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Biomedical subjects

S A Fausti

Publications and source records attributed to S A Fausti.

17 recordsLinked to original sources
PubMed1992

High-frequency audiometric monitoring for early detection of aminoglycoside ototoxicity.

Treatment with aminoglycosides is known to cause irreversible hearing loss, typically affecting higher-frequency hearing first and progressing to lower frequencies. Standardized methodology has not been developed for early detection of ototoxicity. Serial conventional (0.25-8 kHz) and high-frequency (9-20 kHz) hearing threshold monitoring was done prospectively in 53 hospitalized patients administered aminoglycosides. Hearing loss occurred in 47% of the ears studied, with hearing loss first appearing in the high-frequency range in 71% of ears showing change. Analysis of data on an individual basis revealed a five-frequency range most susceptible to initial ototoxicity. Testing only this range would have resulted in early identification of 82% of ears showing change. Results confirm the critical need for serial auditory threshold monitoring encompassing high frequencies in patients receiving aminoglycosides. A shortened five-frequency monitoring protocol is presented and suggested for use with patients unable to tolerate lengthy audiometric testing procedures.

Amikacin↗
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↗
PubMed1992

Early detection of ototoxicity using high-frequency, tone-burst-evoked auditory brainstem responses.

Subjects receiving treatment with ototoxic agents were evaluated concurrently with conventional and high-frequency (> or = 8 kHz) behavioral threshold measures and with ABR to click and to 8, 10, 12, and 14 kHz tone-burst stimuli. Behavioral threshold data revealed ototoxic change in 51 percent of ears evaluated. Of these ears demonstrating behavioral change, 90 percent revealed concurrent ABR changes. If only ABR monitoring with high-frequency tone-burst stimuli had been used, 87 percent of allears showing behavioral change would have been identified. Three fourths of these would have been identified from wave V responses, with 87 percent identified from the two highest frequencies tested for each individual. This research suggests that behavioral change is reflected accurately in the ABR, that high-frequency tone bursts will identify a majority of initial ototoxic changes, and that monitoring hearing with high-frequency, tone-burst-evoked ABRs during treatment with potentially ototoxic agents is significantly more effective than click-evoked ABRs for early detection of ototoxicity.

Acoustic Impedance Tests↗
PubMed1992

Portable stimulus generator for obtaining high-frequency (8-14 kHz) auditory brainstem responses.

Currently, the most useful application of high-frequency (greater than or equal to 8 kHz) auditory evaluation is for serial monitoring of patients receiving potentially ototoxic agents. Many individuals, however, are unable to respond to behavioral auditory test techniques. An objective evaluation method such as the auditory brainstem response (ABR) is valuable with difficult-to-test individuals. Laboratory instrumentation has been demonstrated to evoke high-frequency-specific (8-14 kHz) ABRs with reliable intrasubject latencies over time. This instrumentation is limited, however, because it cannot be transported to the patient confined to a hospital room. A portable device has now been constructed to deliver high-frequency (8-14 kHz) tone-burst stimuli comparable to the lab system. This digital/analog high-frequency tone-burst stimulus generator weighs less than 5 pounds. It can be utilized with any ABR signal averager capable of generating a positive (condensing) click at approximately 4.8 volts. Case studies are presented to demonstrate the frequency-specific responses obtained with these high-frequency tone-burst stimuli.

Acoustic Stimulation↗
PubMed1991

Rise time and center-frequency effects on auditory brainstem responses to high-frequency tone bursts.

The effects of rise time and center frequency on the auditory brainstem response (ABR) elicited by high-frequency tone bursts were examined in six normal-hearing adults. Tone bursts with rise times of 0.1, 0.25, 0.5, and 1.0 msec, duration of 2 msec, and center frequencies of 8, 10, and 12 kHz were used in this study. The absolute latencies of waves I, III, and V were obtained in all subjects, and interpeak intervals of I-III, III-V, and I-V were calculated. As would be expected, rise time significantly affected the absolute latencies of waves I, III, and V, i.e., faster rise times shortened the absolute latencies, but did not affect the interpeak latencies. The tone-burst frequency significantly affected the latency of wave I but not the later waves. No significant differences were found in reliability of the response at different rise times or frequencies, within or across sessions. An estimate of the effective bandwidth of the stimulus suggests that frequency specificity of the response is maintained with fast rise time tone-burst stimuli.

Acoustic Stimulation↗
PubMed1991

Reliability of evoked responses to high-frequency (8-14 kHz) tone bursts.

Instrumentation to evaluate the auditory brainstem response to high-frequency (8-14 kHz) tone bursts has been developed in the Auditory Research Laboratory, Portland, Oregon VA Medical Center. This system is intended to monitor the audition of patients receiving ototoxic drugs who are unresponsive to behavioral test procedures. The reliability of responses obtained with the high-frequency tone-burst system was studied in 30 normal ears. Intrasubject variability of intersession data from response waves I, III, and V to tone bursts of frequencies 8, 10, 12, and 14 kHz was not significantly different from click response variability. The results of this study demonstrate the reliability of the ABR to these high-frequency tone-burst stimuli. This technique may provide early identification of hearing loss in unresponsive subjects receiving treatment with potentially ototoxic agents, thus allowing alternative treatments to minimize or prevent communicative handicap.

Acoustic Stimulation↗
PubMed1991

Masked high-frequency bone-conduction audiometry: test reliability.

The present study examines the reliability of masked high-frequency bone-conduction threshold measurements in 95 normal-hearing subjects. High-frequency pure-tone air-and bone-conduction thresholds were measured with a dedicated laboratory high-frequency auditory evaluation system using matched, modified Koss Pro/4X Plus earphones, and the Pracitronic KH 70/5 bone vibrator. A 400-Hz wide band masking noise centered at the frequency of the test tone was used to mask the nontest ear. Monaural masked bone-conduction threshold measurements were obtained at the ipsilateral mastoid of the ear with better high-frequency hearing. Two measurements were performed in each session, and each subject participated in two sessions. In several comparisons for test-retest consistency, high-frequency bone-conduction threshold measurements were as repeatable as air-conduction thresholds of identical frequency, or bone-conduction thresholds for frequencies of 4 kHz and less. High-frequency bone-conduction threshold measurement appears to be a sufficiently reliable tool for diagnosis of auditory disorders.

Adolescent↗
PubMed1990

Effects of contralateral masking on high-frequency bone-conduction thresholds.

The present study reports effects of contralateral masking on high-frequency threshold force levels in 28 normal-hearing subjects. High-frequency air- and bone-conduction thresholds were measured with a high-frequency auditory evaluation system using matched Koss HV/1A earphones and the Pracitronic KH 70/5 bone vibrator. Measurements were made for both unmasked and masked bone-conduction thresholds at the ipsilateral mastoid of the better ear. The contralateral masked condition was performed using 30-dB-SL 400-Hz narrow-band masking noise centered at frequency of test tone. The results demonstrated that masked high-frequency bone-conduction thresholds were 1.5 to 3.4 dB poorer than the unmasked thresholds and that these differences were statistically significant at 0.01 level of confidence except at 12 kHz. ANSI and ISO standards for bone-conduction threshold force levels for frequencies below 8.0 kHz have been established with contralateral masking stimuli. This study supports the need to use effective contralateral masking to eliminate cross hearing in investigations of high-frequency bone-conduction threshold measurements.

Adult↗
PubMed1990

Reliability and validity of high-frequency (8-20 kHz) thresholds obtained on a computer-based audiometer as compared to a documented laboratory system.

A Macintosh computer-based audiometer (Virtual 320) was evaluated for reliability and validity of high-frequency (8-20 kHz) thresholds by comparison with a well documented laboratory high-frequency evaluation system (PARVA-HF). High-frequency earphones originally provided with the V320 for high-frequency testing required modification to improve reliability in calibration and in subject threshold testing. Twenty normal-hearing adults were evaluated in the 8-20 kHz frequency range on both testing systems. Results of intrasubject multiple-session testing were evaluated to determine the reliability of high-frequency thresholds obtained. The V320 produced reliable results comparable to the PARVA-HF. Validity of high-frequency thresholds was inferred by comparing V320 responses to those obtained with the PARVA-HF. Comparable findings between systems imply validity of thresholds obtained with the V320. Conventional frequency (0.25-8 kHz) threshold evaluation with the V320 and a Grason-Stadler 1701 audiometer also yielded comparable results.

Adult↗
PubMed1986

Age categorization of high-frequency auditory threshold data.

This article presents high-frequency (8- to 20-kHz) auditory threshold measurements for 157 subjects with normal conventional hearing, ranging in age from 6-30 years. Normative descriptive data are provided in five semidecade age categories. Intra-age category mean and variance values for threshold sensitivity and interaural threshold differences are included. Generally, the data are consistent with the expectation of a gradual diminution of high-frequency sensitivity through the adolescent and early adult years. Several unresolved issues related to high-frequency normative data and clinical applicability of high-frequency threshold measurements are discussed.

Adolescent↗
PubMed1986

Effects of middle-ear disease and cleft palate on high-frequency hearing in children.

High-frequency hearing loss in children with cleft palate has been documented recently. The present study was designed to investigate whether hearing loss can result solely as a consequence of middle-ear disease in early life or as a result of cleft palate and its sequelae which include middle-ear disease. Our results demonstrate that auditory functions for test frequencies 250-6 000 Hz were not significantly different among the two investigational groups of children with high incidence of middle-ear disease, and a control group of children with virtually no middle-ear disease. However, for high-frequency thresholds (8 000-20 000 Hz), both groups of children with high incidence of middle-ear disease were statistically different from the control group. Moreover, the children with cleft palate had high-frequency hearing that was statistically similar to that of children with normal orofacial structures and high incidence of middle-ear disease. Middle-ear disease alone, then, is a sufficient condition for loss of high-frequency sensitivity.

Adolescent↗
PubMed1986

A prospective study of high-frequency auditory function in patients receiving oral neomycin.

Orally administered, neomycin is reported to cause ototoxicity rarely. Most reports on hearing loss due to oral neomycin have been case studies. One prospective study of a pediatric sample demonstrated a significant loss of hearing in the frequency range of 2 to 8 kHz in 9 of 17 children. To our knowledge there are no published prospective studies on this type with adult samples and therefore little is known of the true incidence or nature of ototoxicity from oral neomycin. This prospective study presents the results of long-term use of oral neomycin in 30 adult subjects. Hearing sensitivity was serially monitored in the frequency range 250-20,000 Hz. Two of the 30 subjects subsequently revealed ototoxicity. Thus the results of this investigation suggest that clinical use of oral neomycin implies relatively little risk of ototoxicity.

Administration, Oral↗
PubMed1979

A system for evaluating auditory function from 8000--20 000 Hz.

A system for the measurement of auditory function from 8000--20 000 Hz is described. This system introduces advances in: (a) maximum power output, (b) signal fidelity, and (c) transducer characteristics. Two case studies are presented to illustrate the clinical information gained from the measurement of high-frequency auditory sensitivity, which is not readily apparent in conventional threshold assessment.

Adolescent↗
PubMed1979

2AFC versus standard clinical measurement of high frequency auditory sensitivity (8--20 KC/S).

A two-alternative forced choice (2AFC) psychophysical method of assessment was employed to judge the validity of using a standard clinical test procedure for obtaining thresholds in the frequency region 8--20 kc/s. Close agreement was demonstrated between "same-day" thresholds obtained with a standard clinical test procedure and the 2AFC method, for 6 well trained normal-hearing adults. In addition, close agreement was shown between the 2AFC sensitivity measure and the mean of thresholds obtained at 4 separate times during this investigation with the standard method. The standard clinical test method demonstrated good between-test reliability. It is concluded that a standard clinical test technique is a valid and feasible clinical measurement procedure for this high frequency region.

Adolescent↗