Biomedical subjects

C Muchnik

Publications and source records attributed to C Muchnik.

At least 19 recordsLinked to original sources

PubMed2006

Low prevalence of hearing impairment among very low birthweight infants as detected by universal neonatal hearing screening.

OBJECTIVES: To (a) study the prevalence of hearing impairment in a cohort of very low birthweight (VLBW) infants and (b) evaluate the effectiveness of transient evoked otoacoustic emissions (TEOAE) as a first stage in-hospital hearing screening tool in this population. STUDY DESIGN: The study group was a cohort of 346 VLBW infants born in 1998-2000 at The Sheba Medical Center. The prevalence of hearing impairment in the study group was compared with that of all other newborn infants participating in a universal newborn hearing screening programme during the same period. To evaluate the effectiveness of TEOAE, a control group of 1205 healthy newborns who had no known risk factors for hearing impairment was selected. The results and follow up of hearing screening for these infants were examined retrospectively. RESULTS: Only one VLBW infant (0.3%) was diagnosed with bilateral sensory-neural hearing loss. In addition, nine infants (2.7%) were diagnosed with conductive hearing loss. Bronchopulmonary dysplasia and low Apgar score were the most significant factors for predicting the occurrence of conductive hearing loss. The percentage of VLBW infants who successfully passed the in-hospital TEOAE screening was 87.2, compared with 92.2% in the full term control group. No false negative cases were detected on follow up. CONCLUSIONS: The study shows a low incidence of sensory-neural hearing loss in a cohort of VLBW infants and a relatively high incidence of conductive hearing loss. TEOAE screening was found to be an effective first stage in-hospital hearing screening tool in this population.

Apgar Score↗

PubMed2004

Assessment of medial olivocochlear system function in pre-term and full-term newborns using a rapid test of transient otoacoustic emissions.

This study was conducted to investigate maturation of the medial olivocochlear efferent system (MOCS) in pre- and full-term neonates using Quickscreen (Otodynamics Ltd) and to confirm previous findings on transient otoacoustic emission (TEOAE) suppression in neonates. MOCS maturation was investigated in 46 neonates born at the Chaim Sheba Medical Center, Tel Hashomer, Israel, using Quickscreen. All neonates were normal with no family history of general or auditory disease and no risk factors for hearing impairment. MOCS function appears gradually in human pre-term neonates and is considered to reach maturity shortly after term birth. The clinical value of MOCS testing in specific populations of newborns at risk for hearing and/or brainstem function can be legitimately raised as activation of the MOCS clearly alters cochlear output. The present results can be interpreted to support the testing of infants at risk of developing abnormal MOCS function using a commercially available rapid TEOAE measurement system.

Acoustic Stimulation↗

PubMed2001

Speech perception results--the first 10 years of a cochlear implant program.

Long-term speech perception test results for prelingually deaf children were compared with those of postlingually deafened adults, both groups having undergone cochlear implant at our Center. Average open-set score results of adults were similar to those of the children. However, some qualitative differences were demonstrated on the perception of phonological contrasts between the groups.

Adolescent↗

PubMed1999

Subclinical audiological findings in carriers of recessive genes for deafness.

The existence of subclinical signs in the hearing of carriers of recessive mutations for deafness has aroused much controversy in the literature. The present study comprised 30 carriers of recessive mutations for deafness, and a control group of 30 healthy volunteers, matched for gender and age. All participants underwent a series of hearing tests, including pure-tone audiometry, speech tests, Bekesy audiometry and notch noise tests. The main results were: hearing loss in high frequencies (3000 and 4000 Hz), an elevation of the acoustic reflex threshold, as well as an elevation of the identification of 2000 Hz pure tone in the presence of white noise and notch noise. A notch in the Bekesy audiogram was also identified in several carriers. An interaction was found between gender and the carrier trait in the hearing threshold at 4000 Hz, and in the ipsi- and contralateral acoustic reflex at 500 Hz and 1000 Hz. These subclinical signs may be complementary to DNA research in the investigation of genetic deafness of unknown origin.

Adult↗

PubMed1998

Stress reaction to intense sound exposure under different arousal levels in guinea pigs.

The general impact of high intensity sound exposure on 25 guinea pigs was investigated at three different levels of arousal: 10 during general anaesthesia. 10 during partial arousal, and 5 during complete arousal. Parameters recorded before and during noise exposure were mean arterial blood pressure, pulse rate, and plasma norepinephrine levels. The anaesthetized group showed no increase in the three parameters during sound exposure. Under partial arousal, pulse rate and norepinephrine level increased significantly: pulse rate from 224.5 beats/min before exposure to 278.6 beats/min during exposure, and norepinephrine level from 558 pg/ml before sound exposure to 1276 pg/ml during exposure. At the time of the complete arousal state norepinephrine and pulse rates increased significantly during noise exposure, while blood pressure showed no additional increase as a result of sound exposure.

Acoustic Stimulation↗

PubMed1998

Contralateral Acoustic Effect of Transient Evoked Otoacoustic Emissions in Neonates.

Contralateral acoustic stimulation (CAS) has the effect of reducing the amplitude of transient evoked otoacoustic emissions (TEOAE) of the opposite cochlea. This phenomenon is considered to be mediated via the efferent pathway, from the superior olivary complex through the medial olivocochlear system to the contralateral cochlea. The assessment of this suppressive effect provides an objective and noninvasive technique for exploring the function of the efferent auditory system in humans. Two previous studies investigated the suppression effect of TEOAE in newborns and revealed a significant effect in 18 full-term neonates. In this study, the effect of contralateral acoustic stimulation on TEOAE was investigated in 13 full-term neonates (gestational age, 40-42 weeks). The TEOAE were recorded alternately with and without simultaneous, contralateral white noise. The CAS effect of TEOAE was present in all subjects; a mean of 2.21 dB +/- 1.7 (21% +/- 9.3%) was found. Our study demonstrated additional support for the functional maturity of the medial olivocochlear efferent system from birth.

Journal Article↗

PubMed1995

Auditory brainstem response in obstructive sleep apnea patients.

Auditory brainstem responses (ABR) were recorded in 79 patients diagnosed as suffering from obstructive sleep apnea (OSA). The patients were divided into three subgroups (mild, moderate and severe) according to the severity of the syndrome. A statistically significant prolongation was found in the latency values of waves I, III and V in all three subgroups, compared to a control group of 29 healthy subjects. The transmission time between waves I and III and I and V was found to be prolonged in the moderate and severe OSA subgroups, compared to the control group. However, from a clinical point of view only 10% (eight patients) of the OSA group showed a clinically significant prolongation in their ABR latency values compared to the norms (mean +/- 2SD) of the specific ABR recording system used in this study. In addition, 36 of the OSA group underwent uvulopalato-pharyngoplasty (UPPP). There were no statistically significant differences in the ABR recording preoperatively versus post-operatively.

Adult↗

PubMed1995

Auditory brainstem response to bone-conducted clicks in adults and infants with normal hearing and conductive hearing loss.

Knowledge concerning auditory brainstem response (ABR) by bone conduction (BC) is limited, and occasionally controversial. The present study was aimed at further elaboration of this issue. The research population consisted of 107 subjects. Four groups were investigated: group 1, normal-hearing adults aged 20-37 years; group 2, 10 children aged 5.6-8.4 years, with confirmed middle ear effusion (MEE); groups 3 and 4, 22 infants, matched by pairs, aged 5-18 months, 11 with normal otoscopy and 11 with suspected MEE. Comparison between ABR by AC and BC for all four groups is discussed. We observed that the AC-ABR threshold of group 2 was statistically significantly elevated compared to group 1. The same tendency was observed for group 4 compared to group 3. In AC ABR, the mean latency of wave V was significantly prolonged, compared to that of BC ABR in children with confirmed MEE, and infants with suspected MEE. We strongly suggest that by combining AC and BC ABR, more information concerning cochlear reserve status can be obtained in infants and young children who are difficult to test, or wherever a behavioral audiogram cannot be achieved.

Adult↗

PubMed1994

Auditory temporal resolution and open speech recognition in cochlear implant recipients.

The recognition of speech events depends, among other factors, on the resolution function. The present study was conducted to evaluate the auditory temporal resolution function in cochlear implant (CI) subjects by a gap detection threshold (GDT) test. Fourteen postlingual deaf subjects who used the Nucleus 22 Channel CI system participated in the study. They were divided into two subgroups: (1) six patients who did not achieve a significant open speech recognition score; and (2) eight patients who obtained different levels of open speech recognition ability (OSRA). Gap detection thresholds were found for six noise burst durations: 85, 65, 52, 36, 25 and 10 msec. Absolute values of GDT in the CI group were longer compared with those obtained from normal-hearing subjects. The CI values varied in consistence with burst duration; namely, as burst duration decreased, GD increased. This trend was found in CI recipients with OSRA only. Examination of the relationship between GDT and OSRA indicated that the majority of CI recipients who had OSRA showed lower GDT.

Acoustic Stimulation↗

PubMed1993

[Auditory achievements of cochlear implantation].

The cochlear implant, which stimulates the auditory nerve electrically, is a rehabilitative solution for the severely deaf who cannot benefit from a hearing aid. The implant enables them to rejoin the world of sound from which they were disconnected. We present the process of auditory diagnosis which determines the patient's suitability for cochlear implantation, the implant's tuning program and the rehabilitation process it entails. Each of the 22 implanted electrodes is checked through a computer program, and the specifications of the electrical stimulation are established to provide the most comfortable hearing level for the implanted device. These stimulation specifications determine the number of active electrodes and the ideal stimulation model. During the 8-week hearing-training program which follows implantation, the patients acquaint themselves with the new world of sound through which they will communicate with their environment. Of the 16 implanted patients 7 heard only via the implant, without the aid of lipreading, a result which is considered excellent. These patients are able to talk on the telephone with the aid of the implant. 1 patient refused to use the implant, while the others have had good to moderate results. Noteworthy is the fact that even those with only moderate results greatly benefit from the implant, and are not willing to function without it for even a single day.

Adolescent↗

PubMed1993

Normative data for 40-Hz event-related potentials to 500-Hz tonal stimuli in young and elderly subjects.

Recordings of 40-Hz event-related potentials (ERPs) were obtained in 81 young subjects (18-40 years) and in 20 elderly subjects (60-77 years) with hearing normal for their age. The stimuli were 500-Hz logons. The first negative peak (N1) of the response was analyzed. With increasing intensity the amplitude of the responses increased and the latency decreased for all subjects. The 40-Hz ERP was obtained within 10 dB of the behavioral threshold for more than 80% of the population under study. The N1 was prolonged in latency and enhanced in amplitude in the older subjects. No differences were found between young and elderly subjects regarding binaural interaction, or in responses elicited by ipsi- and contralateral stimulation. From the clinical point of view, the 40-Hz ERP recordings of young and elderly subjects are similar.

Acoustic Stimulation↗

PubMed1992

[Cochlear implantation].

Since the Israeli cochlear implant program was started in June 1989, 74 candidates have been evaluated for implantation. The main causes for hearing loss were meningitis (16 patients), aminoglycoside toxicity (9), congenital (6), viral (e.g. mumps) (6), and middle ear infection. Candidates were rejected mainly due to psychosocial factors (40%) and audiological parameters (30%). 16 postlingual deaf were implanted. In 7 of them (43.7%) the results were excellent, in 4 (25.0%) good, in 3 (18.7%) fair; 1 case is currently in a training program and 1 is a failure. There were 2 major complications: facial nerve palsy which necessitated surgical decompression, and insertion of the electrodes into the hypotympanic air cells, corrected by reoperation.

Cochlear Implants↗

PubMed1992

Temporary threshold shift due to noise exposure in guinea pigs under emotional stress.

One of the factors which can affect the amount of temporary threshold shift (TTS) due to acoustic overstimulation is known to be the general metabolic state of the exposed subject. The present study was conducted to elucidate how preexisting intense emotional stress in awake guinea pigs could influence the TTS induced by exposure of 4 kHz at 120 dB SPL for 20 min. Considering the hypersympathetic activity in both 'stress' and 'noise' it was assumed that the two factors would act synergetically on the cochlear function. However, an unexpected result was obtained. The mean threshold for the stressed animals following noise exposure was significantly lower (better) than that of the controlled, sedated, guinea pigs.

Acoustic Stimulation↗

PubMed1992

Cooperation of hearing-impaired elderly subjects for participation in a hearing screening program.

Presbyacusis, the auditory disorder which accompanies the aging process, is well known. However, the practical assistance available to alleviate the breakdown in the communication ability of the older person is unsatisfactory, and provision for public awareness of a rehabilitation strategy has not yet been established in many countries. Four hundred and ninety-eight elderly subjects, aged 65-94 years, were hearing tested in different setups, a geriatric nursing home and in the community. It was found that the need for rehabilitation was high and the willingness to participate in a hearing screening program was low even though the rehabilitation treatment was provided without charge.

Age Factors↗

PubMed1991

The effect of bilateral sympathectomy on noise induced temporary threshold shift.

The cochlea is innervated by sympathetic nerves originating or passing the superior cervical ganglion. The termination of one type (the vascular independent) is in the habenular region close to the auditory nerve fibers, and the other, the perivascular type, is associated with blood vessels, particularly in the spiral vessel of the tympanic lip. Suggested functions have so far received partial evidence in the literature. Borg (1982) suggested the protective value of sympathectomy of the ear in noise. Our experiments further elaborate this protective value, as it was seen that bilateral cervical sympathectomy diminished the temporary threshold shift in awake, sound exposed GP.

Acoustic Stimulation↗

PubMed1991

Sedation effect on temporary threshold shift induced by acoustic overstimulation.

The mechanism by which noise damages the inner ear has not as yet been fully elucidated. Experiments were done to study the influence of the sedation in temporary threshold shift (TS) induced by acoustic overstimulation, as barbiturates were found to improve the brain's tolerance to ischemia. Four groups of guinea pigs (GP) were used. The temporary TS was decreased with the reduction of the temperature in awake, as well as sedated, sound-exposed GP. However, the temporary TS in the sedated, but normothermic GP was as great as in the awake, normothermic group. The high temperature counteracts the protection effect of the sedation in nose-induced hearing loss.

Acoustic Stimulation↗

PubMed1991

Central auditory skills in blind and sighted subjects.

Three different central auditory skills were compared and evaluated in 56 blind and 40 sighted subjects. The study consisted of three experiments conducted in three subgroups. Experiment A was performed in order to evaluate the localization function; experiment B for the temporal auditory resolution ability of the blind adult, and experiment C to test the ability of the blind person to discriminate speech material in noise. In all three experiments the blind subjects obtained significantly better results than the sighted subjects. From these results it was concluded that there is supporting evidence of a certain superiority of the blind individual with regard to central auditory function.

Adolescent↗

PubMed1990

Blood viscosity and sensorineural hearing loss.

Two groups of 33 subjects each, one experimental and one control, matched one-to-one for age and occupation, were chosen from a large number of subjects who were covered by special insurance for annual medical control at our hospital. The periodical checkups included cardiovascular, nervous, and renal systems, as well as vision and hearing. In addition routine blood tests, including whole blood viscosity, were also performed. The experimental group consisted of subjects in whom a bilateral, slight, and unexplained sensorineural loss of hearing was detected in the routine audiological testing, without any known reason. In the control group, the routine hearing tests demonstrated normal hearing. The differences between the two groups were statistically significant in pure-tone threshold level and in speech discrimination score, when the test was performed at a -5dB signal-to-noise ratio. The results of the vestibular tests were normal in both groups. Hematocrit and whole blood viscosity were slightly but significantly higher in the experimental group if compared with the control group. The number of subjects with abnormal whole blood viscosity results was higher in the experimental group. The whole blood viscosity as the etiological factor responsible for the hearing deterioration is described.

Adult↗