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A connection between the Efferent Auditory System and Noise-Induced Tinnitus Generation. Reduced contralateral suppression of TEOAEs in patients with noise-induced tinnitus.

Lalaki P, Hatzopoulos S, Lorito G, Kochanek K, Sliwa L, Skarzynski H - Med. Sci. Monit. (2011)

Bottom Line: Subjective tinnitus is an auditory perception that is not caused by external stimulation, its source being anywhere in the auditory system.Furthermore, evidence exists that exposure to noise alters cochlear micromechanics, either directly or through complex feed-back mechanisms, involving the medial olivocochlear efferent system.The abnormal activity of the efferent auditory system in NIT cases might indicate that either the activity of the efferent fibers innervating the outer hair cells (OHCs) is impaired or that the damaged OHCs themselves respond abnormally to the efferent stimulation.

View Article: PubMed Central - PubMed

Affiliation: Audiology - Neurotology Department., ENT Clinic, Aristotle University of Thessaloniki, Thessaloniki, Greece.

ABSTRACT

Background: Subjective tinnitus is an auditory perception that is not caused by external stimulation, its source being anywhere in the auditory system. Furthermore, evidence exists that exposure to noise alters cochlear micromechanics, either directly or through complex feed-back mechanisms, involving the medial olivocochlear efferent system. The aim of this study was to assess the role of the efferent auditory system in noise-induced tinnitus generation.

Material/methods: Contralateral sound-activated suppression of TEOAEs was performed in a group of 28 subjects with noise-induced tinnitus (NIT) versus a group of 35 subjects with normal hearing and tinnitus, without any history of exposure to intense occupational or recreational noise (idiopathic tinnitus-IT). Thirty healthy, normally hearing volunteers were used as controls for the efferent suppression test.

Results: Suppression of the TEOAE amplitude less than 1 dB SPL was considered abnormal, giving a false positive rate of 6.7%. Eighteen out of 28 (64.3%) patients of the NIT group and 9 out of 35 (25.7%) patients of the IT group showed abnormal suppression values, which were significantly different from the controls' (p<0.0001 and p<0.045, respectively).

Conclusions: The abnormal activity of the efferent auditory system in NIT cases might indicate that either the activity of the efferent fibers innervating the outer hair cells (OHCs) is impaired or that the damaged OHCs themselves respond abnormally to the efferent stimulation.

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Related in: MedlinePlus

Number of subjects exhibiting abnormal TEOAE suppression in NIT (group A) and IT (group B) subjects, as compared to controls.
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f2-medscimonit-17-7-mt56: Number of subjects exhibiting abnormal TEOAE suppression in NIT (group A) and IT (group B) subjects, as compared to controls.

Mentions: Furthermore, 18 out of 28 subjects (64.28%) showed abnormal suppression (<1 dB SPL), 5 of them bilaterally. Abnormal TEOAE suppression was observed in 23 out of the 55 tested ears (41.8%). The number of subjects and ears showing suppression less than 1 dB SPL in the NIT group differed significantly from those in the control group (Table 3 and Figures 2, 3).


A connection between the Efferent Auditory System and Noise-Induced Tinnitus Generation. Reduced contralateral suppression of TEOAEs in patients with noise-induced tinnitus.

Lalaki P, Hatzopoulos S, Lorito G, Kochanek K, Sliwa L, Skarzynski H - Med. Sci. Monit. (2011)

Number of subjects exhibiting abnormal TEOAE suppression in NIT (group A) and IT (group B) subjects, as compared to controls.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539568&req=5

f2-medscimonit-17-7-mt56: Number of subjects exhibiting abnormal TEOAE suppression in NIT (group A) and IT (group B) subjects, as compared to controls.
Mentions: Furthermore, 18 out of 28 subjects (64.28%) showed abnormal suppression (<1 dB SPL), 5 of them bilaterally. Abnormal TEOAE suppression was observed in 23 out of the 55 tested ears (41.8%). The number of subjects and ears showing suppression less than 1 dB SPL in the NIT group differed significantly from those in the control group (Table 3 and Figures 2, 3).

Bottom Line: Subjective tinnitus is an auditory perception that is not caused by external stimulation, its source being anywhere in the auditory system.Furthermore, evidence exists that exposure to noise alters cochlear micromechanics, either directly or through complex feed-back mechanisms, involving the medial olivocochlear efferent system.The abnormal activity of the efferent auditory system in NIT cases might indicate that either the activity of the efferent fibers innervating the outer hair cells (OHCs) is impaired or that the damaged OHCs themselves respond abnormally to the efferent stimulation.

View Article: PubMed Central - PubMed

Affiliation: Audiology - Neurotology Department., ENT Clinic, Aristotle University of Thessaloniki, Thessaloniki, Greece.

ABSTRACT

Background: Subjective tinnitus is an auditory perception that is not caused by external stimulation, its source being anywhere in the auditory system. Furthermore, evidence exists that exposure to noise alters cochlear micromechanics, either directly or through complex feed-back mechanisms, involving the medial olivocochlear efferent system. The aim of this study was to assess the role of the efferent auditory system in noise-induced tinnitus generation.

Material/methods: Contralateral sound-activated suppression of TEOAEs was performed in a group of 28 subjects with noise-induced tinnitus (NIT) versus a group of 35 subjects with normal hearing and tinnitus, without any history of exposure to intense occupational or recreational noise (idiopathic tinnitus-IT). Thirty healthy, normally hearing volunteers were used as controls for the efferent suppression test.

Results: Suppression of the TEOAE amplitude less than 1 dB SPL was considered abnormal, giving a false positive rate of 6.7%. Eighteen out of 28 (64.3%) patients of the NIT group and 9 out of 35 (25.7%) patients of the IT group showed abnormal suppression values, which were significantly different from the controls' (p<0.0001 and p<0.045, respectively).

Conclusions: The abnormal activity of the efferent auditory system in NIT cases might indicate that either the activity of the efferent fibers innervating the outer hair cells (OHCs) is impaired or that the damaged OHCs themselves respond abnormally to the efferent stimulation.

Show MeSH
Related in: MedlinePlus