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PubMed1991

Prognostic validity of brainstem electric response audiometry in infants of a neonatal intensive care unit.

This study compared the results of brainstem electric response audiometry (BERA) in infants of a neonatal intensive care unit to those obtained on the same children with pure-tone audiometry at 3 years of age. Six hundred children were initially tested in infancy, and complete follow-up information was obtained on 333. In 297 (89%) the BERA results accurately predicted the hearing status at the age of 3 years. Twenty-nine (9%) of the discrepancies were related to conductive hearing losses: 17 patients with a conductive hearing loss in the first few months of life had normal hearing at 3 years, and 12 patients normal in infancy had a conductive loss at 3 years. Two patients evaluated as a sensorineural hearing loss by BERA had normal hearing. These may have been due to a conductive loss. Six patients assessed as normal by BERA had significant hearing losses at the age of 3 years. Five of these had normal hearing at one frequency between 1,000 and 4,000 Hz. The sixth may have developed a sensorineural hearing loss after birth.

Audiometry, Evoked Response↗
PubMedDate not supplied

Spectral composition of infant auditory brainstem responses: implications for filtering.

Auditory brainstem responses (ABRs) were recorded from 20 normal neonates and 10 normal-hearing adults. The spectral compositions of ABRs from both groups were compared. Results indicated that significant amounts of low-frequency information are concentrated below 150 Hz in both the neonate and the adult ABRs although the neonate ABR has a slightly greater percentage of low-frequency information than that of the adults. This has implications for filtering during ABR recording. A low high-pass setting which preserves more of the low-frequency information will allow enhanced detectability of wave V in neonate ABRs recorded at low stimulus intensities. Furthermore, our experience indicates that the use of a 30- to 3,000-Hz bandpass is feasible in the neonatal intensive care unit as well as in the regular newborn nursery. Therefore the use of a 30- to 3,000-Hz bandpass is recommended for neonate ABR recordings.

Acoustic Stimulation↗
PubMedDate not supplied

Effects of click polarity on brainstem auditory-evoked potentials in cochlear hearing loss: a working hypothesis.

The rarefaction-condensation differential potential (RCDP) obtained by subtracting brainstem auditory-evoked potentials (BAEPs) to C clicks from those to R clicks has been studied in 32 normal subjects and 31 cases of cochlear hearing loss. In normal subjects, no RCDP was recorded along the lower 30-55 dB of the JV latency-intensity function, thus defining the pre-RCDP range. The pre-RCDP range was always abolished in losses unmasking BAEPs from lower ( < 1 kHz) tonotopic regions. When the BAEP originated from higher ( > 1 kHz) tonotopic regions, the pre-RCDP range was either reduced or abolished. These results led to a working hypothesis based on single-unit data and stating a dual dependence of polarity effects on variables distributed along the tonotopic and intensity dimensions, with respective break-points at 1 kHz, and at the junction of the tip and tail of unit frequency tuning curves. The 1 kHz break-point could represent the upper frequency limit for phase locking in man.

Adolescent↗
PubMed1983

High-pass and notch noise masking in suprathreshold brainstem response audiometry.

The combination of suprathreshold tone-bursts with frequency of 0.5, 1 or 2 kHz and ipsilateral high-pass (HP) or notch noise masking has been studied in 52 adults referred for otoneurological examination on account of unilateral or asymmetric high-frequency hearing loss. Wave V latency changes are similar for both HP and notch noise masking and, in accordance with cochlear tonotopicity, are greater for the lower stimulus frequencies. Results are, however, not always conclusive with either technique, and response identification is problematical at 0.5 kHz. The less demanding HP masking technique is considered the method of choice since possible influence from the stapedius reflex is minimal and a better signal-noise ratio obtained.

Acoustic Stimulation↗
PubMed1989

Low-level 0.5 and 1 kHz auditory brainstem responses. A search for the low-frequency point in the two-point ABR audiogram.

We have compared the auditory brainstem responses (ABRs) to 0.5 and 1 kHz tone burst stimuli with high-pass noise masking in 10 normal-hearing adults. The overall quality of the low-level responses was poor, but a two-point ABR audiogram is feasible by using the summation technique described. The 1 kHz stimulus gave slightly better responses than 0.5 kHz, and a correction factor of 30-40 dB seems necessary. Our data indicate that these low-level, low-frequency responses are frequency-specific.

Adult↗
PubMed1992

Comparing laboratory and portable tone-burst auditory brain-stem-response (ABR) systems for monitoring high-frequency (> or = 8 kHz) auditory function.

High-frequency (8-20 kHz) hearing sensitivity is of special interest because of its early warning potential for ototoxicity. Many ill patients, however, are unable to respond behaviorally to auditory test procedures. To objectively monitor high-frequency auditory function in these patients, laboratory instrumentation to evoke the auditory brain-stem response (ABR) with high-frequency (8-14 kHz) tone-burst stimuli was developed and documented. To provide evaluation at bedside, a portable high-frequency tone-burst generator was developed to elicit the ABR. Combined with a portable signal averager, this system was validated by comparison with the laboratory system. Thirty-five normal-hearing subjects were used to compare ABRs to high-frequency tone bursts from each system. Analysis of responses to tone bursts revealed no significant mean latency differences, and no significant intersession reliability differences between systems. These results confirm that the portable system is comparable to the laboratory system in obtaining reliable high-frequency tone-burst responses.

Acoustic Stimulation↗
PubMed1993

Abnormalities of the auditory brainstem response in vitiligo.

Accumulating evidence suggests that vitiligo is a systemic disease affecting the entire pigmentary system and possibly the melanin-containing cellular elements of the nervous system. In the present paper we comparatively study the auditory brainstem response (ABR) of 30 patients with active vitiligo and 50 healthy human subjects in order to detect possible subclinical abnormalities of the auditory system in this disorder. Our findings reveal a statistically significant (p < 0.01) decrease of the I peak latency and a statistically significant (p < 0.01) increase of the I-III interpeak latency in the patients as compared to the controls. The decrease of the first peak latency may be due to a numerical decrease of active melanocytes in the inner ear which results in an impairment of the ion exchange between the endolymph and perilymph. The increase of the I-III interpeak latency may be explained in terms of an abnormal synaptic activity and transmission of the action potential from the auditory nerve to the superior olive.

Acoustic Stimulation↗
PubMed1993

Wave V latency shifts with age and sex in normals and patients with cochlear hearing loss: development of a predictive model.

In order to study the combined effect of age, sex and cochlear hearing loss on the auditory brainstem response in an adult population, absolute wave V latency measurements were made in 117 ears of 64 patients with cochlear hearing loss and 105 ears of 58 otologically normal control subjects. Among normals, wave V latency was found to increase with age. Latencies in female subjects were significantly shorter than in male subjects. The best predictive model for wave V latency in normals was: wave V latency (ms) = 4.982 + 0.007 x age + 0.091 x sex, where age is measured in years and sex is given a value of 1 for females and 2 for males. In patients with hearing loss, wave V latency increase was determined largely by the degree of hearing loss and the effect of age was moderate. The influence of sex was minimal. Wave V latency in patients with hearing loss was predicted by the formula: wave V latency (ms) = 4.911 + 0.007 x hearing loss + 0.004 x age + 0.081 x sex. These predictive models can be utilized to accurately estimate expected wave V latency in patients with cochlear hearing loss.

Adult↗
PubMed1993

[Relation of evoked otoacoustic emission to structural damage after acoustic overstimulation in cat].

Evoked otoacoustic emissions (e-OAE) at a 2 kHz tone burst were measured in 37 ears of 21 cats. The e-OAE responses were detectable in 30 ears of 19 cats. In most cats (26 out of 30 ears) nonlinear behavior could be identified and saturated above 15 to 20 dBnHL. The responses had very short latencies (to their peak pressures) of 5.53 ms to 7.28 ms. Scanning electron microscopy (SEM) was used to examine feline cochleas for structural damage after exposure to a 2 kHz pure tone (105 dBSPL and 125 dBSPL). Following a 105dB exposure for 30 min acoustic response recovered to normal levels at 120 min after exposure with no significant loss of hair cell stereocilia. Fatigue induced changes in outer hair cell activity may be relevant to the production of TTS. The loss of stereocilia on outer hair cell row 1 and on inner hair cells was seen between 6 and 9 mm from the apex after exposure to a 125dBSPL, 2 kHz pure tone for 30 min and e-OAE disappeared after overstimulation in all these cases. We found that e-OAE was affected by minimal cochlear damage.

Acoustic Stimulation↗
PubMedDate not supplied

Otoacoustic emissions in normal-cycling females.

The purpose of this study was to determine if the menstrual cycle influences the amplitude of transient (TEOAEs) and distortion-product (DPOAEs) otoacoustic emissions. Thirteen normal-hearing, normal-cycling females were monitored weekly for 12 weeks. TEOAE and DPOAE amplitudes were analyzed to determine if amplitude changes could be detected and correlated to phases of the menstrual cycle. No systematic amplitude changes were observed, demonstrating that evoked OAEs are unaffected by physiologic changes associated with the menstrual cycle.

Adult↗
PubMed2001

Control of symptoms in patients with Meniere's disease using middle ear pressure applications: two years follow-up.

The effects of middle ear pressure pulses were studied in 37 patients with a diagnosis of definite Meniere's disease and active vestibular symptoms, 31 of whom had failed to respond to medical treatment including diuretics prior to pressure treatment. The number of vertigo spells during the 6 months prior to treatment and for 6, 18 and 24 months after the start of treatment were evaluated. The functionality level scores were three or worse according to the American Academy of Otolaryngology--Head and Neck Surgery (AAO-HNS) criteria. The results of the study were as follows: 19 patients experienced freedom from vertigo spells; 15 patients reported a significant decrease in the frequency of vertigo spells; and 3 patients did not respond to pressure treatment and were subjected to gentamicin injections, I of whom consequently became deaf in the affected ear. No patient became worse in connection with pressure treatment. With the exception of the three patients who did not respond to pressure treatment, all patients reported an improvement in functionality of at least two levels according to the AAO-HNS functionality scale. No side effects or adverse events were observed during the 2 years of pressure treatment. Overall, the results indicate that pressure treatment provides efficient control of symptoms in patients with intractable forms of Ménière's disease without producing any adverse effects on the inner ear.

Adult↗
PubMed1992

The effects of chronic hypoxia on human auditory system sensitivity.

We have examined the effects of prolonged periods of hypoxia produced at high altitudes on the latency of the auditory brain-stem evoked response (ABER) in 9 subjects at around sea level, 3,500 m, and 4,370 m. Following an ascent from 1,300 m to 3,500 m over 24 h, the mean blood O2 saturation fell to 86.5 +/- 1.2% (+/- S.E.M.) and was associated with a mean prolongation of latency of wave V of the ABER of 0.34 +/- 0.10 ms (p = 0.011 two-tailed paired t-test). Using the stimulus-level/response latency relation determined at around sea-level for each subject, this prolongation of wave V corresponded to a mean reduction in sensitivity of 9.1 dB +/- 1.6 dB. Over a period of 72 h, blood O2 saturation improved slightly (mean 88.1% +/- 1.8%) and mean wave V latency returned to control values. A second rapid ascent to 4,370 m reduced blood O2 to below prerecovery levels (82.5% +/- 1.7%), but in this case there were no significant changes in auditory sensitivity (p = 0.79 two-tailed paired t-test). These data show that mild hypoxia results in an initial decrease in auditory sensitivity. However, the recovery of sensitivity with more prolonged exposure suggests that the auditory system can compensate for chronic mild hypoxia.

Adult↗
PubMedDate not supplied

[The effect on man of weak-intensity acoustic signals].

Studies have been made of the effect of weak clicks, click series, wide band noise with the intensity of 10-20 dB on healthy subjects. Changes in the activity of central mechanisms of perception were evaluated by long-latent auditory evoked potentials, changes in vegetative functions of the organism were checked by analysis of the periodic structure of cardiac activity. It was shown that weak acoustic stimuli exert relatively weak direct influence on the auditory system which is revealed as weak and unstable realization of the stimuli together with the reduction of high-amplitude long-latent auditory evoked potentials. However, significant background effect of these signals on functional condition of human subjects was observed; changes in functional condition presumably affect the activity of central parts of the auditory and associative systems of the brain which is registered as changes in the long-latent auditory evoked potentials.

Acoustic Stimulation↗
PubMedDate not supplied

[Effect of low-energy laser irradiation on the functional state of the acoustic analyzer (experimental study)].

The acoustic function of guinea-pigs (in terms of ERA) before and after middle ear laser treatment (LHe-75, radiation intensity 15-17 mW, total dose 63 J/cm2, number of exposures 14) was investigated. The experiment was carried out using three groups of animals. Group 1 included healthy young animals. Group 2 consisted of adult animals with no signs of otitis media suppurativa. Group 3 involved adult guinea-pigs with chronic suppurative otitis media. After laser treatment all the animals showed increase of amplitudes of all ERA peaks, specifically of the first peak, an increase of the A1/A4 ratio, and an insignificant shortening of L1 at low sound intensities in group 1 and group 2 animals. This may suggest a greater excitation of the first component of the acoustic system. The group 3 animals exhibited a greater L1; this indicates that laser therapy of an untreated cavity during chronic otitis media may aggravate the pathological process. This pathology requires pretreatment of the middle ear cavity and laser therapy in combination with other therapeutic measures. None of the treated animals showed changes of the second time interval, whereas the third time interval (central time of conduction) became shorter, particularly on the side exposed to laser treatment. Our findings demonstrated differences in responses of adult and young animals to laser treatment (distinct shortening of the central time of conduction in those latter) which obviously needs further study.

Animals↗
PubMed1989

Age effect in speech audiometry and in brainstem electric response audiometry.

A review of the files of 152 patients with normal hearing or slight hearing loss revealed in the older age group that (1) scores on the synthetic sentence identification task (SSI, S/N = 0 dB) have a tendency to drop in comparison with the discrimination scores for phonetically balanced words in silence (PB), and that (2) the wave V of the auditory brainstem response shows a greater latency prolongation when the stimulation rate is increased. However, no statistical correlation between these two age-linked phenomena emerged, so they seem to be the result of two independent processes.

Adult↗