Effect of Tinnitus in Distortion Products Otoacoustic Emissions (DPOAEs) in Normal Hearing Patients

Tinnitus is a symptom whose pathophysiology remains still unclear. Its diagnosis and treatment is complicated, due to its subjectivity. The generation of tinnitus is commonly linked with the impaired functioning of the outer hair cells (OHC) inside the cochlea. Distortion product otoacoustic emissions (DPOAEs) are the objective test used to assess their activity. This study investigates the cochlear outer hair cell function in patients with tinnitus and normal hearing using DPOAEs. We performed a prospective study of the cochlear function in normal hearing patients complaining of tinnitus by analysing DPOAEs amplitude and signal/noise (S/N) ratio. We gathered a sample of 21 ears from adults that attended to the ENT Department complaining of tinnitus with normal hearing. We compared their results with a control group of 21 ears, with the same demographic characteristics, presenting normal hearing but without tinnitus in order to exclude the influence of age in DPOAEs results. A decreased mean of S/N levels in DPOAEs was found in tinnitus and normal hearing group comparing with control group, although these differences were not statistically significant (p > 0.05). Based on the results, OHC dysfunction is not necessary to experience tinnitus. The majority of the patients that present OHC dysfunction do not present a tinnitus at the moment. Other mechanisms in auditory pathway may be evaluated in the tinnitus development.

Azathioprine reduces the risk of audiometric relapse in immune-mediated hearing loss

INTRODUCTION

Current schemes for treatment of immune-mediated hearing loss with sporadic short-course, low-dose corticosteroids, are insufficient.

METHODS

To determine the role of azathioprine in the control of auditory impairment, a longitudinal, observational, descriptive study was performed with 20 patients treated with azathioprine (1.5-2.5mg/kg/day into two doses) for 1year. The loss of 10dB on two consecutive frequencies or 15dB on an isolated frequency was considered as relapse.

RESULTS

The mean age of the patients was 52.50years (95%CI: 46.91-58.17), half were women. Bilateral affectation was 65%. 75% had organ specific disease and 25% had systemic autoimmune disease. The difference between baseline PTA (46.49dB; DS18.90) and PTA at 12months (45.47dB; DS18.88) did not reach statistical significance (P=.799). There was a moderate positive correlation between female sex and the presence of systemic disease (R=.577). By applying Student's t for paired data, a significant difference (P=.042) was obtained between the PTA in frequencies up to 1000 Hz (PTA125-1000Hz). The relative incidence rate of relapse per year was .52 relapses/year (95%CI: .19-1.14]). The median time to audiometric relapse-free was 9.70months (DS1.03).

CONCLUSIONS

Azathioprine maintains the hearing threshold, decreases the risk of relapse, and slows down the rate at which patients relapse, altering the course of immune-mediated inner ear disease.