Distortion Product Otoacoustic Emission (DPOAE) as an Appropriate Tool in Assessment of Otoprotective Effects of Antioxidants in Noise-Induced Hearing Loss (NIHL)

Abstract

Distortion product otoacoustic emission (DPOAE) appears to be an objective sensitive test of cochlear function. The aim of this study was to investigate whether DPOAE is an appropriate tool for assessment of minute changes in cochlea due to usage of antioxidant material. 48 workers exposed to continuous noise in a textile factory were randomly assigned into three groups: (1) The Control group (n = 16) received no antioxidant drugs, (2) The N-acetyl-cysteine (NAC) group (n = 16) received oral antioxidant NAC (1200 mg/day), (3) The Ginseng group (n = 16) received oral antioxidant Ginseng (200 mg/day). All three groups had a follow-up period of 2 weeks. The cochlear changes were assessed using DPOAE test before starting the daily work shift on first and 15th day. The associations between groups and DPOAE amplitudes after 2 weeks were analyzed using linear regression analysis. Four separate models were fitted by side of ears and frequency. All models were adjusted for baseline amplitude. Reduced (better) amplitude at DPOAE test was found for NAC and Ginseng groups at high frequencies (4 and 6 kHz) in both ears after 2 weeks compared to control group. Moreover, NAC group showed better DPOAE amplitude than Ginseng group. In conclusion, DPOAE seems to be an appropriate tool in assessing minute changes in the cochlea after antioxidant drugs administration.

Effect of antioxidant supplementation on the auditory threshold in sensorineural hearing loss: a meta-analysis

“…Although Doosti et al 24 demonstrated improvement in the amplitude of DPOAE at high frequencies (4 and 6 kHz) in both ears indicating improvement in hair cell function, they did not present enough data to document auditory threshold improvement/worsening after the use of antioxidants, or data that allowed comparison with those from the other studies, by Doosti et al 25 and Polanski and Cruz, 26 with respect to any effects on the specific frequencies of 4 and 6 kHz.…”

“… Group 1 – ginkgo biloba (120 mg/day) Ginkgo biloba; α-lipoic acid + Vitamin C; Vitamin E. Ginkgo biloba (120 mg/day); α-lipoic acid (60 mg/day) + Vitamin C (600 mg/day); Vitamin E (400 mg/day) 6 months Pre- and post-pure-tone and vocal audiometry There were differences in the audiological thresholds: 500 Hz, 1000 Hz and 8000 Hz, being greater for group 4 when compared to group 2 The results before and after treatment were not significantly different in any treatment group The results did not show a statistically significant difference of the effects of antioxidant substances on the auditory thresholds of this population during the 6-month study period Group 2 – α-lipoic acid (60 mg/day) + vitamin C (600 mg/day) Group 3 – papaverine hydrochloride (100 mg/day) + vitamin E (400 mg/day) Group 4 – placebo. Doosti et al, 2014 24 Noise-induced hearing loss. Control group – no intervention Ginseng Ginseng group – 200 mg/day 14 days (2 weeks) Distortion product otoacoustic emissions – DPOAE (1, 2, 4 and 6 kHz) NAC and ginseng groups showed the result; additionally, the NAC group showed better amplitude of DPOAE than the ginseng group Reduced DPOAE amplitude at high frequencies (4 and 6 kHz) in both ears The generalization of the results found in relation to the protective effects of these interventions requires assays with different doses and in a larger population NAC group – NAC 1200 mg/day Control group N improved: Total N: 16 Ginseng group– 200 mg/day.…”

“…The studies 24 , 25 , 26 , 27 , 28 evaluated different types of hearing loss and, therefore, used different interventions to assess the effect of antioxidant supplementation on their respective types of loss. Moreover, the studies differed regarding the antioxidant supplementation, dose used and time of supplementation.…”

“…Moreover, the studies differed regarding the antioxidant supplementation, dose used and time of supplementation. The tools used for hearing loss evaluation were: pure-tone and speech audiometry, 27 distortion product otoacoustic emissions, 24 pre- and post-pure tone and high-frequency pure-tone audiometry 25 and pre- and post-pure tone audiometry 26 , 28 and therefore, the results were different among the studies.…”

Mitochondrial Hearing Loss: Diagnosis and Management

“…It is important to note that mitochondrial dysfunction can extend beyond the auditory system and affect other organ systems, leading to a wide array of associated symptoms. Neurological abnormalities, such as seizures, developmental delays, and cognitive impairments, may be observed in individuals with mitochondrial hearing loss [2,5,6,[8][9][10]. Additionally, myopathy, characterized by muscle weakness and fatigue, and visual impairment, including optic atrophy and retinitis pigmentosa, can be present in syndromic disease [2,3,5,8].…”