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Biomedical subjects

R H Margolis

Publications and source records attributed to R H Margolis.

At least 19 recordsLinked to original sources
PubMed1992

A clinical profile of otitis media.

An otitis media with effusion algorithm developed by Paradise et al and tested by Cantekin et al has become the basis for many studies of otitis media. However, a two-point scale algorithm (otitis media with effusion-no otitis media with effusion) may be too ambitious (ie, low specificity) and too optimistic (ie, absence of fluid does not necessarily mean normal ear). We propose a four-point profile that characterizes the condition of the middle ear, and we report the validation of the profile against findings at myringotomy. Statistically, a four-point scale profile would substantially increase powers of statistical tests, compared with a two-point scale algorithm (in studies of the same size), when used to study changes of the middle-ear condition over time or to compare treatment effects.

Acoustic Impedance Tests↗
PubMed1992

A comparison of acoustic reflex and auditory brain stem response screening of high-risk infants.

This investigation was undertaken to explore the feasibility of screening for hearing impairment in an intensive care nursery population with a combined acoustic stapedius reflex-ABR approach. Acoustic reflex threshold measurements (AR) were made on intensive care nursery patients in an existing ABR screening program. Pass-fail results were determined for the two methods, separately and in combination. AR screening identified all 10 ears that failed the ABR screen. The cost savings of screening with a combined AR-ABR approach was determined for various pass-fail criteria. The results suggest that the AR-ABR approach can produce a significant cost savings without compromising the sensitivity and specificity of the screening program.

Acoustic Impedance Tests↗
PubMed1992

A look at ear canal changes with jaw motion.

Two procedures were used with one subject to examine changes in the ear canal with jaw motion. Silicone ear impressions were examined to measure the effect of jaw position. Magnetic resonance imaging was used to define the three-dimensional structure of the canal and visualize key underlying tissue. Results showed that inexpensive impressions can detail changes in the cartilaginous region of the canal. Approximately a 25% change in this subject's ear canal with different jaw positions was observed in the anterior/posterior plane with essentially no change in the superior/inferior plane. This is likely related to asymmetric stress from action of the mandibular condyle on neighboring cartilaginous tissue. Solutions to jaw motion-induced feedback problems are suggested.

Ear Canal↗
PubMed1992

Short-term poststimulatory response characteristics of the human acoustic stapedius reflex: monotic and dichotic stimulation.

Two experiments were performed to study short-term poststimulatory response characteristics of the human acoustic stapedius reflex in the time and intensity domains. In experiment 1, monotic magnitude-intensity functions (MIFs) were obtained for a 20-ms test stimulus preceded by a conditioning stimulus varying in duration (20, 50, 100, 500 ms) and level (-10, 0, +10 dB re: stapedius-reflex threshold) and temporally separated from the test stimulus by various interstimulus intervals (ISIs) (0, 20, 50, 100, 500 ms). Experiment 2 was similar in design except that conditioner and test stimuli were presented dichotically and fewer ISIs were used. Both experiments demonstrated that a prior conditioning stimulus produced significant increases in test-stimulus response magnitude. These poststimulatory effects were characterized by complex interactions among stimulus variables (conditioner duration, conditioner level, and interstimulus interval) with similar interactions occurring for both monotic and dichotic stimuli. A simple superposition effect of the responses to the conditioner and test stimulus does not account for the effect of prior stimulation since responses often exceeded the sum of the responses to the conditioner and the test stimulus alone.

Acoustic Stimulation↗
PubMed1992

Effect of ear-canal air pressure on evoked otoacoustic emissions.

The effect of ear-canal air pressure on click-evoked otoacoustic emissions was measured for pressures ranging from 200 to -200 daPa and stimulus levels ranging from 60-90 dB PeSPL. Positive and negative ear-canal pressures (relative to ambient pressure) reduced the emission amplitude by 3-6 dB. A spectral analysis of the emissions revealed that the effect of ear-canal air pressure is that of a high-pass filter with a cutoff frequency of 2600 Hz and a slope of 4 dB/oct. The spectral changes are the expected effect of an increase in stiffness of the middle ear and were independent of pressure polarity and click level. Ear-canal air pressure substantially reduced the reproducibility of the emission waveform, in many cases rendering the emission indistinguishable from background noise. The implication of these findings for hearing screening applications is that a high false alarm rate may occur in normal-hearing patients with intratympanic air pressures that are significantly different from ambient pressure.

Adult↗
PubMed1992

Tympanic electrocochleography for evaluation of endolymphatic hydrops.

There has been increased interest in electrocochleography for the diagnosis and intraoperative monitoring of patients with endolymphatic hydrops. Attention has been focused on the determination of the summating potential:action potential (SP:AP) ratio from alternating polarity clicks. Review of this technique at the University of Minnesota led to a reevaluation of the usual interpretation of these recordings. Separate examination of the rarefaction and condensation click recordings provides insight into abnormal response patterns. Cases are presented to illustrate a variety of normal and abnormal patterns including abnormal differences in the latency of condensation and rarefaction-click-generated action potentials, increased summating potential, uncanceled cochlear microphonic, and reduced action potential and summating potential amplitudes. These response categories may be useful in understanding the pathophysiology of Meniere's disease.

Acoustic Stimulation↗
PubMed1992

Tympanic electrocochleography: normal and abnormal patterns of response.

Electrocochleography has been widely used in human and animal studies of endolymphatic hydrops. A variety of response patterns have been reported in normal and hydropic ears. Recent clinical studies have focused almost exclusively on the amplitude ratio of the summating potential (SP) and action potential (AP) derived from alternating polarity click responses. In this report normal response patterns are described with a tympanic membrane electrode employing condensation, rarefaction and alternating polarity clicks and tone burst stimulation. A variety of response abnormalities are described in patients with suspected endolymphatic hydrops. The exclusive use of alternating polarity clicks is not adequate to reveal the nature of these abnormalities.

Acoustic Stimulation↗
PubMed1992

Comparison of clinical and real-life judgments of loudness discomfort.

The purpose of this study was to determine the relationship between the loudness discomfort level (LDL) and real-life impressions of loudness discomfort. LDLs were measured with an established procedure for a variety of stimuli including FM tones, speech noise, and stimuli recorded from two real-life environments, in two groups of subjects. Sound pressure level distributions were measured in each of two environments at the time of subject recruitment, and LDLs were subsequently measured. LDLs were then compared to the sound pressure levels measured in each environment, and to the impressions of loudness discomfort which subjects reported through the use of a questionnaire. Results indicated large discrepancies between LDLs and judgments of loudness discomfort in real-life environments. The LDL does not appear to be an accurate predictor of subjects' impression of loudness discomfort and may not be appropriate for setting the SSPL of hearing aids.

Adult↗
PubMed1991

Threshold and suprathreshold temporal integration effects in the crossed and uncrossed human acoustic stapedius reflex.

Threshold and suprathreshold temporal integration (TI) effects were studied in the crossed and uncrossed human acoustic stapedius reflex. Changes in reflex threshold were compared at four stimulus durations and for six threshold response criteria; suprathreshold effects were similarly compared at four stimulus durations and at five stimulus sound-pressure levels. Our results showed that reflex thresholds were significantly lower for the uncrossed condition and for longer duration stimuli. Both effects were dependent on threshold response criteria. Threshold TI measurements in both crossed and uncrossed conditions were equivalent at low criterion levels (0%-4%, p greater than 0.05) but were significantly larger in the crossed condition at higher criterion levels (5%-6%, p less than 0.05). Prominent suprathreshold effects also occurred. The main effect was characterized by significantly larger reflex magnitudes in the uncrossed condition. Duration dependent slope differences in magnitude intensity functions (MIFs) were also observed and were characterized by steeper slopes for longer duration stimuli. Saturation effects and/or intensity-dependent slope decelerations in MIFs were predominant in the uncrossed condition and for stimulus durations exceeding 20 ms. These data provide further quantitative evidence for asymmetric threshold and suprathreshold response properties of the crossed and uncrossed human acoustic stapedius reflex and demonstrate the dependence of these effects on stimuli of different durations.

Acoustic Stimulation↗
PubMed1991

Developmental changes in multifrequency tympanograms.

The normal maturational course of tympanometric shape, static aural acoustic admittance and ear canal wall characteristics were investigated in healthy infants, who were followed at various time intervals in the first 4 months of life. Susceptance and conductance tympanograms were recorded from both ears of each subject at four probe frequencies or more. In addition, quantitative pneumatic otoscopy was performed utilizing air pressure changes of the same magnitude as those typically used in tympanometry. Results for the group were an increase in admittance magnitude with increasing age at frequencies above 226 Hz. Admittance phase angle increased with age at all frequencies, indicating a growing contribution of compliant elements in the first 4 months of life. The course of development of input admittance at the tympanic membrane differed among individual infants. Otoscopic findings indicated that external ear canal differences cannot completely account for tympanometric differences between young infants and adults.

Acoustic Impedance Tests↗
PubMed1991

Acoustic reflex measures in audiologic evaluation.

Measurement of the acoustic-stapedius reflex is useful in the diagnosis of certain otologic diseases. The anatomy and physiology of the middle ear muscles and the acoustic reflex arc are reviewed for normal and pathologic ears. The application of acoustic reflex measures to clinical diagnosis is illustrated by a series of case studies.

Auditory Threshold↗
PubMed1991

Audiologic evaluation of the otitis media patient.

Because of the complexity and variability in the expression of otitis media, its effects on auditory function are diverse. The various influences of otitis media on auditory function are described within this article, including acoustic reflex, audiometry, and tympanometry.

Acoustic Impedance Tests↗
PubMed1987

Screening tympanometry: criteria for medical referral.

Tympanograms were obtained from normal preschool and adult subjects with a prototype hand-held tympanometer to obtain normative values for four tympanometric variables: static admittance, equivalent ear canal volume, tympanometric peak pressure, and gradient. Effects of age group, sex, and pump speed (200 or 400 daPa/s) were determined. The results were incorporated into a four-part screening protocol (history, visual inspection, audiometry, and tympanometry) designed to reduce the excessive error rates associated with screening strategies that rely exclusively on tympanometry.

Acoustic Impedance Tests↗
PubMed1986

Simulation of pathological high impedance tympanograms.

The Vanhuyse, Creten, and Van Camp (1975) model for analyzing high frequency tympanograms predicts the shapes of conductance, susceptance, and admittance tympanograms from the relationship between resistance and reactance tympanograms at the tympanic membrane. This model has been applied primarily to low impedance middle-ear pathologies but has not been applied extensively to the more commonly occurring high impedance pathologies. The purpose of this study was to extend the Vanhuyse et al. (1975) model to high impedance pathologies and to identify tympanometric parameters associated with otosclerosis, secretory otitis media, and lateral ossicular fixation. Data from previous experiments on the shape and absolute values of resistance and reactance tympanograms were used to calculate 678-Hz admittance tympanograms that were unique to each of the three high impedance pathologies. Guidelines for differentiating among the middle-ear pathologies on the basis of high frequency tympanometric shapes are presented.

Acoustic Impedance Tests↗
PubMed1986

Tympanometric gradient measured from normal preschool children.

Tympanometric gradient is a quantitative expression of the shape of a tympanogram in the vicinity of the peak. Previous work suggests that gradient measures may be diagnostically and prognostically useful in the assessment and management of middle ear disease. However, since almost all previous work on the subject was performed on tympanograms recorded in 'arbitrary compliance units' which are not comparable to the physical admittance units provided by currently available instrumentation, at this point the tympanometric gradient can only be viewed to be a potentially-useful clinical measure. In this investigation, eight tympanometric gradient measures were calculated from tympanograms obtained from normal preschool age children. The measures were evaluated on the basis of distribution characteristics, relation to static admittance, and effect of pump speed. One of the measures--the pressure interval defined by a 50% reduction in peak eardrum admittance--appears to be the procedure of choice. Measurements obtained from abnormal ears are needed to evaluate the clinical utility of this measurement.

Acoustic Impedance Tests↗