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Results for “Auditory Threshold”

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At least 415 records · Page 23Linked to original sources

PubMed1994

Surgical treatment of Menière's disease.

Surgical treatment is used only for patients with Menière's disease in cases that do not respond to medical therapy. At the present time, the endolymphatic sac shunt operation is performed in cases where the auditory threshold is fluctuant around 30 dB. When the auditory threshold is between 40 and 70 dB we use the vestibular neurectomy by the retrosigmoid approach. In patients with Menière's disease with profound hearing loss the translabyrinthine neurectomy is used. The advantages of the vestibular neurectomy by the retrosigmoid approach compared to the retrolabyrinthine and middle fossa approaches will be described.

Adult↗

PubMed1991

On the pathomechanism of cochlear dysfunction in experimental perilymph fistulas.

The mechanism leading to hearing impairment in perilymph fistulas was investigated in guinea pigs with perforated round window membranes (RWM) by analyzing alterations of inner ear fluid pressure, changes of auditory function following manipulations to get presumed air bubbles out of the cochlea ("positional audiometry"), and temporal bone sections. The instantaneous loss of normal positive inner ear fluid pressure after RWM perforation had no immediate effect on auditory function. Inner ear pressure was restored 4 days following RWM perforation. "Positional audiometry" was negative in guinea pigs with perforated RWM. All ears in which auditory thresholds had increased had additional iatrogenic lesions at the spiral lamina. Fistulas in the RWM per se do not affect auditory thresholds. The question of the surgical repair of fistulas was not directly addressed; it only can be concluded that there are no direct sequelae of an isolated fistula which induce auditory impairment and which could be prevented by surgical repair of the fistula.

Acoustic Stimulation↗

PubMedDate not supplied

[Auditory training with wide-band white noise: effects on the pain threshold and pure tone thresholds].

The auditory training with wide-band white noise is a methodology for the qualitative recovery of the hearing loss in people suffering from sensorineural hearing loss. It is based on the application of a wide-band white modified noise. In a prospective study, we have assessed the modifications of the total auditory threshold (UAt), the conversational auditory threshold (UAc), and the pain threshold (Ud) in a sample of 48 patients, who have followed a program of 15 auditory training with wide-band white noise sessions. The average improvements of the variables expressed in percentage are 0.78% for the UAt, 0.64% for the UAc, and 5.31% for the Ud. From our results, it can be deduced that the auditory training with wide-band white noise does not modify the pure tone thresholds, but it moves the pain threshold towards higher intensities, enlarging the dynamic auditory field.

Acoustic Stimulation↗

PubMedDate not supplied

[Evoked otoacoustic emissions in noise-induced hearing loss].

The Authors evaluated patterns of click-evoked otoacoustic emissions (EOE) in a group of 184 patients exposed to noise in their working environment. The aim of the study was to detect changes in EOE patterns in this group compared to the EOE of healthy subjects. The clinical history of each subject was recorded and otoscopy, pure tone audiogram and impedance tests (tympanometry, stapedial reflex threshold) were carried out in all patients. Noise-induced hearing loss found in 97 patients, unilateral sensorineural hearing loss in 17, other hearing disorders in 24 and normal auditory threshold in 46. EOE recording was carried out in the group of patients with noise-induced hearing loss (97), in the group with normal threshold (46) and in a control group of 15 healthy subjects. EOE recording was obtained using the ILO 88 Otodynamic Analyzer. We introduce a probe into the external ear canal using a non-linear click stimulus (intensity at approximately 85 dB spl) at a 20/sec. rate with a 20 msec. window. Normal EOE were found in the control group. Abnormal EOE were found in 79 cases (81%) of the noise-induced hearing loss group, and in 22 (48%) of the normal threshold group. These data show that noise-exposed subjects have alterations of EOE such as threshold shift missing frequency bands, even in absence of an auditory threshold shift. When EOE were present, the frequency spectrum often showed lack of emissions at high frequencies. This study confirms that cochlear exposure to noise may produce significant alterations of EOE and that this test may be considered highly sensitive in detecting early cochlear damage in chronic acoustic trauma. Therefore, EOE may be used in screening and follow-up of high risk populations such as noise-exposed subjects.

Acoustic Impedance Tests↗

PubMed1985

[Long-term gentamicin ototoxicity in the rat: research on retro-cochlear involvement by study of evoked auditory potentials of the brain stem].

Four groups of rats treated with single (50 mg/kg and 200 mg/kg) or multiple (3 X 200 mg/kg and 5 X 200 mg/kg) doses of gentamycin were studied over a 6-month period and compared with a control group. At 50 mg/kg no significant changes were observed. Significant signs of intoxication were observed at 200 mg/kg doses and at multiple doses. A significant lengthening of the latencies with changes in amplitude and a transitional increase in the auditory threshold were observed as early as the end of treatment. This was followed by a phase of amplitude decrease, a rise in auditory threshold and a decrease in latencies which remains unexplained.

Anesthesia↗

PubMed1999

[Bilateral large vestibular aqueduct syndrome (7 cases reported)].

OBJECTIVE: To explore the CT features and the auditory threshold in patients with bilateral large vestibular aqueduct syndrome. METHOD: The diameter of vestibular aqueduct in CT and the auditory threshold in each ears of seven patients were measured. RESULT: Asymmetry of the enlarged vestibular aqueduct was found in all patients of whom the side the vestibular aqueduct enlarged was found having a greater hearing loss than the other side in the same patient (paried t-test; P < 0.05). CONCLUSION: The measurement of vestibular aqueduct may be useful in determining the prognosis of patients with large vestibular aqueduct syndrome.

Adolescent↗

PubMed1997

[The application of auditory brainstem responses in hearing threshold evaluation].

Auditory brainstem responses (ABR) to click stimula-tion are recorded and analyzed in the patient with traumatic injury to ear. The results showed that the hearing loss (conductive hearing loss of sersorineural hearing loss) can be detected by ABR with the stimulation of pure tone in the range of 2000 to 4000 Hz. It is indicated that the ABR would be an useful methods to evaluate the patient's hearing impairment and the disability extent.

Adolescent↗

PubMed1997

Hearing threshold assessment with auditory brainstem response (ABR) and ElectroCochleoGraphy (ECochG) in uncooperative children.

Two-hundred-and-sixty uncooperative children (442 ears) performed auditory brainstem response (ABR) and Electrocochleography (ECochG) in the same diagnostic session under general anaesthesia, and the results obtained with the two different methods were compared. A difference > or = 20 dB between the two methods was found in 134 ears (30.3%). The presence of middle ear effusion and symptoms of a possible central nervous system pathology were considered in order to verify the evidence of a correlation between the difference in ABR-ECochG results and these clinical parameters. The presence of middle ear effusion was not significantly correlated with differences > or = 20 dB (p = 0.1347). On the contrary, the presence of symptoms indicative of a possible central nervous system (CNS) involvement was significantly correlated with differences > or = 20 dB (p = 0.0000). ABR has to be considered the first choice in hearing assessment strategy, either for screening or diagnosis. However, the diagnosis of hearing loss only on the basis of the presence or absence of wave V requires some care in case of suspected central auditory pathway lesions. In these cases, ECochG may be the only reliable diagnostic tool for hearing assessment in uncooperative subjects.

Adolescent↗

PubMed2003

Hearing loss with stapedotomy in otitis media.

OBJECTIVE: Stapes fixation is often found in patients with either active or inactive otitis media (OM). Stapedotomy is generally not performed in ears with OM because of the potential risk of sensorineural hearing loss (SNHL). Recent studies have demonstrated that the inner ear may be fenestrated in the presence of OM without significantly increased risk of SNHL. The goal of this study was to determine if stapedotomy in the presence of OM significantly increases the incidence of postoperative SNHL. METHODS: Streptococcus pneumoniae or Pseudomonas aeruginosa was injected bilaterally into the middle ears of guinea pigs (n = 18 and 16, respectively). A control group (n = 14) was injected with saline solution. Two days postinjection, a unilateral stapedotomy was performed. Auditory thresholds were evaluated by electrocochleography before and after stapedotomy. RESULTS: Bacterial OM was induced in all ears injected with pneumococci and pseudomonas. Auditory thresholds increased in all ears treated with stapedotomy. Stapedotomy performed in the presence of pseudomonas OM resulted in significantly greater SNHL than in control or pneumococcal ears (P = 0.0055). Hearing thresholds were not significantly different between pneumococcal OM and control ears treated with stapedotomy. CONCLUSION: Stapedotomy in the presence of pseudomonas OM, but not pneumococcal OM, significantly increases the risk of SNHL in the guinea pig model. SIGNIFICANCE: Stapedotomy should be avoided in patients with active OM, particularly in the presence of pseudomonas.

Animals↗

PubMed1995

COAEs and SSOAEs in adults with increased age.

OBJECTIVE: The purpose of this study was to compare click-evoked otoacoustic emissions (COAEs) of subjects having similar auditory thresholds but different age ranges. It is well known that elevated hearing thresholds are common with increasing age and that deterioration of outer hair cells is often noted in cases of hearing loss due to increased age. It has also been reported that evoked otoacoustic emissions (EOAEs) decrease with increased age. However, there is still some question whether changes in EOAEs with aging are associated with the increased hearing threshold or whether there is some additional effect of aging that enfluences EOAEs. DESIGN: COAE input/output functions and synchronized spontaneous OAEs (SSOAEs) were measured in two groups of subjects having similar auditory thresholds, one ranging in age from 19 to 29 yr, the other ranging in age from 40 to 61 yr. Mixed-model ANOVAs were performed to determine whether there were any statistically significant differences in COAEs based on age group. RESULTS: There were no statistically significant differences in COAE level or COAE threshold between age groups. Significant differences in COAEs were found for subjects based on whether they had measurable SSOAEs, regardless of age. CONCLUSIONS: Age does not significantly reduce COAE level nor increase COAE threshold. Other factors, such as presence of SSOAEs and hearing loss, undoubtedly have more influence on COAEs than the factor of age.

Acoustic Stimulation↗

PubMed1988

The contribution of brainstem electric response audiometry (BERA) to the evaluation and management of infants with cleft palate.

In the three-year period ending December 1986, 31 infants followed by the Cleft Palate Team of our institution were evaluated with BERA one or more times. Seventy-four percent presented auditory threshold elevation on initial examination; none was observed to resolve spontaneously in the first year of life. Myringotomy and tympanostomy tube insertion normalized auditory thresholds effectively in most children with serous otitis media. In a few cases, however, recovery required several months. BERA can assist the early detection of children with sensorineural hearing loss. It may also be valuable as an additional consideration in selecting treatment of serous otitis media in these children. Precise guidelines as to the ideal time to perform tympanostomy requires further substantiation of the effects of early hearing loss on speech and language development.

Audiometry, Evoked Response↗

PubMed2001

Distortion product otoacoustic emission input/output functions in normal-hearing and hearing-impaired human ears.

DPOAE input/output (I/O) functions were measured at 7f2 frequencies (1 to 8 kHz; f2/f1 = 1.22) over a range of levels (-5 to 95 dB SPL) in normal-hearing and hearing-impaired human ears. L1-L2 was level dependent in order to produce the largest 2f1-f2 responses in normal ears. System distortion was determined by collecting DP data in six different acoustic cavities. These data were used to derive a multiple linear regression model to predict system distortion levels. The model was tested on cochlear-implant users and used to estimate system distortion in all other ears. At most but not all f2's, measurements in cochlear implant ears were consistent with model predictions. At all f2 frequencies, the ears with normal auditory thresholds produced I/O functions characterized by compressive nonlinear regions at moderate levels, with more rapid growth at low and high stimulus levels. As auditory threshold increased, DPOAE threshold increased, accompanied by DPOAE amplitude reductions, notably over the range of levels where normal ears showed compression. The slope of the I/O function was steeper in impaired ears. The data from normal-hearing ears resembled direct measurements of basilar membrane displacement in lower animals. Data from ears with hearing loss showed that the compressive region was affected by cochlear damage; however, responses at high levels of stimulation resembled those observed in normal ears.

Adolescent↗

PubMedDate not supplied

Auditory deficits and motor dysfunction following iminodipropionitrile administration in the rat.

The behavioral effects of 3,3'-iminodipropionitrile (IDPN) were studied using reflex modification of the acoustic startle response and figure-eight maze activity. A number of experiments were conducted with separate groups of adult male Long-Evans hooded rats exposed to saline or 50-500 mg/kg IDPN for 3 consecutive days. Auditory thresholds (reflex modification), motor activity, and grip strength were measured 1 day, and 1, 3, and 9 weeks postdosing. Reflex inhibition was monitored daily, prior to, during, and for 7 days following exposure. Auditory thresholds for 5- and 40-kHz tones were elevated approximately 25 dB and 50 dB, respectively. The onset of this auditory dysfunction in the 200-mg/kg/day group, as demonstrated by a loss of reflex inhibition, was 2 days for the 40-kHz tone and 4 days for the 5-kHz tone. Motor activity was increased up to 400% in the 200-mg/kg group, whereas there was no alteration in hindlimb grip strength. These data demonstrate dosage- and time-dependent alterations in auditory and motor function following IDPN exposure.

Acoustic Stimulation↗

PubMed2000

Cortical evoked response audiometry thresholds and neuroleptic, sedative, hypnotic drugs.

Cortical evoked response audiometry is adequate for approximating hearing threshold levels with frequency specificity when the psychoacoustic responses lack reliability and reproducibility (compensation claim). It is well-known that control of wakefulness is essential for the reliability of slow vertex responses (SVR). Therefore, sedative, hypnotic, and neuroleptic drugs are supposed to have possible adverse effects on the detection of SVR. In contrast, brainstem evoked responses (BER) have proved not to be significantly affected by therapeutic doses of these compounds. The purpose of our study was to assess the reliability of SVR-threshold definition in subjects taking neuroleptic, sedative, and hypnotic drugs. Fifteen subjects examined for occupational hearing loss at the Fund for Occupational Diseases in Brussels and regularly taking one or several of these drugs were compared with 27 comparable controls. In each subject the auditory thresholds were defined with both techniques: SVR (1, 2, and 3 kHz) and BER (clicks). A highly significant difference is observed between the two groups: In the group receiving drugs, the SVR threshold for 3 kHz is 12.1 dB (average) higher than the BER threshold, whereas in the group without drugs, the SVR threshold for 3 kHz is 7.77 dB (average) lower than the BER threshold. In the drug group, large interindividual differences are observed. It may be concluded that the use of neuroleptics, sedatives, and hypnotics renders the auditory threshold definition with SVR completely unreliable. In using SVR for medicolegal threshold definition, controlling the 3-kHz threshold with BER always is necessary.

Adult↗

PubMedDate not supplied

Mid-frequency hearing loss and reduction of acoustic startle responding in rats following trichloroethylene exposure.

Modification of auditory evoked startle responding using prepulse inhibition was used to examine the effects of trichloroethylene (TCE) exposure on auditory thresholds. Rats were exposed by inhalation to 0, 1500, or 3000 ppm TCE for 18 hours per day, 5 days a week for 3 weeks. Auditory thresholds for 5 and 20 kHz tones were measured before exposure and at 1, 3, and 6 weeks postexposure. In addition, hearing thresholds for 5 and 35 kHz tones were examined at a 5-week postexposure time-point. Results indicated that hearing thresholds for 20 kHz but not for 5 or 35 kHz prepulses were significantly increased in rats exposed to 3000 ppm TCE. These findings demonstrate a selective hearing loss in the 20 kHz range by short-term, high-level TCE exposure. With respect to effects on startle responding per se, the present study also found that compared to controls, TCE-exposed rats failed to show an increase in baseline startle with repeated testing. This difference could not be attributed to differences in body weight and was persistent throughout the postexposure period.

Acoustic Stimulation↗

PubMed2000

Hearing loss following exposure during development to polychlorinated biphenyls: a cochlear site of action.

Maternal exposure to polyhalogenated hydrocarbons results in early postnatal hypothyroxenemia and a low-frequency hearing loss in adult offspring (Goldey et al., 1995a. Toxicol. Appl. Pharmacol. 135, 67-76; Herr et al., 1996. Fundam. Appl. Toxicol. 33, 120-128). The purpose of the present work was to determine whether the site-of-action of this auditory impairment was within the cochlea. Primiparous Long-Evans rats were given daily oral doses of corn oil (control) or 8 mg/kg of the commercial PCB mixture Aroclor 1254 (A1254) from gestation day (GD) 6 through postnatal day (PND) 21. Auditory thresholds for 1-, 4-, 16-, and 40-kHz tones were assessed using reflex modification audiometry in young adult offspring on postnatal days (PND) 92-110. Approximately 6 weeks after auditory assessments, a subset of animals (n=4 per group) were killed for histological assessment of the cochlea. Surface preparations of the organ of Corti were prepared from one cochlea per animal and modiolar sections were prepared from the opposite cochlea. Consistent with previous findings, auditory thresholds for 1-kHz tones were elevated by approximately 25 dB in the A1254-exposed animals. Thresholds for all higher frequencies were not different compared to controls. Surface preparations of the organ of Corti revealed a mild to moderate loss of outer hair cells in the upper-middle and apical turns. Inner hair cells were not affected. Modiolar sections failed to reveal alterations in any other cochlear structures. There was also no apparent loss of ganglion cells. These data clearly link the loss of low-frequency hearing caused by exposure during development to A1254 to a loss of outer hair cells in the organ of Corti. The mechanism that underlies this developmental ototoxicity remains to be determined. These data provide the first evidence of a structural deficit in the nervous system of adult animals exposed to PCBs during development.

Animals↗

PubMed1995

The alpha 2-adrenergic antagonist idazoxan enhances the frequency selectivity and increases the threshold of auditory cortex neurons.

Idazoxan (IDA), an alpha 2 antagonist of adrenoceptors, has been shown to increase cortical release of norepinephrine (NE) by an action mediated primarily by the alpha 2 autoreceptors located on the NE terminals. In the present experiment, IDA application was used to increase the cortial concentration of NE. Single unit activity (n = 107) was recorded in the rat auditory cortex, and the neurons' frequency receptive fields (FRF) were determined before and after systemic (intraperitoneal or intravenous) or local application of IDA. In the whole population (n = 107) there was a decrease in spontaneous activity and/or evoked activity for 84% of the recordings (90/107 cells). Decreased tone-evoked responses were obtained after systemic injections (n = 39), as well as after local applications (n = 68) of IDA. These effects were not observed after either systemic injections (n = 13) or local applications (n = 9) of saline. The signal-to-noise ratio (the mean evoked responses divided by the spontaneous activity) was slightly decreased after systemic injections and slightly increased after local applications. However, after both systemic and local injections the frequency selectivity of the neuronal responses was increased. For a group of neurons (n = 27), testing the FRF at three intensities indicated that this increased selectivity can be expressed at high or middle range intensity but not at low intensity. For 37 cells, the intensity function was tested at the best frequency before and after IDA application, and the threshold for excitatory responses was determined in 28 cases. An increased threshold was observed in 16 of 28 cases after IDA application. Thus, using a pharmacological procedure to increase the extracellular concentration of NE, the dominant inhibitory effect on the auditory cortex neurons led to an enhancement of the frequency selectivity, but also an increase in the threshold of these neurons.

Acoustic Stimulation↗

PubMed1987

The relation between the pure-tone audiogram and the click auditory brainstem response threshold in cochlear hearing loss.

Auditory brainstem response thresholds for 209 ears with cochlear hearing loss were compared with the pure-tone thresholds. It is shown that the pure-tone threshold in the 2- to 4-kHz region has a one-to-one relationship with the auditory brainstem response threshold. Estimating the pure-tone threshold from the auditory brainstem response threshold, the standard error of the estimate is 11 dB. A small part of this estimation error is due to errors in the measurement of the auditory brainstem response threshold and the mean of the pure-tone thresholds at 2 and 4 kHz. The major part is due to unknown factors that are involved in the physiological relationship between the two thresholds.

Audiometry↗