Effect of myricetin on the gene expressions of NOX3, TGF-ß1, prestin, and HSP-70 and anti-oxidant activity in the cochlea of noise-exposed rats.

OBJECTIVES: Noise-induced hearing loss is one of the most common occupational diseases in industrialized countries and can be affected by various environmental and genetic factors. This study was designed to examine the effect of myricetin in preventing this disorder. MATERIALS AND METHODS: Twenty-one Wistar rats were randomly divided into five groups: Non-exposed, noise exposure only, noise exposure with vehicle, noise exposure with myricetin 5 mg/Kg, and noise exposure with myricetin 10 mg/kg. All animals were sacrificed after last noise exposure. The left cochlea was dissected from each rat. It was used for mRNA expression analysis (NOX3, TGF-ß1, prestin, and HSP-70). Blood samples were collected to assess superoxide dismutase (SOD) activity, 1, 1 diphenyl picrylhydrazyl (DPPH), and malondialdehyde (MDA) measurements. RESULTS: Real time-PCR assay revealed that noise decreased NOX3 and increased TGF-ß1, prestin, and HSP-70 gene expressions. Administration of myricetin at the dose of 5 mg/kg, but not at 10 mg/kg, significantly reversed these changes. Noise also increased MDA levels and decreased SOD and DPPH scavenging activities. Myricetin at the doses of 5 and 10 mg/kg also reversed these changes. CONCLUSION: The findings of this study showed that myricetin at the dose of 5 mg/Kg was able to reverse noise-induced abnormalities in gene expression and oxidant/anti-oxidant balance. It is a possibility that myricetin via enhancement of anti-oxidant activity induced these effects.

Hearing Thresholds Changes after MRI 1.5T of Head and Neck.

INTRODUCTION: Exposure to high intensity noise produced by MRI is a cause for concern. This study was conducted to determine the temporary and permanent effects of exposure to noise created by performing MRI on the hearing threshold of the subjects using conventional and extended high frequency audiometry. METHODS: This semiexperimental study was performed on 35 patients referred to Shahid Rahnemoun Hospital for head and neck MRI due to different clinical conditions. The hearing threshold of patients was measured before, immediately after, and 24 hours after performing 1.5 Tesla MRI using conventional and extended high frequency audiometry. SPSS version 18 was used to compare the mean hearing thresholds before and after MRI using paired T test and repeated measures analysis. RESULTS: Comparison of auditory thresholds in conventional and extended high frequencies before and immediately after MRI showed a significant shift at 4 KHz (P = 0.008 and P = 0.08 for right and left ears), 6 KHz (P = 0.03 and P = 0.01 for right and left ears), and 14 KHz (P =0.03 and P = 0.31 for right and left ears). However, there was no significant difference between audiometric thresholds before and 24 hours after MRI. CONCLUSION: Noise due to 1.5 Tesla MRI can only cause transient threshold shift.

Does Malleolus non-Lifting Tympanoplasty have any Advantage Over Malleus Lifting Techniques?

INTRODUCTION: In order to achieve a higher success rate for tympanoplasty, different techniques have been developed, and a wide variety of grafting materials have been developed. One of the techniques currently receiving considerable attention involves not lifting the remaining of eardrum from the malleus and embedding the graft underneath in order to repair the eardrum correctly in its original position, as well as minimizing graft lateralization leading to progression of hearing rehabilitation. We compared the effects of tympanoplasty with and without malleus lifting on hearing loss in patients with chronic otitis media. MATERIALS AND METHODS: In this study, 30 consecutive patients diagnosed as having chronic otitis media without cholesteatoma were randomly assigned to two tympanoplasty groups; with or without malleus lifting. Air and bone conduction thresholds were recorded before and 45 days after the intervention. RESULTS: In groups, except for 8000 Hz, the air conduction was significantly improved following surgery. According to air conduction there was no difference between the groups before surgery at different frequencies, although it was improved to a greater degree in the group without lifting at 250 Hz postoperatively. The average post-operative air-bone gap (ABG) gain was significantly higher in all study frequencies in the target group. One of the effects of this technique is inner-ear protection from physical trauma to the ossicular chain, and prevention of damage to bone conduction. CONCLUSION: A higher hearing threshold and also higher ABG gain can be achieved by not lifting the remaining eardrum from the malleus and embedding the graft undereath it, especially at lower frequencies.

The effect of drill-generated noise in the contralateral healthy ear following mastoid surgery: The emphasis on hearing threshold recovery time.

In mastoid surgeries, contralateral ear noise exposure is a known, identified factor leading to high-frequency hearing loss due to the wide variety of surgical devices that may be used during the surgery. However, the hearing threshold recovery time after this trauma was uncertain. The present study aimed to assess this time. In this prospective survival analysis study, 28 consecutive patients with chronic otitis media who were undergoing tympanomastoidectomy were assessed. Standard pure-tone audiometry (PTA) and distortion-product otoacoustic emission (DPOAE) were measured in all contralateral ears before and 6 h, 24 h, 48 h, 72 h, and 96 h after the surgery. Based on the PTA postoperative hearing loss, survival rates at frequencies of 3000 Hz, 4000 Hz, 6000 Hz, and 8000 Hz were 44.4%, 36.4%, 51.7%, and 47.4%, 24 h after surgery; 11.1%, 9.1%, 10.3%, and 13.2%, 48 h after surgery; and 0%, 0%, 3.4%, and 2.6%, 72 h after surgery, respectively. Based on the PTA and DPOAE, survival rates at all frequencies were 0%, 96 h after the surgery. According to the PTA, mean hearing recovery times were 61.98 ± 26.76 h (3000 Hz), 62.73 ± 26.50 h (4000 Hz), 67.08 ± 25.90 h (6000 Hz), 70.70 ± 24.13 h (8000 Hz), and with regard to DPOAE the recovery times were 58.58 ± 28.39 h (2000 Hz), 63.32 ± 28.83 h (4000 Hz), 65.22 ± 29.13 h (6000 Hz), and 75.14 ± 22.70 h (8000 Hz), respectively. To conclude, high-frequency hearing loss usually occurs following mastoid surgeries that is mainly temporary and reversible after 72 h.

Simultaneous effects of noise exposure and smoking on OAEs.

Noise is one of the most pervasive hazardous factors in the workplace. Noise-induced hearing loss (NIHL) is the most common disorder related to noise exposure. Smoking is probably associated with hearing loss. The simultaneous effect of noise and smoking on hearing is a recent concern. In this study, we assessed the simultaneous effect of noise and smoking on standard pure tone audiometry (PTA) and distortion product otoacoustic emissions (DP-OAEs). This was an historical cohort study on 224 workers exposed to noise who were divided into two groups: Smokers and nonsmokers. DP-OAE response amplitudes were assessed. Data were analyzed by SPSS software (version 19) using Student's t-test and Mann-Whitney U test. One hundred and five subjects were smokers (case group) and 119 individuals were nonsmokers (control group). All the subjects were exposed to 91.08 + 2.29 dBA [time-weighted average (TWA) for an 8 h work shift]. Mean DP-OAE response amplitude at frequencies higher than 1,000 Hz was significantly higher in the smokers than the nonsmokers. This study showed that smoking can aggravate the effect of noise on hearing in DP-OAEs.

Concurrent effect of noise exposure and smoking on extended high-frequency pure-tone thresholds.

OBJECTIVE: Concurrent effect of noise and smoking on hearing loss is a recent concern. In this study, the concurrent effect of noise and smoking on hearing loss in conventional frequencies and frequencies higher than 8 kHz was assessed. DESIGN: This was a cross-sectional study on workers exposed to noise who were divided into two groups: smokers and non-smokers. Hearing thresholds were assessed by conventional audiometry, and HFA. Data were analysed using non-parametric tests and Student's t-test. STUDY SAMPLE: There were 212 workers. RESULTS: Ninety-seven subjects were smokers and 115 individuals were non-smokers. All subjects were exposed to 92.1 ± 2.4 dBA (Leq8h). The highest threshold in conventional and high-frequency audiometry was observed at 6 kHz and 16 kHz, respectively. Hearing threshold at frequencies above 1 kHz was significantly higher in the smokers than non-smokers. There was no correlation between hearing thresholds and pack-years of smoking. CONCLUSIONS: Concurrent exposure to noise and smoking may be associated with more hearing loss than exposure to noise alone in the conventional and high frequencies. However, other differences between smokers and non-smokers may explain these differences as well.

Effect of exposure to a mixture of organic solvents on hearing thresholds in petrochemical industry workers.

INTRODUCTION: Hearing loss is one of the most common occupational diseases. In most workplaces, workers are exposed to noise and solvents simultaneously, so the potential risk of hearing loss due to solvents may be attributed to noise. In this study we aimed to assess the effect of exposure to mixed aromatic solvents on hearing in the absence of exposure to hazardous noise. MATERIALS AND METHODS: In a cross-sectional study, 99 workers from the petrochemical industry with exposure to a mixture of organic solvents whose noise exposure was lower than 85 dBA were compared with 100 un-exposed controls. After measuring sound pressure level and mean concentration of each solvent in the workplace, pure-tone-audiometry was performed and the two groups were compared in terms of high-frequency and low-frequency hearing loss. T-tests and Chi-square tests were used to compare the two groups. RESULTS: The mean hearing threshold at all frequencies among petrochemical workers was normal (below 25 dB). We did not observe any significant association between solvent exposure and high-frequency or low-frequency hearing loss. CONCLUSION: This study showed that temporary exposure (less than 4 years) to a mixture of organic solvents, without exposure to noise, does not affect workers' hearing threshold in audiometry tests.

Conventional Audiometry, Extended High-Frequency Audiometry, and DPOAE for Early Diagnosis of NIHL.

BACKGROUND: Noise most frequently affects hearing system, as it may typically cause a bilateral, progressive sensorineural hearing loss at high frequencies. OBJECTIVES: This study was designed to compare three different methods to evaluate noise-induced hearing loss (conventional audiometry, high-frequency audiometry, and distortion product otoacoustic emission). MATERIAL AND METHODS: This was a cross-sectional study. Data was analyzed by SPSS (ver. 19) using chi square, T test and repeated measures analysis. Study samples were workers from tile and ceramic industry. RESULTS: We found that conventional audiometry, extended high-frequency audiometry, low-tone distortion product otoacoustic emission and high-tone distortion product otoacoustic emission had abnormal findings in 29 %, 69 %, 22 %, and 52 % of participants. Most frequently affected frequencies were 4000 and 6000Hz in conventional audiometry, and 14000 and 16000 in extended high-frequency audiometry. CONCLUSIONS: Extended high-frequency audiometry was the most sensitive test for detection of hearing loss in workers exposed to hazardous noise compared with conventional audiometry and distortion product otoacoustic.

Low level laser effect in treatment of patients with intractable tinnitus due to sensorineural hearing loss.

INTRODUCTION: Tinnitus is defined as a perception of sound without an external acoustic stimulus. Due to large number of causes and limited knowledge of its pathophysiology, tinnitus still remains an obscure symptom. METHODS: This was a cross-sectional study on 120 patients with tinnitus and sensorineural hearing loss who were randomly divided into two groups; one group received low-level laser and the second group used the same instrument but off, for 20 sessions of 20 minutes. A tinnitus handicap inventory (THI) and Visual Analog Scale (VAS) were used to evaluate the severity of patients' symptoms. Severity and frequency of tinnitus were also determined using Audiometric tests. RESULTS: The average age of the 120 patients in the two groups of study were not statistically significantly different. The mean difference of severity of tinnitus between the two groups was statistically significant at the end of the study and 3 month after completion of treatment. The VAS and THI mean differences after the treatment were statistically significant between the two groups but not statistically significant after 3 months of completion the study. CONCLUSION: Low level laser radiation is effective for short-term treatment of Tinnitus caused by sensorineural hearing loss and its impact may be reduced over the time.

Efficacy of low-level laser therapy in the management of tinnitus due to noise-induced hearing loss: a double-blind randomized clinical trial.

Background. Several remedial modalities for the treatment of tinnitus have been proposed, but an effective standard treatment is still to be confirmed. In the present study, we aimed to evaluate the effect of low-level laser therapy on tinnitus accompanied by noise-induced hearing loss. Methods. This was a double-blind randomized clinical trial on subjects suffering from tinnitus accompanied by noise-induced hearing loss. The study intervention was 20 sessions of low-level laser therapy every other day, 20 minutes each session. Tinnitus was assessed by three methods (visual analog scale, tinnitus handicap inventory, and tinnitus loudness) at baseline, immediately and 3 months after the intervention. Results. All subjects were male workers with age range of 30-51 years. The mean tinnitus duration was 1.85 ± 0.78 years. All three measurement methods have shown improved values after laser therapy compared with the placebo both immediately and 3 months after treatment. Laser therapy revealed a U-shaped efficacy throughout the course of follow-up. Nonresponse rate of the intervention was 57% and 70% in the two assessment time points, respectively. Conclusion. This study found low-level laser therapy to be effective in alleviating tinnitus in patients with noise-induced hearing loss, although this effect has faded after 3 months of follow-up. This trial is registered with the Australian New Zealand clinical trials registry with identifier ACTRN12612000455864).

Sensorineural hearing loss after magnetic resonance imaging.

Magnetic resonance imaging (MRI) devices produce noise, which may affect patient's or operators' hearing. Some cases of hearing impairment after MRI procedure have been reported with different patterns (temporary or permanent, unilateral or bilateral, with or without other symptoms like tinnitus). In this report, a case of bilateral sensorineural hearing loss in an otherwise healthy patient underwent brain MRI was described. The patient's hearing loss was accompanied with tinnitus and was not improved after 3 months of followup.

Frequency of Hearing Impairment among Full-term Newborns in Yazd, Iran.

OBJECTIVE: Permanent congenital hearing loss, a common congenital anomaly, may affect speech and language acquisition, academic achievement and social development. Current standards emphasize early recognition of congenital hearing loss. This study was conducted to find the prevalence of hearing impairment in term newborns in Yazd, Iran. METHODS: This was a descriptive-analytic study conducted in Yazd on 7250 term newborns. Otoacoustic emissions (OAEs) test was performed in all newborns during the first 24 hours after birth. Those who failed to respond at the first step were retested 15 days later. Those who failed to respond at the second step too, were tested by acoustic brainstem responses (ABR) test. Chi square test was used for data analysis. FINDINGS: From 7250 newborns in the first step 598 (8.2%) and 682 (9.4%) ears (right and left, respectively) failed. In the second step 51 (0.7%) and 58 (0.8%) ears (right and left, respectively) failed. Consanguinity and route of delivery had significant effect on the frequency of hearing loss. CONCLUSION: The overall frequency of congenital hearing loss in this study was found high.

Hearing Loss due to Carbon Monoxide Poisoning.

Carbon monoxide poisoning is one of the rare causes of hearing loss which may cause reversible or irreversible, unilateral or bilateral hearing loss after acute or chronic exposure. In this report, we present a case of bilateral sensorineural hearing loss in a secondary smelting workshop worker after an acute exposure to carbon monoxide. This complication was diagnosed by pure-tone audiometry and confirmed by transient evoked otoacoustic emissions. Hearing loss has not improved after 3 months of followup.

Effect of workplace noise on hearing ability in tile and ceramic industry workers in Iran: a 2-year follow-up study.

INTRODUCTION: Noise as a common physical hazard may lead to noise-induced hearing loss, an irreversible but preventable disorder. Annual audiometric evaluations help detect changes in hearing status before clinically significant hearing loss develops. This study was designed to track hearing threshold changes during 2-year follow-up among tile and ceramic workers. METHODS: This follow-up study was conducted on 555 workers (totally 1110 ears). Subjects were divided into four groups according to the level of noise exposure. Hearing threshold in conventional audiometric frequencies was measured and standard threshold shift was calculated for each ear. RESULTS: Hearing threshold was increased during 2 years of follow-up. Increased hearing threshold was most frequently observed at 4000, 6000, and 3000 Hz. Standard threshold shift was observed in 13 (2.34%), 49 (8.83%), 22 (3.96%), and 63 (11.35%) subjects in the first and second years of follow-up in the right and left ears, respectively. CONCLUSIONS: This study has documented a high incidence of noise-induced hearing loss in tile and ceramic workers that would put stress on the importance of using hearing protection devices.

Amplitude changes in otoacoustic emissions after exposure to industrial noise.

Noise-induced hearing loss (NIHL) is a frequent problem in industrial settings, especially where a high noise level is present. It is permanent, and irreversible, but preventable. Routine audiometry (an objective and time consuming) test is used for NIHL screening. Otoacoustic emissions (OAEs) are recently proposed as a more sensitive test for early diagnosis of NIHL. In this study, we aimed to compare the results of pure tone audiometry (PTA) with OAE in the diagnosis of NIHL. In a cross-sectional study on 120 workers (in three groups: Not exposed to noise, exposed to noise without NIHL and exposed to noise with NIHL), we compared the results of PTA and OAE. OAE can detect some changes in the function of hearing system in subjects exposed to noise, and these changes are apparently prior to hearing loss, which is diagnosed by PTA. OAE is a more sensitive method for the early diagnosis of cochlear damage than PTA, and can be performed in industrial settings for NIHL screening.

High-frequency audiometry: a means for early diagnosis of noise-induced hearing loss.

Noise-induced hearing loss (NIHL), an irreversible disorder, is a common problem in industrial settings. Early diagnosis of NIHL can help prevent the progression of hearing loss, especially in speech frequencies. For early diagnosis of NIHL, audiometry is performed routinely in conventional frequencies. We designed this study to compare the effect of noise on high-frequency audiometry (HFA) and conventional audiometry. In a historical cohort study, we compared hearing threshold and prevalence of hearing loss in conventional and high frequencies of audiometry among textile workers divided into two groups: With and without exposure to noise more than 85 dB. The highest hearing threshold was observed at 4000 Hz, 6000 Hz and 16000 Hz in conventional right ear audiometry, conventional left ear audiometry and HFA in each ear, respectively. The hearing threshold was significantly higher at 16000 Hz compared to 4000. Hearing loss was more common in HFA than conventional audiometry. HFA is more sensitive to detect NIHL than conventional audiometry. It can be useful for early diagnosis of hearing sensitivity to noise, and thus preventing hearing loss in lower frequencies especially speech frequencies.

Hearing status in neonatal hyperbilirubinemia by auditory brain stem evoked response and transient evoked otoacoustic emission.

Hyperbilirubinemia at neonatal period is one of the major deteriorating factors of the auditory system. If left untreated, it may cause certain cerebral damage. This study aims to evaluate the impact of hyperbilirubinemia on the hearing of neonate. This study was conducted on 35 newborn babies with jaundice (bilirubin more than 20 mg/dL). Auditory brainstem response (ABR) and transient evoked otoacoustic emission (TEOAE) tests were performed, after treatment and one year after. ABR test results indicated that 26 children (74.3%) had normal hearing but 9 (25.7%) suffered from an impairment. As for TEOAE test, 30 children (85.7%) passed whereas the remaining (14.3%) seemed to be failures. The comparative results of the two tests pointed to autonomic neuropathy /autonomic dysreflexia symptoms in 5 babies. Due to the high incidence of autonomic neuropathy/autonomic dysreflexia among hyperbilirubinemic babies, screening in this regard seems reasonable. Our result emphasizes the necessity of more experiments on the afflicted areas.