Auditory Brainstem Response Testing Research Articles

Evaluation of an Investigational Hearing Screening Device (HeLe) to Demonstrate Acoustic Brainstem Response among Normal-hearing Adults.

This pilot human trial demonstrates the ability of the investigational newborn hearing screening device to provide acoustic stimulation to produce evoked potentials, as well as its ability to capture and acquire auditory evoked potentials, especially the auditory brainstem response (ABR) wave V. This pilot study also demonstrates the ease of recognizing and identifying ABR waves in the graphical presentation of the evoked potentials over time. Fourteen normal-hearing adults or a total of twenty-eight (28) normal-hearing adult ears underwent auditory brainstem response testing using the investigational hearing screening device. A commercially available auditory brainstem response detection device was used to confirm that the acquired ABR waves of the investigational device are normal. The ABR waves displayed by the investigation device were also reviewed by the clinical audiologists to determine their recognizability and identifiability. The pilot trial demonstrates the ability of the investigational newborn hearing screening device in providing acoustic stimulation to produce evoked potentials, and in acquiring and capturing ABR waves, specifically the wave V, among normal-hearing adult ears. The clinical audiologists recognized and identified the ABR wave V among the evoked potentials at 40dB, 60dB, and 80dB acoustic stimulation. About eighty-nine percent (89.2%) of all ears tested had identifiable and recognizable wave V upon acoustic stimulation at 40dB. The investigational hearing screening device: (1) can provide acoustic stimulation to produce evoked potentials, (2) can accurately capture and acquire these evoked potentials, (3) can present these evoked potentials in a voltage per time graphical display which an audiologist and trained HCP can easily read and interpret (diagnostic ABR), and (4) can present wave V auditory brainstem potentials that can be easily identified by an audiologist and trained HCP (screening ABR).

Investigation of hearing loss in elderly vertigo and dizziness patients in the past 10 years.

Vertigo and hearing loss are both prevalent in the elderly. This study retrospectively analyzed hearing test results from elderly patients experiencing vertigo and dizziness at ENT outpatient over a 10-year period, in order to study the patterns of hearing loss in this patient population. Nine thousand three hundred eighty four patients over 50 years old underwent retrospective collection and screening of outpatient diagnosis, pure tone audiometry, acoustic immittance measurement (tympanogram) and auditory brainstem response (ABR) test. The patient's audiograms are divided into 7 subtypes according to a set of fixed criteria. Meanwhile, K-Means clustering analysis method was used to classify the audiogram. The Jerger classification of tympanogram in elderly patients with vertigo and dizziness showed the majority falling under type A. The leading audiogram shapes were flat (27.81% in right ear and 26.89% in left ear), high-frequency gently sloping (25.97% in right ear and 27.34% in left ear), and high-frequency steeply sloping (21.60% in right ear and 22.53% in left ear). Meniere's disease (MD; 30.87%), benign recurrent vertigo (BRV; 19.07%), and benign paroxysmal positional vertigo (BPPV; 15.66%) were the most common etiologies in elderly vestibular diseases. We observed statistically significant differences in hearing thresholds among these vestibular diseases (P < 0.001). K-Means clustering analysis suggested that the optimal number of clusters was three, with sample sizes for the three clusters being 2,747, 2,413, and 4,139, respectively. The ANOVA statistical results of each characteristic value showed P < 0.001. The elderly patients often have mild to moderate hearing loss as a concomitant symptom with vertigo. Female patients have better hearing thresholds than males. The dominant audiometric shapes in this patient population were flat, high-frequency gently sloping, and high-frequency steeply sloping according to a set of fixed criteria. This study highlights the need for tailored strategies in managing hearing loss in elderly patients with vertigo and dizziness.

Effects of Cross-linked Hyaluronic Acid in a Rat Model of Vestibular and Cochlear Toxicity.

To investigate the effects of cross-linked hyaluronic acid (CLHA) in an experimental model of vestibulotoxicity and cochleotoxicity. Twenty-eight female Wistar albino rats (200-250 g) were divided into four groups. Group A received 0.06 mL of 13.33 mg/mL gentamicin, Group B received 0.06 mL of CLHA, Group C received 0.03 mL of 26.66 mg/mL gentamicin and 0.03 mL CLHA, and Group D received 0.06 mL of 0.09% saline. All groups underwent auditory brainstem response testing at 4-32 kHz, signal-to-noise ratio of distortion product otoacoustic emission measurements at 1.5-8 kHz and vestibular tests on days 0,1,7,10. The rats were sacrificed, and their labyrinths were histologically assessed and scored. The hearing thresholds of Groups A and C were similar and significantly higher than those of the other groups at all frequencies, beginning from day 1. The vestibular and histological scores of Groups A and C were similar and significantly higher than those of the other groups from day 1. The audiological results, vestibular scores, and histological scores of Groups B and D were similar, except for a temporary middle ear effusion and hearing threshold shift in Group B. No significant deterioration was observed in the audiological, vestibular, and histological analyses of Groups B and D. That both Group A and Group C similarly showed worsening audiological, vestibular, and histological tests suggests that CLHA did not alter the pharmacokinetics and histologic results of gentamicin.

Frequency of hearing impairment in neonates born in a tertiary-care hospital of a developing country: A prospective-observational study.

Objective: To evaluate the frequency of hearing impairment and the prenatal, antenatal, and postnatal variables associated with hearing impairment in neonates at the Indus hospital in Karachi. Study Design: Prospective, Observational, Cohort study. Setting: Department of Pediatrics and Neonatology, Sheikh Saeed Memorial Campus (SSMC) of Indus Hospital and Health Network (IHHN) Karachi, Pakistan. Period: July 2020 to June 2022. Material &amp; Methods: We screened 426 neonates for hearing impairment utilizing otoacoustic emissions (OAEs) Auditory brainstem response test (ABR) and “brainstem auditory evoked response” (BERA). Babies who failed OAE and ABR test underwent BERA. Babies with abnormal BERA report were proven to have hearing impairment. Results: A total of 426 neonates were screened through the study period. Of these 426, 134 (31.5%) were unsuccessful and a second stage OAE test was conducted where 63 (47.0%) passed and 71 (53.0%) did not. The ABR test was administered to 71 neonates, 42 (59.2%) failed the test and received referrals for diagnostic BERA. Of those 42 neonates, 15 neonates tested positive for BERA, 10 of them were found to have sensor neural hearing loss while 5 had conductive hearing loss. Neonatal jaundice patients were more likely to experience hearing impairment (p=0.011). Family history of hearing loss (p=0.001) and fetal distress (p=0.043) were significantly related with hearing impairment. Conclusion: The result of our study has discovered a significant number of risk factors for hearing loss, which is crucial since it will allow for close monitoring of the kids who have these risk factors. Furthermore, our research emphasizes the need of newborn hearing screening in our country, since this screening is not generally carried out in all facilities.

Multi-transfer learning techniques for detecting auditory brainstem response

The assessment of the well-being of the peripheral auditory nerve system in individuals experiencing hearing impairment is conducted through auditory brainstem response (ABR) testing. Audiologists assess and document the results of the ABR test. They interpret the findings and assign labels to them using reference-based markers like peak latency, waveform morphology, amplitude, and other relevant factors. Inaccurate assessment of ABR tests may lead to incorrect judgments regarding the integrity of the auditory nerve system; therefore, proper Hearing Loss (HL) diagnosis and analysis are essential. In order to identify and assess ABR automation while decreasing the possibility of human error, machine learning methods, notably deep learning, may be an appropriate option. To address these issues, this study proposed deep-learning models using the transfer-learning (TL) approach to extract features from ABR testing and diagnose HL using support vector machines (SVM). Pre-trained convolutional neural network (CNN) architectures like AlexNet, DenseNet, GoogleNet, InceptionResNetV2, InceptionV3, MobileNetV2, NASNetMobile, ResNet18, ResNet50, ResNet101, ShuffleNet, and SqueezeNet are used to extract features from the collected ABR reported images dataset in the proposed model. It has been decided to use six measures accuracy, precision, recall, geometric mean (GM), standard deviation (SD), and area under the ROC curve to measure the effectiveness of the proposed model. According to experimental findings, the ShuffleNet and ResNet50 models' TL is effective for ABR to diagnosis HL using an SVM classifier, with a high accuracy rate of 95% when using the 5-fold cross-validation method.

Tympanometric and auditory brainstem response findings among children with down syndrome

Background: The Worldwide prevalence of Down syndrome children with hearing loss is 38–78% with conductive hearing loss accounting for the majority of cases and a documented 20%. Otitis media with effusion (OME) is common in 2-year-olds. Objective: To determine the tympanometric and auditory brainstem response findings among children with Down syndrome. Methodology: Cross sectional observational study was conducted to determine the tympanometric and auditory brainstem response findings among children with Down syndrome on a sample of 98 patients both Male and Female with Non-probability purposive sampling technique. The study was performed at the Children's Hospital and Institute of Child Health in Lahore. The duration of this study was 6 months, from January 2023 to June 2023. Children aged 1 to 6 years were included in this study. A self-structured questionnaire, tympanometry, and auditory brainstem response test were used to accumulate the data. The data was analysed using the SPSS version 24.0 software package. Results: Among the 98 DS patients, there were 52 (70.41%) male patients and 46 (29.59%) female patients. The majority of patients were in the age group 1-3 years, which is 61 (65.31%) in number. From the analysis of the tympanometry test, it was found that the majority of patients had type B tympanograms, which is 55 (56.1%), and type C tympanograms were also shown in 28 (28.6%) patients. Results of BAEP showed that most patients had moderate-degree hearing loss 70 (71.1%) and 15 (15.3%) had normal hearing. Conclusion: This study concluded that the majority of children had moderate degree conductive hearing loss rather than mild to severe degree mixed and sensorineural hearing loss. Key words: Down syndrome, Pediatric Hearing Loss, Tympanometry, Auditory Brainstem Response, Otitis Media with Effusion

Evaluation of the auditory findings of patients with obstructive sleep apnea syndrome

ObjectivesTo investigate the effects of hypoxia occurring in patients with Obstructive Sleep Apnea Syndrome (OSAS) on Auditory evoked late latency, Auditory brainstem response, and the contralateral suppression of otoacoustic emissions. Materials and methods46 patients diagnosed with OSAS were divided into groups as moderate and severe based on their Apnea Hipopnea Index (AHI) values. The control group consisted of 22 healthy individuals. All participants underwent an Auditory Brainstem Response (ABR) test, Auditory Evoked Late Latency Response (LLR), and Contralateral Suppression Otoacoustic Emission (CS-OAE). FindingsThere was no statistical difference between the OSAS group and the control group regarding P1 latency, N1 latency, and P1 and N1 wave amplitude (p > 0.05). In ABR, statistically significant differences were found between the control, moderate OSAS, and severe OSAS groups in wave I in the right and left ear (p < 0.05). In the analyses performed for the otoacoustic emission frequencies with and without contralateral suppression of the right and left ear, suppression was not observed at some frequencies, and this was regarded as statistically significant (p < 0.05). ConclusionIt is considered that OSAS does not have cortical effects but impacts the brainstem region and the cochlea. Bilateral impact, especially observed in wave I of ABR, is prominent on the auditory nerve. Considering that the medial olivo-cochlear (MOC) system is affected in patients with OSAS, it is thought that these patients are inadequate in suppressing noise, and this may cause various problems, particularly the inability to distinguish speech in noisy environments.

Mefloquine-Induced Inner Ear Damage and Preventive Effects of Electrical Stimulation: An Electrophysiological Study

Introduction: Mefloquine is an antimalarial medicine used to prevent and treat malaria. This medicine has some side effects, including ototoxicity. This study, which was designed in two phases, aimed to investigate the side effects of mefloquine and evaluate the preventive effects of electrical stimulation on these side effects. Methods: In the first phase, two doses of mefloquine (50 and 200 μ<sc>M</sc>) were injected into male rats, and after 7 days, they were evaluated by an auditory brainstem response (ABR) test. In the second phase, electrical stimulation was applied for 10 days, and then a toxic dose of mefloquine was injected. Similar to the first phase of the study, the animals were evaluated by an ABR test after 7 days. Results: In the first phase, the results showed that a high dose of mefloquine increased the ABR threshold and wave I latency; however, these changes were not observed in the second phase. Conclusion: Application of electrical stimulation could prevent the ototoxic effects of mefloquine. According to the findings of the present study, electrical stimulation can be used as a preconditioner to prevent the ototoxic effects of mefloquine.

Can Ganciclovir and Quercetin-P188 Ameliorate Cytomegalovirus Induced Hearing Loss?

Determine whether combination therapy with ganciclovir (GCV) and a Quercetin-P188 solution improves hearing outcomes in a murine cytomegalovirus (CMV) model. BALB/c mice were infected with murine CMV on postnatal day 3 (p3). Quercetin was solubilized in saline using P188 (QP188). Treatment groups received either GCV, QP188, GCV and QP188, or P188 delivery vehicle BID at 12-hour intervals via intraperitoneal injection. All treatment groups were treated for 14 days starting at p3. Uninfected controls were treated with the combined regimen, saline or P188 delivery vehicle. Auditory thresholds were assessed using distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) testing at 4, 6, and 8 weeks of age. Temporal bones from separate CMV-infected groups were harvested at p10, and viral load was determined by quantitative polymerase chain reaction. CMV-infected mice receiving combination therapy GCV+QP188 demonstrated statistically significant lower ABR (p < 0.001) and DPOAE thresholds (p < 0.001) compared with mice treated with GCV monotherapy, QP188 monotherapy, and P188 delivery vehicle at 4, 6, and 8 weeks of age. GCV+QP188 combination therapy, GCV monotherapy, and QP188 monotherapy resulted in a nonsignificant reduction in mean viral titers compared to P188 monotherapy (p = 0.08). Combining GCV with the excipients quercetin and P188 effectively ameliorated CMV-induced sensorineural hearing loss in a murine model. This result may be partially explained by a reduction in viral titers in mouse temporal bones that correlate with in vitro studies demonstrating additive antiviral effect in cell culture. NA Laryngoscope, 134:1457-1463, 2024.

Acoustic and optoacoustic stimulations in auditory brainstem response test in salicylate induced tinnitus

As a common debilitating disorder worldwide, tinnitus requires objective assessment. In the auditory brainstem response (ABR) test, auditory potentials can be evoked by acoustic or optoacoustic (induced by laser light) stimulations. In order to use the ABR test in the objective assessment of tinnitus, in this study, acoustic ABR (aABR) and optoacoustic ABR (oABR) were compared in the control and tinnitus groups to determine the changes caused by sodium salicylate (SS)-induced tinnitus in rat. In both aABR and oABR, wave II was the most prominent waveform, and the amplitude of wave II evoked by oABR was significantly higher than that of aABR. Brainstem transmission time (BTT), which represents the time required for a neural stimulation to progress from the auditory nerve ending to the inferior colliculus, was significantly shorter in oABR. In the tinnitus group, there was a significant increase in the threshold of both ABRs and a significant decrease in the amplitude of wave II only in the oABR. Based on our findings, the ABR test has the potential to be used in the assessment of SS-induced tinnitus, but oABR has the advantages of producing more prominent waveforms and significantly reducing the amplitude of wave II in tinnitus.

Quantitative Threshold Determination of Auditory Brainstem Responses in Mouse Models.

The auditory brainstem response (ABR) is a scalp recording of potentials produced by sound stimulation, and is commonly used as an indicator of auditory function. However, the ABR threshold, which is the lowest audible sound pressure, cannot be objectively determined since it is determined visually using a measurer, and this has been a problem for several decades. Although various algorithms have been developed to objectively determine ABR thresholds, they remain lacking in terms of accuracy, efficiency, and convenience. Accordingly, we proposed an improved algorithm based on the mutual covariance at adjacent sound pressure levels. An ideal ABR waveform with clearly defined waves I-V was created; moreover, using this waveform as a standard template, the experimentally obtained ABR waveform was inspected for disturbances based on mutual covariance. The ABR testing was repeated if the value was below the established cross-covariance reference value. Our proposed method allowed more efficient objective determination of ABR thresholds and a smaller burden on experimental animals.

Hearing Following Prolonged and Delayed Ganciclovir Treatment in a Murine Cytomegalovirus Model.

Compare hearing outcomes utilizing standard, prolonged and delayed ganciclovir (GCV) therapy in a murine model of cytomegalovirus (CMV). BALB/c mice were inoculated with mouse cytomegalovirus (mCMV) or saline via intracerebral injection on postnatal day 3 (p3). Intraperitoneal GCV or saline was administered at 12 h intervals for the duration of the standard (p3-p17), delayed (p30-p44), or prolonged treatment windows (p3-p31). Auditory thresholds were assessed using distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) testing at 4, 6, and 8 weeks of age. Blood and tissue samples were harvested from mice on p17 and p37 one hour after GCV administration, and their concentrations were assessed via liquid chromatography-mass spectrometry. A delayed course of GCV improved ABR but not DPOAE thresholds in mCMV-infected mice. A prolonged course of GCV did not provide better hearing thresholds than those administered standard treatment. The average GCV concentration in all 17-day-old mice tissue was significantly higher than those in older 37-day-old mice. Delayed GCV treatment provided a hearing benefit on ABR over untreated mCMV infected mice. Prolonged CGV administration showed no benefit compared to a shorter duration GCV treatment. GCV drug concentrations both systemically and in the cochlea are much lower in older mice. These results have potential implications for the clinical management of cCMV infected children. NA Laryngoscope, 134:433-438, 2024.

Comparative study of SSNHL with and without tinnitus: audiologic and hematologic differences

Background and Objectives Tinnitus is one of the most common symptoms of sudden sensorineural hearing loss (SSNHL), with the incidence of tinnitus in patients with SSNHL ranging from 60% to 90%. Little is known, however, about the specific audiologic and hematologic factors that may be associated with the development of tinnitus. To better understand the relationship between tinnitus and SSNHL, the present study compared audiologic and hematologic factors in SSNHL patients with tinnitus and without tinnitus. Subjects and Method The present study compared 120 patients with SSNHL with tinnitus and 59 patients with SSNHL without tinnitus at their initial examination. Their audiology and hematologic test results were analyzed, and hearing recovery was determined by comparing the hearing thresholds before and after treatment. Results 120 patients with tinnitus showed longer III and V latency in auditory brainstem response (ABR) tests, lower signal-to-noise ratios (SNR) at 2 kHz in transient evoked otoacoustic emissions (TEOAE) tests, and lower response rates at 2 kHz in distortion product otoacoustic emissions (DPOAE) tests of the affected ear (p < 0.05 each) than the 59 patients without tinnitus. However, there were no significant between-group differences in the mean hearing threshold and hearing recovery rate of the affected ear. Patients with tinnitus had significantly worse mean hearing thresholds and hearing thresholds at 4 kHz in the nonaffected ear. The percentages of monocytes and large unstained cells (%LUCs) were higher in the group without tinnitus (p < 0.05), although there were no significant between-group differences in inflammatory markers, such as neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR) and platelet-to-lymphocyte ratio (PLR). Conclusion Tinnitus accompanying SSNHL may be associated with baseline hearing level, as well as being an indicator of damage to outer hair cells and auditory nerves. Additional studies are needed to evaluate hematologic data in SSNHL patients with and without tinnitus.

A machine learning approach for prediction of auditory brain stem response in patients after head-and-neck radiation therapy.

The present study aimed to assess machine learning (ML) models according to radiomic features to predict ototoxicity using auditory brain stem responses (ABRs) in patients with radiation therapy (RT) for head-and-neck cancers. The ABR test was performed on 50 patients having head-and-neck RT. Radiomic features were extracted from the brain stem in computed tomography images to generate a radiomic signature. Moreover, accuracy, sensitivity, specificity, the area under the curve, and mean cross-validation were used to evaluate six different ML models. Out of 50 patients, 21 participants experienced ototoxicity. Furthermore, 140 radiomic features were extracted from the segmented area. Among the six ML models, the Random Forest method with 77% accuracy provided the best result. According to the ML approach, we showed the relatively high prediction power of the radiomic features in radiation-induced ototoxicity. To better predict the outcomes, future studies on a larger number of participants are recommended.

Short-term outcomes of infants with hyperbilirubinemia-associated auditory neuropathy spectrum disorder in neonatal intensive care unit

Hyperbilirubinemia is a high-risk factor for auditory neuropathy spectrum disorder (ANSD) as well as hearing loss in general. This study described the outcomes of hyperbilirubinemia-associated ANSD infants diagnosed in hearing screening in the neonatal intensive care unit (NICU).A total of 578 children with hyperbilirubinemia admitted to the NICU between October 2020 and October 2021 were included in this study. The distortion product otoacoustic emission (DPOAE) and automatic auditory brainstem response (AABR) were combined for hearing screening, and those who failed the DPOAE or/and AABR underwent an auditory brainstem response (ABR) test. Infants with ANSD were followed up for 12 months.Forty infants (40/578, 6.9%) failed the DPOAE or/and AABR tests, of which, 13 (13/578, 2.2%) were diagnosed as ANSD, and 27 (27/578, 4.7%) were diagnosed as having sensorineural hearing loss (SNHL). Of the 13 ANSD infants followed up for 12 months, 7 recovered, 3 improved, 3 did not recover, and 1 was lost, equating to improved or recovered hearing in 75% (9/12) of ANSD infants at 12 months of age. Moreover, the maximum bilirubin in recovered or improved ANSD infants was 408.6 ± 129.0 μmol/L, while the maximum bilirubin in unrecovered ANSD infants was 749.3 ± 323.0 μmol/L. Furthermore, poorly differentiated and absent ABR waveforms were observed in 6 and 14 ears at 1 month, 2 ears were lost, 6 (6/6, 100.0%) and 6 (6/12, 50.0%) ears were recovered or improved at 12 months of age.s: The incidence of hyperbilirubinemia associated-ANSD was 2.2% of infants screened in the NICU. ANSD caused by hyperbilirubinemia may be transient, with most infants improving or recovering hearing by 12 months of age. Infants with poorly differentiated ABR waveforms and low bilirubin concentration are more likely to recover and hearing aids are not recommended in hyperbilirubinemia-associated ANSD below 12 months of age.

SMARCA4 mutation causes human otosclerosis and a similar phenotype in mice

BackgroundOtosclerosis is a common cause of adult-onset progressive hearing loss, affecting 0.3%–0.4% of the population. It results from dysregulation of bone homeostasis in the otic capsule, most commonly leading to...

Detection of auditory brainstem response peaks using image processing techniques in infants with normal hearing sensitivity

IntroductionThe auditory brainstem response (ABR) is measured to find the brainstem-level peripheral auditory nerve system integrity in children having normal hearing. The Auditory Evoked Potential (AEP)s are generated using acoustic stimuli. Interpreting these waves requires competence to avoid misdiagnosing hearing problems. Automating ABR test labeling with computer vision may reduce human error. MethodThe ABR test results of 26 children aged 1 to 20 months with normal hearing in both ears were used. A new approach is suggested for automatically calculating the peaks of waves of different intensities (in decibels). The procedure entails acquiring wave images from an Audera device using the Color Thresholder method, segmenting each wave as a single wave image using the Image Region Analyzer application, converting all wave images into waves using Image Processing (IP) techniques, and finally calculating the latency of the peaks for each wave to be used by an audiologist for diagnosing the disease. FindingsImage processing techniques were able to detect 1, 3, and 5 waves in the diagnosis field with accuracy (0.82), (0.98), and (0.98), respectively, and its precision for waves 1, 3, and 5, were respectively (0.32), (0.97) and (0.87). This evaluation also worked well in the thresholding part and 82.7 % correctly detected the ABR waves. ConclusionOur findings indicate that the audiology test battery suite can be made more accurate, quick, and error-free by using technology to automatically detect and label ABR waves.

Various aspects of hearing loss in newborns: A narrative review.

Hearing loss is considered the most common birth defect. The estimated prevalence of moderate and severe hearing loss in a normal newborn is 0.1%-0.3%, while the prevalence is 2%-4% in newborns admitted to the newborn intensive care unit. Neonatal hearing loss can be congenital (syndromic or non-syndromic) or acquired such as ototoxicity. In addition, the types of hearing loss can be conductive, sensorineural, or mixed. Hearing is vital for the acquisition of language and learning. Therefore, early detection and prompt treatment are of utmost importance in preventing the unwanted sequel of hearing loss. The hearing screening program is mandatory in many nations, especially for high-risk newborns. An automated auditory brainstem response test is used as a screening tool in newborns admitted to the newborn intensive care unit. Moreover, genetic testing and screening for cytomegalovirus in newborns are essential in identifying the cause of hearing loss, particularly, mild and delayed onset types of hearing loss. We aimed to update the knowledge on the various aspects of hearing loss in newborns with regard to the epidemiology, risk factors, causes, screening program, investigations, and different modalities of treatment.

Auditory brainstem functioning in individuals with misophonia

PurposeMisophonia is not investigated much from an audiological perspective. Our study aims to examine the processing of the auditory retro-cochlear pathways in individuals with misophonia. MethodsA cross-sectional study was conducted among university students who had misophonia. The revised Amsterdam Misophonia Scale was used to determine the severity of misophonia. Participants were divided into mild and moderate-severe misophonia and compared with the healthy control group. Auditory Brainstem Response testing was recorded from all the individuals with misophonia. The absolute latency, amplitude, inter-peak latency difference, and inter-rate latency difference were compared between the groups. ResultsOne-way ANOVA result showed no significant difference in all the parameters of auditory brainstem response between the groups. These results are suggestive of normal brainstem processing in individuals with misophonia. ConclusionsThe study concludes that the auditory pathway up to brainstem areas is intact in individuals with misophonia. Further studies are essential on a larger population for generalizing the results.

Single Fraction and Hypofractionated Radiation Cause Cochlear Damage, Hearing Loss, and Reduced Viability of Merlin-Deficient Schwann Cells.

Vestibular schwannomas (VS) are benign intracranial tumors caused by loss of function of the merlin tumor suppressor. We tested three hypotheses related to radiation, hearing loss (HL), and VS cell survival: (1) radiation causes HL by injuring auditory hair cells (AHC), (2) fractionation reduces radiation-induced HL, and (3) single fraction and equivalent appropriately dosed multi-fractions are equally effective at controlling VS growth. We investigated the effects of single fraction and hypofractionated radiation on hearing thresholds in rats, cell death pathways in rat cochleae, and viability of human merlin-deficient Schwann cells (MD-SC). Adult rats received cochlear irradiation with single fraction (0 to 18 Gray [Gy]) or hypofractionated radiation. Auditory brainstem response (ABR) testing was performed for 24 weeks. AHC viabilities were determined using immunohistochemistry. Neonatal rat cochleae were harvested after irradiation, and gene- and cell-based assays were conducted. MD-SCs were irradiated, and viability assays and immunofluorescence for DNA damage and cell cycle markers were performed. Radiation caused dose-dependent and progressive HL in rats and AHC losses by promoting expression of apoptosis-associated genes and proteins. When compared to 12 Gy single fraction, hypofractionation caused smaller ABR threshold and pure tone average shifts and was more effective at reducing MD-SC viability. Investigations into the mechanisms of radiation ototoxicity and VS radiobiology will help determine optimal radiation regimens and identify potential therapies to mitigate radiation-induced HL and improve VS tumor control.