Otoacoustic emissions reveal the micromechanical role of organ-of-Corti cytoarchitecture in cochlear amplification.

The intricate, crystalline cytoarchitecture of the mammalian organ of Corti presumably plays an important role in cochlear amplification. As currently understood, the oblique, Y-shaped arrangement of the outer hair cells (OHCs) and phalangeal processes of the Deiters cells serves to create differential "push-pull" forces that drive the motion of the basilar membrane via the spatial feedforward and/or feedbackward of OHC forces. In concert with the cochlear traveling wave, the longitudinal separation between OHC sensing and forcing creates phase shifts that yield a form of negative damping, amplifying waves as they propagate. Unlike active forces that arise and act locally, push-pull forces are inherently directional-whereas forward-traveling waves are boosted, reverse-traveling waves are squelched. Despite their attractions, models based on push-pull amplification must contend with otoacoustic emissions (OAEs), whose existence implies that amplified energy escapes from the inner ear via mechanisms involving reverse traveling waves. We analyze hybrid local/push-pull models to determine the constraints that reflection-source OAEs place on the directionality of cochlear wave propagation. By implementing a special force-mixing control knob, we vary the mix of local and push-pull forces while leaving the forward-traveling wave unchanged. Consistency with stimulus-frequency OAEs requires that the active forces underlying cochlear wave amplification be primarily local in character, contradicting the prevailing view. By requiring that the oblique cytoarchitecture produce predominantly local forces, we reinterpret the functional role of the Y-shaped geometry, proposing that it serves not as a push-pull amplifier, but as a mechanical funnel that spatially integrates local OHC forces.

Auditory Effects of Acoustic Noise From 3-T Brain MRI in Neonates With Hearing Protection.

BACKGROUND: Neonates with immature auditory function (eg, weak/absent middle ear muscle reflex) could conceivably be vulnerable to noise-induced hearing loss; however, it is unclear if neonates show evidence of hearing loss following MRI acoustic noise exposure. PURPOSE: To explore the auditory effects of MRI acoustic noise in neonates. STUDY TYPE: Prospective. SUBJECTS: Two independent cohorts of neonates (N = 19 and N = 18; mean gestational-age, 38.75 ± 2.18 and 39.01 ± 1.83 weeks). FIELD STRENGTH/SEQUENCE: T1-weighted three-dimensional gradient-echo sequence, T2-weighted fast spin-echo sequence, single-shot echo-planar imaging-based diffusion-tensor imaging, single-shot echo-planar imaging-based diffusion-kurtosis imaging and T2-weighted fluid-attenuated inversion recovery sequence at 3.0 T. ASSESSMENT: All neonates wore ear protection during scan protocols lasted ~40 minutes. Equivalent sound pressure levels (SPLs) were measured for both cohorts. In cohort1, left- and right-ear auditory brainstem response (ABR) was measured before (baseline) and after (follow-up) MRI, included assessment of ABR threshold, wave I, III and V latencies and interpeak interval to determine the functional status of auditory nerve and brainstem. In cohort2, baseline and follow-up left- and right-ear distortion product otoacoustic emission (DPOAE) amplitudes were assessed at 1.2 to 7.0 kHz to determine cochlear function. STATISTICAL TEST: Wilcoxon signed-rank or paired t-tests with Bonferroni's correction were used to compare the differences between baseline and follow-up ABR and DPOAE measures. RESULTS: Equivalent SPLs ranged from 103.5 to 113.6 dBA. No significant differences between baseline and follow-up were detected in left- or right-ear ABR measures (P > 0.999, Bonferroni corrected) in cohort1, or in DPOAE levels at 1.2 to 7.0 kHz in cohort2 (all P > 0.999 Bonferroni corrected except for left-ear levels at 3.5 and 7.0 kHz with corrected P = 0.138 and P = 0.533). DATA CONCLUSION: A single 40-minute 3-T MRI with equivalent SPLs of 103.5-113.6 dBA did not result in significant transient disruption of auditory function, as measured by ABR and DPOAE, in neonates with adequate hearing protection. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: Stage 5.

The effect of tympanostomy tubes on otoacoustic emissions.

PURPOSE: Otoacoustic emissions (OAE) are a common screening tool to evaluate cochlear function. Middle ear dysfunction has been shown to impact results of otoacoustic emission testing, but there are limited data on the effect of tympanostomy tubes on OAE. The purpose of this study was to determine whether tympanostomy tube placement significantly improved OAE. METHODS: A retrospective review of charts was completed for patients younger than 18 years old who underwent tympanostomy tube placement from January 1, 2018 to September 1, 2023 and had preoperative and postoperative OAE testing within 6 months of surgery. The primary variable was presence of OAE preoperatively and postoperatively. Chi-square analysis and t test were used for statistical analysis. RESULTS: A total of 212 ears were examined from 111 pediatric patients who underwent tympanostomy tube placement during the study period. Presence of OAE at 3000, 4000, and 5000 Hz were all noted to significantly increase following tympanostomy tube placement, with OAE presence increasing from approximately 27.8% of the sample preoperatively to 95.3% postoperatively at 3000 and 4000 Hz. Patients who noted improvement had a significantly higher proportion of type B tympanogram preoperatively, compared to a higher proportion of type A tympanogram noted in patients who did not note improvement. CONCLUSION: Tympanostomy tubes can significantly improve otoacoustic emissions in patients with middle ear dysfunction.

Cochlear Function in Adults Exposed to Severe Acute Respiratory Syndrome Coronavirus 2.

INTRODUCTION: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a viral infection with a wide variety of symptoms, including fever, coughing, sneezing, fatigue, and a loss of taste and smell. Moreover, there are some recent studies that investigate the effects of SARS-CoV-2 on hearing and auditory performance. With this current study, we investigate the early effects of the coronavirus disease on hair cells in the cochlea. METHODS: In the current study, there were 25 subjects (17 females, 8 males) who tested positive for polymerase chain reaction on nasopharyngeal swabs. They had reported normal auditory functions and no history of otology before SARS-CoV-2. To determine auditory functions, pure-tone audiometry, otoacoustic emissions (OAE) tests, and threshold equalizing noise (TEN) tests were used. RESULTS: Although the hearing thresholds increased at higher frequencies, they were within normal limits according to four-frequency pure-tone averages. All participants had normal OAE, and there were no detected dead regions for any of the subjects. Even so, there were significant increases in hearing thresholds in TEN. CONCLUSION: There is no cochlear dysfunction discovered by OAE and TEN in SARS-CoV-2-affected individuals. Nonetheless, the increase in hearing thresholds at higher frequencies, other than the pure-tone average frequencies detected by TEN, and the decrease in the presence of detected OAE could be related to deterioration in the basal part of the cochlea.

Applications of the Grading Scales for the Detection of Ototoxicity in Children after Treatment of Neuroblastoma and Extracranial Germinal Tumor.

INTRODUCTION: Advances in treatment have resulted in a significant increase in survival rates for patients cured of malignant diseases such as neuroblastoma (NBL) and extracranial germ cell tumor (GCT). NBL is one of the pediatric cancers during which potentially ototoxic cytostatic drugs (cisplatin and carboplatin) are used for treatment. Other cancers include germinal tumors, hepatoblastoma, sarcomas, and brain tumors. Often, this very aggressive treatment has a high risk of causing long-term side effects, including hearing loss. Hence, the present study aimed to evaluate the usefulness of the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), Brock, Chang, and International Society of Pediatric Oncology (SIOP) Boston scales in terms of detecting the high-frequency nature of hearing loss induced by ototoxic drugs and monitoring hearing status in children after completion of oncological treatment. Additionally, the frequency of hearing loss in children treated for NBL and extracranial GCT was assessed, and the principles of monitoring hearing in these patients were indicated. METHODS: The study group consisted of 78 patients diagnosed with NBL (n = 47) and GCT (n = 31). There were 23 boys and 24 girls in the NBL group, aged 0-16 years, and 21 boys and 10 girls in the GCT group, aged 0-18 years. The control group consisted of 54 patients who had never received oncological treatment, were not taking potentially ototoxic drugs, and appeared socially efficient in the subjective audiological assessment. Audiometric examinations and DP-acoustic otoemission measurements were performed. Additionally, impedance audiometry tests were done to exclude a possible conductive component of the hearing loss. RESULTS: The analysis shows that ototoxicity-induced hearing loss was observed in 13.8-65.5% of children. 75.9% of patients showed hearing loss in the 16 kHz frequency range, and at least 56.8% of patients showed hearing loss in the frequency range above 12.5 kHz. Hearing impairment, relevant to speech understanding, was displayed by more than 40% of children treated for NBL and GCT. CONCLUSIONS: The confirmation of hearing loss in nearly 65% of cases in both patients indicates the necessity to monitor the long-term side effects of anticancer treatment. Acoustic otoemission measurements, the adoption of articulatory indices based on an audiogram, or the use of arbitrary ototoxicity assessment scales such as Brock, Chang, or SIOP Boston are fully justified techniques for studying ototoxicity induced by cytostatic drugs. However, they all require continuous improvement to increase their sensitivity and specificity, especially in the pediatric group.

Radiation dose to the cochlea and its association with sensorineural hearing loss in head and neck cancer-A prospective study.

AIM: To determine the effect of cochlear dose on sensorineural hearing loss in patients with head and neck cancer treated by radiotherapy and chemoradiotherapy. MATERIALS AND METHOD: A two-year longitudinal study was conducted on 130 subjects with various head and neck malignancies who were receiving radiotherapy or chemoradiation. 56 patients received only radiotherapy while 74 patients received concurrent chemoradiation five days a week at a dose of 66-70 Gy. They were categorized as having a radiation dose to the cochlea of <35 Gy, <45 Gy or >45 Gy. Pre- and post-therapy audiological evaluation was done using a Pure-tone audiogram, distortion product otoacoustic emission, and impedence. Hearing thresholds were measured at frequencies up to 16,000 Hz. RESULTS: Out of 130 patients 56 received RT alone and 74 received CTRT. There was statistically significant (p value <0.005) difference in Pure-tone audiometry assessment in both the RT and CTRT groups between subjects who received more than and <45 Gy of radiation to the cochlea. There was no significant difference in distortion product otoacoustic emission assessment between patients who received >45 Gy and <45 Gy radiation to the cochlea. Comparison between subjects who received radiation dose of <35 Gy and >45 Gy revealed significant results in the degree of hearing loss (p value <0.005). CONCLUSION: We observed that patients who received >45 Gy of radiation had more sensorineural hearing loss compared to patients who received <45 Gy. A cochlear dose of <35 Gy is associated with significantly lower hearing loss compared to higher doses. We would like to conclude by emphasizing the importance of regular audiological assessments prior to and post radiotherapy and chemoradiotherapy, with regular follow-ups encouraged over a longer period to improve the quality of life in patients with head and neck malignancy.

Magnitude of medial olivocochlear reflex assayed by tone-burst-evoked otoacoustic emissions: reliability and comparison with click-evoked emissions.

OBJECTIVE: The purpose of this pilot study was to evaluate the magnitude of the medial olivocochlear reflex (MOCR) estimated by the reduction in tone-burst evoked otoacoustic emissions (TBOAEs) measured at three levels and at three frequencies in response to fixed contralateral white noise. Results were compared with commonly used click-evoked otoacoustic emissions (CEOAEs). DESIGN: TBOAEs and CEOAEs, with and without contralateral 60 dB SPL white noise, were measured in response to stimulation at 55, 65, and 75 dB peSPL. In each subject, the set of measurements was performed twice. Of particular interest were the MOCR and its repeatability. STUDY SAMPLE: 15 normally hearing persons (13 women, average age 32.3 years, SD = 8.1). RESULTS: For both CEOAE and TBOAEs, the reliability of the MOCR was much better for broadband measurements than for half-octave-band filtered estimates. At the same time, the reliability of MOCR in half-octave bands was higher for TBOAEs than for CEOAEs, especially at 2 and 4 kHz. CONCLUSIONS: For general applications where broadband MOCR is of interest, the highest magnitude and reliability is provided by CEOAEs. However, TBOAEs may be better if a particular frequency band is of interest.

The effect of cumulative noise exposure on distortion product otoacoustic emissions.

OBJECTIVE: This study aimed to identify the characteristics of distortion product otoacoustic emissions (DPOAEs) that can be used to differentiate noise-induced hearing loss (NIHL) from age-related hearing loss. A potential index to detect NIHL was defined in terms of its susceptibility to cumulative noise exposure but not to age. DESIGN: In this cross-sectional cohort study, a job-exposure matrix was used to calculate the cumulative noise exposure. Multivariate linear regression models were used to examine how age and cumulative noise exposure associated with DPOAEs at individual frequencies after adjusting for hypertension, dyslipidaemia, tobacco use and alcohol consumption. STUDY SAMPLE: The pure-tone audiometry and DPOAEs data collected from 239 male workers in a steel factory. RESULTS: DPOAEs and DPOAE signal-to-noise ratios (SNRs) at all frequencies were found to be correlated with age, and those at 2, 3, 4 and 6 kHz were correlated with both age and noise exposure. The difference between DPOAE SNR at 1 and 3 kHz showed significant correlation with noise exposure but not with age. CONCLUSIONS: The results showed that this DPOAE index, the DPOAE SNR at 1 kHz minus the DPOAE SNR at 3 kHz, could add values to audiometric evaluation of NIHL.

Pure Tone Audiometry and Otoacoustic Emission Evaluation of Hearing Loss in Diabetic Patients in a Selected Urban Population of South-West Nigeria.

BACKGROUND: Diabetes Mellitus (DM) is a clinical condition which is characterized by persistent hyperglycemia resulting from insulin deficiency and/or insulin resistance. The spectrum of hearing impairments among patients with diabetes is wide with majority of the hearing problems not specific to patients with DM. The current study is aimed to evaluate the hearing loss in Diabetic Mellitus patients in a selected urban population of south-west Nigeria using pure tone audiometry and otoacousticemission evaluation. It will correlate the audiological findings with factors such as age, gender, glycemic status, and duration of DM. METHODS: A cross sectional progressive study was carried out from January 2021 to December 2021 on randomly selected 95 consecutive diabetic patients visiting the departments of Otorhinolaryngoloy and Medicine. RESULTS: A total of 95 DM patients attending the ENT clinics of the hospital consented and participated in the study. Their ages ranged from 43 to 82 years and had a mean of 65.3 ± 8.4 years. Majority of the patients were females (73.7%); femaleto- male ratio was approximately 3:1. About half of them were already retired (49.5%) while more than half had at least a tertiary level of education (53.7%).8.4% were reported to have discharge from their ears, 24.2% had itchy sensations and 5.3% had recurrent nasal discharge. The prevalence of hyperglycemia was 36.8% in the subjects; while another 5.3% were hypoglycemic. CONCLUSION: Hearing impairment is significantly associated with the DM and other risk factors in DM patients including older age, occupation, poor glycemic controls, undue noise and alcohol consumption.

CONTEXTE: Le diabète sucré (DM) est un état clinique caractérisé par une hyperglycémie persistante résultant d'une carence en insuline et/ou d'une résistance à l'insuline. L'étude actuelle vise à évaluer la perte auditive chez les patients atteints de diabète sucré dans une population urbaine sélectionnée du sud-ouest du Nigeria en utilisant l'audiométrie tonale et l'évaluation de l'émission otoacoustique. Elle mettra en corrélation les résultats audiologiques avec des facteurs tels que l'âge, le sexe, le statut glycémique et la durée du diabète. MÉTHODES: Une étude transversale progressive a été menée de janvier 2021 à décembre 2021 sur 95 patients diabétiques consécutifs sélectionnés au hasard et se rendant dans les départements d'oto-rhino-laryngologie et de médecine. RÉSULTATS: Au total, 95 patients diabétiques consultant les cliniques ORL de l'hôpital ont consenti à participer à l'étude. Leur âge variait de 43 à 82 ans, avec une moyenne de 65,3 ± 8,4 ans. La majorité des patients étaient des femmes (73,7 %) ; le rapport femmes-hommes était d'environ 3:1. Environ la moitié d'entre eux étaient déjà à la retraite (49,5 %), tandis que plus de la moitié avaient au moins un niveau d'éducation tertiaire (53,7%).8,4 % des patients ont déclaré avoir des écoulements dans les oreilles, 24,2 % des démangeaisons et 5,3 % des écoulements nasaux récurrents. La prévalence de l'hyperglycémie était de 36,8 % chez les sujets, tandis que 5,3 % étaient hypoglycémiques. CONCLUSION: La déficience auditive est significativement associée au diabète et à d'autres facteurs de risque chez les patients atteints de diabète, notamment l'âge avancé, la profession, les mauvais contrôles glycémiques, le bruit excessif et la consommation d'alcool. Mots-clés: Diabète sucré, Perte auditive, Audiométrie, Émission otoacoustique.

Neonatal Hearing Screening Programme And Challenges Faced By The Developing Country: A Tertiary Care Hospital Experience.

OBJECTIVE: To screen new-borns to diagnose any hearing impairment early. METHODS: The prospective, cross-sectionalstudy was conducted at the Department of Otorhinolaryngology, Head and Neck Surgery Liaquat National Hospital, Karachi, from November 1, 2020, to April 30, 2021, and new- borns of either gender aged >12h born via spontaneous vaginal delivery, induced labour, and Caesarean section. A predesigned questionnaire was used to collect detailed case history, including gestational age, duration of labour, and other prenatal, natal, and postnatal risk factors. Otoacoustic emission test was performed, and infants referred twice were scheduled for complete diagnostic evaluation and brainstem evoked response audiometry. Data was analysed using SPSS 23. RESULTS: Of the 267 neonates, 249(93.3%) passed the first screening. Of the remaining 18(6.7%) neonates, 8(44.4%) passed the second screening, while 10(55.5%) were asked to come for a follow-up after three weeks. Of them, 3(30%) returned for check-up, while 7(70%) did not show up. CONCLUSIONS: Neonatal risk factors associated with hearing loss need to be identified, and a comprehensive hearing screening programme is required for neonates.

Results of the Study of the Auditory Analyzer in Newborns with Hyperbilirubinemia.

According to statistics, hyperbilirubinemia is observed during the first week of life in approximately 60% of full-term and 80% of premature newborns. It is known that indirect bilirubin has a neurotoxic effect. Accumulation of unconjugated bilirubin in some brain structures may appear to be a temporary or unexpected impairment in auditory, motor, or cognitive function. The narrowing of the OAE spectrum and low amplitude of the response, the increase in the latent periods of III, IV, V peaks, as well as the prolongation of the time of the central sound conduction of the III-V and I-V waves in all newborns with hyperilirubinemia, indicates a pathology of hearing of central origin with impaired conduction along the auditory pathways at the level the lower and middle thirds of the pons of the brain (Р ≤ 0.05).

Otogelin, otogelin-like, and stereocilin form links connecting outer hair cell stereocilia to each other and the tectorial membrane.

The function of outer hair cells (OHCs), the mechanical actuators of the cochlea, involves the anchoring of their tallest stereocilia in the tectorial membrane (TM), an acellular structure overlying the sensory epithelium. Otogelin and otogelin-like are TM proteins related to secreted epithelial mucins. Defects in either cause the DFNB18B and DFNB84B genetic forms of deafness, respectively, both characterized by congenital mild-to-moderate hearing impairment. We show here that mutant mice lacking otogelin or otogelin-like have a marked OHC dysfunction, with almost no acoustic distortion products despite the persistence of some mechanoelectrical transduction. In both mutants, these cells lack the horizontal top connectors, which are fibrous links joining adjacent stereocilia, and the TM-attachment crowns coupling the tallest stereocilia to the TM. These defects are consistent with the previously unrecognized presence of otogelin and otogelin-like in the OHC hair bundle. The defective hair bundle cohesiveness and the absence of stereociliary imprints in the TM observed in these mice have also been observed in mutant mice lacking stereocilin, a model of the DFNB16 genetic form of deafness, also characterized by congenital mild-to-moderate hearing impairment. We show that the localizations of stereocilin, otogelin, and otogelin-like in the hair bundle are interdependent, indicating that these proteins interact to form the horizontal top connectors and the TM-attachment crowns. We therefore suggest that these 2 OHC-specific structures have shared mechanical properties mediating reaction forces to sound-induced shearing motion and contributing to the coordinated displacement of stereocilia.

Distortion Product Otoacoustic Emission Test is Not the Test to Use in Nonclinical Safety Assessment.

Ototoxicity and ocular toxicity screening are but two examples of specialty product lines that are often employed as Tier II or III nonclinical safety/hazard screening assessments. Compared to the regulatory guidelines that govern over standard toxicology or neurotoxicology programs, there is a paucity of regulatory strategies to address these specialized product lines. With respect to ototoxicity testing, we argue for the inclusion of the "least burdensome principles" adopted by the US FDA in providing the most pragmatic, efficient, and directed identification of potential harm to auditory function in the nonclinical safety arena. We argue for the exclusive use of the auditory brainstem response and the exclusion of the distortion product otoacoustic emissions (DPOAEs) in these Tiered II safety assessment programs. The inclusion of both are a burden on operational staff and, due to the extended episodes of anesthesia required to conduct both assays, this strategy poses a health and welfare concern for the selected animal species to be used. The DPOAE does not provide any sufficiently valid or reliable data above and beyond the gold standard ABR data, followed by complete oto-histopathology and cytocochleogram combination designs.

Hearing Impairment and Audiological Alterations in Euthyroid Hashimoto's Thyroiditis.

INTRODUCTION: Hearing loss may be associated with autoimmune diseases, but it was less studied in Hashimoto's thyroiditis (HT). We aimed to evaluate hearing impairment and audiological alterations in adults with euthyroid HT. METHODS: Adult patients with euthyroid HT (normal thyroid functions, positive antithyroid peroxidase (anti-TPO)/anti-thyroglobulin, and sonographic findings) were compared with controls. We excluded pregnant or older patients (>40 years), those with a history of otological/audiological disease or surgery, otitis media, acoustic trauma, chronic illnesses, use of alcohol, cigarette, medications, rheumatoid factor, antinuclear, antimitochondrial, antiparietal, antineutrophil cytoplasmic, anti-smooth muscle, or antigliadin antibodies, abnormal biochemical or otological findings. Tympanometry which indicates tympanic peak pressure (TPP, daPa), acoustic reflex testing (ART), pure-tone average (PTA), and transient evoked otoacoustic emission (TEOAE) were performed. We grouped the participants according to ART (positive/negative), TEOAE (normal/undetected), and PTA (≤20/>20 decibel). RESULTS: Air conduction thresholds on the right ear at 500, 4,000, 6,000, and 8,000 Hz, PTA, and the left ear at 250, 4,000, 6,000, and 8,000 Hz were higher in euthyroid HT (n = 36) than in controls (n = 40) (p < 0.05). We found less negative TPP and a higher ratio of negative ART in euthyroid HT (p < 0.05). Euthyroid HT predicted undetected TEOAE and increased hearing threshold on the right ear at 500 and 8,000 Hz (p < 0.001). TEOAE detected audiological abnormality at a higher rate. Anti-TPO was positively correlated with TPP and air conduction thresholds, except the right ear at 8,000 Hz. DISCUSSION/CONCLUSION: Hearing and audiological tests may be impaired in euthyroid HT. We recommend close monitoring of audiological functions in these patients. TE-OAE more specifically indicates audiological abnormality.

Audiological involvement in patients with systemic sclerosis.

OBJECTIVES: The aim of the present study was to evaluate hearing loss in patients diagnosed with systemic sclerosis (SSc) and to investigate the relation between hearing loss, subtypes of the disease, its duration and clinical findings, and antibody positivity. METHODS: The study included 47 patients with SSc and 44 healthy controls. Audiometric, tympanometric, and otoacoustic emission measurements were applied to both groups. RESULTS: The evaluation of the participants medical history showed that among the patients with SSc, 19.1% experienced ear fullness, 27.7% experienced vertigo, and 36.2% experienced tinnitus. Hearing loss was detected in 23.4% of the patients with SSc. The corresponding result was 4.3% in the control group with a statistically significant difference (p = 0.001). Transient-evoked otoacoustic emission amplitude values were significantly lower in the patients' both ears with SSc than the control group (p < 0.005). Duration of disease was significantly longer, and diffusing capacity of the lungs for carbon monoxide values were significantly higher in the patients with SSc and sensorineural hearing loss. CONCLUSIONS: The present study found that the incidence of hearing loss was significantly higher in the study group than in the healthy control group. In addition to other organ involvements, cochlear involvement occurs in these patients, and further studies are required.

Hearing Impairment in Infants with Asphyxia.

In recent decades, despite significant advances in medicine and perinatal care, asphyxia remains a serious condition, leading to significant mortality and morbidity. The incidence of severe perinatal asphyxia varies from 1 to 3 per 1000 live births, in developed countries 5-10 per 1000 or more in developing countries, and is the third most common cause of neonatal death (23%) after preterm birth (28%) and severe infection (26%). Neonatal asphyxia is often accompanied by multiple organ failure, mainly involving the kidneys, brain, and heart. Asphyxia results in significant tissue hypoperfusion and reduced oxygen supply, which can cause neurological damage and damage to cochlear hair cells. Under our supervision were 35 (n=30) newborns who were in the neonatal intensive care unit of the Perinatal Center of the Khorezm region in the period from 2018 to 2019. Of these, 22 (I (main) group n=22), who were in the neonatal pathology department, had signs of perinatal CNS damage; The comparison group included 13 newborns (n=13), with Apgar scores >7 in the first minute. There is a clear correlation between the degree of hearing impairment in infants and the degree of pathology of the CNS. However, the degree of impairment of the auditory analyzer increased in parallel with the degree of asphyxia and severity (P≤0,05).

Prenatal Exposure to Tobacco and Alcohol Alters Development of the Neonatal Auditory System.

Prenatal exposures to alcohol (PAE) and tobacco (PTE) are known to produce adverse neonatal and childhood outcomes including damage to the developing auditory system. Knowledge of the timing, extent, and combinations of these exposures on effects on the developing system is limited. As part of the physiological measurements from the Safe Passage Study, Auditory Brainstem Responses (ABRs) and Transient Otoacoustic Emissions (TEOAEs) were acquired on infants at birth and one-month of age. Research sites were in South Africa and the Northern Plains of the U.S. Prenatal information on alcohol and tobacco exposure was gathered prospectively on mother/infant dyads. Cluster analysis was used to characterize three levels of PAE and three levels of PTE. Repeated-measures ANOVAs were conducted for newborn and one-month-old infants for ABR peak latencies and amplitudes and TEOAE levels and signal-to-noise ratios. Analyses controlled for hours of life at test, gestational age at birth, sex, site, and other exposure. Significant main effects of PTE included reduced newborn ABR latencies from both ears. PTE also resulted in a significant reduction of ABR peak amplitudes elicited in infants at 1-month of age. PAE led to a reduction of TEOAE amplitude for 1-month-old infants but only in the left ear. Results indicate that PAE and PTE lead to early disruption of peripheral, brainstem, and cortical development and neuronal pathways of the auditory system, including the olivocochlear pathway.

Risk Factors for Failure in First-Time Hearing Screening Tests among High-Risk Neonates in Neonatal Intensive Care Unit.

OBJECTIVE: The aim of the study was to investigate into the risk factors for failure in the first-time screening test among high-risk neonates in neonatal intensive care unit (NICU) in order to further clarify the etiology of neonatal hearing impairment, thus providing insights into early prevention and intervention. METHODS: We performed automated auditory brainstem response (AABR), distortion product otoacoustic emission (DPOAE), and acoustic immittance (AI) on 2,194 high-risk neonates admitted into the NICU of Shanghai Children's Medical Center from January 2015 to December 2019, and the risk factors, including premature birth, hyperbilirubinemia, and infant respiratory distress syndrome, were analyzed retrospectively by the univariate χ2 test and multivariate stepwise logistic regression analysis. RESULTS: The pass rates of AABR, DPOAE, and AI were 70.21, 78.44, and 93.12%, respectively, in 2,194 cases of high-risk neonates screened, which are significantly lower than those of healthy controls. The most common diagnoses included artificial feeding, preterm birth, C-section, low birth weight (LBW), neonatal hyperbilirubinemia (NHB), neonatal respiratory distress syndrome (NRDS), congenital heart disease (CHD), gestational diabetes mellitus, pregnancy-induced hypertension syndrome, advanced maternal age (AMA), twins, and in vitro fertilization. Stepwise logistic regression analysis indicated that the AABR pass rate was negatively correlated with LBW (p = 0.002), NHB (p < 0.001), NRDS (p = 0.007), artificial or mixed feeding (p = 0.018), and CHD (p = 0.005). The pass rate of DPOAE was negatively correlated with artificial or mixed feeding (p = 0.041), NHB (p < 0.001), LBW (p = 0.007), very LBW (VLBW) (p = 0.008), and C-section (p < 0.001). The pass rate of AI was negatively correlated with revised AMA (≥40 year) (p < 0.001), NHB (p = 0.043), C-section (p = 0.005), and artificial/mixed feeding (p = 0.036). CONCLUSION: The hearing screening pass rates of high-risk neonates in the NICU were lower than those of normal neonates, among which the rate of AABR was significantly lower than that of DPOAE. NRDS, NHB, LBW, revised AMA, CHD, C-section, and artificial feeding are potential risk factors of hearing impairment. The combination of different hearing screening tests is necessary for accurate diagnosis of congenital hearing disorders.

Noise Exposure and Distortion Product Otoacoustic Emission Suprathreshold Amplitudes: A Genome-Wide Association Study.

BACKGROUND: Although several candidate-gene association studies have been conducted to investigate noise-induced hearing loss (NIHL) in humans, most are underpowered, unreplicated, and account for only a fraction of the genetic risk. Mouse genome-wide association studies (GWASs) have revolutionized the field of genetics and have led to the discovery of hundreds of genes involved in complex traits. The hybrid mouse diversity panel (HMDP) is a collection of classic inbred and recombinant inbred strains whose genomes have been either genotyped at high resolution or sequenced. To further investigate the genetics of NIHL, we report the first GWAS based on distortion product otoacoustic emission (DPOAE) measurements and the HMDP. METHODS: A total of 102 strains (n = 635) from the HMDP were evaluated based on DPOAE suprathreshold amplitudes before and after noise exposure. DPOAE amplitude variation was set at 60 and 70 dB SPL of the primary tones for each frequency separately (8, 11.3, 16, 22.6, and 32 kHz). These values provided an indirect assessment of outer hair cell integrity. Six-week-old mice were exposed for 2 h to 10 kHz octave-band noise at 108 dB SPL. To perform local expression quantitative trait locus (eQTL) analysis, gene expression microarray profiles were generated using cochlear RNA from 64 hybrid mouse strains (n = 3 arrays per strain). RESULTS: Several new loci were identified and positional candidate-genes associated with NIHL were prioritized, especially after noise exposure (1 locus at baseline and 5 loci after exposure). A total of 35 candidate genes in these 6 loci were identified with at least 1 probe whose expression was regulated by a significant cis-eQTL in the cochlea. After careful analysis of the candidate genes based on cochlear gene expression, 2 candidate genes were prioritized: Eya1 (baseline) and Efr3a (post-exposure). DISCUSSION AND CONCLUSION: For the first time, an association analysis with correction for population structure was used to map several loci for hearing traits in inbred strains of mice based on DPOAE suprathreshold amplitudes before and after noise exposure. Our results identified a number of novel loci and candidate genes for susceptibility to NIHL, especially the Eya1 and Efr3a genes. Our findings validate the power of the HMDP for detecting NIHL susceptibility genes.

Evaluation of the hearing status in carpenters.

PURPOSE: Carpenters are constantly exposed to a noise level of 82-100 dB(A) in their professional lives. The aim of this study is to evaluate the hearing status of carpenters with pure -tone audiometry and transient evoked otoacoustic emissions test. METHODS: A total of 62 individuals were enrolled. The study group consisted of 31 carpenters and the controls were age and sex matched healthy individuals who were not exposed to continuous or sudden noise. RESULTS: The average age of the carpenters is 44.58 ± 10.33, the average age of the control group is 41.84 ± 8.65 and there was no statistically significant difference (p = 0.262). There was a significant hearing loss in the study group nearly at all frequencies when compared to the control group (p < 0.05). The emission values of the right and left ears of the carpenters were significantly lower than the controls at 2000 and 2800 Hz (p < 0.05). CONCLUSION: Accordingly, carpenters seem to be susceptible to the development of noise-induced hearing loss.