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At least 163 records · Page 9Linked to original sources
PubMed1979

Auditory dysfunction with facial paralysis.

A series of 58 patients with idiopathic facial paralysis were studied to determine if a concomitant cochlear or eight nerve auditory dysfunction could be identified with traditional audiologic tests. Results indicated that only those patients with a facial nerve lesion, proximal to the stapedius branch, experienced reduced tolerance for loud sounds, reduction of speech discrimination at high-intensity levels, and abnormal loudness growth. Such findings suggest that changes in auditory function, accompanying facial nerve paralysis, are a mechanical effect due to absence of stapedial action. Site of lesion tests in this sample failed to demonstrate eighth nerve dysfunction and, thus, does not support a theory of polyneuropathy that involves the auditory nerve.

Adolescent↗
PubMed1983

Compound action potential input-output decruitment. Effect of topically applied antiseptics.

The ototoxic effect of povidone-iodine antiseptics topically applied to the chinchilla round window was examined with particular emphasis on the action potential (AP) input-output function at 2 and 4 kHz. A group of chinchillas exhibited a marked elevation of AP threshold at 8 and 12 kHz, with only a slight threshold elevation at 2 and 4 kHz. A distinct decruitment (less than normal growth of response with increasing sound intensity) of the AP input-output function was, however, found at the lower frequencies. There are implications of an ototoxically induced high-frequency hearing loss on speech frequencies.

Action Potentials↗
PubMed1980

Clinical status of evoked response audiometry.

In the past decade there has been a widespread renewal of interest in the clinical utilization of electroencephalic responses evoked by auditory stimulation. In particular, there has been considerable research conducted on the brain stem response, the frequency following response, and the middle latency response. An overview discussion of some of the latest findings from recent and ongoing investigations is presented. Discussion is centered initially on current ideas, findings, and controversies regarding the origins or site of generation of these responses. Clinical application of the responses is discussed from two perspectives, audiologic applications and neurologic applications. Essential parameters for evoking, recording and analyzing clinically these responses are summarized. Some of the problems resulting from a lack of standardized clinical testing protocols are also mentioned. Key findings from recent clinical studies of some investigators are cited. Also recent data concerning the developmental aspects of the responses on clinical testing are included. Finally, some directions for future research on these responses are discussed. One of the latest techniques for recording and analyzing the responses and its implications for site of lesion neurologic testing are described.

Acoustic Stimulation↗
PubMed1997

Regulation of D-aspartate release and uptake in adult brain stem auditory nuclei after unilateral middle ear ossicle removal and cochlear ablation.

In young adult guinea pigs, the effects of unilateral ossicle removal and cochlear ablation were determined on transmitter release from glutamatergic presynaptic endings and glutamate inactivation via uptake. (i) D-[3H]Aspartate release and uptake were measured in subdivisions of the cochlear nucleus (CN) and in nuclei of the superior olive (SOC) and auditory midbrain (MB) up to 145 days after placing the lesions. Activities were compared to those from age-matched unlesioned controls. Fiber degeneration was visualized histologically. (ii) In the ipsilateral CN, changes in release and uptake were governed by the type of lesion. Ossicle removal produced sparse pruning of fibers only after 112 days and decreased release and uptake at 145 days, consistent with regulatory weakening of excitatory glutamatergic transmission. Cochlear ablation deafferented the CN, producing deficient release and uptake at 2 days and abundant fiber degeneration at 7 days. Subsequently, the residual release and uptake increased in magnitude, consistent with strengthening of excitatory glutamatergic transmission. (iii) In the contralateral CN, after either lesion, changes in release and uptake usually matched those in the ipsilateral CN. Thus, the auditory pathway associated with the lesioned ear probably provided cues for the regulation of synaptic strength in the contralateral CN. (iv) Both lesions increased release in the SOC and MB, and uptake in the SOC, consistent with strengthening of excitatory glutamatergic transmission. Sparse fiber degeneration, suggesting axonal pruning, appeared in the SOC and MB after cochlear ablation. (v) The strengthening of excitatory glutamatergic transmission may facilitate and maintain symptoms such as loudness recruitment and tinnitus which often accompany hearing loss.

Animals↗
PubMed1982

Loudness recruitment: contributing mechanisms as revealed by cochlear AP measures in man.

A measure of the (average) rate of discharge versus intensity function of cochlear fibers can be obtained from cochlear-evoked compound action potentials using a tone-on-tone forward masking technique. The rationale for the method is presented. This technique was used to investigate, indirectly, cochlear fiber responses in human subjects, both with normal hearing and with deafness of cochlear origin and showing signs of loudness recruitment. In animals with pathologic cochleas, and change in rate of fiber discharge with intensity is more rapid than in normal animals. The present study confirms that this also is the case in human cochlear pathology and suggests that this abnormal steepening of rate versus intensity functions contributes to the phenomenon of loudness recruitment.

Audiometry↗
PubMed1980

Dynamic study of the acoustico-facial reflex by impedance measurement.

Dynamic study of the acoustic reflex has brought into evidence that 1. age has a significant influence on various reflex response parameters 2. study of dynamic parameters of the acoustic reflex enables changes in the reflex arc to be objectified. This is therefore an objective measurement of recruitment in impedance measurement. The author proposes to study the following parameters: rise time, recovery time, and the variations of maximum amplitude as function of sound stimulation intensity. Study of these three parameters provides a highly sensitive test of change in the dynamics of the acoustic reflex, for indeed this test reveals pathology well before the Reflex Decay Test does so.

Acoustic Impedance Tests↗
PubMed1980

The graph of loudness recruitment (ABLB-test).

The ABLB-test compares the subjective loudness in patients with unilateral sensorineural hearing loss. The graph of this comparison of loudness at different suprathreshold intensities is of interest for understanding the function of the hair cells.

Auditory Threshold↗
PubMed1979

Electrocochleography and experimentally induced loudness recruitment.

The relationship between changes in loudness and the cochlear whole-nerve potential following experimentally produced deafness was studied in an animal model. Reaction time of a subject's response to an auditory stimulus has been shown to be an index of loudness in human experiments and has been adapted to nonhuman primates. In a series of experiments, four macaque monkeys were operantly conditioned to respond to 8-kHz tones over a range of 3--80 dB SPL, and their reaction times to pure tone stimuli were measured. Whole-nerve cochlear action potentials were recorded from chronic inner-ear electrodes. The relationship between behavioral and electrical measures of loudness recruitment were examined in animals with both temporary and permanent noise-induced hearing loss. Loudness recruitment was demonstrated experimentally after a 1-h exposure to a high-intensity 8-kHz octave band of noise. Excellent agreement was observed between the reaction time function and the action potential input-output function at intervals of 0.5, 12, 24, 48, and 84 h after exposure. Permanent hearing loss was produced in some of these animals by a much longer duration of exposure to the 8-kHz octave band of noise. Recruitment was observed in both the behavioral and the electrical measures. Histological studies of these damaged cochleas revealed primarily outer hair cell destruction, with a relative sparing of inner hair cells and nerve supply. The findings of this study are interpreted as strong support for the clinical electrocochleogram as an objective indicator of the presence of loudness recruitment.

Action Potentials↗
PubMed2006

A meta-analysis of the placebo response in acute migraine and how this response may be influenced by some of the characteristics of clinical trials.

Migraine is the most common cause of vascular headache and a highly prevalent illness. In the last 20 years, the discovery of new agents has increased clinical research on migraine. In most of clinical trials that have been conducted, the efficacy was established using a placebo as a control treatment. The objective of the study reported here was to analyse the response rate in patients who received a placebo as well as to determine how a number of the methodological factors may affect the effect of the placebo in clinical trials of acute migraine. Computer-based information searches were conducted on the Medline database. Data analysis included the outcomes 'pain relief', 'pain-free', 'associated symptoms', 'recurrence', 'patients' opinion' about pain relief and 'adverse events'. Administration route, study design and country in which the study was carried out were the methodological factors that were analyzed. Meta-analysis was computed using Mantel-Haenszel, and a total of 98 papers were considered in the final analysis. After 2 h, 28.6% of the patients of the placebo group improved and 8.8% were pain-free. The percentage of pain-free patients was the highest in the placebo and active drug groups in which the placebo or drug had been administered subcutaneously, in parallel design studies (vs. cross-over trials) and in studies performed in Europe (vs. North America). Adverse events in the placebo group were significantly higher in studies performed in North America. These data reinforce the need for knowing the magnitude of the placebo response in each specific situation during the planning of clinical trials on acute migraine.

Acute Disease↗
PubMed2005

Incapacitating hypersensitivity to one's own body sounds due to a dehiscence of bone overlying the superior semicircular canal. A case report.

We present a case study of a 49-year-old patient with an 8-year history of hypersensitivity to sound produced by intrinsic but not extrinsic sources. Findings that indicated an organic problem were: a supranormal bone conduction threshold of -25 to -15 dB HL from 0.25 to 1 kHz with an air-bone gap of 15 to 45 dB HL, a lower threshold and larger amplitude for vestibular-evoked myogenic potentials, eye movement reactions to sound and trunk pitch sway in response to sound. Results of immitance audiometry and otoacoustic emission testing were within normal limits and indicative of intact middle ear conductance. A high-resolution CT scan of the temporal bone demonstrated a dehiscence of bone overlying the superior semicircular canal. These findings support previous research indicating that auditory energy reaches the cochleo-vestibular receptor systems more easily via transmission through cerebrospinal fluid than through bone. Therefore, a dehiscence of the bone overlying the superior semicircular canal may lead to hypersensitivity to intrinsic sound. We recommend that similar findings in other patients be followed up with an evaluation of middle ear function and the temporal bone with high-resolution CT scan.

Bone Conduction↗
PubMed1999

Electrocochleographic documentation of temporal findings of speech perception in normal and hearing-impaired individuals.

Compound action potentials (CAPs) evoked by the short Japanese syllables /a/ and /ka/ were recorded by extratympanic electrocochleography in 17 subjects with normal hearing (17 ears) and 34 patients with sensorineural hearing losses (35 ears) to investigate the temporal aspects of speech coding for perception. In normal ears, three characteristics were found common to the temporal patterns of all CAPs: (1) a prominent CAP at the beginning of both stimuli; (2) periodic CAPs with the same interval as the pitch period through the vowel part of both stimuli; (3) absence of a prominent CAP at the onset of voice. These characteristics may help to produce consonant recognition. Among the subjects with sensorineural hearing loss, some ears showed the following two characteristics different from those with normal hearing: (1) a significantly lower CAP at the onset of both stimuli than in those with normal hearing; (2) decay of CAPs during the voiced part. These findings may result in abnormal loudness perception in sensorineural hearing loss as produced by loudness recruitment and pathological adaptation. Such different temporal patterns of CAPs may have an adverse influence on the speech discrimination of patients with sensorineural hearing impairments.

Acoustic Stimulation↗
PubMed2002

Influence of early high-dose steroid treatment on Bell's palsy evolution.

The objective of this double-blind, randomized, placebo-controlled study was to test the efficacy of high-dose prednisone, administered as early as possible, in modifying the natural progression of Bell's palsy. Sixty-two consecutive patients, enrolled within 72 hours of facial palsy onset, were assigned to high dose intravenous prednisone in combination with intramuscular polyvitaminic therapy (group A) or polyvitaminic therapy alone (group B). Clinical grading of facial muscle strength and length of absence from work were evaluated. An early worsening of facial muscle strength was observed in controls, leading to the divergence in the trends of the grading scores in the two groups; this result was not confirmed in the long-term follow-up. Treated patients returned to work earlier than controls. In conclusion, early treatment based on high-dose corticosteroids slightly accelerates spontaneous improvement in Bell's palsy.

Adolescent↗
PubMed2005

Auditory-nerve rate responses are inconsistent with common hypotheses for the neural correlates of loudness recruitment.

A number of perceptual phenomena related to normal and impaired level coding can be accounted for by the degree of compression in the basilar-membrane (BM) magnitude response. However, the narrow dynamic ranges of auditory-nerve (AN) fibers complicate these arguments. Because the AN serves as an information bottleneck, an improved understanding of the neural coding of level may clarify some of the limitations of current hearing aids. Here three hypotheses for the neural correlate of loudness recruitment were evaluated based on AN responses from normal-hearing cats and from cats with a noise-induced hearing loss (NIHL). Auditory-nerve fiber rate-level functions for tones were analyzed to test the following hypotheses: Loudness recruitment results from steeper AN rate functions after impairment. This hypothesis was not supported; AN rate functions were not steeper than normal following NIHL, despite steeper estimated BM responses based on the AN data. Loudness is based on the total AN discharge count, and recruitment results from an abnormally rapid spread of excitation after impairment. Whereas abnormal spread of excitation can be observed, steeper growth of total AN rate is not seen over the range of sound levels where recruitment is observed in human listeners. Loudness of a narrowband stimulus is based on AN responses in a narrow BF region, and recruitment results from compression of the AN-fiber threshold distribution after impairment. This hypothesis was not supported because there was no evidence that impaired AN threshold distributions were compressed and the growth of AN activity summed across BFs near the stimulus frequency was shallower than normal.Overall, these results suggest that loudness recruitment cannot be accounted for based on summed AN rate responses and may depend on neural mechanisms involved in the central representation of intensity.

Acoustic Stimulation↗
PubMed1995

Audible and ultrasonic vocalization elicited by single electrical nociceptive stimuli to the tail in the rat.

We describe audible and ultrasonic vocalization elicited in rats by a short electrical pulse applied to the tail. Three types of vocal emissions were recorded: (1) 'peep', characterized by a repartition of energy over a wide range (0-50 kHz) of frequencies without any clear structure; (2) 'chatters', characterized by an audible (frequencies in hearing range of humans) fundamental frequency (2.47 +/- 0.03 kHz) and harmonics; and (3) 'ultrasonic emissions', characterized by a succession of slightly modulated pulses with frequencies in the 20-35 kHz range. Peeps and chatters were never recorded before the application of the stimuli. Several different vocalization patterns were described in terms of these types of responses. Just after the stimulation, all the animals emitted a 1st peep, which was generally (61%) followed by a 2nd one. They appeared with reproducible latencies, durations and envelopes. The envelopes of the audible (peeps and chatters) responses were intensity-dependent. Experimental data (moving the stimulation site, lidocaine injection) indicated that the 1st and 2nd peeps were triggered by two different groups of peripheral fibres with mean conduction velocities of 7.3 +/- 0.8 and 0.7 +/- 0.1 m/sec, respectively. This suggested an involvement of A delta and C fibres. Morphine showed a naloxone-reversible and dose-dependent antinociceptive effect by decreasing the 1st and 2nd peep envelopes. It is concluded that a short stimulus applied to the tail triggers a complex behavioural repertoire. It is proposed that this model will be a useful tool for physiological and pharmacological studies of nociception.

Anesthetics, Local↗
PubMed1983

Response patterns of auditory nerve fibers during temporary threshold shift.

Temporary threshold shifts were studied in chinchillas exposed to noise (octave-band noise centered at 500 Hz, 95 dB SPL, 5 days duration) and the response properties of their auditory nerve fibers were measured. The threshold shifts of the fibers were approximately 35 to 65 dB; these values were equal to or slightly greater than those measured behaviorally. Most units had broad V-shaped tuning curves due to a greater loss in sensitivity near the characteristic frequency (CF) than in the low-frequency tail. In 17% of the units, the thresholds were actually lower in the tail than at CF, so that the tuning curves were W-shaped. The latencies of the fibers were within normal limits in terms of absolute intensity, but shorter than normal in terms of intensity relative to threshold. Other measures such as the spontaneous discharge rate, the discharge rate-intensity functions, and the firing patterns to tone bursts at CF appeared normal. These results indicate that neural response patterns during noise-induced temporary threshold shift are similar to those measured during permanent threshold shift.

Action Potentials↗
PubMed1988

Effects of intense pure tones on auditory temporal acuity.

Gap detection thresholds (GDTs) were obtained from human listeners before and after exposure to a brief 0.4- or 1.7-kHz tone. The temporary threshold shift (TTS) produced 2 min after an exposure was approximately 10 dB. GDT stimuli were octave-band noises centered at one of three frequencies: the exposure frequency, one-half octave above the exposure frequency or one octave above the exposure frequency. GDTs were obtained at 35, 55, and 75 dB SPL at each center frequency. GDT and TTS recovery were monitored at logarithmically-spaced time intervals after the exposures. Following the 1.7-kHz exposure, shifts in post-exposure GDT were only obtained with the low-level stimulus conditions--the magnitude of GDT shift was correlated with the size of the TTS, and the shifts in GDT and absolute threshold required similar amounts of time to recover. Significant post-exposure shifts in GDT were also observed following the 0.4-kHz exposure. However, shifts were found at frequencies where there was no measurable TTS, and they required longer periods of time to recover than did absolute threshold.

Auditory Fatigue↗
PubMed1994

Spatiotemporal encoding of sound level: models for normal encoding and recruitment of loudness.

This study explores the hypothesis that sound level is encoded in the spatiotemporal response patterns of auditory nerve (AN) fibers. The temporal properties of AN fiber responses depend upon sound level due to nonlinearities in the auditory periphery. In particular, the compressive nonlinearity of the inner ear introduces systematic changes in the timing of the responses of AN fibers as a function of level. Changes in single fiber responses that depend upon both sound level and characteristic frequency (CF) result in systematic changes in the spatiotemporal response patterns across populations of AN fibers. This study investigates the changes in the spatiotemporal response patterns as a function of level using a computational model for responses of low-frequency AN fibers. A mechanism that could extract information encoded in this form is coincidence detection across AN fibers of different CFs. This study shows that this mechanism could play a role in encoding of sound level for simple and complex stimuli. The model demonstrates that this encoding scheme would be influenced by auditory pathology that affects the peripheral compressive nonlinearity in a way that is consistent with the phenomenon of recruitment of loudness, which often accompanies sensorineural hearing loss.

Acoustic Stimulation↗
PubMed1995

OHC response recruitment and its correlation with loudness recruitment.

After proper noise exposure, Hensen's cells, which have been shown to follow closely the response characteristics of the outer hair cells, suffered a loss of sensitivity at low and moderate SPLs. The lower the stimulus level, the greater was the loss. When the low-SPL loss did not exceed about 40 dB, input-output functions showed an increased rate of amplitude growth, so that the post-exposure response caught up with its pre-exposure counterpart between 60 and 90 dB SPL, depending on the severity of the loss. These results, together with preceding clinical observations, led us to the conclusion that loudness recruitment occurs at least in part at the hair cell level and is basically a local event as opposed to a pathological spread of excitation. The response recruitment we have discovered appears to result from a decreased effect of the active feedback when the passive cochlear mechanisms are intact. Evidence for these relationships is presented and an explanation is offered for previous experimental successes and failures in observing a steepening of rate-intensity functions in auditory nerve fibers after noise exposures or administration of ototoxic drugs.

Acoustic Stimulation↗