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Influence of aging on medial olivocochlear system function.

Lisowska G, Namyslowski G, Orecka B, Misiolek M - Clin Interv Aging (2014)

Bottom Line: Comparative analysis of the MOC effect for CEOAE and DPOAE showed the weakest effect in the oldest age group (41-60 years) at almost all tested frequencies.Moreover, a weak, albeit significant, positive correlation between the level of OAE and the size of the MOC effect was documented.On the basis of our study, we have found a decrease in the strength of the MOC system with increasing age in normally hearing subjects, as reflected by a decrease of the OAE suppression effects in older individuals and an increase of the number of CEOAE and DPOAE enhancements during contralateral acoustic stimulation in the elderly, especially in the high-frequency range.

View Article: PubMed Central - PubMed

Affiliation: Department of Otolaryngology, Medical University of Silesia, Zabrze, Poland.

ABSTRACT

Background: There is still controversy regarding the influence of aging on medial olivocochlear (MOC) system function. The main objective of this study is to measure age-related changes of MOC system function in people with normal hearing thresholds.

Method: Bilateral assessment of the MOC effect for click-evoked otoacoustic emissions (CEOAEs; at 70±3 dB peak sound pressure level [pSPL], click at 50/second, 260 repeats, 2.5-20 millisecond window) and for distortion product otoacoustic emissions (DPOAEs; with [frequencies] f2/f1=1.22, [levels of primary tones] L1=65 dB SPL and L2=55 dB SPL; DP-grams for 2f1-f2 were collected for the f1 frequencies varying from 977 Hz to 5,164 kHz, with the resolution of four points per octave) was performed in a group of 146 (n=292 ears) healthy, right-handed subjects aged from 10-60 years with a bilateral hearing threshold from 0.25-4.0 kHz, not exceeding 20 dB hearing level; normal tympanograms; and a threshold of the contralateral stapedial reflex for broadband noise (BBN) of 75 dB SPL or higher. The MOC inhibition was assessed on the basis of changes in OAE level during BBN contralateral stimulation at 50 dB sensation level (mean, 65±3 dB SPL).

Results: Comparative analysis of the MOC effect for CEOAE and DPOAE showed the weakest effect in the oldest age group (41-60 years) at almost all tested frequencies. Moreover, a weak, albeit significant, positive correlation between the level of OAE and the size of the MOC effect was documented.

Conclusion: On the basis of our study, we have found a decrease in the strength of the MOC system with increasing age in normally hearing subjects, as reflected by a decrease of the OAE suppression effects in older individuals and an increase of the number of CEOAE and DPOAE enhancements during contralateral acoustic stimulation in the elderly, especially in the high-frequency range.

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Schematic presentation of the protocol for medial olivocochlear system effect analysis.Abbreviations: OAE, otoacoustic emissions; CAS, contralateral acoustic stimulation; BBN, broadband noise; SL, sensation level.
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f1-cia-9-901: Schematic presentation of the protocol for medial olivocochlear system effect analysis.Abbreviations: OAE, otoacoustic emissions; CAS, contralateral acoustic stimulation; BBN, broadband noise; SL, sensation level.

Mentions: For all tested conditions, the MOC assessment was performed according to a single fixed scheme. The test was always performed in three measurement blocks: assessment of otoacoustic emissions without CAS, assessment of otoacoustic emissions with CAS that began about 3 seconds before otoacoustic emissions measurement was begun and ended about 3 seconds after the measurements were taken, and test–retest of otoacoustic emissions without CAS after about 2 minutes, which was designed to assess the stability of the probe in the ear canal. The abovementioned blocks of measurements are presented schematically in Figure 1. Cases in which measured level changes of otoacoustic emissions without CAS differed by more than 1 dB from the first measurement without CAS indicated lack of stability of the probe in the external ear canal; such results were excluded from further analysis. Only a few measurements were excluded from the final analysis because of probe instability. The contralateral stimulation was BBN at 50 dB sensation level (SL) and 125–12,000 Hz. BBN was generated using the Nicolet Spirit Viking™ series system (Natus Medical Incorporated, San Carlos, CA, USA) and was presented to the contralateral ear through an Etymotic ER3 (Elk Grove Village, IL, USA) insert earphone. CAS level was set at 50 dB SL (mean, 65 dB SPL), as such stimulation does not cause a measurable stapedial contralateral reflex in most subjects but does result in significant response from the MOC.24,25 However, the results reported by Guinan et al27 provided some evidence that clicks commonly used to evoke CEOAEs for the MOC tests may also elicit efferent activity by themselves when presented at usually used levels of around 70 dB pSPL, and they may also evoke the acoustic reflex. In addition, clicks presented at the typically used rate of 50/second are potent elicitors of efferent activity.27 Thus, it is possible that in some subjects, small effects of the CAS on CEOAEs observed in the study could be also related to these two mechanisms.


Influence of aging on medial olivocochlear system function.

Lisowska G, Namyslowski G, Orecka B, Misiolek M - Clin Interv Aging (2014)

Schematic presentation of the protocol for medial olivocochlear system effect analysis.Abbreviations: OAE, otoacoustic emissions; CAS, contralateral acoustic stimulation; BBN, broadband noise; SL, sensation level.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4061140&req=5

f1-cia-9-901: Schematic presentation of the protocol for medial olivocochlear system effect analysis.Abbreviations: OAE, otoacoustic emissions; CAS, contralateral acoustic stimulation; BBN, broadband noise; SL, sensation level.
Mentions: For all tested conditions, the MOC assessment was performed according to a single fixed scheme. The test was always performed in three measurement blocks: assessment of otoacoustic emissions without CAS, assessment of otoacoustic emissions with CAS that began about 3 seconds before otoacoustic emissions measurement was begun and ended about 3 seconds after the measurements were taken, and test–retest of otoacoustic emissions without CAS after about 2 minutes, which was designed to assess the stability of the probe in the ear canal. The abovementioned blocks of measurements are presented schematically in Figure 1. Cases in which measured level changes of otoacoustic emissions without CAS differed by more than 1 dB from the first measurement without CAS indicated lack of stability of the probe in the external ear canal; such results were excluded from further analysis. Only a few measurements were excluded from the final analysis because of probe instability. The contralateral stimulation was BBN at 50 dB sensation level (SL) and 125–12,000 Hz. BBN was generated using the Nicolet Spirit Viking™ series system (Natus Medical Incorporated, San Carlos, CA, USA) and was presented to the contralateral ear through an Etymotic ER3 (Elk Grove Village, IL, USA) insert earphone. CAS level was set at 50 dB SL (mean, 65 dB SPL), as such stimulation does not cause a measurable stapedial contralateral reflex in most subjects but does result in significant response from the MOC.24,25 However, the results reported by Guinan et al27 provided some evidence that clicks commonly used to evoke CEOAEs for the MOC tests may also elicit efferent activity by themselves when presented at usually used levels of around 70 dB pSPL, and they may also evoke the acoustic reflex. In addition, clicks presented at the typically used rate of 50/second are potent elicitors of efferent activity.27 Thus, it is possible that in some subjects, small effects of the CAS on CEOAEs observed in the study could be also related to these two mechanisms.

Bottom Line: Comparative analysis of the MOC effect for CEOAE and DPOAE showed the weakest effect in the oldest age group (41-60 years) at almost all tested frequencies.Moreover, a weak, albeit significant, positive correlation between the level of OAE and the size of the MOC effect was documented.On the basis of our study, we have found a decrease in the strength of the MOC system with increasing age in normally hearing subjects, as reflected by a decrease of the OAE suppression effects in older individuals and an increase of the number of CEOAE and DPOAE enhancements during contralateral acoustic stimulation in the elderly, especially in the high-frequency range.

View Article: PubMed Central - PubMed

Affiliation: Department of Otolaryngology, Medical University of Silesia, Zabrze, Poland.

ABSTRACT

Background: There is still controversy regarding the influence of aging on medial olivocochlear (MOC) system function. The main objective of this study is to measure age-related changes of MOC system function in people with normal hearing thresholds.

Method: Bilateral assessment of the MOC effect for click-evoked otoacoustic emissions (CEOAEs; at 70±3 dB peak sound pressure level [pSPL], click at 50/second, 260 repeats, 2.5-20 millisecond window) and for distortion product otoacoustic emissions (DPOAEs; with [frequencies] f2/f1=1.22, [levels of primary tones] L1=65 dB SPL and L2=55 dB SPL; DP-grams for 2f1-f2 were collected for the f1 frequencies varying from 977 Hz to 5,164 kHz, with the resolution of four points per octave) was performed in a group of 146 (n=292 ears) healthy, right-handed subjects aged from 10-60 years with a bilateral hearing threshold from 0.25-4.0 kHz, not exceeding 20 dB hearing level; normal tympanograms; and a threshold of the contralateral stapedial reflex for broadband noise (BBN) of 75 dB SPL or higher. The MOC inhibition was assessed on the basis of changes in OAE level during BBN contralateral stimulation at 50 dB sensation level (mean, 65±3 dB SPL).

Results: Comparative analysis of the MOC effect for CEOAE and DPOAE showed the weakest effect in the oldest age group (41-60 years) at almost all tested frequencies. Moreover, a weak, albeit significant, positive correlation between the level of OAE and the size of the MOC effect was documented.

Conclusion: On the basis of our study, we have found a decrease in the strength of the MOC system with increasing age in normally hearing subjects, as reflected by a decrease of the OAE suppression effects in older individuals and an increase of the number of CEOAE and DPOAE enhancements during contralateral acoustic stimulation in the elderly, especially in the high-frequency range.

Show MeSH
Related in: MedlinePlus