Contralateral Acoustic Effect of Transient Evoked Otoacoustic Emissions in Neonates (original) (raw)
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Clinical Otolaryngology and Allied Sciences, 2004
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 con®rm previous ®ndings 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 speci®c 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.
Early Maturation of Evoked Otoacoustic Emissions and Medial Olivocochlear Reflex in Preterm Neonates
Pediatric Research, 2006
The present study was designed to investigate the early maturation of the brainstem regulation of the cochlear function in preterm neonates. Evoked otoacoustic emissions (EOAE) and their regulation via the medial olivocochlear efferent (MOC) reflex were investigated in a large population of preterm neonates and compared with full-term neonates and young babies from birth to 4 y and school-aged children. In 28-wk preterm neonates, EOAE were seen in the mid-frequency range. These responses extended both to the low (down to 1025 Hz) and high (up to 6152 Hz) frequency ranges at 38 wk of gestational age and remained stable up to 4 mo. At this stage, the amplitude of EOAE overlapped adult values. EOAE amplitudes then decreased to reach adult values at 3 y of age. Maturation of MOC efferents innervating the outer hair cells was investigated by studying the suppressive effect of contralateral sound on the EOAE amplitudes (MOC reflex). The first MOC responses were recorded in preterm neonates of 32-33 wk of gestational age, reaching adult-like values at 37 wk of gestational age. The maximum effect of MOC efferent activation occurred between 2000 and 4000 Hz. These results suggest that, in humans, MOC efferents mature in utero. Thus, testing the MOC reflex may have a clinical relevance to detect an abnormal development of the auditory pathways, particularly of a brainstem circuitry not explored through conventional testing.
2014
Conflict of interest: non-existent rigid in order to maintain their structure and flexible so as to enable stretching and shortening in a rapid contraction. This contraction elicits wave amplification and a mechanical force towards the external auditory canal, where they may be captured in the form of OAE 2 which may be spontaneous or evoked. A study suggests that the outer hair cells (OHC) become capable of synapsing with the efferent system only after the 22 nd week of pregnancy. Thus, the authors believe that the cochlea has not yet reached its functional maturity before the 22 nd week and that, the end of this maturation process should probably occur during the pregnancy's last trimester 3 , or, from the 28 th week onwards. Another study found the presence of otoacoustic emissions beginning at 27 weeks gestational age 4. Evoked otoacoustic emissions (EOAE) are registered after sound stimulation that may be transient (TEOAE) produced by click signals, that are short lasting with a very wide frequency range and the ABSTRACT Purpose: to evaluate and compare the amplitude of transient evoked otoacoustic emissions, observing the variables gender and ear in preterm and term newborns with and without hearing impairment risk. Methods: the group studied consisted of 156 newborns of both genders, aged up to 54 postconceptional weeks, allocated into three groups according to their gestational age. Group G1 was composed of 83 term newborns and G2 of 73 preterm infants. The latter was subdivided into G2A, composed of 42 newborns without hearing loss risk and G2B of 31 newborns at risk. The transient evoked otoacoustic emissions were obtained by nonlinear click stimulus presented at 84 dB SPL with the Echocheck ILO OAE Screener, Otodynamics. For data analysis, the following statistical tests were used: Mann-Whitney, chi-square or Fisher exact test, Kruskal-Wallis ANOVA and Dunn multiple, post marked Wilcoxon with p< 0, 05 was considered significant. Results: the amplitude of the transient evoked otoacoustic emissions was greater in G1 (p= 0.017) than in G2 (p= 0.048) in the right and left ear and these difference was significant. Group G1 (p = 0,009) presented statistically greater amplitude in otoacoustic emissions than G2B in the right ear. Conclusion: the term group presented greater amplitude in otoacoustic emissions than the pre-term group. No difference in otoacoustic emissions was observed in the variables gender or ear.
Differences in otoacoustic emissions in infants and adults with normal hearing
HVM Bioflux, 2015
Introduction There has been an increasing interest in studying OAE in order to understand and investigate the cochlear function both in adults and infants, since the first description of OAE by Kemp in 1978. There still is no complete description of the most basic aspects of audition although studies of ear development were performed even before 1970 (Abdala 2000). It is believed that the study of OAE in human beings can serve as good criterion to investigate the physiological events of cochlear maturation, because OAE provide a glimpse into the human cochlea during the earliest segments of perinatal and postnatal life. The maturational processes underlying the acoustical and mechanical functioning of the human ear and the detectable functional differences in OAE responses represent a challenging and interesting scientific problem. There is evidence that OAE (TEOAE or/and DPOAE) differ in newborn compared to older children and adults with normal hearing (Norton et al 1990; Kok et al...
Audiology and Neurotology Extra, 2012
We investigated the effect of contralateral suppression of linear transient evoked otoacoustic emissions (TEOAEs) in 16 preterm children born with risk factors for hearing loss. We evaluated those children, together with a control group of term children, at 8–10 years of age. The magnitude of the TEOAE suppression effect in both ears was significantly smaller in the preterm children than in the term children (p < 0.05). There is increasing evidence of adverse school-age outcomes (including hearing loss) in preterm children. Such outcomes can interfere with the school performance of those infants. The TEOAE suppression effect seems to be a promising early marker of hearing outcomes in preterm infants.
Hearing Research, 1999
It is generally accepted that stimulation of the efferent auditory system results in changes of cochlear activity. A simple method of activating the olivocochlear pathway by contralateral electrical stimulation of the round window (ES-RW) was used in this study with the aim of comparing the efficacy of acoustically and/or electrically evoked contralateral suppression. The suppression of transient evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) was elicited by contralateral acoustic stimulation (AS) (61 dB SPL continuous white noise), and/or by electrical stimulation of an electrode implanted at the contralateral round window (monopolar rectangular pulses 0.1 ms, repetition rate 300 Hz, intensity 50^100 WA) in 12 guinea pigs. The average value of contralateral suppression of TEOAEs amounted to 1.04 þ 0.48 dB for acoustic stimulation and 0.97 þ 0.53 dB for round window electrical stimulation. The simultaneous presentation of both acoustic and electrical stimulation had only a slight additive effect and resulted in 1.27 þ 0.79 dB diminution of TEOAEs. The suppression of DPOAEs during contralateral acoustic and electrical stimulation was evident mainly at low and middle frequencies (1^4 kHz). In two guinea pigs the maximum DPOAE suppression was present at high frequencies. The average values of contralateral suppression measured at individual f 2 frequencies of DPOAEs were similar to those calculated from 1/4 octave power spectrum analysis of the TEOAEs in half of the animals. The results demonstrated that contralateral ES-RW had a similar suppressive effect on TEOAEs and DPOAEs as did contralateral AS and simultaneous AS+(ES-RW). The results of spectral analysis suggested that both modes of contralateral stimulation excited similar sensory cochlear elements and induce comparable suppression of both TEOAEs and DPOAEs. ß 1999 Elsevier Science B.V. All rights reserved.
Otoacoustic emissions in neonates measured with different acquisition protocols
International Journal of Pediatric Otorhinolaryngology, 2012
The purpose of this study was to investigate transiently evoked otoacoustic emissions recorded from the cochleas of neonates using three acquisition protocols: non-linear; linear; and QuickScreen. In the non-linear mode, a series of four clicks was used, with three clicks at the same level and polarity and a fourth at three times greater amplitude and inverted polarity. In the linear protocol, all stimuli were presented at the same level and polarity. Both modes used a 20 ms recording window, but the third QuickScreen screening mode used the non-linear click sequence and a shorter 12 ms window.
Hearing Research, 1996
Input-output (I/O) functions of click-evoked otoacoustic emissions (CEOAEs) were obtained over a 12 dB range for 64 normally hearing adult listeners with and without contralateral broadband noise (BBN). Contralateral acoustic stimulation (CAS) is a convenient way of suppressing responses to ipsilateral stimuli, probably acting via the medial olivocochlear system (MOCS). The present study shows that this contralateral sound suppression of CEOAEs is largest at low stimulus levels. In fact, the curves obtained under CAS approach the curves obtained without CAS as stimulus level rises. I/O slope analysis for the whole study population (n = 64) showed a slight but significant rise in slope with BBN, which may be interpreted as I/O function decompression. A loss of contralateral suppression effect at high ipsilateral stimulus levels was found in both very low and very high amplitude CEOAE subjects, despite the fact that I/O slopes differed between these two groups, whereas rise in slope under contralateral stimulation failed to be found for these same 2 groups of 16 subjects each. These findings clearly indicate that the MOCS is mostly functional at low sound levels, and suggest that the study of CEOAE I/O slope alteration under CAS may help specify one form of MOCS action on cochlear functioning.
Although the suppressive effect of the medial olivocochlear system (MOCS) on peripheral auditory active mechanisms is well documented in humans, the effect of efferent inhibition over prolonged periods of acoustic stimulation is less well documented, especially as observed by transient evoked otoacoustic emission (TEOAE) suppression. The present study evaluated the relationship between the duration of contralateral acoustic stimulation and the suppression of TEOAE in 10 normal-hearing adults. TEOAE recordings with linear clicks (60 dB SPL) were measured at four intervals during 15 min of continuous contralateral white noise (45 dB SL), followed by two post-noise recordings. An identical within-subject control condition was recorded without contralateral noise. Experimental and control measurements were repeated three times, on separate days. Results revealed significant and sustained TEOAE amplitude reduction for the entire duration of contralateral stimulation. Suppression increased gradually for the duration of contralateral noise presented, but not sufficiently to be statistically significant. Three minutes after noise termination, TEOAE amplitudes increased to values significantly above control recordings. The MOCS is able to sustain suppression over a prolonged duration of contralateral stimulation, supporting its role as an active modulator of outer hair cell mechanics during ongoing stimuli.