Does Hypochlorous Acid Cause Ototoxicity? An Experimental Study.

AIM: Hypochlorous acid (HOCl) is a weak acid that ionizes in water. It is an effective antiseptic exhibiting low toxicity on living tissues. We aimed to investigate the ototoxic effects of HOCl on an animal model by using electrophysiological and histological methods. MATERIALS AND METHODS: The study comprised 32 Sprague-Dawley rats, which were separated into four groups: control group (A), saline solution group (B), 70% isopropyl alcohol + 2% chlorhexidine group (C), and HOCl group (D). After recording the auditory brainstem response (ABR) for basal hearing thresholds (8, 16, 24, and 32 kHz), 0.03 ml of the aforementioned materials was injected intratympanically three times every 2 days in groups B, C, and D. ABR measurements were repeated on the 7th and 21st days. All animals were sacrificed, and temporal bones were prepared for examinations of cochlear histology and vascular endothelial growth factor immunohistochemistry. RESULTS: Basal hearing levels were normal across all frequencies and groups, with no statistical differentiation. On the 7th and 21st days after the ABR test, all other groups demonstrated a significant deterioration in hearing levels compared with group A. When the results from 7th and 21st days were compared within group D, a partial recovery was observed. In histopathology, groups C and D demonstrated moderate and severe cochlear degeneration, along with decreased immunoreactivity in the organ of Corti, stria vascularis, and spiral ligament. CONCLUSION: This is the first study to evaluate the safety of using HOCl in otology. Although HOCI is less ototoxic than the disinfectant used, it may have a toxic effect on cochlea.Level of Evidence: Animal Research.

Does Oral Monosodium Glutamate Have a Cochleotoxic Effect? An Experimental Study.

INTRODUCTION: The effect of orally consumed monosodium glutamate (MSG), which is a common additive in the food industry, on the cochlea has not been investigated. The present study aimed to investigate the possible cochleotoxic effects of oral MSG in guinea pigs using electrophysiological, biochemical, and histopathological methods. METHODS: Thirty guinea pigs were equally divided into control and intervention groups (MSG 100 mg/kg/day; MSG 300 mg/kg/day). At 1 month, 5 guinea pigs from each group were sacrificed; the rest were observed for another month. Electrophysiological measurements (distortion product otoacoustic emission [DPOAE] and auditory brainstem response [ABR]), glutamate levels in the perilymph and blood samples, and histopathological examinations were evaluated at 1 and 2 months. RESULTS: Change in signal-to-noise ratio at 2 months was significantly different in the MSG 300 group at 0.75 kHz and 2 kHz (p = 0.013 and p = 0.044, respectively). There was no statistically significant difference in ABR wave latencies of the guinea pigs given MSG compared to the control group after 1 and 2 months; an increase was noted in ABR thresholds, although the difference was not statistically significant. In the MSG groups, moderate-to-severe degeneration and cell loss in outer hair cells, support cells, and spiral ganglia, lateral surface junction irregularities, adhesions in stereocilia, and partial loss of outer hair cell stereocilia were noted. CONCLUSION: MSG, administered in guinea pigs at a commonly utilized quantity and route of administration in humans, may be cochleotoxic.

Repeated Atmospheric Pressure Alteration Effect on the Cochlea in Rats: Experimental Animal Study.

OBJECTIVE: This study aimed to evaluate the effects of repeated pressure alterations on cochlear structures in rats in an attempt to understand indirectly the inner ear status of flight crew who are repeatedly exposed to pressure alterations.METHODS: There were 12 adult Wistar albino rats equally divided into 2 groups: Group 1 (controls) and Group 2 (study group). The animals in Group 2 were exposed to repeated pressure changes in a pressure cabin which is regulated by manometers. The animals in Group 1 were placed in the cabin without being exposed to pressure changes. Auditory brainstem response (ABR) testing was performed in all animals at the beginning and at the end of the study. After 12 wk the animals were sacrificed and their cochleas were investigated using scanning electron microscopy (SEM).RESULTS: In the study group, hearing decreases at 2 kHz, 4 kHz, 6 dB at 8 kHz, and 32 kHz were encountered at the end of 3 mo. On SEM evaluation of the control group, the outer hair cells (OHC) and stereocilia were normal throughout the cochlea. In the study group, there were irregularities in lateral surface connections and separations, collapse, and adhesions in the basal segment of the cochlea and partial loss of stereocilia throughout the cochlea.CONCLUSION: Repeated alterations in the atmospheric pressure can lead to damage in the inner ear with subtle or evident hearing loss. Frequent flyers like air workers may be at risk of inner ear damage, which may be considered an occupational health problem.Eroglu S, Dizdar HT, Cevizci R, Cengiz AB, Ogreden S, Bulut E, Ilgezdi S, Dilci A, Ustun S, Sirvanci S, Kaya OT, Bayazit D, Caki BO, Oktay MF, Bayazit Y. Repeated atmospheric pressure alteration effect on the cochlea in rats: experimental animal study. Aerosp Med Hum Perform. 2021; 92(7):550555.

The Outcomes of Cochlear Implantation in Usher Syndrome: A Systematic Review.

OBJECTIVE: To systematically appraise the implementation of cochlear implantation (CI) in Usher Syndrome (USH) Types 1, 2, and 3 patients, and analyze who would benefit from CI. DATA SOURCES: A comprehensive search of PubMed, Embase, CINAHL, and Cochrane Library electronic databases from inception through June 2020 was performed. There were no language restrictions. STUDY SELECTION: The PRISMA strategy was followed. Included studies discuss USH patients who underwent CI regardless of age, nationality, or clinical subtype. All included studies report post-implantation functional, cognitive, or quality of life outcomes. Only reviews were excluded. RESULTS: Fifteen studies met the inclusion criteria. USH patients experienced improvements in PTA and speech perception and expression outcomes after CI, as well as improvements in phonological memory and quality of life measures. Overall, patients implanted at younger ages outperformed older patients in audiological testing. Similarly, patients with prolonged auditory deprivation had relatively poor performance outcomes in sentence recognition and speech detection following CI. CONCLUSIONS: Most USH patients benefit from CI. USH patients who undergo CI at younger ages generally achieve better hearing, speech, and cognitive outcomes. CI at older ages can still prove beneficial if appropriate auditory amplification is started at the right time. Further research is warranted to fill the gap in understanding regarding the gene mutations underlying the pathophysiology of USH that have favorable CI outcomes as well as the optimal time to perform CI.

Altering the gut microbiome to potentially modulate behavioral manifestations in autism spectrum disorders: A systematic review.

There is a potential association between gastrointestinal (GI) symptoms and the severity of autism spectrum disorder (ASD). Given this correlation, the possible impact of probiotics and prebiotics have been explored in research studies to modify the gut microbiome and ameliorate behavioral manifestations of ASD via modulating the gut-brain-microbiome axis. This systematic review focuses on the interplay between these factors in altering the behavioral manifestations of ASD. Probiotic supplementation tended to mitigate some of the behavioral manifestations of ASD, with less of a discernible trend on the microbiome level. Studies supplementing multiple probiotic species, such as microbiota transfer therapy, or including prebiotics performed better than single strain supplementation. Our analysis suggests that gut dysbiosis may increase intestinal permeability, leading to more severe GI symptoms and a systemic inflammatory response, which can alter permeability across the blood-brain barrier and synaptogenesis in the brain. Future studies are warranted to understand the precise contribution of altering gut microbiome on clinical manifestations of ASD that will open up avenues to develop preventive and treatment modalities.

Blood pressure, autonomic stress, and inflammatory markers during sleep deprivation and recovery in healthy men.

OBJECTIVE: Recent community-based studies have identified sleep deprivation (SD) as an important modifiable risk factor for hypertension However, the underlying mechanisms linking SD to hypertension remain elusive. Thus, this study investigates blood pressure (BP) responses to cardiac autonomic stress tests in the presence of SD. Furthermore, we analyzed vascular inflammatory biomarkers as a possible underlying factor linking SD to increased BP. METHODS: Ten healthy male volunteers (age, 21.6±1.2 years) underwent repeated autonomic stress tests for three consecutive days (baseline, SD, and recovery). The autonomic stress tests included the Valsalva maneuver, mental arithmetic, isometric handgrip, and cold pressor tests. Each day, resting BPs were measured, venous blood samples were collected for intercellular adhesion molecule 1, vascular cell adhesion molecule 1, and E-selectin measurements, and stress tests were performed between 0900 and 1100. Ambulatory BP was recorded during the entire SD period (24 h). RESULTS: One-night SD abolished BP reactivity to the Valsalva maneuver, isometric hand grip, and cold pressor tests, which returned after recovery sleep. Ambulatory BP monitoring showed that the mean systolic and diastolic BPs were 121.1±8.5 mm Hg and 72.8±6.3 mm Hg, respectively, between 0700 and 2300 and 120.3±9.6 mm Hg and 74.1±6.1 mm Hg, respectively, between 2300 and 0700 during the SD day (p>0.05 for both). Vascular inflammatory markers seemed unrelated to BP changes. CONCLUSION: Acute SD altered BP responses to cardiac autonomic stress tests in healthy men without affecting resting BP levels. SD led to a non-dipping pattern in BP oscillation. Collectively, these findings highlight the importance of sleep in regulating BP.

Association of Conductive Hearing Loss with the Structural Changes in the Organ of Corti.

OBJECTIVE: The aim of the study was to evaluate the association of conductive hearing loss (CHL) with the structural changes in the organ of Corti. METHODS: Twenty ears of 10 healthy adult Wistar albino rats were included in the study. The right ears (n = 10) of the animals served as controls (group 1), and no surgical intervention was performed in these ears. A tympanic membrane perforation without annulus removal was performed under operative microscope on the left ears (n = 5) in 5 of 10 animals (group 2). A tympanic membrane perforation with annulus removal was performed under operative microscope on the left ears (n = 5) of the remaining 5 animals (group 3). Auditory brainstem response testing was performed in the animals before the interventions. After 3 months, the animals were sacrificed, their temporal bones were removed, and inner ears were investigated using scanning electron microscopy (SEM). The organ of Corti was evaluated from the cochlear base to apex in the modiolar axis, and the parameters were scored semiquantitatively. RESULTS: In group 1, the pre- and post-intervention hearing thresholds were similar (p > 0.05). In group 2, a hearing decrease of at least 5 dB was encountered in all test frequencies (p > 0.05). In group 3, at the frequency range of 2-32 kHz, there was a significant hearing loss after 3 months (p < 0.01). After 3 months, the hearing thresholds in group 2 and 3 were higher than group 1 (p < 0.01). The hearing threshold in group 3 was higher than group 2 (p < 0.01). On SEM evaluation, the general cell morphology and stereocilia of the outer hair cells were preserved in all segments of the cochlea in group 1 with a mean SEM score of 0.2. There was segmental degeneration in the general cell morphology and outer hair cells in group 2 with a mean SEM score of 2.2. There was widespread degeneration in the general cell morphology and outer hair cells in group 3 with a mean SEM score of 3.2. The SEM scores of group 2 and 3 were significantly higher than group 1 (p < 0.05). The SEM scores of group 3 were significantly higher than group 2 (p < 0.05). CONCLUSION: CHL may be associated with an inner ear damage. The severity of damage appears to be associated with severity and duration of CHL. Early correction of CHL is advocated in order to reverse or prevent progression of the inner ear damage, which will enhance the success rates of hearing restoration surgeries. Subjective differences and compliance of the hearing aid users may be due to the impact of CHL on inner ear structures.

Contralateral suppression of transient evoked otoacoustic emissions in children with phonological disorder.

BACKGROUND: Perception of acoustic details in the speech signal is important for speech sound development. The medial olivocochlear pathway, a part of the auditory efferent system, plays a role in stimulus-related control of the cochlea. One clinical tool to evaluate the medial olivocochlear activity, which is thought to improve speech perception in noise, is the suppression of otoacoustic emissions. AIMS: This study investigated the suppression of transient evoked otoacoustic emissions in children with phonological disorder in comparison with that in typically developing controls. STUDY DESIGN: Case-control study. METHODS: A total of 23 children with phonological disorder (aged 5-10 years) and 21 age- and sex-matched controls (P > 0.05) participated in the study. Participants had pure-tone thresholds ≤ 15 dB hearing loss and normal middle ear functions. Transient evoked otoacoustic emissions with and without contralateral acoustic stimulation were measured. RESULTS: Although the mean transient evoked otoacoustic emissions suppressions were lower in the group with phonological disorder than in the controls, these differences were not statistically significant (P > 0.05). No left/right ear asymmetry of transient evoked otoacoustic emissions suppression was detected in either of the groups (P > 0.05). CONCLUSION: Children with phonological disorder did not show alterations in medial olivocochlear functioning in the medial olivocochlear activity as measured by the contralateral suppression of transient evoked otoacoustic emissions.

Evaluating the Efficacy of Taurodeoxycholic Acid in Providing Otoprotection Using an in vitro Model of Electrode Insertion Trauma.

Cochlear implants (CIs) are widely used to provide auditory rehabilitation to individuals having severe to profound sensorineural hearing loss (SNHL). However, insertion of electrode leads to inner trauma and activation of inflammatory and apoptotic signaling cascades resulting in loss of residual hearing in implanted individuals. Pharmaceutical interventions that can target these signaling cascades hold great potential for preserving residual hearing by preventing sensory cell damage. Bile salts have shown efficacy in various regions of the body as powerful antioxidants and anti-inflammatory agents. However, their efficacy against inner ear trauma has never been explored. The objective of this study was to determine whether taurodeoxycholic acid (TDCA), a bile salt derivative, can prevent sensory cell damage employing an in vitro model of electrode insertion trauma (EIT). The organ of Corti (OC) explants were dissected from postnatal day 3 (P-3) rats and placed in serum-free media. Explants were divided into control and experimental groups: (1) untreated controls; (2) EIT; (3) EIT+ TDCA (different concentrations). Hair cell (HC) density, analyses of apoptosis pathway (cleaved caspase 3), levels of reactive oxygen species (ROS) as well as inducible nitric oxide synthase (iNOS) activity and Mitochondrial Membrane Potential (MMP) were assayed. Treatment with TDCA provided significant otoprotection against HC loss in a dose-dependent manner. The molecular mechanisms underlying otoprotection involved decreasing oxidative stress, lowering levels of iNOS, and abrogating generation of cleaved caspase 3. The results of the present study suggest that TDCA provides efficient otoprotection against EIT, in vitro and should be explored for developing pharmaceutical interventions to preserve residual hearing post-cochlear implantation.

Biocompatibility of Bone Marrow-Derived Mesenchymal Stem Cells in the Rat Inner Ear following Trans-Tympanic Administration.

Recent advancements in stem cell therapy have led to an increased interest within the auditory community in exploring the potential of mesenchymal stem cells (MSCs) in the treatment of inner ear disorders. However, the biocompatibility of MSCs with the inner ear, especially when delivered non-surgically and in the immunocompetent cochlea, is not completely understood. In this study, we determined the effect of intratympanic administration of rodent bone marrow MSCs (BM-MSCs) on the inner ear in an immunocompetent rat model. The administration of MSCs did not lead to the generation of any oxidative stress in the rat inner ear. There was no significant production of proinflammatory cytokines, tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6 and IL-12, due to BM-MSCs administration into the rat cochlea. BM-MSCs do not activate caspase 3 pathway, which plays a central role in sensory cell damage. Additionally, transferase dUTP nick end labeling (TUNEL) staining determined that there was no significant cell death associated with the administration of BM-MSCs. The results of the present study suggest that trans-tympanic administration of BM-MSCs does not result in oxidative stress or inflammatory response in the immunocompetent rat cochlea.

The Effect of Auricular Graft Donor Site on Morbidity and Cosmetic Appearance in Cartilage Tympanoplasties.

OBJECTIVES: The aim of the present study was to compare the postoperative morbidity and cosmetic results between the use of the scapha and the use of the tragus as the auricular cartilage graft donor site in patients who had undergone cartilage tympanoplasty. The fascia graft was used as the control. MATERIALS AND METHODS: The patient's visual symmetry, cosmetic satisfaction, and anthropometric measurements were studied to objectively evaluate the cosmetic condition. The formation of skin scar changes, pigmentation changes, and sensory changes as clinical criteria were compared. RESULTS: A total of 234 patients and their 257 operated ears were included in the study. Forty prospectively operated ears with preoperative findings were also included. All patients (100%) felt that their results were good, as indicated by the visual analog scale, and the anthropometric ear measurements used to reinforce the data showed no significant differences between the groups. A significant difference with respect to clinical sensory changes was found between the groups only in patients undergoing unilateral surgery via the retro auricular approach (p<0.05). There was no difference between the scapha and tragus groups with respect to scar formation or skin pigmentation change. CONCLUSION: Neither scapha nor tragus use for graft retrieval led to dissatisfaction or cosmetic problems in the postoperative period. Sensory changes in the skin on clinical evaluation were less common in patients in whom the scapha donor site was preferred than in cases in which the tragus was used.

Evaluating the Efficacy of L-N-acetylcysteine and Dexamethasone in Combination to Provide Otoprotection for Electrode Insertion Trauma.

BACKGROUND: Electrode insertion trauma (EIT) during cochlear implantation (CI) can cause loss of residual hearing. L-N-acetylcysteine (L-NAC) and dexamethasone (Dex) have been individually shown to provide otoprotection albeit at higher concentrations that may be associated with adverse effects. Objective/Aims: The aim of this study is to determine whether L-NAC and Dex could be combined to decrease their effective dosage. MATERIALS AND METHODS: The organ of Corti (OC) explants were divided into various groups: 1) control; 2) EIT; 3) EIT treated with different concentrations of Dex; 4) EIT treated with different concentrations of L-NAC; 5) EIT treated with L-NAC and Dex in combination. Hair cell (HC) density, levels of oxidative stress, proinflammatory cytokines and nitric oxide (NO) was determined. RESULTS: There was a significant loss of HCs in explants subjected to EIT compared to the control group. L-NAC and Dex in combination was able to provide significant otoprotection at lower concentrations compared to individual drugs. CONCLUSIONS AND SIGNIFICANCE: A combination containing L-NAC and Dex is effective in protecting sensory cells at lower protective doses than each compound separately. These compounds can be combined allowing a decrease of potential side effects of each compound and providing significant otoprotection for EIT.

Effect of perinatal biotin deficiency on auditory pathway of the Wistar-Albino rats.

Aim: Severe biotin deficiency associated with biotinidase enzyme deficiency in newborns is seen as severe neurological problems and hearing loss. However, the effect on the infant of deficiencies in the maternal diet during pregnancy are not clear. Material and methods: The study included 16 female Wistar albino rats and 4 male Wistar albino rats, that were mated and then the females were separated into 4 groups. At 40 days after the birth, 3 pups were selected from each group, and these 12 pups were evaluated with DPOAE and ABR electrophysiologically and the cochlea was examined ultrastructurally with electron microscopy. Results: In the DPOAE evaluation, At 8000 and 11,000 Hz, the signal-noise ratios in the B-N and B-B groups were statistically significantly higher (p < .05). In ABR, lengthening of the latency periods was determined in all the waves at both 8 and 16 kHz in the B-B group. When the IPL periods were examined, lengthening in IPL 1-5 was statistically significant in the B-B group only at 8 kHz. Conclusions: Biotin can be said to have an effect on hearing pathways. However, specifically where on the hearing pathways that biotin is involved has not been clarified.

Does noise exposure during pregnancy affect neonatal hearing screening results?

OBJECTIVE: The aim is to investigate whether noise is effective on hearing screening tests of neonates born to mothers exposed to noise during pregnancy. MATERIAL AND METHOD: Screening results of 2653 infants from the period of January 2013-May 2017 were evaluated. Transient Evoked Otoacoustic Emissions (TEOAE) and Auditory Brainstem Response (ABR) were used. Infants of 65 mothers exposed to noise (LAeq 80-85 dBA/8 hours/day) during pregnancy (Week ± SD; 32.58 ± 2.71) comprised the study group while the control group consisted of infants of 2588 mothers without noise exposure. RESULTS: Among the 65 infants, 23 (35.4%) passed screening at the first emission test (OAE1); 34 (52.3%) at the second emission test (OAE2); 7 (10.8%) at the ABR stage, 1 (1.5%) infant was referred to a tertiary center. In the control group, 458 (17.7%) infants passed at OAE1; 1822 (70.4%) at OAE2; 289 (11.2%) at ABR stages, 19 (0.7%) infants were referred to a tertiary center. The rate of infants that passed screening at OAE1 in the study group was high (P = 0.00001). Sixty-four (98.46%) infants in the study group and 2569 (99.26%) infants in the control group passed the tests. The difference between the two groups was not significant, indicating that exposure to noise during pregnancy had no unfavorable effects on auditory functions (P = 0.392). CONCLUSION: Unfavorable effect of noise exposure during pregnancy was not observed on auditory functions of the infants. The higher rate of infants that passed the screening test at OAE1 stage in the study group raised the question, "Does the exposure of the noise at exposure action levels (80-85 dB A) during pregnancy contribute to auditory maturation of fetus?"

The Effects of Experimental Intratympanic Steroid Administration on Organ of Corti Type 1 Spiral Ganglion

Abstract Introduction It is unclear how effective is the intratympanic (IT) steroid treatment on organ of Corti type 1 spiral ganglion, its optimal dosage and frequency of administration. The effect of dexamethasone on cochlear functions in individuals with a normal hearing ability is also unknown. Objective The aim of this study was to evaluate, at the electrophysiological and ultrastructural levels, the effect of IT dexamethasone administration in guinea pigs with normal hearing on organ of Corti type 1 spiral ganglion. Methods A total of 20 guinea pigs (n = 40 ears) whose hearing was detected to be normal by electrophysiological tests were included in the study and randomly divided into 6 groups. Four groups were considered study groups, while 2 groups were considered control groups. Dexamethasone was administered intratympanically in doses of 2 mg/mL and 4 mg/mL in the guinea pigs in the study groups. The animals in the control groups received physiological saline in equal doses as the study groups. All interventions were performed under general anesthesia, and the electrophysiological tests were repeated following the IT injections. Results No statistically significant differences were found among the groups when the IT injections were evaluated in terms of the electrophysiological measurements (p > 0.05). The ultrastructural evaluation showed a cellular mitochondrial increase in the spiral ganglions of the cochlea in the groups in which dexamethasone was administered in a dose of 4 mg/mL. Conclusion According to the findings of this study, it can be suggested that the IT injection of dexamethasone is safe, and when applied in a dose of 4mg/mL, it increases metabolic activity at the cellular level.

The Effects of Experimental Intratympanic Steroid Administration on Organ of Corti Type 1 Spiral Ganglion.

Introduction It is unclear how effective is the intratympanic (IT) steroid treatment on organ of Corti type 1 spiral ganglion, its optimal dosage and frequency of administration. The effect of dexamethasone on cochlear functions in individuals with a normal hearing ability is also unknown. Objective The aim of this study was to evaluate, at the electrophysiological and ultrastructural levels, the effect of IT dexamethasone administration in guinea pigs with normal hearing on organ of Corti type 1 spiral ganglion. Methods A total of 20 guinea pigs ( n = 40 ears) whose hearing was detected to be normal by electrophysiological tests were included in the study and randomly divided into 6 groups. Four groups were considered study groups, while 2 groups were considered control groups. Dexamethasone was administered intratympanically in doses of 2 mg/mL and 4 mg/mL in the guinea pigs in the study groups. The animals in the control groups received physiological saline in equal doses as the study groups. All interventions were performed under general anesthesia, and the electrophysiological tests were repeated following the IT injections. Results No statistically significant differences were found among the groups when the IT injections were evaluated in terms of the electrophysiological measurements ( p > 0.05). The ultrastructural evaluation showed a cellular mitochondrial increase in the spiral ganglions of the cochlea in the groups in which dexamethasone was administered in a dose of 4 mg/mL. Conclusion According to the findings of this study, it can be suggested that the IT injection of dexamethasone is safe, and when applied in a dose of 4 mg/mL, it increases metabolic activity at the cellular level.

Assessment of Reduced Tolerance to Sound (Hyperacusis) in University Students.

INTRODUCTION: Hyperacusis is defined as a reduction in tolerance to ordinary environmental sounds. Hyperacusis can occur in individuals of all age groups, making daily life difficult for the sufferers. Although there is no objective test to accurately diagnose hyperacusis, questionnaires are useful for the assessment of hyperacusis. The aim of this study was to explore the reduced sound tolerance in university students using a hyperacusis questionnaire (HQ). MATERIALS AND METHODS: A total of 536 university students (300 females and 236 males) aged between 18 and 25 years, with a mean age of 21.34 ± 1.87 years, were assessed using an HQ developed by Khalfa. The mean total score of all the participants was 16.34 ± 7.91, and 5.78% of the participants had total scores indicating hyperacusis, where a majority of them were females. RESULTS: Females had significantly higher scores than men in terms of both the total and the attentional and emotional dimensions. The scores of the participants who reported noise exposure or a decrease in their tolerance to noise were significantly higher than those of the other participants. Even among young adults, there was a group of participants suffering from some problems related to decreased tolerance to everyday sounds. DISCUSSION: Although the Turkish translation of the HQ seems to be a reliable tool for evaluating hyperacusis in young adults, further work with various populations of different age groups is required to establish validity and to assess the psychometric qualities of the Turkish form.

DNA methylation of the prestin gene and outer hair cell electromotileresponse of the cochlea in salicylate administration

Background/aim: Activity of the prestin gene may have a role in the pathogenesis of salicylate-induced ototoxicity. We investigated DNA methylation for prestin gene exon 1 in salicylate-injected guinea pigs.Materials and methods: Fifteen guinea pigs (30 ears) underwent audiological evaluation including 1000 Hz probe-tone tympanometry and a distortion product otoacoustic emission (DPOAE) test. The animals were randomly divided into three groups. Groups 2 (8 ears) and 3 (14 ears) were injected with intramuscular saline and sodium salicylate (200 mg/kg), respectively twice daily for 2 weeks. Group 1 (8 ears) received no injection. DPOAE measurements were performed at baseline; after 1, 2, 4, and 8 h (acute effect); and after 1 and 2 weeks (chronic effect). After audiological measurements, the animals were sacrificed for DNA isolation.Results: While a significant decrease (P < 0.01) was found for the acute effect in all frequencies in Group 3 according to baseline measurements, there was no difference in terms of chronic effect. DNA methylation increased during the acute phase of salicylate administration, whereas it returned to initial levels during the chronic phase.Conclusion: Salicylate-induced changes in DPOAE responses may be related to prestin-gene methylation. These results may have important implications for salicylate ototoxicity.

A New Hypothesis on the Frequency Discrimination of the Cochlea.

OBJECTIVE: Medial olivocochlear efferent (MOCE) neurons innervate outer hair cells (OHCs) of the cochlea, which in turn leads to basilar membrane motion. We hypothesized that MOCE-induced alterations in basilar membrane motion, independent of traveling waves, is responsible for the cochlear frequency discrimination of sound. MATERIALS AND METHODS: Eleven guinea pigs underwent bilateral otoscopic and audiologic evaluations under general anesthesia. The study comprised two parts. Part I (n=11) included spontaneous otoacoustic emission (SOAE) recordings with or without contralateral pure-tone acoustic stimuli (1 and 8 kHz) at 60 dB sound pressure level (SPL). Part II involved pure-tone (1 or 8 kHz) acoustic trauma in the right ears of two randomly selected subgroups (G1: 1 kHz; n=4 and G8: 8 kHz; n=4). The remaining three animals served as controls. After frequency-specific deafness was confirmed by distortion product otoacoustic emission (DPOAE), SOAEs were recorded in the left ears in the presence of a contralateral pure-tone (1 and 8 kHz) stimulus of 60 dB SPL. Furthermore, the surface of the organ of Corti was examined by scanning electron microscopy (SEM). RESULTS: The contralateral pure tone led to frequency-specific activation in SOAEs in part I (without trauma) and part II (with trauma) measurements. SEM showed heterogeneous OHC damage along the cochlea in traumatized ears with pure tone. CONCLUSION: We suggest that MOCEs convey acoustic information from traumatized ears to intact ears. Traumatized ears can show frequency-specific activation in the presence of diffuse damage in OHCs that excludes the passive transmission of the pressure wave from the perilymph to the basilar membrane.

Otoacoustic Emissions in Young Children with Autism.

OBJECTIVE: The aim of this study is to investigate otoacoustic emissions (OAEs) in young children with autism compared with those in an age-matched control group. MATERIALS AND METHODS: Thirty-eight children with autism aged 3-6 years and 27 typically developing (normally developing) control subjects participated in this study. All the participants had normal hearing and middle-ear function. Auditory brainstem responses were used to determine the hearing status in the autism group. Transient-evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs) were measured in the two groups. RESULTS: The TEOAE response level was higher in the autism group. Analysis of the DPOAE response showed that the mean emission levels at 1.5, 2 , 3, and 6 kHz and signal/noise ratios at 2, 4, 6, and 8 kHz were higher in the autism group (p<0.05). The greatest between-group differences were observed in the DPOAE signal levels at 2, 3, and 6 kHz (p=0.000). No statistically significant difference was found between the noise levels in the autism and control groups (p>0.05). CONCLUSION: The emission responses in the autism group were higher than those in the control group. The increase in DPOAEs at high frequencies may be related to the higher outer cell activation in the autism group. Further studies with larger sample sizes comprising younger children are needed to confirm the result and investigate the possible association between the increased OAEs and auditory sensitivity reported in autism.