DPOAE Amplitudes Research Articles

Exploring the origins of decreased sound tolerance in tinnitus patients.

This study aimed to confirm the characteristics of auditory function alterations in tinnitus patients with concomitant decreased sound tolerance (ST) and provide insights for developing tailored therapeutic approaches. A retrospective analysis was conducted on patient records from a tertiary university hospital's tinnitus clinic between March 2020 and June 2023. Demographic attributes and audiological profiles were reviewed. Patients were categorized into Group 1 if loudness discomfort level test outcomes were 77 dB or below, measured using an average of frequencies from 250 Hz to 8 kHz. The remaining patients were allocated to Group 2. Among the 434 tinnitus patients, 115 (26.5%) demonstrated decreased ST and were classified as Group 1. This group exhibited higher DPOAE amplitudes (p < 0.001), shortened latency, and decreased threshold of ABR wave V bilaterally (p < 0.05). No significant disparities were observed in gender, age, tinnitus handicap inventory, visual analog scale, and pure-tone audiometry results except subjective hyperacusis. Binary logistic regression analysis utilizing the forward conditional method revealed that the difference between groups was independently linked to DPOAE response at 7,277 Hz on the left side [B = 0.093, p < 0.001, EXP(B) = 1.07, 95% CI = 1.044-1.153]. Increased DPOAE amplitude and shorter and decreased ABR wave V in tinnitus patients with decreased ST might suggest a possible association with lesions in or around the superior olivary complex or higher central auditory pathway, potentially linked to the inhibition of medial olivocochlear efferents.

Otoprotective Effects of Quercetin Against Oxidative Damage in the Rat's Cochlea Induced by Noise and Silver Nanoparticles.

The aim of this study was to investigate the otoprotective effects of Quercetin (Que) against both noise-induced hearing loss (NIHL) and the ototoxicity of silver nanoparticles (SNPs) in rats. Forty-two male Wistar rats were divided into seven groups (n=6): control, SNPs, Que (100mg/kg) plus SNPs (100mg/kg), noise (104dB), Que plus noise, noise plus SNPs, and noise plus Que plus SNPs. In the weight change results, there was no significant difference between the groups exposed to noise plus SNPs and SNPs compared to the control group. However, animals had significant changes in DPOAE amplitude at 1 and 3days post-exposure when compared to baseline. Additionally, the DPOAE value of rats administered with Que plus SNPs was higher than in all other groups. Que also decreased the levels of TACT, MDA, IL-6, TNF-α, and NOX3 in the groups exposed to noise and SNPs and increased the SOD level and expression of myosin heavy chain VII (MYH7) and β-tubulin III (TUBB3) proteins. Furthermore, Que decreased structural changes in the animals' cochlea. Our findings indicate that pretreatment with Que efficiently counteracted the adverse effects of noise and SNPs on inner hair cell, outer hair cell, and nerve cells, which are responsible for high-frequency perception.

Mouse models reveal P2X2 receptor-mediated hearing adaptation is an indicator of noise-induced hearing loss vulnerability

Transgenic mouse models targeting the P2rx2 gene encoding the ATP-gated ion channel P2X2R subunit have revealed a cochlear humoral control mechanism where sustained elevation of background noise drives adaptation of hearing sensitivity over several minutes, requiring hours to reset (evident as “temporary threshold shift” in ABR thresholds, and reduction in DPOAE amplitudes; Housley et al. PNAS 2013, Cederholm et al. Purinergic Signalling 2019, Housley et al. Curr. Opinion. Physiol. 2020). Exposure of P2rx2 knockout (KO) mice to sustained noise (85 dB SPL) fails to elicit the ∼15 dB reduction in ABR thresholds that wildtype (WT) controls demonstrate. While acute hearing sensitivity is maintained, when these P2rx2KO mice are exposed to long-term moderate (75 dB SPL) white noise, they develop high frequency hearing loss not seen in WT controls. This “Purinergic Hearing Adaptation” otoprotection postulate is supported by human studies, where P2RX2 loss of function mutations lead to autosomal dominant progressive hearing loss that is exacerbated with exposure to environmental noise (DFNA41; Yan et al. PNAS 2013). Thus, noise-mediated release of ATP into the cochlear partition drives sustained suppression of the “cochlear amplifier,” supporting cochlear sensori-neural function across a lifetime that complements dynamic medial olivocochlear efferent-based otoprotection.

Is atrial fibrillation a risk factor for hearing loss?

In the present study, we sought to evaluate the results of hearing loss in AF patients.This study involved 50 patients with AF, as determined by means of electrocardiogram, and 50 patients without AF. The pure-tone audiometry (PTA) threshold values were measured at low, medium and high frequencies for both ears. The signal-to-noise ratio (SNR) DPOAEs and TEOAEs were also analyzed for both ears separately.Both the airway and bone conduction PTA thresholds at 3, 4 and 6 kHz (kilohertz) were significantly lower in the AF group than in the control group (p<0.05). The AF patients exhibited worse hearing and worse TEOAE results at 1, 2, 3 and 4 kHz. In fact, the TEOAE amplitudes of the AF group were significantly lower in both the right and left ears at 2, 3 and 4 kHz when compared with the control group (p<0.05). Moreover, the DPOAE amplitudes in the AF group were statistically significantly lower at 3.4 kHz in both ears when compared with the control group (p<0.05).In light of these findings, we believe that AF is a risk factor for hearing.

Galectin-3 protects auditory function in female mice

Sex differences in the development of sensorineural hearing loss have been recognized in various inner ear disorders, but the molecular basis for such differences is poorly understood. Autosomal genes have been shown to cause sex differences in disease susceptibility, but many genes exerting sex-dependent effects on auditory function remain to be identified. Galectin-3 (Gal-3), a protein encoded by the autosomal gene Lgals3, is a member of the β-galactoside-binding protein family, and has been linked to multiple biological processes, including immune responses, apoptosis, and cell adhesion. Here, we investigated auditory function and hair cell integrity in Gal-3 knockout (KO, Lgals3−/−) and wild-type (WT, Lgals3+/+) mice from age 1 to 6 months. KO mice show a more rapid age-related increase in ABR thresholds compared to WT mice. Noticeably, the threshold deterioration in female KO mice is significantly greater than in the male KO and WT mice. The ABR threshold elevation manifests over a broad frequency range in female KO mice, whereas the threshold elevations are confined to high frequencies in the male KO and WT mice. Moreover, DPOAE input/output functions reveal a similar pattern of auditory dysfunction, with the female KO mice displaying a significantly greater reduction in DPOAE amplitudes than male KO mice and WT mice of both sexes. Finally, age-related outer hair cell loss is greater for female KO mice compared to male KO mice and WT mice of both sexes. Together, these results indicate that Gal-3 deficiency exacerbates age-related cochlear degeneration and auditory dysfunction in female mice. Our study identifies Gal-3 as a sex-dependent molecule for maintaining female cochlear integrity.

The Association between Prenatal Nicotine Exposure and Offspring's Hearing Impairment.

The objective of this study is to evaluate whether there is an association between in-utero exposure to nicotine and subsequent hearing dysfunction. Secondary analysis of a multicenter randomized trial to prevent congenital cytomegalovirus (CMV) infection among gravidas with primary CMV infection was conducted. Monthly intravenous immunoglobulin hyperimmune globulin therapy did not influence the rate of congenital CMV. Dyads with missing urine, fetal or neonatal demise, infants diagnosed with a major congenital anomaly, congenital CMV infection, or with evidence of middle ear dysfunction were excluded. The primary outcome was neonatal hearing impairment in one or more ears defined as abnormal distortion product otoacoustic emissions (DPOAEs; 1 to 8 kHz) that were measured within 42 days of birth. DPOAEs were interpreted using optimized frequency-specific level criteria. Cotinine was measured via enzyme-linked immunosorbent assay kits in maternal urine collected at enrollment and in the third trimester (mean gestational age 16.0 and 36.7 weeks, respectively). Blinded personnel ran samples in duplicates. Maternal urine cotinine >5 ng/mL at either time point was defined as in-utero exposure to nicotine. Multivariable logistic regression included variables associated with the primary outcome and with the exposure (p < 0.05) in univariate analysis. Of 399 enrolled patients in the original trial, 150 were included in this analysis, of whom 46 (31%) were exposed to nicotine. The primary outcome occurred in 18 (12%) newborns and was higher in nicotine-exposed infants compared with those nonexposed (15.2 vs. 10.6%, odds ratio [OR] 1.52, 95% confidence interval [CI] 0.55-4.20), but the difference was not significantly different (adjusted odds ratio [aOR] = 1.0, 95% CI 0.30-3.31). This association was similar when exposure was stratified as heavy (>100 ng/mL, aOR 0.72, 95% CI 0.15-3.51) or mild (5-100 ng/mL, aOR 1.28, 95% CI 0.33-4.95). There was no association between nicotine exposure and frequency-specific DPOAE amplitude. In a cohort of parturients with primary CMV infection, nicotine exposure was not associated with offspring hearing dysfunction assessed with DPOAEs. · Nicotine exposure was quantified from maternal urine.. · Nicotine exposure was identified in 30% of the cohort.. · Exposure was not associated with offspring hearing dysfunction..

Audiologic characterization using clinical physiological measures: Normative data from macaque monkeys

Clinical auditory physiological measures (e.g., auditory brainstem responses, ABRs, and distortion product otoacoustic emissions, DPOAEs) provide diagnostic specificity for differentially diagnosing overt hearing impairments, but they remain limited in their ability to detect specific sites of lesion and subtle levels of cochlear damage. Studies in animal models may hold the key to improve differential diagnosis due to the ability to induce tightly controlled and histologically verifiable subclinical cochlear pathologies. Here, we present a normative set of traditional and clinically novel physiological measures using ABRs and DPOAEs measured in a large cohort of male macaque monkeys. Given the high similarities between macaque and human auditory anatomy, physiology, and susceptibility to hearing damage, this normative data set will serve as a crucial baseline to investigate novel physiological measures to improve diagnostics. DPOAE amplitudes were robust at f2 = 1.22, L1/L2 = 65/55, increased with frequency up to 10 kHz, and exhibited high test re-test reliability. DPOAE thresholds were lowest from 2-10 kHz and highest < 2 kHz. ABRs with a standard clinical electrode montage (vertex-to-mastoid, VM) produced Waves I-IV with a less frequently observed Wave-I, and lower thresholds. ABRs with a vertex-to-tympanic membrane (VT) electrode montage produced a more robust Wave-I, but absent Waves II-IV and higher thresholds. Further study with the VM montage revealed amplitudes that increased with stimulus level and were largest in response to click stimuli, with Wave-II showing the largest ABR amplitude, followed by -IV and -I, with high inter- and intra-subject variability. ABR wave latencies decreased with stimulus level and frequency. When stimulus presentation rate increased or stimuli were presented in close temporal proximity, ABR amplitude decreased, and latency increased. These findings expand upon existing literature of normative clinical physiological data in nonhuman primates and lay the groundwork for future studies investigating the effects of noise-induced pathologies in macaques.

INFLUENCE OF BLOOD GROUP ON EVOKED OTOACOUSTIC EMISSIONS

OAE testing is more sensitive in the detection of the early onset of cochlear pathologies before a change in hearing thresholds. In the development of cochlear hair cells in the foetus human blood group antigens were involved. The present study is aimed to investigate the effect of blood group on evoked otoacoustic emissions amongAim: young adults in the Indian context. A total of 120 normal young adults of age 18 – 30 years were selected and groupedMethod: according to the ABO system of blood group, each consists of 30 participants and recorded both DPOAE and TEOAE. Results: The DPOAE and TEOAE amplitude showed signicant difference across frequencies and ears which do not follow a uniform pattern of signicance in all blood groups indicating no effect of blood group in OAE amplitude. The present studyConclusion: revealed no effect of blood group over evoked otoacoustic emission, though the results report a signicant difference among the majority of the test frequencies which is not uniform indicating any inuence, and this opens the possibility of other factors inuencing the OAE response.

Assessing the Clinical Value of Objective and Patient-Reported Audiovestibular Outcome Measures in the Risk Estimation of Systemic Cobalt Toxicity for Patients With a Metal-on-Metal Hip Implant.

Based on limited evidence from case reports and small cohort studies of metal-on-metal (MoM) hip implant patients with presumed systemic cobalt (Co) toxicity, and a few animal studies on Co-induced damage to the otovestibular system, it was hypothesised that Co exhibits an ototoxic potential alongside other systemic manifestations. Preliminary investigations from our research group in MoM patients confirmed this assumption for the auditory system, whereas no signs of Co-induced vestibular impairment were detected, and a clear dose-response relationship between the auditory function and the blood Co levels was lacking. Therefore, the current study aimed to extend and validate these findings in a larger sample of MoM patients and control subjects, to explore the potential clinical value of audiovestibular outcome measures in the risk estimation of systemic Co toxicity in this patient population. Fifty patients (32 to 68 years) with a primary unilateral/bilateral MoM hip implant were matched for age, gender, and noise exposure to 50 nonimplanted control subjects. Both groups underwent the same protocol, consisting of an objective auditory [i.e., conventional and high-frequency audiometry, transient-evoked and distortion (TEOAEs and DPOAEs), auditory brainstem responses] and vestibular (i.e., cervical and ocular vestibular evoked myogenic potentials, horizontal and vertical video head impulse tests) test battery, a questionnaire inquiring auditory, balance, and general neurological symptoms, and a blood sample collection to determine the plasma Co concentration. The auditory test battery presented consistently higher audiometric thresholds in the MoM patient group, with group differences ranging from 2.1 to 5.7 dB in the lower frequencies (0.25 to 6.0 kHz) and from 4.6 to 9.3 dB in the high frequencies (8.0 to 14.0 kHz). Group differences at high frequencies were statistically significant ( p ≤ 0.001). Additionally, significantly lower TEOAE ( p = 0.009) and DPOAE ( p < 0.001) amplitudes were observed in the MoM patients when the better ear was included in the analysis, and more absent TEOAE and DPOAE responses were found between 1.0 and 4.0 kHz (0.008 ≤ p ≤ 0.039). Within the vestibular test battery, the MoM patients showed longer N1 and P1 ocular vestibular evoked myogenic potentials latencies for the left ear, and lower video head impulse test gains for the left anterior and right posterior semicircular canals (0.005 ≤ p ≤0.035). The patient-reported (questionnaire) outcome delivered no significant group differences ( p > 0.01). Six patients had elevated Co levels according to our local institutional threshold (>4 or 5 µg/l for unilateral or bilateral MoM hip implants, resp.), but their audiovestibular outcome measures did not differ significantly from those of the other patients. Corresponding to our preliminary investigations, the results indicate possibly Co-induced (predominantly high-frequency) auditory impairment, probably triggered by toxic damage to the cochlear structures. However, the low mean difference values, the lack of group differences for the patient-reported outcome measures, and the lack of any relationship with the blood Co levels strongly reduce the clinical relevance of these findings. Therefore, the risk of Co-induced ototoxic impairment is considered to be clinically negligible for the majority of MoM hip implant patients, and the use of auditory tests in the risk estimation of systemic Co toxicity should be decided on a case-by-case basis.

Impulse Noise Induced Hidden Hearing Loss, Hair Cell Ciliary Changes and Oxidative Stress in Mice.

Recent studies demonstrated that reversible continuous noise exposure may induce a temporary threshold shift (TTS) with a permanent degeneration of auditory nerve fibers, although hair cells remain intact. To probe the impact of TTS-inducing impulse noise exposure on hearing, CBA/J Mice were exposed to noise impulses with peak pressures of 145 dB SPL. We found that 30 min after exposure, the noise caused a mean elevation of ABR thresholds of ~30 dB and a reduction in DPOAE amplitude. Four weeks later, ABR thresholds and DPOAE amplitude were back to normal in the higher frequency region (8–32 kHz). At lower frequencies, a small degree of PTS remained. Morphological evaluations revealed a disturbance of the stereociliary bundle of outer hair cells, mainly located in the apical regions. On the other hand, the reduced suprathreshold ABR amplitudes remained until 4 weeks later. A loss of synapse numbers was observed 24 h after exposure, with full recovery two weeks later. Transmission electron microscopy revealed morphological changes at the ribbon synapses by two weeks post exposure. In addition, increased levels of oxidative stress were observed immediately after exposure, and maintained for a further 2 weeks. These results clarify the pathology underlying impulse noise-induced sensory dysfunction, and suggest possible links between impulse-noise injury, cochlear cell morphology, metabolic changes, and hidden hearing loss.

INTERMITTENT TINNITUS IN ADULTS: AN INSIGHT INTO COVERT HEARING LOSS

Objectives: Association of high frequency hearing loss/minor damage in peripheral auditory system in continuous chronic tinnitus with normal PTA is well established.The purpose of the study was to verify whether this finding is true for intermittent unilateral or bilateral tinnitus patients with normal PTA using EHF audiometry and conventional DPOAEs. Materials and method:This study was conducted on 45 normal hearing adults between the age ranges of 18-30 years. Among them 30 adults comprised of study group with intermittent tinnitus which varies in laterality.Tinnitus evaluation was done on these population followed by THI administration. DPOAE and EHF audiometry was completed on all subjects after conventional hearing assessment program. Result and Discussion:Kruskal Wallis H test &amp; Wilcoxon signed rank test was used to compare OAE amplitude &amp; EHF thresholds.Spearman's correlation was used to evaluate the correlation between DPOAE amplitude with EHF threshold. Reduced hearing sensitivity in the extended high frequency region may be early predictor of outer hair cell dysfunction in the most basal area.Findings of this study suggest that intermittent tinnitus may also lead to subtle lesion at the basal region of cochlea which would result in a significant hearing loss with continuous tinnitus in future. Conclusion:Intermittent tinnitus may increase the fragility of peripheral auditory system which may lead to permanent lesions and would be evident as elevated thresholds in conventional PTA.

Otoferlin Is Required for Proper Synapse Maturation and for Maintenance of Inner and Outer Hair Cells in Mouse Models for DFNB9.

Deficiency of otoferlin causes profound prelingual deafness in humans and animal models. Here, we closely analyzed developmental deficits and degenerative mechanisms in Otof knock-out (Otof–/–) mice over the course of 48 weeks. We found otoferlin to be required for proper synapse development in the immature rodent cochlea: In absence of otoferlin, synaptic pruning was delayed, and postsynaptic boutons appeared enlarged at 2 weeks of age. At postnatal day 14 (P14), we found on average ∼15 synapses per inner hair cell (IHC) in Otof–/– cochleae as well as in wild-type controls. Further on, the number of synapses in Otof–/– IHCs was reduced to ∼7 at 8 weeks of age and to ∼6 at 48 weeks of age. In the same period, the number of spiral ganglion neurons (SGNs) declined in Otof–/– animals. Importantly, we found an age-progressive loss of IHCs to an overall number of 75% of wildtype IHCs. The IHC loss more prominently but not exclusively affected the basal aspects of the cochlea. For outer hair cells (OHCs), we observed slightly accelerated age-dependent degeneration from base to apex. This was associated with a progressive decay in DPOAE amplitudes for high frequency stimuli, which could first be observed at the age of 24 weeks in Otof–/– mice. Our data will help to plan and predict the outcome of a gene therapy applied at various ages of DFNB9 patients.

Distortion product otoacoustic emissions in very preterm infants: A longitudinal study

BackgroundVery preterm infants are at a greater risk of developing neurodevelopmental impairments such as neuro-motor delays, vision and hearing deficits (Roze and Breart, 2004; Saigal and Doyle, 2008) [1,2]. The hearing difficulties in preterm infants vary depending on the co-morbid conditions. However, prematurity itself is considered as a risk factor that influence the functioning of auditory system. AimThe current study aims to compare the DPOAEs in very preterm infants and term infants at 1 month, 3 months and 6 months of age (corrected age in preterm infants). MethodDPOAEs were recorded in 72 very preterm infants and 30 term infants at 1 month, 3 months and 6 months of age. All these infants had obtained ‘pass’ results in newborn hearing screening using ABR. DPOAE f2 test frequency was measured at six frequencies (1500 Hz, 2000 Hz, 3000 Hz, 4500 Hz, 6000 Hz and 8000 Hz) with primary tone stimulus intensity L1 equal to 65 dBSPL and L2 equal to 55 dBSPL with primary tone f2/f1 frequency ratio of 1.2. Otoscopic examination and tympanometry was performed prior to DPOAE testing, to ascertain normal middle ear status. ResultsDPOAE amplitude did not change significantly between two groups from 1 month till 6 months of age (p > 0.05). DPOAE amplitude and noise floor in very preterm infants were not different from term infants and DPOAE amplitude did not vary significantly across f2 frequencies at various time periods. ConclusionThe current study findings provided evidence that prematurity did not constitute as a factor to influence the results of DPOAE in very preterm infants who passed newborn hearing screening test. Any significant reduction in DPOAE amplitude or absence of DPOAE in very preterm infants has to be considered and monitored effectively, as it may not reflect a developmental process of cochlear function; instead it could indicate the presence of inner ear or middle ear pathology.

Effects of long-term Doppler ultrasound exposure on cochlea and cochlear nucleus in prenatal period in an experimental model

Background New generation Doppler ultrasonography (DUSG) application effects on cochlea and cochlear nucleus (CN) are unclear. We aimed to investigate the effects of new generation DUSG application at different frequencies in prenatal period on cochlea and CN in rats. Objective Twenty-four pregnant female rats were divided into three groups (n = 8). Group 1 was the control group and was not subjected to any treatment. Group 2 was determined as the USG every day (USGED) treatment group. Group 2 has received DUSG application every day from the 4th to 18th day (20 min/15 per day). Group 3 has received DUSG application as “2 days/one dose as every other day application” (USG2D1) from the 4th to 18th day (20 min/8 every other day). Twenty-four female rats were sacrificed in 21 days. Also, 24 pups were sacrificed after two days. First day after born, the cochlear activities of the right ears of all pups were examined using DPOAEs. Second day, neural tissues from CN were evaluated histopathologically and immunohistochemically. Results There was no any statistical difference between the groups in respect of histopathologically. USGED group showed mild caspase-3 positive neurons and glial cells. However, there was no significant difference between the USGED and other groups (p>.05). Similarly, the rats applied with USG2D1 had mild caspase-3 expression, but no significant difference between the USG2D1 and other groups (p>.05). Differences in DPOAE amplitudes, and therefore in cochlear activity, between the groups were revealed. The decrease in cochlear activity between the groups involved frequencies at 2, 8, 16, and 32 kHz (p<.05). Conclusions Multiple administration of new generation DUSG to pregnant rats has not shown harmful effects on the cochlear neural tissue. High frequencies are more sensitive in cochlea to apply DUSG.

Assessment of Hidden Hearing Loss in Individuals Exposed to Occupational Noise Using Cochlear, Neural, Temporal Functions and Quality of Life Measures.

The present study aims to identify the objective tests that can identify hidden hearing loss in a group of individuals exposed to occupational noise, which is not otherwise evident as a clinically relevant permanent threshold shift. A standard group comparison design was used to study the hidden auditory effect of occupational noise on traffic police officers. A total of 50 participants (n = 25 exposed to occupational noise; n = 25 non-occupational noise-exposed) were included in the study. The test battery comprised of behavioral tests (hearing thresholds from 250 to 16,000Hz), fine structure Distortion product otoacoustic emissions (DPOAE's) as physiological measure, Click and CE-chirp® evoked auditory brain stem response (ABR) as electrophysiological, and Gap detection test (GDT) and Temporal modulation transfer function (TMTF) as psychophysical measures. Among the measures evaluated, extended high-frequency audiometry, fine structure DPOAE amplitude, CE-chirp® ABR, GDT, and TMTF showed a significant difference (p < 0.05) between the traffic police individuals exposed to occupational noise and the controls. However, routine audiometry and click-evoked ABR did not show any significant differences. The high-frequency audiometric thresholds, fine structure DPOAEs, CE-chirp® evoked ABR, GDT and TMTF have been shown to be affected in individuals exposed to occupational noise. This finding indicates a hidden hearing loss in the study group. Hence, this study paves the way for early identification and intervention of noise-induced hearing loss by including these measures along with routine test protocol in susceptible individuals.

Outer hair cell functioning in infants with iron deficiency anemia

BackgroundDistortion product otoacoustic emissions (DPOAE) in infants with Iron Deficiency Anemia (IDA) helps in understanding the cochlear status especially the functioning of outer hair cells. ObjectivesTo analyze the presence of DPOAE across frequencies and DP amplitude in infants with and without IDA. MethodDPOAE were recorded on 40 infants with IDA and 40 infants without IDA in the age range of 6–24 months. Cubic DPOAEs (2f1-f2) were measured at six f2 frequencies (1500 Hz, 2000 Hz, 3000 Hz, 4500 Hz, 6000 Hz & 8000 Hz) with primary tone stimulus of intensity L1 equal to 65 dBSPL and L2 equal to 55 dBSPL. Immittance audiometry was performed using 226 Hz probe tone prior to DPOAE recording to ascertain normal middle ear functioning. ResultsDPOAEs were present in all infants with and without IDA across frequencies tested. DP amplitude across the frequencies did not show any statistically significant difference (p < 0.05) between anemic and non-anemic groups. There was no statistically significant difference observed when both the groups were compared in terms of gender and age. ConclusionThe study indicated that reduced iron levels does not have any influence on outer hair cell functioning as there were no changes observed in the DPOAE amplitude levels between infants with IDA and infants without IDA. Iron status does not seem to have a direct effect on outer hair cell functioning in infants. However, fine structure DPOAEs can reveal even more precise changes (if any) that are caused due to iron deficiency.

Role of Otoacoustic Emission in Early Detection of Cisplatin Induced Ototoxicity.

Cisplatin is a chemotherapeutic agent effective against head and neck carcinoma but unfortunately it is cochleotoxic. This study has been designed to investigate the efficacy of OAE in identifying early effects of cisplatin on the cochlea and the importance of protocol for audiological monitoring of cisplatin induced ototoxicity. This is a prospective observational study conducted from October 2012 to September 2014 on 70 patients, receiving Cisplatin for various malignant conditions. Audiological criteria for ototoxicity was considered as a difference of 10 d B or more in pure tone thresholds of two or more adjacent frequencies in conventional audiometry and in DPOAE-Signal noise ratio less than 6dB or DPOAE amplitude less than 20 dBSPL (irrespective of SNR > 6dB). According to PTA, 60.7% patients showed ototoxicity after completion of chemotherapy. In DPOAE, according to SNR and amplitude criteria more than 60% patients showed ototoxicity after first cycle of cisplatin at high frequencies (4-8kHz). DPOAEs is a sensitive tool for early detection of ototoxicity and protocol is necessary for monitoring ototoxicity in patients receiving cisplatin to improve the quality of life.

The Ototoxic Potential of Cobalt From Metal-on-Metal Hip Implants: Objective Auditory and Vestibular Outcome.

During the past decade, the initial popularity of metal-on-metal (MoM) hip implants has shown a progressive decline due to increasingly reported implant failure and revision surgeries. Local as well as systemic toxic side effects have been associated with excessive metal ion release from implants, in which cobalt (Co) plays an important role. The rare condition of systemic cobaltism seems to manifest as a clinical syndrome with cardiac, endocrine, and neurological symptoms, including hearing loss, tinnitus, and imbalance. In most cases described in the literature, revision surgery and the subsequent drop in blood Co level led to (partial) alleviation of the symptoms, suggesting a causal relationship with Co exposure. Moreover, the ototoxic potential of Co has recently been demonstrated in animal experiments. Since its ototoxic potential in humans is merely based on anecdotal case reports, the current study aimed to prospectively and objectively examine the auditory and vestibular function in patients implanted with a MoM hip prosthesis. Twenty patients (15 males and 5 females, aged between 33 and 65 years) implanted with a primary MoM hip prosthesis were matched for age, gender, and noise exposure to 20 non-implanted control subjects. Each participant was subjected to an extensive auditory (conventional and high-frequency pure tone audiometry, transient evoked and distortion product otoacoustic emissions [TEOAEs and DPOAEs], auditory brainstem responses [ABR]) and vestibular test battery (cervical and ocular vestibular evoked myogenic potentials [cVEMPs and oVEMPs], rotatory test, caloric test, video head impulse test [vHIT]), supplemented with a blood sample collection to determine the plasma Co concentration. The median [interquartile range] plasma Co concentration was 1.40 [0.70, 6.30] µg/L in the MoM patient group and 0.19 [0.09, 0.34] µg/L in the control group. Within the auditory test battery, a clear trend was observed toward higher audiometric thresholds (11.2 to 16 kHz), lower DPOAE (between 4 and 8 kHz), and total TEOAE (1 to 4 kHz) amplitudes, and a higher interaural latency difference for wave V of the ABR in the patient versus control group (0.01 ≤ p < 0.05). Within the vestibular test battery, considerably longer cVEMP P1 latencies, higher oVEMP amplitudes (0.01 ≤ p < 0.05), and lower asymmetry ratio of the vHIT gain (p < 0.01) were found in the MoM patients. In the patient group, no suggestive association was observed between the plasma Co level and the auditory or vestibular outcome parameters. The auditory results seem to reflect signs of Co-induced damage to the hearing function in the high frequencies. This corresponds to previous findings on drug-induced ototoxicity and the recent animal experiments with Co, which identified the basal cochlear outer hair cells as primary targets and indicated that the cellular mechanisms underlying the toxicity might be similar. The vestibular outcomes of the current study are inconclusive and require further elaboration, especially with respect to animal studies. The lack of a clear dose-response relationship may question the clinical relevance of our results, but recent findings in MoM hip implant patients have confirmed that this relationship can be complicated by many patient-specific factors.

The characteristic of otoacoustic emissions in full-term neonates according to ABO blood groups

IntroductionPrevious research has suggested that individuals with different blood groups show varied incidences of noise-induced hearing loss. The reduced otoacoustic emissions amplitudes indicate the higher possibilities of outer hair cell damage for noise exposure. ObjectiveThe objective is to analyze the characteristics of otoacoustic emissions, including the occurrence of spontaneous otoacoustic emission and the amplitudes of distortion product otoacoustic emission at certain frequencies in full term neonates with different ABO blood groups. MethodsA total of 80 selected full-term female neonates who passed the initial newborn hearing screen were enrolled into the study, with equal number of participants in four ABO blood groups (Blood Group A, Blood Group B, Blood Group AB, Blood Group O). Measurements of spontaneous otoacoustic emission and distortion product otoacoustic emission were performed in both ears for all participants. Results(1) The blood group O participants showed significantly fewer spontaneous otoacoustic emission occurrences than the other three blood groups (A=70%, B=80%, AB=67%, O=25%, p< 0.05). (2) The blood group O participants showed lower DPOAE amplitudes at 1257 Hz (M = 4.55 dB, SD = 8.36), 1587 Hz (M = 11.60 dB, SD = 6.57), 3174 Hz (M = 7.25 dB, SD = 5.99), 5042 Hz (M = 13.60, SD = 6.70) than participants with the other three blood groups in left ears (p < 0.05). In right ears, the blood group O participants showed reduced amplitudes at 1257Hz (M=6.55dB, SD=8.36), 1587Hz (M=13.60dB, SD=6.57), 3174Hz (M=7.65dB, SD=6.43), 5042Hz (M=13.65dB, SD=6.50) than participants from non-O blood groups (p<0.05). ConclusionFemale individuals with blood group O have lower otoacoustic emissions values than individuals with the other three blood groups. We need to further investigate the possible relationships between ABO blood group and cochlear function, including the potential influences of noise damage on cochlear outer hair cells.

Clinical observation of the relationship between the newborn hearing screening and ABO blood groups

Objective:To analyze the relationship between ABO blood groups and otoacoustic emissions in full-term newborns, including the occurrence of SOAE and the amplitudes of DPOAE. Method:A total of eighty normal hearing female neonates were included in the study, with equal number of participants in each of the ABO blood group. Measurements of SOAE and DPOAE were collected from both ears of all participants. Result:The blood group O subjects showed significantly fewer SOAE occurrences and lower DPOAE amplitudes at 793 Hz, 1 257 Hz and 1 587 Hz than subjects with other three blood groups both in the left and right ears. Conclusion:The full-term neonates with blood group O have lower SOAE occurrence than other three blood group individual. The blood group O individuals have the lowest amplitude at 793 Hz, 1 257 Hz and 1 587 Hz of both ears.