Direct SARS-CoV-2 infection of the human inner ear may underlie COVID-19-associated audiovestibular dysfunction

Persistent ENT Manifestations in Individuals who Recovered from COVID-19: A Systematic Review

Introduction  Long coronavirus disease (COVID) refers to the persistence of symptoms long after the recovery from the acute phase of the illness, and it is due to the interplay of various inflammatory mechanisms. This has led to emergence of new deficits, including otorhinolaryngological symptoms, in patients wo have recovered from COVID. The plethora of otorhinolaryngological symptoms associated with long COVID are tinnitus, sensorineural hearing loss (SNHL), vertigo, nasal congestion, sinonasal discomfort, hyposmia/anosmia, dysgeusia, sore throat, dry cough, dyspnea, dysphagia, and hoarseness of voice. Objective  To evaluate the possible ENT symptoms in patients wo have recovered from COVID and to combine those findings with our experience. Data Synthesis  We conducted a search on the PubMed, ENT Cochrane, Web of Science, and Google Scholar databases, and a total of 44 studies were selected for the present review. Conclusion  Otorhinolaryngological complications such as tinnitus, SNHL, vertigo, nasal congestion, sinonasal discomfort, hyposmia/anosmia, dysgeusia, sore throat, dry cough, dyspnea, dysphagia, and hoarseness of voice have been widely reported among in long-COVID patients.

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.

Risk of Hearing Loss in Neonates and Toddlers with in Utero Exposure to SARS-CoV-2

OBJECTIVE

Given the prevalence of neonatal hearing loss (HL) associated with intrauterine viral exposures, the goal of this study is to provide information on neonatal HL in the context of the COVID-19 pandemic.

METHODS

Data were drawn from the COVID-19 Mother Baby Outcomes (COMBO) Initiative. 1007 participants completed the newborn hearing screen as part of routine clinical care (COMBO-EHR cohort) and 555 completed the National Survey of Children's Health (NSCH) at 2 and/or 3 years of age for research purposes (COMBO-RSCH cohort). Maternal SARS-CoV-2 infection status during pregnancy was determined through electronic health records and maternal-reported questionnaires.

RESULTS

In adjusted multivariate logistic regression models covarying for newborn age at assessment, mode of delivery, and gestational age at delivery, there was no significant association between intrauterine SARS-CoV-2 exposure and newborn hearing screening failure (OR = 1.05, 95% CI = 0.39-2.42, p = 0.91) in the COMBO-EHR cohort. In the COMBO-RSCH cohort, there were similar non-significant associations between intrauterine exposure to SARS-CoV-2 and maternal-reported concern for HL on the NSCH (OR = 1.19 [95% CI = 0.30-4.24], p = 0.79).

CONCLUSION

There is no association between intrauterine exposure to SARS-CoV-2 and failed hearing screen in neonates. Similarly, based on the NSCH, there is no association between intrauterine exposure to SARS-CoV-2 and maternal-reported concern for hearing in toddlers. These results offer reassurance given the widespread nature of this pandemic with tens of millions of fetuses having a history of intrauterine exposure.

LEVEL OF EVIDENCE

Level 4 Laryngoscope, 2024.

Ex vivo challenge models for infectious diseases

Traditionally, molecular mechanisms of pathogenesis for infectious agents were studied in cell culture or animal models but have limitations on the extent to which the resulting data reflect natural infection in humans. The COVID-19 pandemic has highlighted the urgent need to rapidly develop laboratory models that enable the study of host-pathogen interactions, particularly the relative efficacy of preventive measures. Recently, human and animal ex vivo tissue challenge models have emerged as a promising avenue to study immune responses, screen potential therapies and triage vaccine candidates. This approach offers the opportunity to closely approximate human disease from the perspective of pathology and immune response. It has advantages compared to animal models which are expensive, lengthy and often require containment facilities. Herein, we summarize some recent advances in the development of ex vivo tissue challenge models for COVID-19, HIV-1 and other pathogens. We focus on the contribution of these models to enhancing knowledge of host-pathogen interactions, immune modulation, and their value in testing therapeutic agents. We further highlight the advantages and limitations of using ex vivo challenge models and briefly summarize how the use of organoids provides a useful advancement over current approaches. Collectively, these developments have enormous potential for the study of infectious diseases.

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).

Migraine inhibitor olcegepant reduces weight loss and IL-6 release in SARS-CoV-2-infected older mice with neurological signs

COVID-19 can cause neurological symptoms such as fever, dizziness, and nausea. However, such neurological symptoms of SARS-CoV-2 infection have been hardly assessed in mouse models. In this study, we infected two commonly used wild-type mouse lines (C57BL/6J and 129/SvEv) and a 129S calcitonin gene-related peptide (αCGRP) null-line with mouse-adapted SARS-CoV-2 and demonstrated neurological signs including fever, dizziness, and nausea. We then evaluated whether a CGRP receptor antagonist, olcegepant, a "gepant" antagonist used in migraine treatment, could mitigate acute neuroinflammatory and neurological signs of SARS-COV-2 infection. First, we determined whether CGRP receptor antagonism provided protection from permanent weight loss in older (>18 m) C57BL/6J and 129/SvEv mice. We also observed acute fever, dizziness, and nausea in all older mice, regardless of treatment. In both wild-type mouse lines, CGRP antagonism reduced acute interleukin 6 (IL-6) levels with virtually no IL-6 release in mice lacking αCGRP. These findings suggest that migraine inhibitors such as those blocking CGRP receptor signaling protect against acute IL-6 release and subsequent inflammatory events after SARS-CoV-2 infection, which may have repercussions for related pandemic or endemic coronavirus outbreaks.IMPORTANCECoronavirus disease (COVID-19) can cause neurological symptoms such as fever, headache, dizziness, and nausea. However, such neurological symptoms of severe acute respiratory syndrome CoV-2 (SARS-CoV-2) infection have been hardly assessed in mouse models. In this study, we first infected two commonly used wild-type mouse lines (C57BL/6J and 129S) with mouse-adapted SARS-CoV-2 and demonstrated neurological symptoms including fever and nausea. Furthermore, we showed that the migraine treatment drug olcegepant could reduce long-term weight loss and IL-6 release associated with SARS-CoV-2 infection. These findings suggest that a migraine blocker can be protective for at least some acute SARS-CoV-2 infection signs and raise the possibility that it may also impact long-term outcomes.

Increased Incidence of Vestibular Disorders in Patients With SARS-CoV-2

Objective

Determine the incidence of vestibular disorders in patients with SARS-CoV-2 compared to the control population.

Study Design

Retrospective.

Setting

Clinical data in the National COVID Cohort Collaborative database (N3C).

Methods

Deidentified patient data from the National COVID Cohort Collaborative database (N3C) were queried based on variant peak prevalence (untyped, alpha, delta, omicron 21K, and omicron 23A) from covariants.org to retrospectively analyze the incidence of vestibular disorders in patients with SARS-CoV-2 compared to control population, consisting of patients without documented evidence of COVID infection during the same period.

Results

Patients testing positive for COVID-19 were significantly more likely to have a vestibular disorder compared to the control population. Compared to control patients, the odds ratio of vestibular disorders was significantly elevated in patients with untyped (odds ratio [OR], 2.39; confidence intervals [CI], 2.29-2.50; P < 0.001), alpha (OR, 3.63; CI, 3.48-3.78; P < 0.001), delta (OR, 3.03; CI, 2.94-3.12; P < 0.001), omicron 21K variant (OR, 2.97; CI, 2.90-3.04; P < 0.001), and omicron 23A variant (OR, 8.80; CI, 8.35-9.27; P < 0.001).

Conclusions

The incidence of vestibular disorders differed between COVID-19 variants and was significantly elevated in COVID-19-positive patients compared to the control population. These findings have implications for patient counseling and further research is needed to discern the long-term effects of these findings.

Bilateral, Sequential Sudden Hearing Loss in a Patient With Multiple COVID-19 Infections and Potential Implications on Subsequent Cochlear Implant Performance

Viruses are often implicated as a cause of sensorineural hearing loss (SNHL), particularly sudden cases, including COVID-19. Determining the viral mechanism that leads to hearing loss is necessary for its future prevention and treatment. The 47-year-old woman who is the subject of this case study presented with sudden SNHL following multiple infections of COVID-19. Following a trial of a contralateral routing of sound device, she received a right cochlear implant (CI). Following a period of high performance, additional cases of COVID-19 infection and device failure issues resulted in the explant/reimplant of 1 ear and implantation of the contralateral ear. Despite extensive rehabilitation after these events, the patient continues to experience difficulties in speech understanding, not reaching her initial high levels of right ear performance. Further research is needed to determine the implications of COVID-19 as it relates to SNHL. This case study aimed to highlight the course of treatment and provide insight into the impact of COVID-19 on sudden hearing loss and its relationship to CI performance.

COVID-19 vaccination-related tinnitus is associated with pre-vaccination metabolic disorders

Cases of tinnitus have been reported following administration of COVID-19 vaccines. The aim of this study was to characterize COVID-19 vaccination-related tinnitus to assess whether there is a causal relationship, and to examine potential risk factors for COVID-19 vaccination-related tinnitus. We analyzed a survey on 398 cases of COVID-19 vaccination-related tinnitus, and 699,839 COVID-19 vaccine-related reports in the Vaccine Adverse Effect Reporting System (VAERS) database that was retrieved on 4 December 2021. We found that following COVID-19 vaccination, 1) tinnitus report frequencies for Pfizer, Moderna and Janssen vaccines in VAERS are 47, 51 and 70 cases per million full vaccination; 2) the symptom onset was often rapid; 3) more women than men reported tinnitus and the sex difference increased with age; 4) for 2-dose vaccines, the frequency of tinnitus was higher following the first dose than the second dose; 5) for 2-dose vaccines, the chance of worsening tinnitus symptoms after second dose was approximately 50%; 6) tinnitus was correlated with other neurological and psychiatric symptoms; 7) pre-existing metabolic syndromes were correlated with the severity of the reported tinnitus. These findings suggest that COVID-19 vaccination increases the risk of tinnitus, and metabolic disorders is a risk factor for COVID-19 vaccination-related tinnitus.

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.

Pre-registered controlled comparison of auditory function reveals no difference between hospitalised adults with and without COVID-19

OBJECTIVE

Several viruses are known to have a negative impact on hearing health. The global prevalence of COVID-19 means that it is crucial to understand whether and how SARS-CoV2 affects hearing. Evidence to date is mixed, with studies frequently exhibiting limitations in the methodological approaches used or the populations sampled, leading to a substantial risk of bias. This study addressed many of these limitations.

DESIGN

A comprehensive battery of measures was administered, including lab-based behavioural and physiological measures, as well as self-report instruments. Performance was thoroughly assessed across the auditory system, including measures of cochlear function, neural function and auditory perception. Hypotheses and analyses were pre-registered.

STUDY SAMPLES

Participants who were hospitalised as a result of COVID-19 (n = 57) were compared with a well-matched control group (n = 40) who had also been hospitalised but had never had COVID-19.

RESULTS

We find no evidence to support the hypothesis that COVID-19 is associated with deficits in auditory function on any auditory test measure. Of all the confirmatory analyses, only the self-report measure of hearing decline indicated any difference between groups.

CONCLUSION

Results do not support the hypothesis that COVID-19 infection has a significant long-term impact on the auditory system.

Human otic progenitor cell models of congenital hearing loss reveal potential pathophysiologic mechanisms of Zika virus and cytomegalovirus infections

Congenital hearing loss is a common chronic condition affecting children in both developed and developing nations. Viruses correlated with congenital hearing loss include human cytomegalovirus (HCMV) and Zika virus (ZIKV), which causes congenital Zika syndrome. The mechanisms by which HCMV and ZIKV infections cause hearing loss are poorly understood. It is challenging to study human inner ear cells because they are encased in bone and also scarce as autopsy samples. Recent advances in culturing human stem cell-derived otic progenitor cells (OPCs) have allowed us herein to describe successful in vitro infection of OPCs with HCMV and ZIKV, and also to propose potential mechanisms by which each viral infection could affect hearing. We find that ZIKV infection rapidly and significantly induces the expression of type I interferon and interferon-stimulated genes, while OPC viability declines, at least in part, from apoptosis. In contrast, HCMV infection did not appear to upregulate interferons or cause a reduction in cell viability, and instead disrupted expression of key genes and pathways associated with inner ear development and function, including Cochlin, nerve growth factor receptor, SRY-box transcription factor 11, and transforming growth factor-beta signaling. These findings suggest that ZIKV and HCMV infections cause congenital hearing loss through distinct pathways, that is, by inducing progenitor cell death in the case of ZIKV infection, and by disruption of critical developmental pathways in the case of HCMV infection.

IMPORTANCE

Congenital virus infections inflict substantial morbidity and devastating disease in neonates worldwide, and hearing loss is a common outcome. It has been difficult to study viral infections of the human hearing apparatus because it is embedded in the temporal bone of the skull. Recent technological advances permit the differentiation of otic progenitor cells (OPCs) from human-induced pluripotent stem cells. This paper is important for demonstrating that inner ear virus infections can be modeled in vitro using OPCs. We infected OPCs with two viruses associated with congenital hearing loss: human cytomegalovirus (HCMV), a DNA virus, or Zika virus (ZIKV), an RNA virus. An important result is that the gene expression and cytokine production profiles of HCMV/ZIKV-infected OPCs are markedly dissimilar, suggesting that mechanisms of hearing loss are also distinct. The specific molecular regulatory pathways identified in this work could suggest important targets for therapeutics.

Detection of SARS-CoV-2 virus in middle ear effusions and its association with otitis media with effusion

A large-scale outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) occurred in Shanghai, China, in early December 2022. To study the incidence and characteristics of otitis media with effusion (OME) complicating SARS-CoV-2, we collected 267 middle ear effusion (MEE) samples and 172 nasopharyngeal (NP) swabs from patients. The SARS-CoV-2 virus was detected by RT-PCR targeting. The SARS-CoV-2 virus, angiotensin-converting enzyme 2 (ACE2), and transmembrane serine protease 2 (TMPRSS2) expression in human samples was examined via immunofluorescence. During the COVID-19 epidemic in 2022, the incidence of OME (3%) significantly increased compared to the same period from 2020 to 2022. Ear symptoms in patients with SARS-CoV-2 complicated by OME generally appeared late, even after a negative NP swab, an average of 9.33 ± 6.272 days after COVID-19 infection. The SARS-CoV-2 virus was detected in MEE, which had a higher viral load than NP swabs. The insertion rate of tympanostomy tubes was not significantly higher than in OME patients in 2019-2022. Virus migration led to high viral loads in MEE despite negative NP swabs, indicating that OME lagged behind respiratory infections but had a favorable prognosis. Furthermore, middle ear tissue from adult humans coexpressed the ACE2 receptor for the SARS-CoV-2 virus and the TMPRSS2 cofactors required for virus entry.

Inner Ear Organoids: Strengths and Limitations

Inner ear organoids derived from differentiation of human pluripotent stem cells have recently gained momentum as tools to study inner ear development and developmental defects. An additional exciting aspect about this technology is represented by its translational potential, specifically, the use of organoids to validate therapeutics for hearing and balance restoration on human/patient-specific cells. This latter aspect will be briefly discussed here including opportunities and current limitations.

[Pediatric sensorineural hearing loss related COVID-19. Clinical cases]

COVID-19 is an acute respiratory coronavirus infection in 2019 caused by the SARS-CoV-2 virus. Currently, the number of neurological complications in the acute or delayed period of coronavirus disease is increasing, including peripheral disorders of the auditory analyzer.

OBJECTIVE

To present clinical cases of sensorineural hearing loss in children under 5 years of age after a novel coronavirus infection.

MATERIAL AND METHODS

We report 3 cases of unilateral and 1 case of bilateral acquired deep sensorineural hearing loss, while the association with SARS-CoV-2 has been confirmed anamnetically and/or laboratory.

RESULTS

The SARS-CoV-2 virus can have a depressing effect on the cochlea on its own or enhance the toxic effect of viruses during the recovery period after COVID-19. The true frequency of acute sensorineural hearing loss of infectious origin in childhood and, as its outcome, the formation of persistent hearing impairment has not been determined.

CONCLUSION

Viruses are volatile, contagious, and clinically dangerous due to their complications. Vaccination is the most effective measure for the prevention of infectious diseases.

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.

Systematic review: Impact of stem cells-based therapy, and platelet-rich plasma in hair loss and telogen effluvium related to COVID-19

Background

The incidence of hair loss (HL) and telogen effluvium (TE) in COVID-19 patients has been reported in several studies.

Objectives

Evaluate both the increased incidence of HL and TE in COVID-19 and the effectiveness of Platelet-Rich Plasma (PRP), Adipose-derived Mesenchymal Stem Cells (AD-MSCs), and Human Follicle Stem Cells (HFSCs) in these patients.

Methods

The protocol was developed by the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. A multistep search of PubMed, MEDLINE, Embase, Clinicaltrials. gov, Scopus, and Cochrane databases has been performed to identify papers focusing on HL and TE COVID-19 related, and papers focusing on AD-MSCs, HFSC, and PRP use.

Results

Of the 404 articles initially identified focusing on HL and TE, 44 were related to COVID-19, and finally, only 6 were analyzed. On the other way, 331 articles focusing on AD-MSCs, HFSC, and PRP were initially identified. Of these, only 6 articles PRP (n = 3), AD-MSCs, and HFSCs (n = 3) have been analyzed.

Conclusion

Collected data confirmed both an increased incidence of HL and TE in COVID-19 patients, preliminarily, the related effectiveness of AD-MSCs, HFSCs, and PRP without major side effects.

[Organoids-the key to novel therapies for the inner ear? German version]

The sensitivity and the complexity of the human inner ear in conjunction with the lack of regenerative capacity are the main reasons for hearing loss and tinnitus. Progress in the development of protective and regenerative therapies for the inner ear often failed in the past not least due to the fact that no suitable model systems for cell biological and pharmacological in vitro studies were available. A novel technology for creating "mini-organs", so-called organoids, could solve this problem and has now also reached inner ear research. It makes it possible to produce inner ear organoids from cochlear stem/progenitor cells, embryonic and induced pluripotent stem cells that mimic the structural characteristics and functional properties of the natural inner ear. This review focuses on the biological basis of these inner ear organoids, the current state of research and the promising prospects that are now opening up for basic and translational inner ear research.

Sensorineural Hearing Loss as a Complication of COVID-19 and the COVID-19 Vaccine

The relationship between COVID-19 and sensorineural hearing loss (SNHL) continues to solidify in light of a growing body of evidence. In addition to the well-established COVID-19 symptoms and sequelae, otolaryngologists have observed an increased incidence of SNHL in patients with COVID-19 and following COVID-19 immunizations. Although the precise mechanisms behind this association remain unclear, various hypotheses are discussed within the scientific literature. This case report expands on the relationship between COVID-19 and SNHL by discussing a unique case of bilateral tinnitus and subsequent SNHL shortly following COVID-19 immunization. It contributes to the growing body of evidence associating COVID-19 with SNHL, underlining the importance of further research to understand potential causal mechanisms. It underscores the clinical importance of monitoring hearing in COVID-19 patients and those receiving immunizations, advocating for increased awareness among clinicians to facilitate early identification and appropriate intervention in cases of COVID-19-related hearing loss.

COVID-19 and Vestibular Symptoms and Assessment: A Review

BACKGROUND

The current pandemic of COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in significant morbidity and mortality primarily associated with respiratory failure. However, it has also been reported that COVID-19 can evolve into a nervous system infection. The direct and indirect mechanisms of damage associated with SARS-CoV-2 neuropathogenesis could affect our sensory functionality, including hearing and balance.

SUMMARY

In order to investigate a possible association between SARS-CoV-2 viral infection and possible damage to the vestibular system, this review describes the main findings related to diagnosing and evaluating otoneurological pathologies.

KEY MESSAGES

The clinical evidence shows that SARS-CoV-2 causes acute damage to the vestibular system that would not leave significant sequelae. Recovery is similar to vestibular pathologies such as vestibular neuronitis and benign paroxysmal positional vertigo. Further basic science, clinical, and translational research is needed to verify and understand the short- and long-term effects of COVID-19 on vestibular function.

Post-COVID-19 Syndrome: Audiometric Findings in Patients with Audiological Symptoms

Since the SARS-CoV-19 pandemic, the possibility of audiological involvement by this virus has been speculated without being able to generate a true cause-effect relationship. The objective of this observational, descriptive cross-sectional study is to describe the audiometric findings of post-COVID-19 patients with audiological symptoms. A sample of 47 patients with a diagnosis of COVID-19 infection was included: The age range was between 18 and 50 years old, the mean age was 37.0 years with a standard deviation of ±8.3 years, and 32 patients (68.1%) were female and 15 male patients (31.9%). Patients were recruited by the Otolaryngology service at Civil Fray Antonio Mayor Hospital from September 2020 to December 2022. Tonal audiometry was performed in a window of no more than 3 months from the onset of symptoms. The Chi-square test was used and odds ratios (OR) were established to associate the variables of post-COVID-19 audiological symptoms and the prevalence of hearing loss. A 95% confidence interval (CI) and statistical significance were considered of p ≤ 0.05. The audiological symptoms presented a prevalence of 74.4% for a sensation of ear fullness, 59.6% for tinnitus, and 51.1% for a sensation of hearing loss.

Mitigating neurological, cognitive, and psychiatric sequelae of COVID-19-related critical illness

Despite advances in the treatment and mitigation of critical illness caused by infection with SARS-CoV-2, millions of survivors have a devastating, post-acute infection syndrome known as long COVID. A large proportion of patients with long COVID have nervous system dysfunction, which is also seen in the distinct but overlapping condition of post-intensive care syndrome (PICS), putting survivors of COVID-19-related critical illness at high risk of long-lasting morbidity affecting multiple organ systems and, as a result, engendering measurable deficits in quality of life and productivity. In this Series paper, we discuss neurological, cognitive, and psychiatric sequelae in patients who have survived critical illness due to COVID-19. We review current knowledge of the epidemiology and pathophysiology of persistent neuropsychological impairments, and outline potential preventive strategies based on safe, evidence-based approaches to the management of pain, agitation, delirium, anticoagulation, and ventilator weaning during critical illness. We highlight priorities for current and future research, including possible therapeutic approaches, and offer considerations for health services to address the escalating health burden of long COVID.

Neurofilament Expression as a Biomarker of Post-COVID-19 Sudden Sensorineural Hearing Loss

Sudden sensorineural hearing loss (SSHL) affects a patient's quality of life and requires rapid treatment. The etiology is viral, vascular, and autoimmune, even though, in most cases, it remains idiopathic SSHL. Since 2019, several different complications have been identified following COVID-19 infection. The post-COVID-19 ENT manifestations reported in the literature are sore throat, headache, pharyngeal erythema, nasal obstruction, rhinorrhea, upper respiratory tract infection, and tonsil enlargement. Cases of SSHL, vestibular neuronitis, and audio-vestibular disorders (such as tinnitus, dizziness, and vertigo) have also been reported, albeit in a smaller percentage of patients. We reported our experience of a case of post-COVID-19 SSHL in the absence of any other type of post-COVID symptoms or brain and internal auditory canal magnetic resonance imaging and magnetic resonance angiography modifications. We aimed to identify a serological biomarker of sudden sensorineural hearing loss, and we also dosed and monitored the value of the serum neurofilament light (NfL). the best of our knowledge, this is the first report that associates SSHL and the serological increase in NfL as a potential biomarker of neuronal-disease-related damage.

The Pathogenesis of Cytomegalovirus and Other Viruses Associated with Hearing Loss: Recent Updates

Virus infection is one of the most common etiologies of hearing loss. Hearing loss associated with viral infection can be unilateral or bilateral, mild or severe, sudden or progressive, and permanent or recoverable. Many viruses cause hearing loss in adults and children; however, the pathogenesis of hearing loss caused by viral infection is not fully understood. This review describes cytomegalovirus, the most common virus causing hearing loss, and other reported hearing loss-related viruses. We hope to provide a detailed description of pathogenic characteristics and research progress on pathology, hearing phenotypes, possible associated mechanisms, treatment, and prevention measures. This review aims to provide diagnostic and treatment assistance to clinical workers.

Natural history of long-COVID in a nationwide, population cohort study

Previous studies on the natural history of long-COVID have been few and selective. Without comparison groups, disease progression cannot be differentiated from symptoms originating from other causes. The Long-COVID in Scotland Study (Long-CISS) is a Scotland-wide, general population cohort of adults who had laboratory-confirmed SARS-CoV-2 infection matched to PCR-negative adults. Serial, self-completed, online questionnaires collected information on pre-existing health conditions and current health six, 12 and 18 months after index test. Of those with previous symptomatic infection, 35% reported persistent incomplete/no recovery, 12% improvement and 12% deterioration. At six and 12 months, one or more symptom was reported by 71.5% and 70.7% respectively of those previously infected, compared with 53.5% and 56.5% of those never infected. Altered taste, smell and confusion improved over time compared to the never infected group and adjusted for confounders. Conversely, late onset dry and productive cough, and hearing problems were more likely following SARS-CoV-2 infection.

In vitro high-content tissue models to address precision medicine challenges

The field of precision medicine allows for tailor-made treatments specific to a patient and thereby improve the efficiency and accuracy of disease prevention, diagnosis, and treatment and at the same time would reduce the cost, redundant treatment, and side effects of current treatments. Here, the combination of organ-on-a-chip and bioprinting into engineering high-content in vitro tissue models is envisioned to address some precision medicine challenges. This strategy could be employed to tackle the current coronavirus disease 2019 (COVID-19), which has made a significant impact and paradigm shift in our society. Nevertheless, despite that vaccines against COVID-19 have been successfully developed and vaccination programs are already being deployed worldwide, it will likely require some time before it is available to everyone. Furthermore, there are still some uncertainties and lack of a full understanding of the virus as demonstrated in the high number new mutations arising worldwide and reinfections of already vaccinated individuals. To this end, efficient diagnostic tools and treatments are still urgently needed. In this context, the convergence of bioprinting and organ-on-a-chip technologies, either used alone or in combination, could possibly function as a prominent tool in addressing the current pandemic. This could enable facile advances of important tools, diagnostics, and better physiologically representative in vitro models specific to individuals allowing for faster and more accurate screening of therapeutics evaluating their efficacy and toxicity. This review will cover such technological advances and highlight what is needed for the field to mature for tackling the various needs for current and future pandemics as well as their relevancy towards precision medicine.

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.

Auditory function in symptomatic patients recovered from SARS-CoV-2 and unexposed patients: An analytical cross-sectional study

Objective

To describe audiological symptoms, audiometric profile, and distortion product otoacoustic emission in symptomatic patients recovering from SARS-CoV-2 infection (positive RT-PCR test) and asymptomatic patients (negative RT-PCR test).

Methods

An analytical cross-sectional study was conducted using data obtained from clinical charts, physical examination, audiometry, and distortion product otoacoustic emission on 40 patients [case patients (CP)] recovering from SARS-CoV-2 infection diagnosed by a positive RT-PCR test and 22 asymptomatic participants with a negative RT-PCR test [non-case (NC)].

Results

Sixty-two patients (mean age: 31.1 and 28.2 years in the CP and NC groups, respectively) were included. All participants were young without significant comorbidities, risk factors for hearing loss or otological history. Vertigo (5%), tinnitus (17.5%) and aural fullness/hearing loss (35%) were found in the CP group. A statistically significant difference was found in specific frequencies (1000, 4000, and 8000 Hz) and pure tone average (low and high conversational frequencies with increased threshold in the PC group compared with the NC group), which was not found in distortion product otoacoustic emission.

Conclusion

Audiovestibular symptoms are frequent in symptomatic patients recovering from SARS-CoV-2 infection. SARS-CoV-2 infection was consistently associated with an increased audiometric hearing threshold at specific frequencies and low tone average.

Pathophysiology and mechanisms of hearing impairment related to neonatal infection diseases

The inner ear, the organ of equilibrium and hearing, has an extraordinarily complex and intricate arrangement. It contains highly specialized structures meticulously tailored to permit auditory processing. However, hearing also relies on both peripheral and central pathways responsible for the neuronal transmission of auditory information from the cochlea to the corresponding cortical regions. Understanding the anatomy and physiology of all components forming the auditory system is key to better comprehending the pathophysiology of each disease that causes hearing impairment. In this narrative review, the authors focus on the pathophysiology as well as on cellular and molecular mechanisms that lead to hearing loss in different neonatal infectious diseases. To accomplish this objective, the morphology and function of the main structures responsible for auditory processing and the immune response leading to hearing loss were explored. Altogether, this information permits the proper understanding of each infectious disease discussed.

Health progression for Covid-19 survivors hospitalized in geriatric clinics in Sweden

OBJECTIVE

To analyse if the health progression of geriatric Covid-19 survivors three months after an acute Covid-19 infection was worse than in other geriatric patients. Specifically, we wanted to see if we could see distinct health profiles in the flow of re-admitted Covid-19 patients compared to re-admitted non-Covid-19 controls.

DESIGN

Matched cohort study.

SETTING AND PARTICIPANTS

Electronic medical records of geriatric patients hospitalised in geriatric clinics in Stockholm, Sweden, between March 2020 and January 2022. Patients readmitted three months after initial admission were selected for the analysis and Covid-19 survivors (n = 895) were compared to age-sex-Charlson comorbidity index (CCI)-matched non-Covid-19 controls (n = 2685).

METHODS

We assessed using binary logistic and Cox regression if a previous Covid-19 infection could be a risk factor for worse health progression indicated by the CCI, hospital frailty risk score (HFRS), mortality and specific comorbidities.

RESULTS

The patients were mostly older than 75 years and, already at baseline, had typically multiple comorbidities. The Covid-19 patients with readmission had mostly had their acute-phase infection in the 1st or 2nd pandemic waves before the vaccinations. The Covid-19 patients did not have worse health after three months compared to the matched controls according to the CCI (odds ratio, OR[95% confidence interval, CI] = 1.12[0.94-1.34]), HFRS (OR[95%CI] = 1.05[0.87-1.26]), 6-months (hazard ratio, HR[95%CI] = 1.04[0.70-1.52]) and 1-year-mortality risk (HR[95%CI] = 0.89[0.71-1.10]), adjusted for age, sex and health at baseline (the CCI and HFRS).

CONCLUSIONS AND IMPLICATIONS

The overall health progression of re-hospitalized geriatric Covid-19 survivors did not differ dramatically from other re-hospitalized geriatric patients with similar age, sex and health at baseline. Our results emphasize that Covid-19 was especially detrimental for geriatric patients in the acute-phase, but not in the later phase. Further studies including post-vaccination samples are needed.

Hearing screening test in neonates born to COVID-19-positive mothers

SARS-CoV-2, the responsible virus for the COVID-19 pandemic, has demonstrated neurotropic properties indicated by cases presenting with auditory and vestibular system insults. The expression of ACE-2 receptors in the placenta and the detection of IgM antibodies against the virus in the fetuses of pregnant women suffering from COVID-19 render vertical transmission of the infection to the fetus possible. Thus, our study aims to examine whether, similar to other viruses like CMV, SARS-CoV-2 is responsible for congenital hearing loss. This is a retrospective study in a regional pediatric hospital. The medical records of newborns (n = 111) born by mothers positive for COVID-19 during pregnancy who underwent screening hearing tests with Transient Evoked Otoacoustic Emissions (TEOAE) and Automatic Auditory Brainstem Response (AABR) from February 2020 to June 2022 were reviewed. Neonates with additional aggravating factors for congenital hearing loss were excluded from the study. For the study period, nine mothers were found positive during the first trimester, twenty mothers in the second trimester, and eighty-three mothers in the third trimester. TEOAEs test and AABR test scored PASS bilaterally in all neonates tested.

CONCLUSION

Infection with COVID-19 during pregnancy was not a risk factor for hearing loss, similar to other studies.

WHAT IS KNOWN

• The pathogenetic mechanism of the viral-induced impairment of the organ of Corti includes direct damage to the hair cells and indirect damage due to the induction of the innate inflammatory response. • Early data suggested that the SARS-CoV-2 virus also has neurotropic properties with manifestations from the sensory epithelia.

WHAT IS NEW

• Although the intrauterine infection remains controversial, the expression of the ACE-2 receptor on the placenta and the detection of IgM antibodies, as well as the covid-19 genome in fetuses, make the vertical transmission tenable. • In our study, the newborn hearing screening results indicate that COVID-19 infection during pregnancy is not a risk factor for hearing loss.

The association between COVID-19 vaccination and idiopathic sudden sensorineural hearing loss, clinical manifestation and outcomes

PURPOSE

Previous data demonstrated an increased incidence of Idiopathic Sensorineural Hearing Loss (ISSNHL) in 2021 compared to 2019-2020, suggesting an association with the anti-COVID-19 vaccine. We aimed to assess our center's incidence and compare the clinical manifestations and outcomes of vaccinated vs. unvaccinated patients.

METHODS

A retrospective chart review of all patients diagnosed with ISSNHL during 2021 was conducted and compared to patients who presented in 2018-2020. Patient demographics, audiometry features, vaccination status, and prognosis were evaluated.

RESULTS

Throughout 2021, 51 patients were diagnosed with ISSNHL, compared with 31 during 2020, 38 in 2019, and 41 in 2018, demonstrating a 64%, 34%, and 24% increase, respectively. Among patients who presented in 2021, 13 (25.4%) received the anti-COVID-19 vaccine within 30 days before their presentation, and 4 received it within 96 h. Most presented after receiving the second or third dose. Patient characteristics, audiometry features, and prognosis did not significantly differ between vaccinated and unvaccinated patients.

CONCLUSIONS

A marked incline was seen in the 2021 ISSNHL incidence at our medical center, of which 25% of cases were within a month post-anti-COVID-19 vaccination. No significant difference was found in clinical manifestations and outcomes between vaccinated and nonvaccinated patients. While other justifications could be sought, an association cannot be ruled out, and further research is needed.

Induced Pluripotent Stem Cell-Derived Organoids: Their Implication in COVID-19 Modeling

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a significant global health issue. This novel virus's high morbidity and mortality rates have prompted the scientific community to quickly find the best COVID-19 model to investigate all pathological processes underlining its activity and, more importantly, search for optimal drug therapy with minimal toxicity risk. The gold standard in disease modeling involves animal and monolayer culture models; however, these models do not fully reflect the response to human tissues affected by the virus. However, more physiological 3D in vitro culture models, such as spheroids and organoids derived from induced pluripotent stem cells (iPSCs), could serve as promising alternatives. Different iPSC-derived organoids, such as lung, cardiac, brain, intestinal, kidney, liver, nasal, retinal, skin, and pancreatic organoids, have already shown immense potential in COVID-19 modeling. In the present comprehensive review article, we summarize the current knowledge on COVID-19 modeling and drug screening using selected iPSC-derived 3D culture models, including lung, brain, intestinal, cardiac, blood vessels, liver, kidney, and inner ear organoids. Undoubtedly, according to reviewed studies, organoids are the state-of-the-art approach to COVID-19 modeling.

[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.

Self-Reported Long COVID and Its Association with the Presence of SARS-CoV-2 Antibodies in a Danish Cohort up to 12 Months after Infection

The majority of long coronavirus disease (COVID) symptoms are not specific to COVID-19 and could be explained by other conditions. The present study aimed to explore whether Danish individuals with a perception that they suffer from long COVID have antibodies against the nucleocapsid antigen, as a proxy for detecting previous infection. The study was conducted in February and March 2021, right after the second surge of the COVID-19 pandemic in Denmark. All members of the social media group on Facebook "Covidramte med senfølger" ("long COVID sufferers'') above the age of 17 years and living in Denmark were invited to participate in a short electronic questionnaire about long COVID risk factors and symptoms. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) protein was detected in blood samples as a proxy for natural SARS-CoV-2 infection. The final study population comprised 341 participants (90.6% females) who completed blood sampling and answered the questionnaire. A total of 232 (68%) were seropositive (median age, 49.5 years; interquartile range [IQR], 41 to 55 years; 90.1% females). There was no significant difference between sexes and serostatus. Seronegative and seropositive individuals had a similar burden of symptoms that could be attributed to long COVID. Time since perceived COVID-19 was significantly longer in the group of seronegative individuals than the seropositive ones (P < 0.001). This study suggests that long-COVID sufferers are mostly women and showed that a third of the participants did not have detectable anti-N-protein antibodies. It emphasizes the importance of early confirmation of COVID-19, as this study indicates an overlap between long-COVID symptoms and symptoms that are possibly of another origin. IMPORTANCE This cohort study included questionnaire data as well as anti-nucleocapsid antibody analysis, allowing us to determine whether participants were seropositive due to vaccination or natural infection. The study emphasizes the importance of early confirmation of COVID-19, as antibodies recede with time, and it indicates an overlap between long COVID symptoms and symptoms possibly of another origin.

Neuromasts and Olfactory Organs of Zebrafish Larvae Represent Possible Sites of SARS-CoV-2 Pseudovirus Host Cell Entry

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the acute respiratory disease coronavirus disease 2019 (COVID-19), which has resulted in millions of deaths globally. Here, we explored the mechanism of host cell entry of a luciferase-ZsGreen spike (SARS-CoV-2)-pseudotyped lentivirus using zebrafish embryos/larvae as an in vivo model. Successful pseudovirus entry was demonstrated via the expression of the luciferase (luc) gene, which was validated by reverse transcription-PCR (RT-PCR). Treatment of larvae with chloroquine (a broad-spectrum viral inhibitor that blocks membrane fusion) or bafilomycin A1 (a specific inhibitor of vacuolar proton ATPases, which blocks endolysosomal trafficking) significantly reduced luc expression, indicating the possible involvement of the endolysosomal system in the viral entry mechanism. The pharmacological inhibition of two-pore channel (TPC) activity or use of the tpcn2^dhkz1a mutant zebrafish line also led to diminished luc expression. The localized expression of ACE2 and TPC2 in the anterior neuromasts and the forming olfactory organs was demonstrated, and the occurrence of endocytosis in both locations was confirmed. Together, our data indicate that zebrafish embryos/larvae are a viable and tractable model to explore the mechanism of SARS-CoV-2 host cell entry, that the peripheral sense organs are a likely site for viral host cell entry, and that TPC2 plays a key role in the translocation of the virus through the endolysosomal system. IMPORTANCE Despite the development of effective vaccines to combat the COVID-19 pandemic, which help prevent the most life-threatening symptoms, full protection cannot be guaranteed, especially with the emergence of new viral variants. Moreover, some resistance to vaccination remains in certain age groups and cultures. As such, there is an urgent need for the development of new strategies and therapies to help combat this deadly disease. Here, we provide compelling evidence that the peripheral sensory organs of zebrafish possess several key components required for SARS-CoV-2 host cell entry. The nearly transparent larvae provide a most amenable complementary platform to investigate the key steps of viral entry into host cells, as well as its spread through the tissues and organs. This will help in the identification of key viral entry steps for therapeutic intervention, provide an inexpensive model for screening novel antiviral compounds, and assist in the development of new and more effective vaccines.

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

INTRODUCTION

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a viral infection with a wide variety of symptoms, including fever, coughing, sneezing, fatigue, and a loss of taste and smell. Moreover, there are some recent studies that investigate the effects of SARS-CoV-2 on hearing and auditory performance. With this current study, we investigate the early effects of the coronavirus disease on hair cells in the cochlea.

METHODS

In the current study, there were 25 subjects (17 females, 8 males) who tested positive for polymerase chain reaction on nasopharyngeal swabs. They had reported normal auditory functions and no history of otology before SARS-CoV-2. To determine auditory functions, pure-tone audiometry, otoacoustic emissions (OAE) tests, and threshold equalizing noise (TEN) tests were used.

RESULTS

Although the hearing thresholds increased at higher frequencies, they were within normal limits according to four-frequency pure-tone averages. All participants had normal OAE, and there were no detected dead regions for any of the subjects. Even so, there were significant increases in hearing thresholds in TEN.

CONCLUSION

There is no cochlear dysfunction discovered by OAE and TEN in SARS-CoV-2-affected individuals. Nonetheless, the increase in hearing thresholds at higher frequencies, other than the pure-tone average frequencies detected by TEN, and the decrease in the presence of detected OAE could be related to deterioration in the basal part of the cochlea.

Tinnitus and biopsychosocial ramifications of COVID-19 associated with severe suicide attempt-a case report

The COVID-19 disease has been linked to multiple physical and mental health consequences which may be partially attributed to multi-system modulation by inflammatory cytokines. Post-acute sequelae (PASC) of SARS-CoV-2 infection, colloquially known as "Long Covid", has become an established entity. However, screening guidelines and interventions for COVID-19 survivors remain elusive. The neuropsychiatric sequelae of COVID-19 seem to originate from a cumulation of biopsychosocial factors which may predispose individuals to acute psychiatric decompensation irrespective of a previously diagnosed mental illness. We present a case report which illustrates how cognitive issues and medical complaints may negatively interact resulting in significant depression and a severe suicide attempt.

Modelling inner ear development and disease using pluripotent stem cells - a pathway to new therapeutic strategies

The sensory epithelia of the mammalian inner ear enable sound and movement to be perceived. Damage to these epithelia can cause irreversible sensorineural hearing loss and vestibular dysfunction because they lack regenerative capacity. The human inner ear cannot be biopsied without causing permanent damage, significantly limiting the tissue samples available for research. Investigating disease pathology and therapeutic developments have therefore traditionally relied on animal models, which often cannot completely recapitulate the human otic systems. These challenges are now being partly addressed using induced pluripotent stem cell-derived cultures, which generate the sensory epithelial-like tissues of the inner ear. Here, we review how pluripotent stem cells have been used to produce two-dimensional and three-dimensional otic cultures, the strengths and limitations of these new approaches, and how they have been employed to investigate genetic and acquired forms of audiovestibular dysfunction. This Review provides an overview of the progress in pluripotent stem cell-derived otic cultures thus far, focusing on their applications in disease modelling and therapeutic trials. We survey their current limitations and future directions, highlighting their prospective utility for high-throughput drug screening and developing personalised medicine approaches.

The Absence of Permanent Sensorineural Hearing Loss in a Cohort of Children with SARS-CoV-2 Infection and the Importance of Performing the Audiological "Work-Up"

BACKGROUND

Currently, the novel coronavirus (SARS-CoV-2) causes an acute respiratory illness named COVID-19 and is a controversial risk factor for hearing loss (HL). Herein, we aim to describe the associated symptoms and to evaluate hearing function in the COVID-19 pediatric population.

METHODS

A retrospective cross-sectional observational study was carried out on 37 children who contracted COVID-19 infection with no previous audio-vestibular disorders. Clinical data on the infections were collected, and an audiological assessment of all affected children was performed by using different diagnostic protocols according to their age.

RESULTS

Fever, upper respiratory and gastrointestinal manifestations were common presentations of infection. Audiological function was normal in 30 (81.08%) children, while 7 children showed an increased hearing threshold: 6 (16.21%) had transient conductive hearing loss (CHL) due to middle ear effusion and normalized at the follow-up and 1 had sensorineural hearing loss (SNHL). A single child was affected by bilateral SNHL (2.7%); however, he underwent a complete audiological work-up leading to a diagnosis of genetic HL due to a MYO6 gene mutation which is causative of progressive or late onset SNHL.

CONCLUSIONS

HL needs to be considered among the manifestations of COVID-19 in children, nevertheless, we found cases of transient CHL. The onset of HL during or following COVID-19 infection does not eliminate the indication for maintaining audiological surveillance and audiological work-ups, including genetic diagnosis, to avoid the risk of mistaking other causes of HL.

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.

Induced Pluripotent Stem Cells, a Stepping Stone to In Vitro Human Models of Hearing Loss

Hearing loss is the most prevalent sensorineural impairment in humans. Yet despite very active research, no effective therapy other than the cochlear implant has reached the clinic. Main reasons for this failure are the multifactorial nature of the disorder, its heterogeneity, and a late onset that hinders the identification of etiological factors. Another problem is the lack of human samples such that practically all the work has been conducted on animals. Although highly valuable data have been obtained from such models, there is the risk that inter-species differences exist that may compromise the relevance of the gathered data. Human-based models are therefore direly needed. The irruption of human induced pluripotent stem cell technologies in the field of hearing research offers the possibility to generate an array of otic cell models of human origin; these may enable the identification of guiding signalling cues during inner ear development and of the mechanisms that lead from genetic alterations to pathology. These models will also be extremely valuable when conducting ototoxicity analyses and when exploring new avenues towards regeneration in the inner ear. This review summarises some of the work that has already been conducted with these cells and contemplates future possibilities.

Is COVID-19 to Blame for Sensorineural Hearing Deterioration? A Pre/Post COVID-19 Hearing Evaluation Study

OBJECTIVES

Here, we aimed to (a) determine whether a clinically significant sensorineural hearing loss (SNHL) change could be detected in post-coronavirus disease (COVID-19) hearing levels on comparing them with pre-infection hearing levels after controlling for the effect of age and (b) to identify risk factors, such as hypertension, diabetes, and smoking, which increase the likelihood of hearing loss in COVID-19 patients.

METHODS

We retrospectively analyzed hearing thresholds in unvaccinated patient's pre- and post-COVID-19 infection. Thresholds were controlled for age and the duration between the pre- and post-COVID-19 hearing evaluations. Correlations between additional COVID-19-related symptoms, hypertension, diabetes, and smoking and hearing threshold changes were analyzed.

RESULTS

A significant (but not clinical) threshold elevation was found post-COVID-19 infection. However, on controlling for age and the duration between the pre- and post-COVID-19 hearing evaluations, no significant threshold elevation was found. No significant correlation was found between hearing threshold changes and additional COVID-19-related symptoms, hypertension, diabetes, or smoking.

CONCLUSION

COVID-19 did not lead to a significant hearing threshold elevation in our cohort, even among patients with additional COVID-19 symptoms, hypertension, or diabetes mellitus or among those who smoked.

LEVEL OF EVIDENCE: 3

nonrandomized controlled cohort, follow-up study Laryngoscope, 2022.

Advancements in inner ear development, regeneration, and repair through otic organoids

The vertebrate inner ear contains a diversity of unique cell types arranged in a particularly complex 3D cytoarchitecture. Both of these features are integral to the proper development, function, and maintenance of hearing and balance. Since the elucidation of the timing and delivery of signaling molecules to produce inner ear sensory cells, supporting cells, and neurons from human induced pluripotent stem cells, we have entered a revolution using organ-like 'otic organoid' cultures to explore inner ear specific genetic programs, developmental rules, and potential therapeutics. This review aims to highlight a selection of reviews and primary research papers from the past two years of particular merit that use otic organoids to investigate the broadly defined topics of cell reprogramming, regeneration, and repair.

Toward Personalized Diagnosis and Therapy for Hearing Loss: Insights From Cochlear Implants

ABSTRACT

Sensorineural hearing loss (SNHL) is the most common sensory deficit, disabling nearly half a billion people worldwide. The cochlear implant (CI) has transformed the treatment of patients with SNHL, having restored hearing to more than 800,000 people. The success of CIs has inspired multidisciplinary efforts to address the unmet need for personalized, cellular-level diagnosis, and treatment of patients with SNHL. Current limitations include an inability to safely and accurately image at high resolution and biopsy the inner ear, precluding the use of key structural and molecular information during diagnostic and treatment decisions. Furthermore, there remains a lack of pharmacological therapies for hearing loss, which can partially be attributed to challenges associated with new drug development. We highlight advances in diagnostic and therapeutic strategies for SNHL that will help accelerate the push toward precision medicine. In addition, we discuss technological improvements for the CI that will further enhance its functionality for future patients. This report highlights work that was originally presented by Dr. Stankovic as part of the Dr. John Niparko Memorial Lecture during the 2021 American Cochlear Implant Alliance annual meeting.

Audiological profile of adult long COVID patients

Introduction

Hearing loss is one of the self-reported symptoms of Long COVID patients, however data from objective and subjective audiological tests demonstrating diminished hearing in Long COVID patients has not been published.

Materials and methods

Respondents of a large Long COVID online survey were invited to the ENT-department for an otologic exam. The participants were split into three groups based on their history of SARS-CoV-2 infection and persistence of symptoms. Respondents with a history of a SARS-CoV-2 infection were allocated to the Long COVID group, if they reported persistent symptoms and to the Ex COVID group, if they had regained their previous level of health. Participants without a history of SARS-CoV-2 infection made up the No COVID control group. In total, 295 ears were examined with otoscopy, tympanograms, pure tone audiometry and otoacoustic emissions. Ears with known preexisting hearing loss or status post ear surgery, as well as those with abnormal otoscopic findings, non-type A tympanograms or negative Rinne test were excluded.

Results

Compared to the No COVID and Ex COVID groups, we did not find a clinically significant difference in either hearing thresholds or frequency specific TEOAEs. However, at 500 Hz the data from the left ear, but not the right ear showed a significantly better threshold in the Ex COVID group, compared to Long COVID and No COVID groups. Any of the other tested frequencies between 500 Hz and 8 kHz were not significantly different between the different groups. There was a significantly lower frequency-specific signal-to-noise-ratio of the TEOAEs in the Long COVID compared to the No COVID group at 2.8 kHz. At all other frequencies, there were no significant differences between the three groups in the TEOAE signal-to-noise-ratio.

Conclusion

This study detected no evidence of persistent cochlear damage months after SARS-CoV-2 infection in a large cohort of Long COVID patients, as well as those fully recovered.