Role of viral infection in sudden hearing loss

Exploring delivery systems for targeted nanotechnology-based gene therapy in the inner ear

Hearing loss places a significant burden on our aging population. However, there has only been limited progress in developing therapeutic techniques to effectively mediate this condition. This review will outline several of the most commonly utilized practices for the treatment of sensorineural hearing loss before exploring more novel techniques currently being investigated via both in vitro and in vivo research. This review will place particular emphasis on novel gene-delivery technologies. Primarily, it will focus on techniques used to deliver genes that have been shown to encourage the proliferation and differentiation of sensory cells within the inner ear and how these technologies may be translated into providing clinically useful results for patients.

Incidence of hearing loss following COVID-19 among young adults in South Korea: a nationwide cohort study

Background

The association of COVID-19 with hearing loss (HL) is unclear among young adults and needs to be investigated. This study was conducted to determine the association of COVID-19 with HL and sudden sensorineural hearing loss (SSNHL) in young adults.

Methods

This nationwide population-based cohort study used data from the Korea Disease Control and Prevention Agency-COVID-19-National Health Insurance Service. The study population consisted of young adult citizens aged 20-39 years without a history of HL. All participants were followed up from July 1, 2022 until HL, death, or December 31, 2022. A positive diagnosis of SARS-CoV-2 infection was determined through laboratory testing employing real-time reverse transcription polymerase chain reaction assays using nasopharyngeal or oropharyngeal swabs. The primary and secondary outcomes were HL and SSNHL, respectively. Age, sex, household income, Charlson comorbidity index, COVID-19 vaccination, hypertension, diabetes, and dyslipidemia-adjusted subdistribution hazard ratios (aSHRs) and 95% confidence intervals (CIs) were evaluated using the Fine-Gray subdistribution hazard regression model, considering overall death as a competing event to compare the aSHRs between COVID-19 positive and negative groups.

Findings

A total of 6,716,879 young adults were eligible for the analyses. During 40,260,757 person-months (PMs) of follow-up, 38,269 cases of HL and 5908 cases of SSNHL were identified. The risk of HL (incidence: 11.9 versus 3.4/10,000 PMs; SHR, 3.51; 95% CI, 3.39-3.63; aSHR, 3.44; 95% CI, 3.33-3.56; P < 0.0001) and SSNHL (incidence: 1.8 versus 0.5/10,000 PMs; SHR, 3.58; 95% CI, 3.29-3.90; aSHR, 3.52; 95% CI, 3.23-3.83; P < 0.0001) was higher in COVID-19 group as compared to no COVID-19 group. In the sensitivity analyses that evaluated HL and SSNHL risks after adopting multiple imputations, utilizing inverse probability of treatment weighting, limiting study population to the cohort with a health screening examination, the results were consistent to the primary analysis.

Interpretation

Our findings suggest a heightened risk of HL and SSNHL following COVID-19 in young adults. Due to study limitations, including the lack of objective audiological data, issues with generalizability to other populations, and the retrospective design, careful interpretation is necessary. Further studies with objective audiological data and a longer follow-up period are warranted.

Funding

IITP (Institute for Information & Communications Technology Planning & Evaluation; IITP-2024- RS-00156439) and Jeju National University Hospital Research Fund (2023).

Sudden Hearing Loss in the Active Duty Population: An Epidemiological Study

INTRODUCTION

Hearing loss among military personnel is a well-known challenge, reported as the second most common VA service-connected disability. Although most hearing loss occurs gradually, a subset occurs suddenly and significantly impacts quality of life and military readiness and is considered as a medical emergency. This study aims to evaluate the incidence of sudden hearing loss among different subpopulations within the military system to better identify at-risk groups.

MATERIALS AND METHODS

This study was a retrospective population-based study reviewing all cases of diagnosed sudden hearing loss between January 1, 2016 and December 31, 2021 within active duty service members in the U.S. DoD. Statistical analysis of multiple subpopulations was performed.

RESULTS

There were 2,650 cases of sudden hearing loss diagnosed in active duty service members during the study period, with an average incidence of 32.9 cases per 100,000 people per year, compared with 5 to 27 cases per 100,000 people per year reported in civilian populations. Senior officers demonstrated significantly increased rates of sudden hearing loss with 103.9 cases per 100,000 people per year, likely as a result of increased age, as did Air Force personnel with 45.1 cases per 100,000 people per year. There was no difference in incidence based on military occupational specialty, though service members located overseas were noted to have decreased incidence compared with those stationed within the USA. There was no significant difference during the years before coronavirus-19 pandemic (2016-2019) compared to the years following the start of the pandemic (2020-2021).

CONCLUSIONS

Sudden hearing loss appears to occur more frequently in military personnel than in the civilian population. The increased incidence in senior officers is likely driven by increased age, though further evaluation into the discrepancies between reported incidence of hearing loss among enlisted service members and officers is warranted. Although military occupational specialty did not demonstrate any significant difference in incidence, for thus far unknown reasons those in the Air Force demonstrated increased rates of sudden hearing loss. Although other potentially at-risk groups were identified, focused efforts to better understand contributing factors to elevated incidence in senior officers and Air Force personnel will help to better mitigate the incidence and effects of sudden hearing loss.

Peripheral and brainstem auditory evaluation in post-COVID-19 individuals

PURPOSE

The purpose of this study was to investigate the peripheral and central auditory pathways in adult individuals after COVID-19 infection.

METHOD

A total of 44 individuals aged between 19 and 58 years, of both genders, post-COVID-19 infection, confirmed by serological tests, with no previous hearing complaints and no risk factors for hearing loss, were assessed. All the participants underwent the following procedures: pure tone audiometry, logoaudiometry, immitanciometry, and Brainstem Auditory Evoked Potentials (BAEP), in addition to answering a questionnaire about auditory symptoms.

RESULTS

Thirteen individuals (29.5 %) had some hearing threshold impairment, mainly sensorineural hearing loss. In the BAEP, 18 individuals (40.9 %) presented longer latencies, mainly in waves III and V. According to the questionnaire answers, 3 individuals (9.1 %) reported worsened hearing and 7 (15.9 %) tinnitus that emerged after the infection. As for the use of ototoxic drugs during treatment, 7 individuals (15.9 %) reported their use, of which 5 showed abnormalities in peripheral and/or central auditory assessments.

CONCLUSION

Considering the self-reported hearing complaints after COVID-19 infection and the high rate of abnormalities found in both peripheral and central audiological assessments, it is suggested that the new COVID-19 may compromise the auditory system. Due to the many variables involved in this study, the results should be considered with caution. However, it is essential that audiological evaluations are carried out on post-COVID-19 patients in order to assess the effects of the infection in the short, medium, and long term. Future longitudinal investigations are important for a better understanding of the auditory consequences of COVID-19.

Sudden Sensorineural Hearing Loss in Patients Aged from 15 to 40 Years

Objectives: The purpose of this study was to investigate the hearing characteristics and causes of sudden sensorineural hearing loss (SSNHL) in patients aged from 15 to 40 years, focusing on audiological outcomes one year after the diagnosis. Methods: The medical records of individuals with SSNHL who were referred to our tertiary-level audiologic center were reviewed. All patients had undergone comprehensive diagnostic evaluations, including high-resolution 3D-FLAIR delayed magnetic resonance imaging (MRI), cone beam computed tomography (CBCT), and screening for coagulation, infectious, and autoimmune diseases. Results: Overall, 56 patients (mean age 28.1 ± 7.6 years) were included in the study. The hearing threshold in the affected ear improved significantly from 56.0 ± 18.0 dB at the diagnosis to 46.9 ± 22.3 dB after one year (p = 0.02). The degree of hearing loss, audiometric configurations, hearing improvements, and adherence to hearing treatments showed considerable variability among patients. Aural fullness, tinnitus, and hyperacusis were the predominant symptoms associated with SSNHL, and their prevalence decreased significantly over time. The diagnostic protocol led to the identification of the specific cause of SSNHL in 75% (42/56) of patients. The known etiology was found to be otological (39.3%), infectious (21.4%), autoimmune (7.1%), vascular (5.4%), or neoplastic (1.8%). In particular, Menière's disease (n = 12), isolated cochlear endolymphatic hydrops (n = 6), HSV-1 (n = 5), and EBV (n = 4) infections were the most frequent causes of SSNHL. Conclusions: The identification of the specific etiology of SSNHL may facilitate a more personalized approach to management and treatment.

Association of sudden sensorineural hearing loss with meteorological factors: a time series study in Hefei, China, and a literature review

Air pollution can cause disease and has become a major global environmental problem. It is currently believed that air pollution may be related to the progression of SSNHL. As a rapidly developing city in recent years, Hefei has serious air pollution. In order to explore the correlation between meteorological variables and SSNHL admissions, we conducted this study. This study investigated the short-term associations between SSNHL patients admitted to the hospital and Hefei climatic variables. The daily data on SSNHL-related hospital admissions and meteorological variables containing mean temperature (T-mean; °C), diurnal temperature range (DTR; °C), atmospheric pressure (AP; Hp), and relative humidity (RH; %), from 2014 to 2021 (2558 days), were collected. A time-series analysis integrating distributed lag non-linear models and generalized linear models was used. PubMed, Embase, Cochrane Library, and Web of Science databases were searched. Literature published up to August 2023 was reviewed to explore the potential impact mechanisms of meteorological factors on SSNHL. The mechanisms were determined in detail, focusing on wind speed, air pressure, temperature, humidity, and air pollutants. Using a median of 50.00% as a baseline, the effect of exceedingly low T-mean in the single-day hysteresis effect model began at a lag of 8 days (RR = 1.032, 95% CI: 1.001 ~ 1.064). High DTR affected the admission rate for SSNHL on lag 0 day. The significance of the effect was the greatest on that day (RR = 1.054, 95% CI: 1.007 ~ 1.104) and then gradually decreased. High and exceedingly high RH affected the admission rate SSNHL on lag 0 day, and these effects lasted for 8 and 7 days, respectively. There were significant associations between all grades of AP and SSNHL. This is the first study to assess the effect of meteorological variables on SSNHL-related admissions in China using a time-series approach. Long-term exposures to high DTR, RH values, low T-mean values, and all AP grades enhance the incidence of SSNHL in residents. Limiting exposure to extremes of ambient temperature and humidity may reduce the number of SSNHL-related hospital visits in the region. It is advisable to maintain a suitable living environment temperature and avoid extreme temperature fluctuations and high humidity. During periods of high air pollution, it is recommended to stay indoors and refrain from outdoor exercise.

Google Trends Analysis of Otologic Symptom Searches Following COVID-19

Introduction

COVID-19 infection was accompanied by otologic symptoms, a pattern that was captured early by Google Trends. The objective of this study is to investigate searches for otologic symptoms and identify correlations with the pandemic onset.

Materials and Methods

Search interest for otologic symptoms was gathered using Google Trends from two years before and two years following the pandemic start date. A two-tailed Mann-Whitney U test was used to identify significant changes and effect size.

Results

In total, search interest for 14 terms was collected, with significant changes identified in 11. Six terms showed increased search interest, with the most significant rises observed for headache (r=0.589, p<0.001), dizziness (r=0.554, p<0.001), and tinnitus (r=0.410, p<0.001). Search interest decreased for five terms, with the most notable declines found in searches for migraine headache (r=0.35, p<0.001) and phonophobia (r=0.22, p=0.002). No significant changes were seen in ear pressure (p=0.142), neck pain (p=0.935), and sudden hearing loss (p=0.863) searches.

Conclusion

COVID-19 infection is often accompanied otologic symptoms and holds a diagnostic role. Fluctuating search interest may be attributed to a true increase in cases, media trends, or people's desires to stay informed. Google Trends robustly captured trends in search interest and presented itself as a valuable epidemiological tool.

Sudden Sensorineural Hearing Loss after COVID-19 Vaccination: A Review of the Available Evidence through the Prism of Causality Assessment

Sudden sensorineural hearing loss (SSNHL), a rare audiological condition that accounts for 1% of all cases of sensorineural hearing loss, can cause permanent hearing damage. Soon after the launch of global COVID-19 vaccination campaigns, the World Health Organization released a signal detection about SSNHL cases following administration of various COVID-19 vaccines. Post-marketing studies have been conducted in different countries using either pharmacovigilance or medico-administrative databases to investigate SSNHL as a potential adverse effect of COVID-19 vaccines. Here, we examine the advantages and limitations of each type of post-marketing study available. While pharmacoepidemiological studies highlight the potential association between drug exposure and the event, pharmacovigilance approaches enable causality assessment. The latter objective can only be achieved if an expert evaluation is provided using internationally validated diagnostic criteria. For a rare adverse event such as SSNHL, case information and quantification of hearing loss are mandatory for assessing seriousness, severity, delay onset, differential diagnoses, corrective treatment, recovery, as well as functional sequelae. Appropriate methodology should be adopted depending on whether the target objective is to assess a global or individual risk.

Sudden Secondary Sensorineural Hearing Loss Following Hand, Foot, and Mouth Disease in an Adult Patient: A Case Report

Introduction: Sudden sensorineural hearing loss (SSNHL) can present as sudden hearing loss within 72 hours. Studies have shown that viral infection, including direct invasion, indirect reactions, stress responses, and immune-mediated hearing loss, is the main cause of SSNHL. Viral infection may play an important role in SSNHL by causing injury to the inner ear through blood or cerebrospinal fluid. In this article, we describe an adult case of SSNHL following hand, foot, and mouth disease (HFMD). Case Report: A 34-year-old man presented with sudden hearing loss in the right ear 4 days after HFMD onset. Tinnitus, ear fullness, and a slightly heavy head appeared synchronously as accompanying symptoms. Before 6 days, he had a fever for 2 days (the highest temperature was 39.4°C), followed by vesicles in the oral mucosa and papules on the hands and feet after cohabitation with his child diagnosed with HFMD.

Exploring functional connectivity alterations in sudden sensorineural hearing loss: A multilevel analysis

Sudden sensorineural hearing loss (SSNHL) constitutes an urgent otologic emergency, marked by a rapid decline of at least 30 dB across three consecutive frequencies within 72 h. While previous studies have noted brain region alterations encompassing both auditory and non-auditory areas, this research examines functional connectivity changes across integrity, network, and edge levels in SSNHL. The cohort included 184 participants: 107 SSNHL patients and 77 age- and sex-matched healthy controls. Our investigation comprises: (1) characterization of overall functional connectivity degree across 55 nodes in nine networks (p < 0.05, corrected for false discovery rate), exposing integrity level changes; (2) identification of reduced intranetwork connectivity strength within sensory and attention networks (somatomotor network, auditory network, ventral attention network, dorsal attention network) in SSNHL individuals (p < 0.05, Bonferroni corrected), and reduced internetwork connectivity across twelve distinct subnetwork pairs (p < 0.05, FDR corrected); (3) revelation of increased internetwork connectivity in SSNHL patients, primarily spanning dorsal attention network, fronto parietal network, default mode network, and limbic network, alongside widespread reductions in connectivity patterns among the nine distinct resting-state brain networks. The study further uncovers negative correlations between SSNHL duration and intranetwork connectivity of the auditory network (p < 0.001, R = -0.474), and between Tinnitus Handicap Inventory (THI) scores and internetwork connections linking auditory network and dorsal attention network (p < 0.001, R = -0.331). These observed alterations provide crucial insights into the neural mechanisms underpinning SSNHL and extend our comprehension of the brain's network-level responses to sensory loss. By unveiling the intricate interplay between sensory deprivation, adaptation, and cognitive processes, this study lays the groundwork for future research targeting enhanced diagnosis, treatment, and rehabilitation approaches for individuals afflicted by SSNHL.

Chronic Toxoplasma gondii Infection Modulates Hearing Ability across the Adult Life Span

While several studies have shown associations between hearing disorders and congenital toxoplasmosis, the present study investigated the impact of chronic, latent Toxoplasma gondii (T. gondii) infection on hearing loss. We used a regression analysis to explore whether latent T. gondii infection modulates changes in hearing thresholds over an age range from 20 to 70 years. We analyzed audiometric data of 162 T. gondii IgG-positive and 430 T. gondii-negative participants, collected in the Dortmund Vital Study (DVS, ClinicalTrials.gov Identifier: NCT05155397), a prospective study on healthy cognitive aging. The regression analysis indicated that latent toxoplasmosis was associated with an accelerated development in hearing loss over the observed age range. Hearing loss was less frequent in IgG-positive than in IgG-negative participants up to the age of about 40 for a low (0.125-1 kHz)-frequency range. For high (2-8 kHz) frequencies, this pattern reversed for ages above 65 years. We discuss these findings on hearing function in the context of a recently proposed model, suggesting that latent toxoplasmosis can differentially affect brain functions across a lifespan.

Comparison of Batroxobin Versus the Combination of Batroxobin and Intratympanic Dexamethasone Injection in the Treatment of Sudden Sensorineural Hearing Loss

Introduction: Sudden sensorineural hearing loss (SSNHL) manifests as an abrupt decline in hearing by at least 30 dB within a 3 day period. Intratympanic dexamethasone injection (ITDI) has gained recognition as a potential treatment for SSNHL. This study aims to investigate the efficacy of combining batroxobin with ITDI (Bat and ITDI) in treating SSNHL patients and its influence on peripheral blood inflammatory indicators. Methods: SSNHL patients were retrospectively categorized into the control group (treated with Bat) and the observation group (treated with Bat and ITDI). The study involved analyzing clinical baseline data, evaluating clinical efficacy, and comparing the total effective rates among SSNHL patients with different audiometric curve types in the observation group. Routine blood tests were performed on peripheral blood samples to calculate the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), and to determine C-reactive protein (CRP) levels. Adverse reactions and complications were closely monitored. Results: Following treatment, both groups displayed improvements in hearing, with the observation group exhibiting a significantly higher total effective rate (75.90%) than the control group (59.78%). For patients with 3 distinct types of sudden hearing loss (high-frequency, flat-frequency, total deafness), Bat and ITDI treatment demonstrated increased total effective rate for patients with different sudden hearing loss types (high-frequency, flat-frequency, and total deafness). Both groups experienced reduced peripheral blood CRP levels and the NLR/PLR values, with the observation group demonstrating lower values. Additionally, across the 4 audio metric subtypes, the levels of peripheral blood CRP, NLR, and PLR decreased in SSNHL patients, and the observation group had a lower incidence of adverse reactions compared to the control group. Conclusions: Bat and ITDI emerge as notably more effective for SSNHL patients, displaying potential for reducing peripheral blood inflammatory indicator levels and mitigating the incidence of adverse reactions or complications, thereby enhancing safety.

Sudden Hearing Loss Waves: The Effect of COVID-19 Infection and Vaccination on the Inner Ear

Sudden sensorineural hearing loss (SSNHL) has emerged as a potential complication of COVID-19 infection and vaccination. Various mechanisms by which the SARS-CoV-2 virus can cause hearing loss have been reported, including direct viral invasion, neuroinflammation, blood flow disturbances, and immune-mediated response. However, the temporal relationship between COVID-19 infection and SSNHL remains unclear, with mixed findings and conflicting results reported in different studies. Similarly, while anecdotal reports have linked COVID-19 vaccination to SSNHL, evidence remains scarce. Establishing a correlation between COVID-19 vaccines and SSNHL implies a complex and multifactorial pathogenesis involving interactions between the immune system and the body's stress response. Nevertheless, it is important to consider the overwhelming evidence of the vaccines' safety and efficacy in limiting the spread of the disease and remains the primordial tool in reducing death.

Acute labyrinthitis: a manifestation of COVID-19 in a teenager

Audiovestibular symptoms following COVID-19 have been long acknowledged, especially in adults. However, acute labyrinthitis presenting as an early manifestation of COVID-19 has not been reported in children. We report COVID-19-induced acute labyrinthitis in a teenager. We report on a boy in his early adolescence with a sudden onset of spinning sensation, imbalance and unilateral hearing loss with a positive SARS-CoV-2 test. Vestibular investigations point towards right labyrinthine hypofunction, and an audiometry test revealed right-sided severe hearing loss. Symptoms improved gradually with steroids and vestibular rehabilitation therapy. However, the long-term repercussions of post-COVID-19 acute labyrinthitis are unknown and must be followed up closely. To our knowledge, this is the first reported case of acute labyrinthitis secondary to COVID-19 in paediatrics. Additionally, we conducted a literature search to elucidate the outcome of COVID-19-induced acute vestibular syndrome in children.

Cochlear Implantation in Patients with Bilateral Sudden Sensorineural Hearing Loss after COVID-19 Infection

COVID-19 infection is associated with a variety of neurological manifestations. Since the inner ear is vulnerable to viruses, sensorineural hearing loss (SNHL) has been reported to occur following SARS-CoV-2 infection. We present here two cases of profound SNHL following SARS-CoV-2 infection. Pure-tone audiograms confirmed profound SNHL. The tympanogram and Auditory Brainstem Responses showed no abnormal symptoms. MRIs and CTs identified some changes but no significant anatomical nor physiological manifestations explaining the obvious cause for hearing loss. High doses of oral corticosteroids with additional conservative therapy were given with no therapeutic response, and therefore, cochlear implant surgery was performed. One case was bilaterally treated, and the other one received an implantation on one side. Both surgeries were carried out without intra- nor postoperative complications. Interestingly, in both cases, advanced fibrotic tissue was found during surgery. Both cases reported successful rehabilitation and are satisfied with their new sound perception following cochlear implantation.

Efficacy and safety of Ginkgo biloba extract as an adjuvant in the treatment of Chinese patients with sudden hearing loss: a meta-analysis

CONTEXT

Ginkgo biloba Linn (Ginkgoaceae) [leaves extract (GBE)] is authorized for the treatment of sudden hearing loss (SHL); however, its clinical feasibility in SHL has not been thoroughly investigated.

OBJECTIVE

To evaluate the efficacy and safety of adjuvant GBE in the treatment of SHL.

MATERIALS AND METHODS

We used PubMed, EMBASE, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Wanfang, Chinese Scientific Journal Database, China Biomedical Database for literature research, starting from inception to 30 June 2022. The key terms: Ginkgo biloba extract, Sudden Sensorineural Deafness. This meta-analysis contained randomized controlled trials that compared the safety and efficacy of the combination of GBE and general treatments (GT) with GT alone for SHL. The extracted data were analyzed using Revman5.4 software with risk ratio (RR), 95% confidence intervals (CI) and mean difference (MD).

RESULTS

Our meta-analysis included 27 articles with a total of 2623 patients. The results revealed that the effects of GBE adjuvant therapy was superior than GT (total effective rate: RR = 1.22, 95% CI: 1.18-1.26, p < 0.00001), the pure tone hearing threshold (MD = 12.29, 95% CI: 11.74-12.85, p < 0.00001) and hemorheology indexes (whole blood high shear viscosity: MD = 1.46, 95% CI: 0.47-2.44, p = 0.004) after treatment were significantly improved compared to non-treatment, while there was no significant difference as for hematocrit (red blood cells) (MD = 4.15, 95% CI: -7.15-15.45, p = 0.47).

CONCLUSION

The efficacy of GBE + GT for the treatment of SHL may be more promising than GT alone.

Beyond TORCH: A narrative review of the impact of antenatal and perinatal infections on the risk of disability

Infections and inflammation during pregnancy or early life can alter child neurodevelopment and increase the risk for structural brain abnormalities and mental health disorders. There is strong evidence that TORCH infections (i.e., Treponema pallidum, Toxoplasma gondii, rubella virus, cytomegalovirus, herpes virus) alter fetal neurodevelopment across multiple developmental domains and contribute to motor and cognitive disabilities. However, the impact of a broader range of viral and bacterial infections on fetal development and disability is less well understood. We performed a literature review of human studies to identify gaps in the link between maternal infections, inflammation, and several neurodevelopmental domains. We found strong and moderate evidence respectively for a higher risk of motor and cognitive delays and disabilities in offspring exposed to a range of non-TORCH pathogens during fetal life. In contrast, there is little evidence for an increased risk of language and sensory disabilities. While guidelines for TORCH infection prevention during pregnancy are common, further consideration for prevention of non-TORCH infections during pregnancy for fetal neuroprotection may be warranted.

[The role of TLR4/NF-κB signaling pathway in sleep deprivation induced Meniere's disease]

Objective:By detecting the levels of proteins in the Toll-like receptor-4/nuclear factor-κB （TLR4/NF-κB） signaling pathway and downstream proinflammatory cytokines in peripheral blood of patients with Meniere's disease （MD）, Pittsburgh Sleep Quality Index （PSQI） scores were collected to investigate the correlation between sleep disorders and MD and the role of TLR4/NF-κB signaling pathway in mediating sleep disorders inducing MD. Methods:Thirty-two MD patients and 20 family members of patients without middle ear and inner ear related diseases were selected. Basic data, PSQI and fasting peripheral blood of all subjects were collected. Enzyme linked immunosorbent assay.The levels of interleukin-1β（IL-1β）, tumor necrosis factor-α（TNF-α）, monocyte chemokine-1（MCP-1）, Toll-like receptor 4（TLR4） and nuclear factor-κB（NF-κB） in peripheral blood were detected by ELISA, and the data were statistically analyzed. Results:①PSQI score of MD group was higher than that of normal control group, and the difference was statistically significant（P<0.01）; The scores of every factors of PSQI in MD group were higher than those in normal control group, and the scores of factors 2, 4 and 6 were significantly different from those in normal control group. ②In the MD group, there were 18 patients with sleep disorders, with a prevalence rate of 56.25%, including 6 males with a prevalence rate of 50.00% and 12 females with a prevalence rate of 60.00%. ③The levels of five test indexes in MD group, sleep disorder group and non-sleep disorder group were higher than those in control group, and the levels of TLR4 and NF-κB in MD group were significantly different from those in control group（P<0.05）. The levels of IL-1β, TNF-α, TLR4 and NF-κB in sleep disorder group were significantly different from those in control group（P<0.05）. The levels of five test indexes in non-sleep disorder group were not statistically significant compared with those in control group. The levels of five test indexes in the MD sleep disorder group were higher than those in the MD group and the non-sleep disorder group, with no statistical significance. The levels of five test indexes in MD group were higher than those in non-sleep disorder group, with no statistical significance（P>0.05）. Conclusion:①Sleep disorders may be one of the important predisposing factors of some MD, and the effects of sleep disorders on MD are different between the sexes. ②Sleep disorders may activate TLR4/NF-κB signaling pathway to induce MD. The selection of TLR4/NF-κB signaling pathway related proteins and downstream pro-inflammatory factor inhibitors to intervene MD may provide a new idea for protecting the hearing balance function of MD.

A review of the auditory-gut-brain axis

Hearing loss places a substantial burden on medical resources across the world and impacts quality of life for those affected. Further, it can occur peripherally and/or centrally. With many possible causes of hearing loss, there is scope for investigating the underlying mechanisms involved. Various signaling pathways connecting gut microbes and the brain (the gut-brain axis) have been identified and well established in a variety of diseases and disorders. However, the role of these pathways in providing links to other parts of the body has not been explored in much depth. Therefore, the aim of this review is to explore potential underlying mechanisms that connect the auditory system to the gut-brain axis. Using select keywords in PubMed, and additional hand-searching in google scholar, relevant studies were identified. In this review we summarize the key players in the auditory-gut-brain axis under four subheadings: anatomical, extracellular, immune and dietary. Firstly, we identify important anatomical structures in the auditory-gut-brain axis, particularly highlighting a direct connection provided by the vagus nerve. Leading on from this we discuss several extracellular signaling pathways which might connect the ear, gut and brain. A link is established between inflammatory responses in the ear and gut microbiome-altering interventions, highlighting a contribution of the immune system. Finally, we discuss the contribution of diet to the auditory-gut-brain axis. Based on the reviewed literature, we propose numerous possible key players connecting the auditory system to the gut-brain axis. In the future, a more thorough investigation of these key players in animal models and human research may provide insight and assist in developing effective interventions for treating hearing loss.

The functional status of vestibular otolith and conductive pathway in patients with unilateral idiopathic sudden sensorineural hearing loss

Background

The cause of idiopathic sudden sensorineural hearing loss (ISSNHL) remains unknown. It has been found that the functional status of the vestibular otolith is relevant to its prognosis; however, the evaluation of the vestibular otolith (intra-labyrinth) and superior and inferior vestibular nerve pathways (retro-labyrinth) in ISSNHL patients is not well-documented.

Objective

This study aimed to investigate the functional status of the vestibular otolith and conductive pathway in patients with unilateral ISSNHL and analyze the correlations between vestibular evoked myogenic potentials (VEMPs) and hearing improvement after treatment.

Methods

A total of 50 patients with unilateral ISSNHL underwent a battery of audio-vestibular evaluations, including pure tone audiometry, middle ear function, air-conducted sound-cervical VEMP (ACS-cVEMP), ACS-ocular VEMP (ACS-oVEMP), galvanic vestibular stimulation-cervical VEMP (GVS-cVEMP), and GVS-ocular VEMP (GVS-oVEMP). The results of auditory and VEMPs were retrospectively analyzed.

Results

The abnormal rates of ACS-cVEMP, ACS-oVEMP, GVS-cVEMP, and GVS-oVEMP in affected ears were 30, 52, 8, and 16%, respectively. In affected ears, the abnormal rate of ACS-oVEMP was significantly higher than that of ACS-cVEMP (p = 0.025), while it was similar between GVS-cVEMP and GVS-oVEMP (p = 0.218). Compared with GVS-cVEMP, affected ears presented with a significantly higher abnormal rate of ACS-cVEMP (p = 0.005), and the abnormal rate of ACS-oVEMP was significantly higher than that of GVS-oVEMP (p < 0.001). No significant difference existed in latency and amplitude between affected and unaffected ears in ACS-VEMPs or GVS-VEMPs (p > 0.05). The abnormal rate of VEMPs in the poor recovery group was significantly higher than that of the good recovery group (p = 0.040). The abnormality percentages of ACS-oVEMP and GVS-oVEMP in the poor recovery group were significantly higher than that of the good recovery group (p = 0.004 and 0.039, respectively). The good hearing recovery rates were 76.47% in the normal VEMPs group, 58.33% in the intra-labyrinth lesion group, and 22.22% in the retro-labyrinth lesion group. Hearing recovery worsened as a greater number of abnormal VEMPs was presented.

Conclusion

Besides Corti's organ, the impairment of otolithic organs was prominent in patients with ISSNHL. The normal VEMPs group had the highest rate of good recovery, followed by the intra-labyrinth lesion group and the retro-labyrinth lesion group presented with the lowest recovery rate. Abnormalities in ACS-oVEMP and/or GVS-oVEMP were indicators of a poor prognosis.

Impact of environmental noise exposure as an inducing factor on the prognosis of sudden sensorineural hearing loss: a retrospective case-control study

Objective

The study aimed to evaluate the clinical characteristics and prognostic factors associated with unilateral sudden sensorineural hearing loss (SSNHL) related to environmental noise exposure before its onset.

Methods

A total of 50 unilateral SSNHL patients exposed to environmental noise before onset (case group) and 924 unilateral SSNHL patients without any exposure to obvious inducing factors before onset (control group) were enrolled between January 2018 and October 2022. We retrospectively analyzed differences between both groups using the chi-square test, Fisher's exact tests, independent t-tests, and Mann-Whitney U-tests as appropriate before and after propensity score matching (PSM) based on sex, age, and initial pure-tone average (PTA). Prognostic factors for the case group were analyzed using univariate and multivariate logistic analyses between the effective and ineffective groups.

Results

Before PSM, significant differences were noted in age, sex, time to treatment, the proportion of combined diabetes mellitus, initial PTA, hearing gain, the incidence of vertigo or aural fulness, the rate of vestibular dysfunction or inner ear MRI abnormalities, the effective rate, the glucose and homocysteine levels, and the proportion of audiogram curve types (P < 0.05) between both groups. After PSM, compared to the control group, a longer time to treatment (Z= -3.02, P < 0.05), higher final PTA (Z= -2.39, P < 0.05), lower hearing gain (Z= -3.46, P < 0.05), lower rate of vestibular dysfunction (χ² = 55.1, P < 0.001), and lower effective rate (χ² = 4.87, P < 0.05) were observed in the case group. There was a significant difference between the audiogram curve types in both groups (χ² = 14.9, P < 0.05). Time to treatment (95% confidence interval: 0.692-0.965, P < 0.05) and final PTA (95% confidence interval: 0.921-0.998, P < 0.05) were associated with the clinical outcomes for the case group.

Conclusion

Unilateral SSNHL patients exposed to environmental noise triggers before onset showed a poorer effective rate and a lower rate of vestibular dysfunction than those who were not. The time to treatment and final PTA were associated with the prognosis of these patients.

Differentially expressed miRNA profiles of serum-derived exosomes in patients with sudden sensorineural hearing loss

Objectives

This study aimed to compare the expressed microRNA (miRNA) profiles of serum-derived exosomes of patients with sudden sensorineural hearing loss (SSNHL) and normal hearing controls to identify exosomal miRNAs that may be associated with SSNHL or serve as biomarkers for SSNHL.

Methods

Peripheral venous blood of patients with SSNHL and healthy controls was collected to isolate exosomes. Nanoparticle tracking analysis, transmission electron microscopy, and Western blotting were used to identify the isolated exosomes, after which total RNA was extracted and used for miRNA transcriptome sequencing. Differentially expressed miRNAs (DE-miRNAs) were identified based on the thresholds of P < 0.05 and |log₂fold change| > 1 and subjected to functional analyses. Finally, four exosomal DE-miRNAs, including PC-5p-38556_39, PC-5p-29163_54, PC-5p-31742_49, and hsa-miR-93-3p_R+1, were chosen for validation using quantitative real-time polymerase chain reaction (RT-qPCR).

Results

Exosomes were isolated from serum and identified based on particle size, morphological examination, and expression of exosome-marker proteins. A total of 18 exosomal DE-miRNAs, including three upregulated and 15 downregulated miRNAs, were found in SSNHL cases. Gene ontology (GO) functional annotation analysis revealed that target genes in the top 20 terms were mainly related to "protein binding," "metal ion binding," "ATP binding," and "intracellular signal transduction." Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that these target genes were functionally enriched in the "Ras," "Hippo," "cGMP-PKG," and "AMPK signaling pathways." The expression levels of PC-5p-38556_39 and PC-5p-29163_54 were significantly downregulated and that of miR-93-3p_R+1 was highly upregulated in SSNHL. Consequently, the consistency rate between sequencing and RT-qPCR was 75% and sequencing results were highly reliable.

Conclusion

This study identified 18 exosomal DE-miRNAs, including PC-5p-38556_39, PC-5p-29163_54, and miR-93-3p, which may be closely related to SSNHL pathogenesis or serve as biomarkers for SSNHL.

An online survey on clinical characteristics of otologic symptoms linked to COVID-19 infection

Objective

To report the otologic symptoms that present in patients with COVID-19 infection and investigate the pathogenic characteristics during the period of the pandemic.

Materials and methods

This cross-sectional descriptive study included participants with COVID-19 infection. COVID-19 infection was verified in these patients by nucleic acid test or antigen test. An online questionnaire was developed to analyze the association between the COVID-19 pandemic and the characteristics of otologic symptoms.

Results

This study included 2,247 participants, of which nearly half had one or more otologic symptoms. The presents of otologic symptoms were associated with gender (OR = 1.575, p < 0.0001), age (OR = 0.972, p < 0.0001), and occupation (healthcare worker: p < 0.0001; personnel of enterprises or institutions: OR = 1.792, p < 0.0001; student: OR = 0.712, p < 0.044). The otologic symptoms following COVID-19 infection in order were vertigo (25.95%), tinnitus (19.05%), otalgia (19.00%), aural fullness (17.18%), hearing loss (11.62%), otorrhea (1.25%), and facial paralysis (0.27%).

Conclusion

The present study shows that otologic symptoms are common among the COVID-19 infected participants and that these symptoms mostly recover spontaneously. During the corona-virus pandemic, the involvement of the cochleovestibular system and facial nerve should not be overlooked while treating the COVID-19 infected individuals.

Effect of Herpes Zoster Treatment and Sudden Sensorineural Hearing Loss Using National Health Insurance Claims Data of South Korea

Background and objectives: Herpes zoster (HZ) is caused by the reactivation of a pre-existing latent varicella zoster virus, which is one of the viruses that causes hearing loss, and hearing loss may occur due to a systemic immune response even if it does not invade the auditory nerve. This study aimed to determine the correlation between sudden sensorineural hearing loss (SSNHL) in older adult patients who received HZ treatment. Materials and Methods: We used the cohort data of patients aged 60 years and above (n = 624,646) between 2002 and 2015 provided by the National Health Insurance Service. The patients were divided into two groups: those who were diagnosed with HZ between 2003 and 2008 (group H, n = 36,121) and those who had not been diagnosed with HZ between 2002 and 2015 (group C, n = 584,329). Results: In the main model (adjusted HR = 0.890, 95% CI = 0.839-0.944, p < 0.001) adjusted for sex, age, and income, and the full model (adjusted HR = 0.894, 95% CI = 0.843-0.949, p < 0.001) adjusted for all comorbidities, group H had a lower risk of SSNHL than group C. Conclusions: This study showed that patients who received HZ treatment had a lower incidence of SSNHL within five years after diagnosis.

Novel Nanoencapsulation Technology and its Potential Role in Bile Acid-Based Targeted Gene Delivery to the Inner Ear

Hearing loss impacts a large proportion of the global population. Damage to the inner ear, in particular the sensitive hair cells, can impact individuals for the rest of their lives. There are very limited options for interventions after damage to these cells has occurred. Targeted gene delivery may provide an effective means to trigger appropriate differentiation of progenitor cells for effective replacement of these sensitive hair cells. There are several hurdles that need to be overcome to effectively deliver these genes. Nanoencapsulation technology has previously been used for the delivery of pharmaceuticals, proteins and nucleic acids, and may provide an effective means of delivering genes to trigger appropriate differentiation. This review investigates the background of hearing loss, current advancements and pitfalls of gene delivery, and how nanoencapsulation may be useful.

Delivery of Dexamethasone to the Round Window Niche by Saturated Gelatin Sponge for Refractory Sudden Sensorineural Hearing Loss: A Preliminary Study

OBJECTIVE

The aim of this study was to evaluate the hearing outcome of dexamethasone sodium phosphate (DSP) delivery to the round window niche by saturated gelatin sponge for refractory sudden sensorineural hearing loss.

PATIENTS

Twenty patients with unilateral sudden sensorineural hearing loss with an improvement of pure-tone average (PTA) less than 10 dB after primary systemic treatment with steroids.

INTERVENTIONS

Delivery of DSP to the round window niche via saturated sponge gelatin for 2 weeks.

MAIN OUTCOME MEASURES

Pure-tone audiometry was taken at the beginning and 4 to 8 weeks after the end of the salvage treatment.

RESULTS

PTA thresholds were improved at least 10 dB in 11 of 20 patients (55%) by a mean value of 11.9 dB. The hearing threshold at 500, 1000, and 2000 Hz were improved after salvage treatment, but there was no significant change at 4000 Hz. The PTAs also recovered after the salvage treatment.

CONCLUSIONS

Delivery of DSP to the round window niche via saturated gelatin sponge is a simple and feasible way to treat refractory sudden sensorineural hearing loss with a risk of permanent tympanic membrane perforation.

Cardiovascular risk factors among patients with acute unilateral inner ear hypofunction: A case-control study

Objectives

To assess the prevalence of cardiovascular risk factors (CVRFs) and their impact on acute unilateral inner ear hypofunction (AUIEH), including acute unilateral peripheral vestibulopathy (AUPVP), sudden sensorineural hearing loss (SSNHL) and acute unilateral audiovestibular hypofunction (AUAVH).

Methods

One hundred and twenty-five patients consecutively diagnosed with AUPVP, SSNHL or AUAVH and 250 sex- and age-matched controls were included. Cases presented a mean age of 58.6 ± 14.7 years and included 59 women and 66 men. The correlation between CVRFs (high blood pressure [HBP], diabetes mellitus [DM], dyslipidemia [DLP], cardiocerebrovascular disease [CCVD]) and AUIEH was assessed by multivariate conditional logistic regression analysis.

Results

A higher prevalence of CVRFs was identified in patients than in controls (30 individuals with DM, 53 with HBP, 45 with DLP and 14 with a previous history of CCVD, p < .05). A significantly elevated risk of AUIEH was found in patients with two or more CVRFs (adjusted odds ratio [OR] 5.11; 95% CI 2.23-11.70). Previous CCVD individually predicted AUIEH (OR 8.41; 95% CI 2.36-29.88). Subgroup analysis showed the same tendency for AUPVP and SSNHL.

Conclusion

Acute unilateral inner ear hypofunction patients presented significantly more CVRFs than controls, and the presence of two or more CVRFs was associated with AUIEH. Future studies evaluating vascular risk in AUIEH may include AUPVP and SSNHL patients from the same source population to better characterize risk profiles that can indicate a vascular origin.

Level of Evidence

3b.

Inflammatory Indicators in Peripheral Blood in Sudden Sensorineural Hearing Loss Patients With Different Audiogram Shapes

Objective: A retrospective study was conducted to explore the immune-inflammatory responses in sudden sensorineural hearing Loss (SSNHL) patients with different audiogram shapes. Methods: One hundred and ten inpatients with SSNHL were assigned to 4 subgroups according to the audiogram shape and treated with systemic methylprednisolone. The numbers of white blood cells, neutrophils, lymphocytes, platelets, and monocytes were counted. The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and the monocyte-to-lymphocyte ratio (MLR) were calculated and statistically analyzed. Results: Neutrophil-to-lymphocyte ratio, MLR, and systemic immune index (SII) of SSNHL patients were significantly higher than the control group, while PLR was not statistically significant. There were no statistical differences in NLR, PLR, MLR, and SII among the 4 subgroups. Conclusion: Immune-inflammatory response may be a common pathogenesis in all SSNHL patients with different audiogram shapes. The predictive value of these hematologic markers needs further research in the future.

The Role of IL-6 in Inner Ear Impairment: Evidence from 146 Recovered Patients with Omicron Infected in Tianjin, China

PURPOSE

To explore the effect of inflammatory factors on inner ear impairment in a sample of Omicron-infected patients with a high rate of vaccination in China.

METHODS

One hundred and forty-six recovered Omicron-infected patients performed the distortion product otoacoustic emission (DPOAE) test and serum test for inflammatory factors; demographic data and vaccination statuses were collected from the questionnaire.

RESULTS

Out of 146 patients, the DPOAE pass rate was 81.5% (119/146). Inner ear impairment was significantly correlated with IL-6 titer. The odds ratio (aOR) was 1.24 (95% CI: 1.04-1.49) after adjusting for age, sex, and vaccine characteristics. Notably, this relationship only existed in the 18-60 years group. There were no significant protective effects of vaccination on inner ear function.

CONCLUSIONS

Inner ear impairment still exists in Omicron-infected patients, which was significantly correlated with IL-6 titer. This relationship was mainly observed in young and middle-aged people, possibly due to a stronger immune response in this age group. The protective effect of vaccination on the inner ear could not be proved.

Cardiovascular Risk and Sudden Sensorineural Hearing Loss: A Systematic Review and Meta-Analysis

OBJECTIVES/HYPOTHESIS

It was previously suggested that patients with idiopathic sudden sensorineural hearing loss (ISSNHL) have a higher risk of cardiovascular disease. The aim of this study is to determine if ISSNHL patients have an increased cardiovascular risk by means of a systematic review and meta-analysis.

METHODS

A systematic literature review was performed using PubMed, Embase, Cochrane Libraries and Web of Science. Studies with a clear definition of ISSNHL, investigating an association between traditional vascular risk factors and ISSNHL were included. Adhering to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, two reviewers extracted the data, assessed the risk of bias and performed the analysis of the collected evidence.

RESULTS

Nineteen case-control studies and two cohort studies were included (102,292 patients). Individual studies argued for higher prevalence of hypercholesterolemia, diabetes mellitus (DM) and higher blood pressure (HBP) in ISSNHL patients with a range of odds ratios (ORs) from 1.03 to 19. Pooled analysis of adjusted ORs revealed a significantly increased risk of ISSNHL for patients with hypertriglyceridemia (OR 1.54; 95% confidence interval [CI] 1.18-2.02) and high levels of total cholesterol (TC) (OR 2.09; 95% CI 1.52-2.87 after sensitivity analysis), but not for HBP, DM, or high levels of low- and high-density lipoproteins.

CONCLUSION

An association between higher vascular risk profile and ISSNHL seems apparent in high levels of triglycerides (TG) and TC, but more studies are needed to confirm this hypothesis due to the high levels of data heterogeneity in the literature.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:15-24, 2023.

The Incidence of Sudden Sensorineural Hearing Loss (SSNHL) in COVID-19 Patients in Tertiary Care Referral Units

COVID-19 is a new pandemic infectious disease that emerged in Wuhan, China, at the end of 2019. We aimed to evaluate the sudden sensorineural hearing loss (SSNHL) prevalence after COVID-19 infection or even vaccination. This is a two-center retrospective, observational cross-sectional study performed at tertiary care referral Audiovestibular Medicine Units at the period between August 1, 2020, and October 31, 2021. All SSNHL patients diagnosed in a period of a month with COVID-19 or vaccinated with a COVID-19 vaccine were included in this study. Fifty-three cases with confirmed COVID-19 and one patient vaccinated with a COVID-19 vaccine 1 week before, who reported sudden sensory neural hearing loss, were included in this study. Forty-eight patients had unilateral hearing loss and 6 patients had bilateral hearing loss. Forty-nine patients had typical COVID-19 symptoms; one patient discovered them after complaining of anosmia and ageusia and one patient after COVID-19 vaccination; and three patients were complaining only from hearing loss and had a PCR test for nasopharyngeal swabs to prove infection. Different degrees of SSNHL ranged from mild to severe and most of the patients had severe hearing loss. With more patients, COVID-19 may be a potential factor in sudden sensorineural hearing loss. It should be kept in mind that SSNHL may be the only indicator used to identify COVID-19 cases.

[Speech intelligibility in adults after the new coronavirus infection (COVID-19)]

OBJECTIVE

The research was aimed to assess speech intelligibility in adults after the new coronavirus infection (COVID-19), state of peripheral and central parts of auditory system and cognitive functions.

MATERIAL AND METHODS

26 people complaining about hearing loss, poor speech intelligibility and/or tinnitus after COVID-19 were examined. All the patients underwent the basic audiological assessment before COVID-19. Extended testing in patients after COVID-19 included: pure tone audiometry, impedancemetry, speech audiometry in quiet and noise (evaluation of monosyllabic words intelligibility and the Russian matrix sentence test RuMatrix), the alternating binaural speech test, the dichotic digits test and the Montreal Cognitive Assessment (MoCA).

RESULTS

The most significant deviations from the normative values were obtained in the RuMatrix test and the dichotic digits test that may be due to both central auditory processing disorder and memory impairment. Low MoCA scores were obtained in 62% of patients.

CONCLUSION

Deterioration of speech intelligibility after COVID-19 was revealed, both in patients with hearing loss and with normal hearing that corresponded to their complaints. It may be caused by central auditory disorder, memory impairment or cognitive status lesion. The correlation found between the results of the RuMatrix test in noise and the severity of the COVID-19 may indicate the impact of the virus on the auditory cortex.

Hearing loss in outbred Hartley guinea pigs experimentally infected with Pichinde virus as a surrogate model of human mammarenaviral hemorrhagic fevers

Lassa fever (LF) is a neglected tropical disease that is caused by Lassa virus (LASV), a human hemorrhagic fever-causing mammarenavirus. A notable sequela of LF is sensorineural hearing loss (SNHL) that can develop in about 33% of the patients. Animal models of LF-associated SNHL have been limited in size and scope because LASV is a biosafety level 4 (BSL4) pathogen that requires its handling in a high biocontainment laboratory. In this report, we describe the development of an alternative arenavirus hearing loss model by infecting outbred Hartley guinea pigs with a virulent strain (rP18) of the Pichinde virus (PICV), which is a guinea pig-adapted mammarenavirus that has been used as a surrogate model of mammarenaviral hemorrhagic fevers in a conventional (BSL2) laboratory. By measuring auditory brainstem response (ABR) throughout the course of the virulent rP18 PICV infection, we noticed that some of the animals experienced an acute but transient level of hearing loss. Cochleae of hearing-impaired animals, but not of controls, had demonstrable viral RNA by quantitative RT-PCR, indicating the presence of virus in the affected inner ear with no overt histopathological changes. In contrast, neither the outbred Hartley guinea pigs infected with a known avirulent strain (rP2) of PICV nor those that were mock-infected showed any evidence of hearing loss or viral infection of the inner ear. This is the first report of an immunocompetent small animal model of mammarenavirus-induced hearing loss that can be used to evaluate potential therapeutics against virus-induced hearing impairment under a conventional laboratory setting.

Update on Findings about Sudden Sensorineural Hearing Loss and Insight into Its Pathogenesis

Sudden sensorineural hearing loss (SSNHL) is routinely encountered and is one of the most common emergent diseases in otolaryngology clinics. However, the etiology of SSNHL remains unclear. Due to the inaccessibility of the living human inner ear for biopsy, studies investigating the etiology of SSNHL have been performed by analyzing data obtained from examinations using peripheral blood or imaging. We updated the findings obtained from serological, magnetic resonance imaging, genetic, and viral examinations to reveal the etiology of SSNHL. Regarding viral examination, we focused on sensorineural hearing loss associated with coronavirus disease (COVID-19) because the number of correlated reports has been increasing after the outbreak. The updated findings revealed the following three possible mechanisms underlying the development of SSNHL: thrombosis and resulting vascular obstruction in the cochlea, asymptomatic viral infection and resulting damage to the cochlea, and cochlear inflammation and resulting damage to the cochlea. Thrombosis and viral infection are predominant, and cochlear inflammation can be secondarily induced through viral infection or even thrombosis. The findings about sensorineural hearing loss associated with COVID-19 supported the possibility that asymptomatic viral infection is one of the etiologies of SSNHL, and the virus can infect inner ear tissues and directly damage them.

COVID-19 from the perspective of otorhinolaryngology: An analysis of bibliometrics

Background

Since it began in December 2019, the coronavirus disease 2019 (COVID-19) outbreak has not been completely contained. COVID-19 has attracted the interest of nations throughout the globe. The global coronavirus outbreak has had an especially devastating effect on otolaryngology. The virus is commonly associated with otorhinolaryngological symptoms. COVID-19 research is becoming more common in otorhinolaryngology. Although various studies on covid-19-related Otorhinolaryngology manifestations have been published, there has been no bibliometric analysis of these articles concentrating on COVID-19-related Otorhinolaryngology research.

Methods

Original publications on Otolaryngological symptoms on COVID-19 were extracted from the Social Sciences Citation Index (SSCI) and the Science Citation Index-Expanded (SCI-E) databases in Clarivate Analytics' Web of Science Core Collection (WoSCC) between January 2020 and May 2022. CiteSpace and VOSviewer were utilized to detect and assess the research focus and trends in this field by extracting the country/region, institution, author, journal, references, and keywords related to this topic.

Results

A total of 631 journals from 97 countries were included in the total of 1,528 articles. Most of the articles on this topic were published in the United States, which had the most citations and the highest H-index. Huazhong University of Science and Technology is the institution with the largest number of articles in the research of COVID-19-related Otorhinolaryngology diseases. Claire Hopkins was the most prolific author belonging to Guy's and St. Thomas' NHS Foundation Trust. Huang CL from Jin Yin-tan Hospital received the most citations among all authors. The most cited article was Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China, which was created by Huang CL. Most of the studies relating to COVID-19 and Otorhinolaryngology diseases were published in the European Archives of Oto-Rhino-Laryngology.

Conclusion

COVID-related research in the field of otorhinolaryngology has been studied in terms of descriptive quantitative metrics, which show that academics from around the world are working together to combat this pandemic.

Sudden sensorineural hearing loss and coronavirus disease 2019

Objective

To determine if otolaryngologists and audiologists of the American Academy of Otolaryngology – Head and Neck Surgery have noticed an increase in the incidence of sudden sensorineural hearing loss during the coronavirus disease 2019 pandemic.

Methods

A questionnaire was developed for the purpose of providing a cross-sectional descriptive analysis of perceived association between the coronavirus disease 2019 pandemic and an increase in the incidence of sudden sensorineural hearing loss.

Results

Of respondents, 63.0 per cent did not notice an increase in sudden sensorineural hearing loss during the coronavirus disease 2019 pandemic. There was a weak positive correlation between patients identified with sudden sensorineural hearing loss and the percentage of coronavirus disease 2019 positive patients reported by each medical care provider (Spearman correlation = 0.20, 95 per cent confidence interval = 0.05–0.33). There was no association between geographical location and perceived increase in sudden sensorineural hearing loss (p = 0.38).

Conclusion

The majority of respondents did not perceive an increase in the incidence of sudden sensorineural hearing loss during the coronavirus pandemic, regardless of geographical region.

Idiopathic sudden sensorineural hearing loss: A critique on corticosteroid therapy

Idiopathic sudden sensorineural hearing loss (ISSNHL) is a condition affecting 5-30 per 100,000 individuals with the potential to significantly reduce one's quality of life. The true incidence of this condition is not known because it often goes undiagnosed and/or recovers within a few days. ISSNHL is defined as a ≥30 dB loss of hearing over 3 consecutive audiometric octaves within 3 days with no known cause. The disorder is typically unilateral and most of the cases spontaneously recover to functional hearing within 30 days. High frequency losses, ageing, and vertigo are associated with a poorer prognosis. Multiple causes of ISSNHL have been postulated and the most common are vascular obstruction, viral infection, or labyrinthine membrane breaks. Corticosteroids are the standard treatment option but this practice is not without opposition. Post mortem analyses of temporal bones of ISSNHL cases have been inconclusive. This report analyzed ISSNHL studies administering corticosteroids that met strict inclusion criteria and identified a number of methodologic shortcomings that compromise the interpretation of results. We discuss the issues and conclude that the data do not support present treatment practices. The current status on ISSNHL calls for a multi-institutional, randomized, double-blind trial with validated outcome measures to provide science-based treatment guidance.

Unilateral sudden sensorineural hearing loss in post-COVID-19 patients: Case report

Sudden sensorineural hearing loss (SSNHL) is an otologic emergency. Sensorineural hearing loss needs to be distinguished from conductive when patients present with sudden hearing loss at the primary care level. Prompt diagnosis of sensorineural hearing loss with pure tone audiometry and immediate treatment by an otolaryngologist can improve the hearing outcome. To date, few case reports exist about SSNHL among post-COVID-19 patients, and none were reported in Malaysia. Here, we present two cases of SSNHL in patients after COVID-19 infection. We wish to highlight the association of SSNHL following COVID-19 infection for timely referral towards better audiology outcomes. Permanent hearing loss will lead to another negative impact on the long-term quality of life of COVID-19 patients.

Audio-Vestibular Profile of COVID-19; Systematic Review and Meta-analysis

Introduction

After more than a year of the COVID-19 pandemic, audio-vestibular problems have been reported as consequences. Several limited case report studies with different methodologies were published. This study aimed to describe the impact of COVID-19 on the auditory-vestibular system and communication problems in subjects with hearing impairment.

Materials and Methods

The current systematic review was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline. PubMed, Web of Science, and Google Scholar were searched to find relevant articles using combined keywords.

Results

Out of 26 final studies, 20 studies dealt with the effects of COVID-19 on the auditory and vestibular system, and six articles examined the COVID-19 effects on hearing-impaired people and patients. In these studies, dizziness (17.8%), tinnitus (8.1%), and vertigo (2.8%) were common symptoms. Most studies were case reports (42.30%), and in terms of quality, nine studies (34.61%) were in the suitable quality group.

Conclusions

COVID-19 might cause auditory-vestibular system problems by directly affecting the structures or functions of the inner ear or by weakening the immune system. The need for taking preventive measures during the COVID-19 pandemic has caused communication and social challenges, particularly for people with hearing loss.

The New Coronavirus Infection (COVID-19) and Hearing Function in Adults

In this study, we assessed the impact of COVID-19 on the hearing function in adults. A total of 161 subjects were examined, and the results of a previous audiological examination of 24 patients were reviewed. Pure tone audiometry, impedancemetry, speech audiometry in quiet and noise, the Binaural Fusion Test, the dichotic digits test, and a cognitive status examination were performed. A total of 81% of patients complained about hearing disorders, and 43% noted memory impairment. According to pure tone audiometry, 24% of the subjects had normal hearing, while 76% had some degree of hearing loss. No significant changes in hearing thresholds were found in comparison with audiological examinations performed before COVID-19. Disorder of monosyllabic words’ intelligibility in quiet was found in 33% of patients, and in 42% in noise, along with low indicators in the dichotic digits test in 54% of patients. Moreover, 71% of patients had low scores on the MoCA scale that indicated cognitive impairment. Conclusions: The deterioration of speech test scores in patients after COVID-19 can occur due to central auditory processing disorders (CAPD), memory impairment, or changes in cognitive status in general.

Recurrent sudden sensorineural hearing loss-A literature review

Objective

Sudden sensorineural hearing loss (SSNHL) is one of the few emergent otologic conditions. Although more than half of all patients would benefit from timely treatment, recurrence occasionally develops unexpectedly. The aim of our study is to evaluate the recurrence rate after SSNHL, and present the prognosis after first-episode and recurrent SSNHL.

Methods

A literature search was conducted of the PubMed and Embase electronic databases.

Results

Seven studies with a total of 3781 patients were included, and 96 patients experienced recurrence. The recurrence rate ranged between 1.4% and 17%. The average time to recurrence was about 2 years in most studies. The majority of the studies reported using systemic steroids for treating first-episode SSNHL, and one study used a plasma expander in patients with recurrent SSNHL. The recovery rate for first-episode patients was 58%-79%, while that for recurrent SSNHL ranged widely, from 21% to 86%. There were no common risk factors for SSNHL recurrence among the studies, although low-frequency hearing loss, the presence of tinnitus during follow-up, and an increased neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio have been proposed.

Conclusion

Understanding the recurrence rate, risk factors, and prognosis after recurrence of SSHNL is crucial for comprehensive medical care; in this respect, further prospective studies with long-term follow-up may be instructive.

Level of Evidence

4.

Air Pollution Exposure and the Relative Risk of Sudden Sensorineural Hearing Loss in Taipei

(1) Background: The etiologies of sudden sensorineural hearing loss (SSHL) remain unclear. The level of mean particulate matter with a diameter of 2.5 μm or less (PM2.5) was not associated with SSHL, but the maximum PM2.5 level exhibited a negative association with SSHL in Korea. Exposure to nitrogen dioxide (NO2) for 2 weeks increased the risk of SSHL. The lag effects of SSHL after air pollution exposure were limited. We aimed to evaluate the association of SSHL with air pollution exposure to determine whether air pollution exposure caused delayed effects. (2) Methods: This observational study used inpatient data obtained from electronic health records at the Tri-Service General Hospital from 2011 to 2019. The data of all SSHL patients were retrieved. The air quality dataset from Songshan station from 2011 to 2019 was used. The main outcomes were the relative risks (RRs) of SSHL associated with PM2.5, O3, and NO2 exposures within 1 month. The relationships between these factors were examined using distributed lag nonlinear time series models. (3) Results: The RR of SSHL associated with PM2.5 exposure was 1.195 (95% confidence interval (C.I.: 1.047-1.363) for a 10 unit increase at a lag of 7 days. The RR of SSHL associated with O3 exposure was 1.14 (95% C.I.: 1.003-1.3) for a 10 unit increase at a lag of 9 days. The RR of SSHL associated with NO2 exposure was 1.284 (95% C.I.: 1.05-1.57) for a 10 unit increase at a lag of 23 days. (4) Conclusions: In our study, SSHL was confirmed to be associated with air pollution exposure with a lag effect. We discussed possible mechanisms to explore possible biological hypotheses and support further research. Large-scale studies including participants with other ethnicities and causal relationships are needed to confirm our findings.

Audiological findings in individuals diagnosed with COVID-19

Purpose

It is thought that COVID-19 may cause hearing loss, but its effects on the hearing system are not clear. This study aimed to reveal the effects of COVID-19 on the auditory system by using various audiological measurement methods in individuals diagnosed with COVID-19.

Methods

Thirty individuals between the ages of 18–45, who were diagnosed with COVID-19 by PCR at least one month ago, and had no pre-COVID-19 hearing loss complaints, constituted the test group. Thirty individuals aged between 18 and 30 years and who had no history of hearing loss constituted the control group. Audiological evaluations of all participants were made with pure-tone audiometry, high-frequency audiometry, transient-evoked otoacoustic emission (TEOAE), distortion product otoacoustic emission (DPOAE), and auditory brainstem response (ABR) measurements.

Results

A significant difference was found between the groups at all high frequencies between 4 and 14 kHz (p < 0.05). TEOAE amplitudes at 1500 Hz, 2000 Hz and 4000 Hz frequencies and DPOAE amplitudes at 4003 Hz and higher frequencies were significantly lower in the test group (p < 0.05). While there was a significant difference between the I, III and V absolute latencies between the groups (p < 0.05), there was no significant difference between the I-III, III-V and I-V interpeak latencies (p > 0.05) as a result of the ABR test.

Conclusion

This study showed that COVID-19 can cause cochlear damage, especially at high frequencies. More studies are needed to determine the effects of COVID-19 on the auditory system.

Association between human papillomavirus infection and sudden sensorineural hearing loss: A nationwide population-based cohort study

BACKGROUND

While the etiology of sudden sensorineural hearing loss (SSNHL) remains unclear, viral infection has been suggested as a possible cause. Human papillomavirus (HPV) might trigger immune-mediated reaction and induce inflammatory cytokines which are injurious to the cochlea. This study aimed to investigate the association between HPV infection and the risk of developing SSNHL using a nationwide population-based data set.

METHODS

In this study, we used the population-based National Health Insurance Research Database of Taiwan to enroll 49,247 individuals with HPV infection from January 1st, 2000, to December 31st, 2013, and compared with a control group of 98,494 individuals who had never been diagnosed with HPV infection (at a 1:2 ratio matched by age, sex, index year, and comorbidities) in relation to the risk of subsequent SSNHL. The primary outcome was the time from the index date to the date when the first diagnosis of SSNHL occurred, death, withdrawal from the National Health Insurance Program, or the end of the study. Cox model with frailty was conducted to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), relative to comparison group. Sensitivity analyses were performed to validate our findings.

FINDINGS

The adjusted hazard ratio (aHR) of developing SSNHL was 1.37 (95% CI, 1.07-1.74) after adjustment for demographic characteristics, comorbidities, and medications. Sensitivity analyses showed consistent positive association. In our sub-group analysis, a significantly higher effect of HPV on SSNHL was noted in the patients with a previous diagnosis of cerebrovascular disease, compared with those without cerebrovascular disease (aHR: 4.59 versus 1.27, p-value for interaction = 0.024).

INTERPRETATION

HPV infections are associated with higher risk of subsequent SSNHL in the Taiwanese population. More research is needed to examine the causality and to determine the potential efficacy of specific precautions.

FUNDING

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Audiovestibular Disorders after COVID-19 Vaccine: Is There an Association?

The SARS-CoV-2 vaccination campaign is probably one of the most historic public hygiene measures in modern medicine. The drama of the pandemic has forced the scientific community to accelerate the development and commercialization of vaccines, thereby enhancing the phases of active surveillance. Among the adverse events following immunization (AEFI) reported, those of an audiovestibular interest, such as sudden sensorineural hearing loss (SSNHL), tinnitus, dizziness, and vertigo, constitute a very small percentage. There are many plausible etiological hypotheses, and scientific research needs to pay more attention to the correct collection of data, which up until now have often been inadequate and fragmented, on which to base future studies. SSNHL, new onset tinnitus, vertigo, and dizziness require a prompt evaluation, while the proposed treatment is the same as it is for events unrelated to vaccination. These are uncommon adverse events, and the risk rates for these diseases have not increased in conjunction with the COVID-19 vaccinations, therefore there is no justification of any hesitation towards the vaccination campaign.

Otologic and vestibular symptoms in COVID-19: A scoping review

Background

Otologic and vestibular symptoms have been seen in patients confirmed to have COVID-19 disease. Further discussion of these symptoms may provide insight into short- and long-term management for these patients.

Objective

The aim of this review was to describe the otologic and vestibular symptoms that present in patients with COVID-19. The primary outcomes of this review were onset, duration and clinical outcomes of these symptoms.

Sources of Evidence

Pub Med, APAMed Central, Herdin, CINAHL, Scopus, Springer Link, ProQuest Coronavirus Research Database, and Google Scholar were searched for the articles to be included.

Eligibility Criteria

Studies included were those involving adult patients diagnosed with COVID-19 who experienced hearing loss, ear pain, ear discharge, otitis media, vertigo, or tinnitus. Studies were eligible for inclusion if there was a description of the otologic dysfunction, specifically onset, duration, or clinical outcomes.

Results

The majority of patients who experienced hearing loss (68%), tinnitus (88%), vertigo/dizziness (30%), ear pain (8%), and discharge (100%) did so within a month of experiencing the typical symptoms of COVID-19. A majority also experienced complete resolution of their symptoms within 2 weeks. Standard treatment for COVID-19 was usually provided but when specific diagnoses are made for these symptoms (e.g., sudden sensorineural hearing loss, otitis media, vestibular neuritis), they are treated in the same manner as one would for non-COVID-19 cases, in addition to the management for COVID-19. In certain cases, there may be a need for additional work-up to rule out other causes.

Conclusions

Otologic and vestibular symptoms were present in COVID-19 patients, majority as part of the systemic nature of the disease. The onset, duration, and course were consistent with the natural history of a systemic viral infection. COVID-19 should be considered in any patient with a new-onset hearing loss, tinnitus, or vertigo/dizziness, even in the absence of infectious or respiratory symptoms.

Short- and Long-Term Self-Reported Audiovestibular Symptoms of SARS-CoV-2 Infection in Hospitalized and Nonhospitalized Patients

BACKGROUND

Audiovestibular symptoms during the acute stage have been reported in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), while very few studies investigated the long-term audiovestibular manifestations of SARS-CoV-2.

OBJECTIVE

The objective of this study was to examine the occurrence of short- and long-term audiovestibular symptoms associated with SARS-CoV-2 infection.

METHOD

In this cross-sectional study, a questionnaire was distributed to severe hospitalized cases and nonhospitalized patients with mild disease, all with confirmed SARS-CoV-2 test results. Participants were inquired to report audiovestibular symptoms during the acute phase and at 6-month follow-up after contracting SARS-CoV-2.

RESULTS

A total of 301 participants completed the questionnaire. Auditory symptoms were reported by 21.9% and 1.99% of patients during the acute phase and 6 months post SARS-CoV-2 infection, respectively. During the acute phase of SARS-CoV-2 infection, aural fullness represents the most common symptoms (18.94%) followed by tinnitus (9.97%) and hearing loss (6.31%). Vestibular symptoms were reported by 34% during the acute phase; most commonly was dizziness (29.9%) followed by vertigo (24.25%) and unsteadiness (8.31%). Long-term and persistent vestibular problems were reported by 3.99% patients. There were no statistically significant differences in self-reported audiovestibular symptoms between patients with severe SARS-CoV-2 disease compared to those with mild disease.

CONCLUSION

The current study showed that audiovestibular symptoms are common among SARS-CoV-2 infected patients during the acute phase of the disease. However, these symptoms are mostly temporary and showed complete spontaneous recovery during the first 2 weeks postinfection.

A case of sudden mixed hearing loss in SARS-CoV-2

The current global pandemic caused by coronavirus has uncovered multiple symptoms, including sudden hearing loss in either one or both ears, with different outcomes. We present a 68-year-old female with sudden onset bilateral hearing loss, fever, generalized body weakness, and gastrointestinal disturbances. She tested positive for severe acute respiratory syndrome coronavirus 2, was isolated, and was treated with a variety of medications for 5 days before being discharged home to self-isolate. The audiological assessment revealed both sensorineural and conductive hearing loss with a progressive favorable outcome on follow-up visits, with resolution occurring approximately 2 months after the onset. The majority of cases have reported sensorineural hearing loss. However, this case is one of the few that has reported mixed hearing loss. This report highlights an alternate clinical feature of the coronavirus that requires a comprehensive audiological examination by clinicians to ensure proper identification and treatment.

Prevalence of cardiovascular risk factors in superior vestibular neuritis: A cross-sectional study following STROBE guidelines

OBJECTIVE

To compare the prevalence of cardiovascular risk factors (CVRF) in patients with superior vestibular neuritis (SVN) versus the general French population, and to examine the possibility of vascular etiology in acute superior vestibular deficit.

MATERIAL AND METHODS

A single-center retrospective study compared the prevalence of hypercholesterolemia, hypertension, diabetes, smoking, cardiovascular disease and atrial fibrillation between patients with SVN and the French general population. Inclusion criteria comprised: rotatory vertigo lasting several days, without hearing impairment or neurological signs, with anterior and lateral semicircular canal involvement on video-Head-Impulse-Test (vHIT). A senior radiologist analyzed superior vestibular nerve and inner ear structure enhancement on cerebellopontine MRI.

RESULTS

One hundred and eighteen cases of SVN were included from May 2016 to February 2020. Statistical analyses concerned 106 cases. The SVN population had significantly less hypercholesterolemia (RR=0.40) than the general French population. There was no significant difference concerning other CVRFs. Superior vestibular nerve enhancement was observed on 84% of MRIs.

CONCLUSION

Prevalence of CVRF was not higher in patients with SVN than in the general population. The present study highlighted involvement of the superior vestibular nerve more than of the anterior vestibular artery in SVN.