The Study of Otoacoustic Emissions and the Suppression of Otoacoustic Emissions in Subjects with Tinnitus and Normal Hearing: An Insight to Tinnitus Etiology

Introduction Analysis of the suppression effect is a simple method to evaluate cochlear status and central auditory mechanisms and, more specifically, the medial olivocochlear system. This structure may be involved in the generation of mechanisms that cause tinnitus and in the pathophysiology of tinnitus in patients with tinnitus and normal hearing. Objective To review the literature of the etiology of tinnitus on the lights of otoacoustic emissions in patients with normal hearing. Data Synthesis Individuals with tinnitus and normal hearing have a higher prevalence of alterations in transient-evoked otoacoustic emissions and distortion-product otoacoustic emissions than normal subjects. This fact suggests that dysfunctions of the outer hair cells (OHCs) might be important in the generation of the tinnitus; however, this feature is not always present in those who have the symptoms of tinnitus. Final Comments These findings suggest that OHC dysfunction is not necessary for tinnitus development—that is, there might be mechanisms other than OHC damage in the tinnitus development. On the other hand, OHC dysfunction alone is not sufficient to cause the symptom, because a great many individuals with OHC dysfunction did not complain about tinnitus. .

The study of otoacoustic emissions and the suppression of otoacoustic emissions in subjects with tinnitus and normal hearing: an insight to tinnitus etiology.

Introduction Analysis of the suppression effect is a simple method to evaluate cochlear status and central auditory mechanisms and, more specifically, the medial olivocochlear system. This structure may be involved in the generation of mechanisms that cause tinnitus and in the pathophysiology of tinnitus in patients with tinnitus and normal hearing. Objective To review the literature of the etiology of tinnitus on the lights of otoacoustic emissions in patients with normal hearing. Data Synthesis Individuals with tinnitus and normal hearing have a higher prevalence of alterations in transient-evoked otoacoustic emissions and distortion-product otoacoustic emissions than normal subjects. This fact suggests that dysfunctions of the outer hair cells (OHCs) might be important in the generation of the tinnitus; however, this feature is not always present in those who have the symptoms of tinnitus. Final Comments These findings suggest that OHC dysfunction is not necessary for tinnitus development-that is, there might be mechanisms other than OHC damage in the tinnitus development. On the other hand, OHC dysfunction alone is not sufficient to cause the symptom, because a great many individuals with OHC dysfunction did not complain about tinnitus.

Association between suppression of otoacoustic emissions and annoyance levels in tinnitus patients with normal hearing.

OBJECTIVE: To correlate the annoyance of tinnitus assessed by the Tinnitus Handicap Inventory and on a visual analogue scale with the evoked otoacoustic emission test result in tinnitus patients with normal hearing. STUDY DESIGN: Case-control study. SETTING: Public tertiary hospital. SUBJECTS AND METHODS: The sample was initially based on a population of 80 subjects with tinnitus; 20 of them had normal hearing and normal evoked otoacoustic emission test results and comprised the study group. For the purpose of comparison, a control group was formed, which consisted of 17 subjects with no hearing complaints and normal hearing. The participants were submitted to hearing tests, immittance testing and tests for the evaluation of acoustic reflexes, distortion product otoacoustic emissions, transient evoked otoacoustic emissions (TEOAEs), and suppression of TEOAEs. The tests were performed in a sound-treated booth using a linear contralateral noise of 60 dB. The presence of suppression effects was defined when the response amplitude was 0.5 dB or higher. RESULTS: Abnormal evoked otoacoustic emission suppression test results were observed in 52.9% of tinnitus patients and in 32.4% of control subjects (p = 0.086). Suppression effects of TEOAEs were absent in 38.5% of subjects with minimal or mild discomfort and in 61.9% of subjects with moderate or severe discomfort (p = 0.183). CONCLUSION: It was not possible to associate the annoyance caused by tinnitus with the TEOAE suppression test results, although suppression effects were found to decrease with increasing annoyance.

Effect of hormone replacement therapy on the auditory brainstem response of postmenopausal women.

OBJECTIVE: To investigate whether hormone replacement therapy modifies the auditory brainstem response in postmenopausal women. METHODS: Nineteen postmenopausal women received hormone replacement therapy (study group) and 25 received no treatment nor placebo (control group). In both groups, age ranged from 45 to 60 years and pure-tone sensitivity was 25 dB or better at frequencies between 500 and 2000 Hz. Auditory brainstem response was evaluated before and after 3 months of hormone use in the study group. The control group was also evaluated at the same periods. The following auditory brainstem response parameters were compared between the two groups: latencies of waves I, III, and V; I-III, III-V, and I-V interpeak intervals. RESULTS: Mean age did not differ between groups (study group: 51.5 ± 0.7 years; control: 52.9 ± 0.6 years). No significant differences in wave latencies, or interpeak intervals were observed between the two groups (p > 0.05).