Sensorineural Research Articles

The Long-Term Effect of Cochlear Implantation on Tinnitus: A Systematic Review and Meta-Analysis.

This systematic review investigates the long-term effect of cochlear implantation (CI) on clinical outcomes in tinnitus patients with sensorineural hearing loss (SNHL). PubMed, Embase, and the Cochrane Library were searched from inception to 30 April 2024. Manual searches of reference lists supplemented these searches when necessary. Original studies included in the meta-analysis had to contain comparative pre- and postoperative data for SNHL patients who underwent CI. Outcomes measured were the Tinnitus Handicap Inventory (THI), Visual Analog Scale (VAS), and Tinnitus Questionnaire (TQ). A total of 28 studies comprising 853 patients showed significant tinnitus improvement after CI: THI mean difference (MD) -14.02 [95%CI -15.29 to -12.76, p < 0.001], TQ MD -15.85 [95%CI -18.97 to -12.74, p < 0.05], and VAS MD -3.12 [95%CI -3.49 to -2.76, p < 0.05]. Subgroup analysis indicated a significant difference between follow-up periods in THI (p < 0.0001) and VAS loudness (p = 0.02). Cochlear implantation substantially improves tinnitus in patients with hearing loss, though the effect may diminish over time. Further research is needed to confirm these findings.

Identification of novel CDH23 variants linked to hearing loss in a Chinese family: A case report.

Deafness is associated with both environmental and genetic factors, with hereditary deafness often caused by mutations in deafness-related genes. Identifying and analyzing deafness-related genes will aid in early diagnosis and pave the way for treating inherited deafness through gene therapy in the future. A 15-month-old girl underwent audiological examination at the outpatient clinic of the hospital due to hearing loss and her brother was diagnosed with profound bilateral sensorineural hearing loss at the age of 3. The diagnosis was determined as extremely severe sensorineural hearing loss caused by genetic factors. Clinical data of the patient were collected, and peripheral blood samples were obtained from both the patient and her family members for DNA extraction and sequencing. By utilizing targeted capture next-generation sequencing to further screen for deafness-related genes, 2 novel variants in CDH23 were identified as the causative factors for the patient's deafness. This study identified 2 novel heterozygous mutations in a Chinese family. Both the proband and her sibling have non-syndromic hearing loss (NSHL) and carry distinct heterozygous mutations of cadherin-like 23 (CDH23). One mutation, CDH23:c.2651 A>G, originated from their mother and paternal family, affecting the exon23 domain of CDH23. The other mutation, CDH23:c.2113 G>T, was inherited from their paternal grandmother, impacting the exon19 domain of CDH23. These 2 novel mutations likely cause NSHL by affecting protein function. This finding suggests that identifying 2 novel mutations in CDH23 contributes to the genetic basis of NSHL.

The Impact of Monoclonal Antibody Usage on Hearing Outcomes: A Systematic Review.

To ascertain trends in ototoxicity observed with monoclonal antibodies (mABs) and understand the impact they may have on hearing function. PubMed, Embase, Scopus. A systematic review was performed following PRISMA guidelines. Data were reviewed for demographics, utilized mABs with respective indication and dosing, audiometric outcomes, and treatment for otologic effects. Of 757 studies reviewed, a total of 44 were included, encompassing 18,046 patients treated with mABs. Mean age of the sample was 57.8 years old. The search yielded 18 agents of ototoxicity, with reported symptoms of ototoxicity such as hearing loss, tinnitus, and/or aural fullness occurring in 1079 of total patients. Main agents causing ototoxicity were teprotumumab (n = 17/44 studies), nivolumab (n = 10/44), ipilimumab (n = 9/44), pembrolizumab (n = 5/44), and rituximab (n = 4/44). Thirty-one of 44 studies encompassing eight agents reported audiometric data for ototoxic agents, showing sensorineural hearing loss primarily in the high-frequency range. Only two articles performed ultrahigh-frequency audiograms. Monoclonal antibody usage is expanding, but the vast majority of studies lack substantial audiometric data. Where reported, study design and inclusion criteria vary greatly. Future studies would benefit from rigid inclusion of audiometric data, prospective study design, and consideration of formal ototoxicity screening. Otolaryngologists should be aware of the cochlear immune response and potential impact of this expanding medication class on hearing function. Laryngoscope, 2024.

Tonotopic and Default Frequency Fitting for Music Perception in Cochlear Implant Recipients

Cochlear implants are an effective technique for enhancing speech perception abilities in quiet environments for people with severe to profound deafness. Nevertheless, complex sound signals perception, such as music perception, remains challenging for cochlear implant users. To assess the benefit of a tonotopic map on music perception in new cochlear implant users. A prospective, randomized, double-blind, 2-period crossover study including 26 new cochlear implant users was performed over a 6-month period (June 2021 to November 2021). An anatomical tonotopic map was created using postoperative flat-panel computed tomography and a reconstruction software based on Greenwood function. New cochlear implant users older than 18 years with bilateral severe to profound sensorineural hearing loss or complete hearing loss for less than 5 years were selected in the University Hospital Centre of Rennes in France. The trial was conducted from June to November 2021 (inclusion) and to February 2022 (end of the assessment procedure at 12 weeks postactivation), and the analysis itself was completed in December 2022. Each participant was randomized to receive a conventional map followed by a tonotopic map or vice versa. Participants performed pitch-scaling tasks (multidimensional qualitative assessment, melodic contour identification, melodic recognition test) after 6 weeks of each setting. Thirteen participants were randomized to each sequence. Two of the 26 participants recruited (1 in each sequence) had to be excluded due to the COVID-19 pandemic. The multidimensional qualitative assessment (Gabrielsson test), melodic contour identification, and melodic recognition scores were significantly higher with the tonotopic setting than the conventional one (mean effect [ME], 7.8; 95% CI, 5.0-10.5; ME, 12.1%; 95% CI, 5.7%-18.4%; ME, 14.4%, 95% CI, 8.5%-20.2%; and ME, 2.1, 95% CI, 1.7-2.5, respectively). Among the different dimensions evaluated by the Gabrielsson test, the mean scores for clarity, spaciousness, fullness, nearness, and total impression were significantly higher with tonotopic fitting. Ninety-two percent of the participants kept the tonotopy-based map after the study period. In this randomized clinical trial of patients with new cochlear implants, a tonotopic-based fitting was associated with better results in perception of complex sound signals such as music listening experience. ClinicalTrials.gov Identifier: NCT04922619.

Ototoxicity-Alleviating and Cytoprotective Allomelanin Nanomedicine for Efficient Sensorineural Hearing Loss Treatment.

Sensorineural hearing loss (SNHL) represents a significant clinical challenge, predominantly attributed to oxidative stress-related mechanisms. In this work, we report an innovative antioxidant strategy for mitigating SNHL, utilizing synthetically engineered allomelanin nanoparticles (AMNPs). Empirical evidence elucidates AMNPs' profound capability in free radical neutralization, substantiated by a significant decrement in reactive oxygen species (ROS) levels within HEI-OC1 auditory cells exposure to cisplatin or hydrogen peroxide (H2O2). Comparative analyses reveal that AMNPs afford protection against cisplatin-induced and noise-induced auditory impairments, mirroring the effect of dexamethasone (DEX), a standard pharmacological treatment for acute SNHL. AMNPs exhibit notable cytoprotective properties for auditory hair cells (HCs), effectively preventing ototoxicity from cisplatin or H2O2 exposure, as confirmed by both in vitro assays and cultured organ of Corti studies. Further in vivo research corroborates AMNPs' ability to reverse auditory brainstem response (ABR) threshold shifts resulting from acoustic injury, concurrently reducing HCs loss, ribbon synapse depletion, and spiral ganglion neuron degeneration. The therapeutic benefits of AMNPs are attributed to mitigating oxidative stress and inflammation within the cochlea, with transcriptome analysis indicating downregulated gene expression related to these processes post-AMNPs treatment. The pronounced antioxidative and anti-inflammatory effects of AMNPs position them as a promising alternative to DEX for SNHL treatment.

Novel Clinical Manifestation and Favorable Treatment Outcome of Cochlear Implant in a Chinese Family With Likely Pathogenic Variant of the P2RX2 Gene.

The rapid development and clinical application of sequencing technologies enable the genetic diagnosis of inherited deafness. P2RX2, as the gene responsible for autosomal dominant non-syndromic deafness-41 (DFNA41), has been proven to be essential for life-long normal hearing and for the protection of noise-induced hearing loss (NIHL). Our present study reports a missense variant in the P2RX2 gene (c.178G > T (p.V60L)), for the second time worldwide, in a five-generation kindred living in Henan, China. Despite carrying the same variant, the affected members in this family appear to present with earlier-onset hearing loss and poorer hearing compared to the original DFNA41 families. In addition, this study supplements some content that was not covered in previous reports. We quantitatively evaluated the pain perception ability of some members using the Pain Vision PS-2100 system, and further found an interesting clinical manifestation, that is, hyperalgesia, in heterozygotes for P2RX2 p.V60L. The cochlear implant (CI) was also provided for the proband of profound deafness, resulting in satisfactory clinical outcomes. Finally, we carried out a systematic review of recently published articles on the P2RX2 gene, which is beneficial for better understanding the role of the P2RX2 gene in the auditory system and the pathogenic mechanisms in sensorineural hearing loss (SNHL).

Functional pathogenicity of ESRRB variant of uncertain significance contributes to hearing loss (DFNB35)

Advances in next-generation sequencing technologies have led to elucidation of sensorineural hearing loss genetics and associated clinical impacts. However, studies on the functional pathogenicity of variants of uncertain significance (VUS), despite their close association with clinical phenotypes, are lacking. Here we identified compound heterozygous variants in ESRRB transcription factor gene linked to DFNB35, specifically a novel splicing variant (NM_004452.4(ESRRB): c.397 + 2T>G) in trans with a missense variant (NM_004452.4(ESRRB): c.1144C>T p.(Arg382Cys)) whose pathogenicity remains unclear. The splicing variant (c.397 + 2T>G) caused exon 4 skipping, leading to premature stop codon formation and nonsense-mediated decay. The p.(Arg382Cys) variant was classified as a VUS due to its particularly higher allele frequency among East Asian population despite disease-causing in-silico predictions. However, functional assays showed that p.(Arg382Cys) variant disrupted key intramolecular interactions, leading to protein instability. This variant also reduced transcriptional activity and altered expression of downstream target genes essential for inner ear function, suggesting genetic contribution to disease phenotype. This study expanded the phenotypic and genotypic spectrum of ESRRB in DFNB35 and revealed molecular mechanisms underlying ESRRB-associated DFNB35. These findings suggest that variants with high allele frequencies can also possess functional pathogenicity, providing a breakthrough for cases where VUS, previously unexplored, could be reinterpreted by elucidating their functional roles and disease-causing characteristics.

Patient-related outcome measures (PROM) in adult cochlear implant patients

Cochlear implants (CI) provide individuals with severe sensorineural hearing loss the opportunity for artificial auditory perception. The standardized documentation of speech intelligibility tests is widespread, while the systematic capture of patient-related outcome measures (PROMs) remains inconsistent. Relevant PROM instruments were evaluated and selected based on the criteria of dissemination, clarity, and relevance, integrated into routine clinical practice, and tested at longitudinal time points. A total of three PROM instruments were selected and successfully integrated into the clinical routine. The comparison of 2measurement points from 25individuals showed improvements in subjective speech comprehension and tinnitus perception. This study demonstrates the clinical implementation and integration of PROMs in adult CI candidates and patients. The PROMs are apromising tool to support various phases of treatment, both as adecision aid for potential CI candidates and for monitoring after implantation.

Auditory Prognosis of Patients With Sudden Sensorineural Hearing Loss in Relation to the Presence of Acute Vestibular Syndrome: A Systematic Literature Review and Meta-Analysis.

Hearing recovery following idiopathic sudden sensorineural hearing loss (ISSNHL) is influenced by various prognostic factors, and the presence of acute vestibular syndrome (AVS) may adversely impact auditory outcomes. Evaluating vestibular function in SSNHL patients could offer insights into predicting hearing recovery. This systematic review aims to assess whether the presence of AVS exacerbates the audiological prognosis of ISSNHL. A comprehensive systematic review was conducted using databases such as PubMed, Cochrane Library, EMBASE, and Scopus, encompassing articles published in the last decade. Included were retrospective and prospective case-control and cohort studies, as well as randomized clinical trials. Meta-analysis was performed based on the findings from these studies. Among 386 articles identified, six addressed the systematic review's question, all being retrospective studies. These articles collectively involved 393 patients for the meta-analysis. Vestibular function assessment methods varied widely, posing challenges for direct comparisons. The likelihood of unfavorable hearing outcomes was 2.29 times higher in patients with associated AVS. Hearing recovery was 3.22 times more likely to be worse in patients with altered cervical vestibular evoked myogenic potentials-air-conducted sound. Abnormal caloric test results showed no significant association with worse hearing prognosis, although patients with unaltered caloric tests demonstrated a significantly greater improvement in pure-tone audiometry. Hearing recovery from ISSNHL appears to be diminished in patients with associated AVS and abnormal vestibular test results.

Working conditions and health status in workers in boiler and welding production in power engineering

Introduction. Preserving the health of qualified workers of older age groups is especially important under conditions of exposure to occupational hazards. The purpose of the study was to assess the influence of occupational hazards on the development of occupational and somatic diseases among workers of various age groups in the main occupations of mechanical engineering. Materials and methods. The study tested the results of hygienic research at workplaces of an enterprise in the power engineering industry in the manufacture of welded metal structures. We assessed the health status in workers based on the results of an in-depth medical examination and ultrasound examination of the vessels of the upper extremities with assessment of blood flow indices. Using a survey method, data were obtained on assessing the influence of production factors on the health status in workers. Results. The working conditions in the main occupational workers groups were assessed as harmful grades 1–3, the priority occupational hazards were: increased noise, and at the workplaces of electric gas workers there were also fibrogenic aerosols, chemical substances, and heavy physical work. Electric and gas welders and boilermakers work in the most unfavourable conditions, about 30% of whom continue to work after reaching retirement age. We have established a significant gain in the incidence of arterial hypertension and sensorineural hearing loss among workers over 40 years of age and an increase in the prevalence of all chronic diseases in the age group over 60 years. Limitations. The study is limited by the number of workers examined and the lack of ability to assess the health status of the studied contingent of workers over time. Conclusion. In conditions of exposure to elevated noise and other occupational hazards, there is an enhancement in the prevalence of work-related and somatic diseases in workers over 40 years of age. With advancing age, the rise in the vascular resistance index is observed, however, the first signs of peripheral blood flow disturbance are often recorded at a young age. In this regard, it is necessary to introduce methods of early diagnosis and prevention of occupational and work-related pathology.

Cochlear Implant Artifacts in Continuous Electroencephalogram Recording.

Cochlear implants to aid sensorineural hearing loss are becoming commonplace. In this study, we describe two cases that showed artifacts related to the cochlear implant device during scalp EEG recording. To our knowledge, cochlear implant artifacts have not been reported previously. Recognizing cochlear implant artifacts will avoid misinterpretation and resultant inappropriate treatment.

Indices of vertebral vein discirculation in workers in noise occupaions

Introduction. Occupational sensorineural hearing loss (OSNHL) is a gradual bilateral hearing loss developing over several years as a result of exposure to constant or non-constant noise (mainly high-frequency) at the workplace as one of the main causes in etiology, researchers name a violation of blood supply and vascular stenosis. The purpose of the study is to evaluate the indices of venous dyscirculation under the influence of industrial noise at the early stages of the development of OSNHL. Materials and methods. Twenty two male patients who have been working in conditions exceeding the maximum permissible noise levels for more than 5 years were examined, and the comparison group included 29 healthy male volunteers from 27 to 55 years old who do not work in the production sector. All the subjects were examined by an otorhinolaryngologist, a neurologist, and a therapist. Audiometry was performed on two axes for everyone. Air and bone conduction were performed separately for each ear. All patients underwent a triplex scan of the arteries and veins of the neck and brain in the supine and standing positions. Results. In comparison with the control group of healthy volunteers who did not work in industrial noise conditions, workers in noise occupations had a significant increase in blood flow, which averaged 25.2 cm/sec. When measuring the diameters of the vertebral veins, a tendency to vasodilation was revealed. Limitations. The limitation was the small sample size, due to the low patient turnover at the preclinical stage. Conclusion. The complex effect of noise on the body leads to changes in the wall of the venous network, a violation of venous outflow and can manifest itself not only with clinical complaints, but also in the form of episodic dizziness, cephalgia, which in turn can worsen the course of the development of OSNHL. It is necessary to perform ultrasound dopplerography of the neck veins for all workers of noise occupations at the preclinical stage to assess the risk of OSNHL occurrence.

Comprehensive diagnosis and genetic analysis of two children with ring chromosome 18

To clarify the genetic diagnosis of two children with ring chromosome 18 and explore their mechanisms and clinical phenotypes. Two patients treated at the Children's Hospital of Henan Province respectively in June 2022 and March 2023 were selected as the study subjects. Genetic testing and diagnosis were carried out through copy number variation sequencing (CNV-seq), G-banded chromosomal karyotyping, and whole exome sequencing (WES). Child 1 had mainly manifested developmental delay, white matter hypoplasia, type 1 diabetes mellitus, and micropenis. He was found to have a chromosomal karyotype of 46,XY,r(18)(p11.21q22.1)[40]/46,XY[7], and CNV-seq results showed that he has a 14.86 Mb deletion at 18p11.21p11.32 and a 14.02 Mb deletion at 18q22.1q23. Child 2 had peculiar facial features, delayed white matter myelination, developmental delay, atrial septal defect, severe sensorineural deafness, and congenital laryngeal stridor. He was found to have a chromosomal karyotype of 46,XY,r(18)(p11.2q23). CNV-seq result proved that he had a 14.86 Mb deletion at 18p11-21p11.32 and a 20.74 Mb deletion at 18q21.32q23. WES has failed to detect single nucleotide variants (SNVs) in either child, but revealed a large segmental deletion at chromosome 18 in both of them. Both children were diagnosed with ring chromosome 18 syndrome. The different size of the deletional fragments in the 18q region and mosaicism of ring chromosome 18 in child 1 may underlay the variation in their clinical phenotypes. The type 1 diabetes mellitus and micropenis noted in both children are novel features for ring chromosome 18 syndrome.

Comparison of horizontal plane auditory spatial discrimination abilities and testing methods in patients with symmetrical sensorineural hearing loss

Objective: To evaluate auditory spatial discrimination capabilities in patients with mild to moderately severe symmetrical sensorineural hearing loss (SNHL) and to compare the impact of different psychophysical testing methods on Minimum Audible Angle (MAA) and test duration. Methods: A total of 105 symmetrical SNHL patients aged from 18 to 60 years old were enrolled from April to July 2023, including 56 males and 49 females. They were divided into three groups based on PTA: mild, moderate, and moderately severe hearing loss, with 35 individuals in each group. Additionally, a control group of 35 individuals with normal hearing was tested, including 18 males and 17 females. Participants underwent four distinct psychophysical discrimination tests: the block up-down, 1-up/1-down, 1-up/2-down, and 1-up/3-down procedures. We recorded the MAA and test duration for each. We employed repeated measures of ANOVA to compare the MAA and test duration across different methods and groups, and Pearson's correlation to assess the relationship between MAA and degree of hearing loss. Results: MAA of sound localization in patients with symmetrical SNHL was significantly positively correlated with the degree of hearing loss (r=0.59, P<0.01). Significant deterioration in MAA was observed as hearing loss progressed to the moderate level (PTA≥35 dBHL, P<0.01). The testing methods significantly influenced MAA and testing duration (F=24.02, P<0.01; F=75.56, P<0.01) and the 1-up/1-down method was the quickest, averaging only (0.69±0.32) mins. Conclusions: The horizontal plane auditory spatial discrimination abilities in patients with symmetrical SNHL is impaired progressively with increasing hearing loss, notably beyond moderate hearing loss levels. Different psychophysical methods influence both MAA and test duration, the quicker 1-up/1-down method is recommended for assessing MAA in symmetrical SNHL patients.

The Role of Platelet-Rich Plasma in the Management of Sensorineural Hearing Loss: Current Evidence and Emerging Trends.

Sensorineural hearing loss (SNHL) is a common form of hearing impairment characterized by damage to the inner ear or auditory nerve, resulting in significant communication difficulties and reduced quality of life. Current treatment options, including hearing aids, cochlear implants, and corticosteroids, primarily focus on symptom management and do not address the underlying pathophysiological damage. Platelet-rich plasma (PRP), an autologous concentrate rich in platelets and growth factors, has emerged as a potential regenerative therapy due to its ability to promote tissue repair and cellular regeneration. This review provides a comprehensive overview of the role of PRP in the management of SNHL, examining the current evidence from preclinical and clinical studies. We discuss the mechanisms through which PRP may promote auditory tissue regeneration and repair, analyze its efficacy and safety profile, and explore innovative approaches and future directions in its application for SNHL. Despite promising preliminary findings, further research is needed to optimize PRP protocols, establish standardized treatment guidelines, and conduct large-scale randomized controlled trials to validate efficacy. This review aims to highlight the potential of PRP as a novel therapeutic strategy in treating SNHL and its possible integration into current clinical practices, offering new hope for patients with this debilitating condition.

Cognitive Changes Up to 4 Years After Cochlear Implantation in Older Adults: A Prospective Longitudinal Study Using the RBANS-H.

Hearing loss is a worldwide health problem that currently affects around 20% of the world's population. Untreated hearing loss can have a significant impact on daily life, it can cause social isolation, loneliness, frustration, and higher anxiety and depression rates. Furthermore, older adults with hearing impairment have a higher risk for accelerated cognitive decline compared with normal-hearing individuals. Previous research indicated a positive effect of cochlear implantation on Health-related Quality of life (HRQoL) and cognitive functioning 1 year after cochlear implantation. The aim of this study was to evaluate the long-term effect of cochlear implantation on cognition and HRQoL in older adults with severe-to-profound hearing loss. All included subjects were 55 years or older with postlingual, bilateral, severe-to-profound hearing loss, and received a unilateral cochlear implant. Cognition was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status for Hearing Impaired Individuals (RBANS-H), and HRQoL was evaluated using the following five questionnaires: Nijmegen Cochlear Implant Questionnaire (NCIQ); Hearing Implant Sound Quality Index (HISQUI); Speech, Spatial, and Qualities of Hearing Scale (SSQ12); Hospital Anxiety and Depression scale (HADS); and Type D questionnaire (DS14). Individuals were evaluated preoperatively, and annually up to 4 years after CI activation. After cochlear implantation an improvement in hearing, cognition, and HRQoL was observed. When comparing preoperative and 12 months postoperative results a significant improvement was observed in the total RBANS-H score (mean [SD], 92.78 [±15.08] versus 98.35 [±14.18], p < 0.001) and the subdomain scores for "Immediate Memory" (94.13 [±18.75] versus 105.39 [±19.98], p = 0.005), "Attention" (86.17 [±19.02] versus 91.57 [±15.35], p = 0.048), and "Delayed memory" (97.91 [±14.51] versus 103.83 [±14.714], p = 0.017). When comparing preoperative results with 4 years postoperative results, a significant improvement was observed in "Immediate Memory" (94.13 [±18.75] versus 101.91 [±16.09], p = 0.020) and a significant decline was observed in "Visuospatial Memory" (97.04 [±17.47] versus 87.26 [±13.41], p = 0.013). Compared with the preoperative results, no significant improvement was observed in the total RBANS-H score 4 years after implantation. A significant improvement was observed for the HRQoL questionnaires, that is, NCIQ, HISQUI19, SSQ12, HADS, and DS14, 1 year after cochlear implantation. When comparing preoperative results with 4-year postoperative results, significant improvement was observed for the NCIQ and DS14 social inhibition scores. Long-term results of the SSQ12 and HISQUI19 were lacking. Unilateral cochlear implantation in an adult population with bilateral severe-to-profound sensorineural hearing loss has a positive effect on cognitive functioning and HRQoL 1 year after activation. This positive effect on cognitive functioning was no longer observed 4 years after cochlear implantation. Further research is needed to explain individual variation in the evolution of cognitive functioning.

Sudden sensorineural hearing loss: audiological profile during the COVID-19 pandemic.

Sudden sensorineural hearing loss (SSNHL) is an otological emergency that requires prompt recognition and intervention to prevent devastating impacts on people's lives. During the COVID-19 pandemic, sensory deprivations have been reported in patients positive for SARS-CoV-2 virus, including deleterious effects on the auditory pathway. This study aims to describe the audiological profile of individuals with SSNHL during the COVID-19 pandemic and to correlate hearing recovery in subgroups of individuals with or without COVID-19. Prospective cohort including patients diagnosed with SSNHL evaluated in a tertiary care center between March 2020 and September 2022. Hearing loss was confirmed with pure-tone and speech audiometry, with Speech Recognition Threshold (SRT) and word recognition score (WRS). Audiometric testing was performed at the moment of diagnosis, then 7, 30 and 120 days after diagnosis. The average degree of hearing loss was assessed by calculating the 4-frequency pure tone average (4fPTA). The investigation of COVID-19 included RT-PCR technique for the SARS-CoV-2 virus and collection of information regarding disease severity. A statistical analysis was performed using an analysis of covariance (ANCOVA) model to compare the 4fPTA between the four groups (with and without a history of COVID-19, unilateral and bilateral cases) at the end of the follow-up period. Fifty-two patients with SSNHL were assessed, 40 (76.9%) with unilateral and 12 (23.1%) with bilateral hearing loss, totaling 64 ears included. Of those, 15 (28.8%) patients tested positive for SARS-CoV-2 and were symptomatic for COVID-19. Of all unilateral cases, 22.5% were seropositive and showed symptoms of COVID-19, a number that increased to 50% for bilateral cases. Comparing the COVID-19 positive groups, individuals with unilateral SSNHL went from 40 dB as their average 4fPTA at onset to 20 dB as their average 4fPTA after 120 days, whereas those with bilateral SSNHL went from an initial average of 60 dB to a final average of 66 dB. Although the 4fPTA value of individuals with unilateral SSNHL improved in 7 days, the mean values showed no significant difference between positive and negative groups. There was a higher incidence of bilateral simultaneous SSNHL in patients who had not been vaccinated against COVID-19 and who presented with symptoms of severe COVID-19. Infection with SARS-CoV-2 resulted in more severe SSNHL, in bilateral SSNHL, and in poorer recovery from SSNHL in bilateral cases. Bilateral SSNHL was seen more frequently in patients who had not received vaccination against COVID-19.

Intratympanic injection of MSC-derived small extracellular vesicles protects spiral ganglion neurons from degeneration

Sensorineural hearing loss is one of the most prevalent sensory deficits. Spiral ganglion neurons (SGNs) exhibit very limited regeneration capacity and their degeneration leads to profound hearing loss. Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEV) have been demonstrated to repair tissue damage in various degenerative diseases. However, the effects of MSC-sEV on SGN degeneration remain unclear. In this study, we investigated the efficacy of MSC-sEV for protection against ouabain-induced SGN degeneration. MSC-sEV were derived from rat bone marrow and their components related to neuron growth were determined by proteomic analysis. In primary culture SGNs, MSC-sEV significantly promoted neurite growth and growth cone development. The RNA-Seq analysis of SGNs showed that enriched pathways include neuron development and axon regeneration, consistent with proteomics. In ouabain induced SGN degeneration rat model, MSC-sEV administration via intratympanic injection significantly enhanced SGN survival and mitigated hearing loss. Furthermore, after ouabain treatment, SGNs displayed evident signs of apoptosis, including nuclei condensation and fragmentation, with numerous cells exhibiting TUNEL-positive. However, administration of MSC-sEV effectively decreased the number of TUNEL-positive cells and reduced caspase-3 activation. In conclusion, our findings demonstrate the potential of MSC-sEV in preventing SGN degeneration and promoting neural growth, suggesting intratympanic injection of MSC-sEV is a specific and efficient strategy for neural hearing loss.

Is There an Association Between Sudden Sensorineural Hearing Loss and Coronavirus Disease 2019? A Comparison Between the Pre-pandemic and Pandemic Periods in Portugal

Is There an Association Between Sudden Sensorineural Hearing Loss and Coronavirus Disease 2019? A Comparison Between the Pre-pandemic and Pandemic Periods in Portugal

BRCA1 Promotes Repair of DNA Damage in Cochlear Hair Cells and Prevents Hearing Loss.

Cochlear hair cells (HCs) sense sound waves and allow us to hear. Loss of HCs will cause irreversible sensorineural hearing loss. It is well known that DNA damage repair plays a critical role in protecting cells in many organs. However, how HCs respond to DNA damage and how defective DNA damage repair contributes to hearing loss remain elusive. In this study, we showed that cisplatin induced DNA damage in outer hair cells (OHCs) and promoted OHC loss, leading to hearing loss in mice of either sex. Cisplatin induced the expression of Brca1, a DNA damage repair factor, in OHCs. Deficiency of Brca1 induced OHC and hearing loss, and further promoted cisplatin-induced DNA damage in OHCs, accelerating OHC loss. This study provides the first in vivo evidence demonstrating that cisplatin mainly induces DNA damage in OHCs and that BRCA1 promotes repair of DNA damage in OHCs and prevents hearing loss. Our findings not only demonstrate that DNA damage-inducing agent generates DNA damage in postmitotic HCs but also suggest that DNA repair factors, like BRCA1, protect postmitotic HCs from DNA damage-induced cell death and hearing loss.