz in both groups but was poorer at almost all Fourier components in group B.

Acoustic Stimulation↗
PubMed1993

High-frequency tone burst-evoked ABR latency-intensity functions.

High-frequency tone burst stimuli (8, 10, 12, and 14 kHz) have been developed and demonstrated to provide reliable and valid auditory brainstem responses (ABRs) in normal-hearing subjects. In this study, latency-intensity functions (LIFs) were determined using these stimuli in 14 normal-hearing individuals. Significant shifts in response latency occurred as a function of stimulus intensity for all tone burst frequencies. For each 10 dB shift in intensity, latency shifts for waves I and V were statistically significant except for one isolated instance. LIF slopes were comparable between frequencies, ranging from 0.020 to 0.030 msec/dB. These normal LIFs for high-frequency tone burst-evoked ABRs suggest the degree of response latency change that might be expected from, for example, progressive hearing loss due to ototoxic insult, although these phenomena may not be directly related.

Acoustic Stimulation↗
PubMed1994

Effects of signal-to-noise ratio on the auditory brainstem response to 0.5 and 2 kHz tone bursts in broadband noise and highpass noise or notch noise.

This study investigated the effects of signal-to-noise ratio (S/N) on the latency and amplitude of th3 auditory brainstem response (Wave V) using 0.5 and 2 kHz tone bursts in highpass/notch noise and broadband noise. Normal listeners were presented with 40 and 80 dB nHL tone bursts in quiet and in noise at S/Ns of 10, 15, 20, and 25 dB. The latency data suggest that, at moderate and high intensities, highpass/notch noise or broadband noise is preferred to the quiet condition because of the improved frequency specificity provided by the masking. Highpass/notch noise appears preferable to broadband noise when testing at moderate to high levels because the former produced larger Wave V amplitudes to 0.5 and 2 kHz tone bursts at 80 dB nHL. The 80 dB nHL data also suggest that S/Ns of 15-25 dB should be selected when the highpass/notch noise is mixed with moderate to high level 0.5 and 2 kHz tone bursts. In contrast to the 80 dB nHL data, Wave V amplitudes to the 40 dB nHL tone bursts suggest that testing in quiet may be preferred to testing in noise when 0.5 and 2 kHz tone bursts are presented at low levels. This is because of the simplicity of instrumentation and because larger amplitudes were observed in quiet than in noise.

Acoustic Stimulation↗
PubMed1992

ABR screening for acoustic neuromata: the role of rate-induced latency shift measurements.

The audiological assessment of patients considered 'at risk' for an acoustic neuroma is problematic when the patient has a severe hearing loss. The utility of ABR rate-induced latency shift (RLS) measurements was investigated in 189 patients who had passed a conventional assessment and 31 patients with an acoustic neuroma. A test based on the RLS of wave V using rates of 11.1 s-1 and 88.8 s-1 had a sensitivity of 89.5% and a specificity of 90.8% when applied with a dual interpretive criterion which included the loss of wave V at the higher rate. This test was included in an ABR screening protocol which had a sensitivity of 100% and a specificity of 97.9%. The RLS test requires no correction for age, sex, hearing loss or stimulus intensity and may be used in patients with severe hearing loss for whom other ABR tests are inappropriate.

Adult↗
PubMed1993

Correcting for factors affecting ABR wave V latency.

The latency of auditory brainstem response (ABR) wave V has been shown to be affected by several subject and technical factors. Previous studies have often concluded with a recommendation to account or correct for one or more of these factors when latency is used as a means of detecting retrocochlear dysfunction. This study investigated the effect of subject age, sex, hearing loss and stimulus intensity on ABR wave V latency in a group of 189 clinical subjects in whom retrocochlear disease was effectively excluded. Regression analysis showed that all four factors exerted a significant influence on latency and that hearing loss and intensity were most effectively represented when combined to form a sensation level variable, together with a measure of audiogram slope.

Acoustic Stimulation↗
PubMed2003

Stacked tone-burst-evoked auditory brainstem response (ABR): preliminary findings.

In 1997, Don and his co-workers described a new method for evaluating the auditory brainstem response (ABR)--yielding the stacked-wave-V ABR--which may permit the reliable detection of even small vestibular schwannomas (VSs). However, this method requires a masking technique that may not be readily available to the clinician. Furthermore, relatively high-level noise is required and may be annoying to the patient. An alternative method that might permit the same manipulation of the ABR was thus explored whereby tone-bursts (TBs) were used to obtain frequency-specific ABRs. The goal of the study was to determine whether TBs could be used to achieve the sort of de-convolution and subsequent enhancement of wave V reported with the original method of Don et al. First, the TB-stacked ABR (wave V) was compared to that obtained using derived narrowband masked ABRs in young normal-hearing subjects. Second, the TB method was employed in subjects with unilateral VSs and in patients with unilateral sensory hearing loss in a preliminary clinical trial. The observed results are promising for the use of the TB method as an alternative approach to ABR 'stacking' and warrant further research and development of the TB method.

Adult↗
PubMed2006

Amplitude-modulated auditory steady-state responses in younger and older listeners.

The primary purpose of this investigation was to determine whether temporal coding in the auditory system was the same for younger and older listeners. Temporal coding was assessed by amplitude-modulated auditory steady-state responses (AM ASSRs) as a physiologic measure of phase-locking capability. The secondary purpose of this study was to determine whether AM ASSRs were related to behavioral speech understanding ability. AM ASSRs showed that the ability of the auditory system to phase lock to a temporally altered signal is dependent on modulation rate, carrier frequency, and age of the listener. Specifically, the interaction of frequency and age showed that younger listeners had more phase locking than old listeners at 500 Hz. The number of phase-locked responses for the 500 Hz carrier frequency was significantly correlated to word-recognition performance. In conclusion, the effect of aging on temporal processing, as measured by phase locking with AM ASSRs, was found for low-frequency stimuli where phase locking in the auditory system should be optimal. The exploration, and use, of electrophysiologic responses to measure auditory timing analysis in humans has the potential to facilitate the understanding of speech perception difficulties in older listeners.

Adult↗