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R Probst

Publications and source records attributed to R Probst.

At least 91 records · Page 5Linked to original sources
PubMed1991

A child with an unusually high-level spontaneous otoacoustic emission.

We describe a child who emitted a continuous audible sound from his left ear. A high-level spontaneous otoacoustic emission was measured at the frequency of 5.64 kHz with an amplitude of 55 dB sound pressure level. A high-frequency hearing loss was measured in both ears; however, it was more pronounced in the emitting ear. The emission failed to synchronize to external click stimuli. This spontaneous emission is probably related to a cochlear defect, but it should not contribute additionally to the child's existing auditory impairment.

Acoustics↗
PubMed1991

Click- and tone-burst-evoked otoacoustic emissions in normally hearing ears and in ears with high-frequency sensorineural hearing loss.

Otoacoustic emissions (OAEs) evoked by clicks and tone bursts (TBs) were measured using a minor modification of the 1987 Bray and Kemp system in normal and hearing-impaired ears with high-frequency sensorineural hearing loss. Sixty ears of 60 subjects were tested. The average behavioral hearing threshold of 20 normally hearing ears was measured for the different "nonlinear" stimulus groups and defined as 0 dBnHL. Emissions were recorded in another 20 normally hearing ears and in 20 ears with steep high-frequency sensorineural hearing loss above 2kHz. An unfiltered click of 80 microseconds duration and TBs at frequencies of 0.5, 1, 2, 3, 4, 5, and 6 kHz served as stimuli. The ears with high-frequency hearing loss were clearly distinguished from the normal ears in that emission energy decreased with higher frequency stimuli above 2 kHz. The mean slopes of the response-growth functions were significantly higher at lower audiometric thresholds. The normal ears showed a slope of 0.21-0.35 dB/dBnHL above 2 kHz while the slope of the pathological ears was 0.04-0.13 dB/dBnHL. These differences in TBOAEs could possibly be used clinically to carry out hearing tests that are more frequency-specific than those measuring solely click-evoked OAEs. Pathological ears had emissions in the lower frequency range, where they had a normal audiometric threshold. However, these emissions had significantly far lower amplitudes at frequencies around 0.5 and 1 kHz when compared to normal ears. This reduced emission energy may indicate a cochlear impairment of the pathological ears in frequency ranges where they still had normal audiometric thresholds.

Acoustic Stimulation↗
PubMed1991

[The clinical use of oto-acoustic emissions of cochlear distortion products].

Otoacoustic emissions of cochlear distortion products (DPOAEs) were measured in normally hearing and hearing-impaired human ears. A total of 133 subjects (231 ears) were tested. Two puretone stimuli f1 and f2 were delivered to a sound probe fixed in the outer ear canal. The frequencies of the two primaries were chosen so that their geometric mean represented pure-tone audiometric frequencies. The otoacoustic emission was measured at the distortion product frequency 2f1-f2 by spectral averaging. For 199 ears, the levels of the primaries were 73 dBHL for L1 and 67 dBHL for L2. Statistical analysis was carried out in 77 ears of 46 subjects with normal hearing (average hearing levels at pure-tone audiometric thresholds less than or equal to 10 dBHL) and 36 ears of 25 subjects exhibiting near-normal hearing (average hearing levels at pure-tone audiometric thresholds less than or equal to 20 dBHL). The mean DPOAE amplitudes were similar in these two groups of ears. In 111 of these 113 ears (98.2%), DPOAEs were detected at three or more of the six tested frequencies between 1 and 6 kHz. DPOAEs were measured in more than 75% of ears at each frequency between 1-6 kHz and in more than 86% between 1-4 kHz. Eighty-six hearing-impaired ears of 44 subjects with sensorineural hearing loss formed the patient group. A highly significant correlation between pure-tone audiometric thresholds and DPOAE amplitudes was demonstrated in the frequency range of 1-4 kHz. Percentiles of DPOAE amplitudes were calculated in 22 ears with a mean pure-tone threshold less than or equal to 5 dBHL and in 12 specially selected pathological ears.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1991

Reporting click-evoked and distortion-product otoacoustic emission results with respect to the pure-tone audiogram.

Measurement of transiently evoked otoacoustic emissions, elicited primarily using click stimuli, and distortion-product otoacoustic emissions is gaining prominence as a clinical technique. One proposed application is the estimation of hearing levels. In this report, several formats for describing otoacoustic emission test results obtained from adult subjects are discussed. Descriptive analyses involve comparisons of individual results with normative data obtained from a group of normally hearing adults.

Acoustic Stimulation↗
PubMed1991

The influence of systematic primary-tone level variation L2-L1 on the acoustic distortion product emission 2f1-f2 in normal human ears.

The purpose of the present study was to determine the effect of primary-tone level variation, L2--L1, on the amplitude of distortion-product otoacoustic emissions (DPOAEs). The DPOAE at the frequency 2f1--f2 (f2 greater than f1) was measured in 20 ears of ten normally hearing subjects. Acoustic distortion products were generated by primaries f1 and f2 with geometric mean frequencies of 1, 2, and 4 kHz. The f2/f1 ratios were 1.25 (1 kHz), 1.23 (2 kHz), and 1.21 (4 kHz). The primary-tone level L1 was kept constant at either 65 or 75 dB SPL while the second primary-tone level L2 was varied between 20 and 90 dB SPL in 5-dB steps. The level differences L2--L1 generating maximal DPOAE amplitudes depended on L1 and on the geometric mean frequency of f1 and f2. There were large interindividual differences. Overall, the L2--L1 evoking maximal mean DPOAE amplitudes was --10 dB for geometric mean frequencies of 1 and 2 kHz with both L1 = 65 dB SPL and L1 = 75 dB SPL. For 4 kHz, L2-L1 was --5 dB with L1 = 65 dB SPL and 0 dB with L1 = 75 dB SPL. The mean slopes of the DPOAE growth functions in the initial linearly increasing portions were steeper at higher stimulus frequencies, increasing from 0.52 at 1 kHz to 0.72 at 4 kHz for L1 = 65 dB SPL and from 0.48 at 1 kHz to 0.72 at 4 kHz for L1 = 75 dB SPL.

Adult↗
PubMed1991

A review of otoacoustic emissions.

Otoacoustic emissions measured in the external ear canal describe responses that the cochlea generates in the form of acoustic energy. For the convenience of discussing their principal features, emitted responses can be classified into several categories according to the type of stimulation used to evoke them. On this basis, four distinct but interrelated classes can be distinguished including spontaneous, transiently evoked, stimulus-frequency, and distortion-product otoacoustic emissions. The present review details the findings that have been described for each emission type according to this classification schema. Additionally, the known features of emitted responses are discussed for both normally hearing and hearing-impaired humans and experimental animals, and with respect to their potential clinical applications. The findings reviewed here clearly indicate that future studies of otoacoustic emissions will significantly increase our understanding of the basic mechanisms of cochlear function while, at the same time, provide a new and important clinical tool.

Animals↗
PubMed1991

Resection of endobronchial tumors using a tracheoscope and neodymium:YAG laser.

A modified technique for palliative resections of malignant endobronchial tumors with the Nd:YAG laser is described. A special tracheoscope was used in conjunction with the instrument guide of a laser bronchoscope. The main advantage of this technique is easy and simultaneous access to both lungs for ventilation and surgical procedures. The method helps to separate surgical from anesthetic manipulations. The experience of over 70 operations using this technique provides evidence that the use of a tracheoscope is a safe and efficient method of endoscopic resections of larger intrabronchial tumors.

Bronchial Neoplasms↗
PubMed1991

Repeatability of transiently evoked otoacoustic emissions in normally hearing humans.

Transiently evoked otoacoustic emissions (TEOAEs) were stimulated using clicks. Responses were measured in each ear of 10 adult subjects during three test sessions separated by 3-day intervals. The purpose was to determine the amount of short-term variability in the amplitude of the emissions when measured under similar test conditions. For each of two modes of determining the stimulus level, mean overall response levels varied approximately 1 dB with repeated measurements. The spectra of the responses were analyzed in discrete frequency bands from 0.7 to 5.8 kHz. Response energy peaked at 1.2 kHz and was reduced markedly above 4 kHz. Variability within individual spectral bands was approximately 1 dB from 0.9 to 4.1 kHz and was slightly greater for 0.7 kHz. The amplitude of TEOAEs is stable over successive short-term measurements. The technique can be used as a sensitive means of monitoring cochlear function.

Adult↗
PubMed1990

[Causes and assessment of hearing impairment].

Hearing loss is a very common disorder. It is discussed, using the aid of a topical classification. An introductory description of new basic knowledge about the peripheral hearing organ is given first. Such knowledge has had an important influence on the understanding and the evaluation of hearing loss. The diagnosis of conductive hearing loss is relatively easy to make. It represents mainly a quantitative disorder without much loss of qualitative information, and it can often be improved surgically. Conversely, sensorineural hearing loss is always associated with a loss in the quality of the acoustic information. Its most common causes are functional disturbances of the cochlea. The mechanical elements within the cochlea seem to be particularly vulnerable. The differentiation between a cochlear and a retrocochlear hearing loss can be made with confidence using modern audiological tests. This differentiation is particularly important for the early diagnosis of acoustic tumors.

Audiometry↗
PubMed1990

High frequency jet ventilation via a tracheoscope for endobronchial laser surgery.

Palliative surgery of malignant endobronchial tumours is associated with various anaesthetic risks. A technique is described using a neodymium:yttrium-aluminium-garnet (Nd:YAG) laser in combination with a special tracheoscope and high frequency jet ventilation (HFJV). The purpose of this technique is to provide separation of anaesthetic and surgical manipulations, good conditions of ventilation and easy access to the lungs for the surgeon. We present our experience with 14 adult patients in whom large endobronchial neoplasms were resected using this technique under intravenous anaesthesia and muscle relaxation. Careful perioperative monitoring and a good outcome allowed us to conclude that this set-up may contribute to improving efficiency and safety of endoscopic resections of endobronchial and/or endotracheal tumours.

Adult↗
PubMed1990

[Fronto-basal fractures in the child].

The particularities and the authors' management of frontobasal fractures in children are discussed on the basis of cases treated at the authors' department during the last five years. Fifteen children aged between four and 16 years (mean eight years) made up 14.5% of all frontobasal fractures. The causes of the injury were equally divided between falls from a height of at least 2 m and traffic accidents. All children except one were treated immediately after the accident. The exception was a child with an accident two and a half years before operation and two episodes of late onset meningitis. The diagnoses were mainly made with the help of high resolution computer-tomographies, which permitted a correct localization of the fractures site. The exact course of the fracture was recognized correctly in seven of eleven cases. Each case was managed in interdisciplinary fashion together with the neurosurgeon and the general surgeon. If nonoperative management was chosen, a computer-tomography about six weeks after the injury had to demonstrate the return to normal appearance of the paranasal sinus. If a dural tear was ascertained, a repair with a rhinosurgical approach was favored and, thereby, a definite closure was obtained in seven out of nine cases. One case was primarily managed by a combined rhino- and neurosurgical approach, while two cases were reoperated neurosurgically because of persistent cerebrospinal fluid leakage after the rhinosurgical repair. No other postoperative complications, such as meningitis or a third operation, were encountered. The authors believe that these favorable results were obtained because of individual management of each case by an interdisciplinary team working closely together.

Adolescent↗
PubMed1990

Otoacoustic emissions in human ears: normative findings.

Otoacoustic emissions can be separated into two interrelated classes according to the type of eliciting stimulus. On the basis of this categorization, four discrete subtypes can be recognized that include spontaneous, transiently evoked, stimulus-frequency, and distortion-product otoacoustic emissions. Methods of recording and findings in the ears of normally hearing humans are reviewed for each emission type.

Cochlea↗
PubMed1989

Magnetic resonance imaging--a useful tool for airway assessment.

The case is presented of a 58-year old man with a malignant non-Hodgkin's lymphoma of the root of the tongue. Preoperative magnetic resonance imaging (MRI) proved extremely useful in the evaluation of the upper aerodigestive tract, by providing sagittal sections of the hypopharynx and the inlet of the larynx. Thus, a potentially difficult intubation was confirmed in a patient in whom other investigations would not have produced comparable conclusions. Difficulties in airway management were avoided by performing a tracheostomy under local anesthesia. This represents a novel application of MRI, which might contribute to the safety of airway management.

Airway Obstruction↗
PubMed1988

[Tinnitus].

Explore the source record for details and available documents.

Humans↗
PubMed1988

Spontaneous otoacoustic emissions in a nonhuman primate. I. Basic features and relations to other emissions.

Otoacoustic emissions in both ears of a rhesus monkey exhibiting stable spontaneous emissions (SOEs) were monitored over a 1-year period. The amplitudes and frequencies of both SOEs and stimulus-frequency emissions (SFEs) were routinely recorded, while transiently evoked (EOE) and distortion-product emissions (DPEs), at the frequency 2f1-f2, were occasionally examined. Between evaluation sessions, both the frequencies and amplitudes of SFEs remained relatively stable in both ears, while the frequencies and amplitudes of SOEs were less constant. Isosuppression contours for SOEs, plotted as a function of frequency and level of tonal maskers, revealed sharp tuning consistent with normal frequency selectivity. Detailed analyses of long-term measurements showed that SOEs occurred most frequently at the peaks of the SFE response. A regular frequency spacing between neighboring amplitude maxima and minima of the SFEs was consistent with the notion that this particular emitted response may result from a periodic disruption of the orderly pattern of sensory cells along the organ of Corti. Intramuscular administration of aspirin abolished SOE and SFE responses, while DPEs remained relatively unchanged suggesting the involvement of separate mechanisms in the generation of different emissions.

Acoustic Stimulation↗
PubMed1988

Spontaneous otoacoustic emissions in a nonhuman primate. II. Cochlear anatomy.

Both cochleas of a rhesus monkey exhibiting stable spontaneous and stimulus-frequency emissions were evaluated histologically using surface-preparation methods to determine if certain features of these emissions could be related to structural properties of the organ of Corti (OC). The comprehensive assessment included preparation of routine cytocochleograms and a detailed study of the arrangement of cochlear sensory cells, best revealed by the precise positional relationships between stereocilia bundles, in selected areas representing low-, medium-, and high-frequencies. Several additional measurements were made in an area extending from about 25-60% distance from the apex, which was estimated to encompass the cochlear region where emissions were generated. These quantifications included measures, in both micrometers and Hertz, of the distances between irregularities in the lateral border of the OC due to a sporadically occurring fourth row of outer hair cells (OHCs). Measures, in micrometers, of the changes in the radial extent of the corresponding OC in the presence or absence of this extra fourth row of OHCs were also made. A final measure within low-, medium-, and high-frequency OC regions consisted of describing the angles that the tips of the stereocilia bundles were displaced from an axis parallel to the tunnel of Corti. For comparative purposes, similar plots were made in comparable regions of the OC in the normal and experimental cochleas of three additional rhesus monkeys in which one ear had been systematically exposed to noise. In the emitting-monkey cochlea, there was a mild loss of sensory cells scattered throughout the OC which was generally greater for the OHCs. No evidence of small circumscribed lesions, defined as a loss of more than four adjacent hair cells, was found. The most striking observation which varied in degree across the three other monkeys was a generalized irregularity in the cellular organization of the OHC region which was most pronounced in the low- and midfrequency regions of the OC. The notable cellular disorganization specific to the apical half of the cochlea was reflected by an increased variance in the distribution of deviation angles measured for corresponding stereocilia bundles. Outer hair cells in the remaining basal region of the OC were arranged in three regular rows with the usual stereocilia orientation.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustics↗