SARS-CoV-2 vaccine-associated-tinnitus: A review

A Direct Relationship Between 'Blood Stasis' and Fibrinaloid Microclots in Chronic, Inflammatory, and Vascular Diseases, and Some Traditional Natural Products Approaches to Treatment

'Blood stasis' (syndrome) (BSS) is a fundamental concept in Traditional Chinese Medicine (TCM), where it is known as Xue Yu (). Similar concepts exist in Traditional Korean Medicine ('Eohyul') and in Japanese Kampo medicine (Oketsu). Blood stasis is considered to underpin a large variety of inflammatory diseases, though an exact equivalent in Western systems medicine is yet to be described. Some time ago we discovered that blood can clot into an anomalous amyloid form, creating what we have referred to as fibrinaloid microclots. These microclots occur in a great many chronic, inflammatory diseases are comparatively resistant to fibrinolysis, and thus have the ability to block microcapillaries and hence lower oxygen transfer to tissues, with multiple pathological consequences. We here develop the idea that it is precisely the fibrinaloid microclots that relate to, and are largely mechanistically responsible for, the traditional concept of blood stasis (a term also used by Virchow). First, the diseases known to be associated with microclots are all associated with blood stasis. Secondly, by blocking red blood cell transport, fibrinaloid microclots provide a simple mechanistic explanation for the physical slowing down ('stasis') of blood flow. Thirdly, Chinese herbal medicine formulae proposed to treat these diseases, especially Xue Fu Zhu Yu and its derivatives, are known mechanistically to be anticoagulatory and anti-inflammatory, consistent with the idea that they are actually helping to lower the levels of fibrinaloid microclots, plausibly in part by blocking catalysis of the polymerization of fibrinogen into an amyloid form. We rehearse some of the known actions of the constituent herbs of Xue Fu Zhu Yu and specific bioactive molecules that they contain. Consequently, such herbal formulations (and some of their components), which are comparatively little known to Western science and medicine, would seem to offer the opportunity to provide novel, safe, and useful treatments for chronic inflammatory diseases that display fibrinaloid microclots, including Myalgic Encephalopathy/Chronic Fatigue Syndrome, long COVID, and even ischemic stroke.

Altered auditory brainstem responses are post-acute sequela of SARS-CoV-2 (PASC)

The Post-acute Sequela of SARS-CoV-2 (PASC) syndrome, also known as Long-COVID, often presents with subjective symptoms such as brain fog and cognitive fatigue. Increased tinnitus, and decreased hearing in noise ability also occur with PASC, yet whether auditory manifestations of PASC are linked with the cognitive symptoms is not known. Electrophysiology, specifically the Auditory Brainstem Response (ABR), provides objective measures of auditory processing. We hypothesized that ABR findings would be linked to PASC and with subjective feelings of cognitive fatigue. Eighty-two individuals, 37 with PASC (mean age: 47.5, Female: 83%) and 45 healthy controls (mean age: 38.5, Female: 76%), were studied with an auditory test battery that included audiometry and ABR measures. Peripheral hearing thresholds did not differ between groups. The PASC group had a higher prevalence of tinnitus, anxiety, depression, and hearing handicap in addition to increased subjective cognitive fatigue. ABR latency findings showed a significantly greater increase in the wave V latency for PASC subjects when a fast (61.1 clicks/sec) compared to a slow click (21.1 clicks/sec) was used. The increase in latency correlated with cognitive fatigue scores and predicted PASC status. The ABR V/I amplitude ratio was examined as a measure of central gain. Although these ratios were not significantly elevated in the full PASC group, to minimize the cofounding effect of age, the cohort was median split on age. Elevated V/I amplitude ratios were significant predictors of both predicted PASC group classification and cognitive fatigue scores in the younger PASC subjects compared to age-matched controls providing evidence of elevated central gain in younger individuals with PASC. More frequent tinnitus also significantly predicted higher subjective cognitive fatigue scores. Our findings suggest that PASC may alter the central auditory pathway and lead to slower conduction and elevated auditory neurophysiology responses at the midbrain, a pattern associated with the typical aging process. This study marks a significant stride toward establishing an objective measure of subjective cognitive fatigue through assessment of the central auditory system.

Tinnitus and COVID-19: effect of infection, vaccination, and the pandemic

Introduction

The COVID-19 pandemic, which began worldwide around March 2020, has had an impact on hearing health, specifically tinnitus and hearing loss. Physiologically, COVID-19 infection, or medication used to treat the infection, has been reported to be a potential risk factor for tinnitus onset. In addition, tinnitus was reported to be a long COVID symptom or to occur after a COVID-19 vaccination in some cases. With most reports focused on the clinical population, this study aimed to investigate how the onset of tinnitus is associated with COVID-19 infection, long COVID, and COVID-19 vaccination in the general population based on self-report, while accounting for otologic and psychological symptoms.

Methods

In this study, a cross-sectional online survey that included general demographic questions, questions about tinnitus, hearing loss, hyperacusis, emotional status, and the Tinnitus Functional Index (TFI) was conducted.

Results

Completed survey data of 1,511 respondents who reported having tinnitus or believed to have COVID-associated tinnitus were included in the analysis. Participants were categorized into four groups based on their judgment regarding the etiology of their tinnitus: (1) COVID infection group, (2) long COVID group, (3) COVID vaccination group, and (4) pre-existing tinnitus group. The results suggest that tinnitus severity (estimated using TFI scores) was significantly lower in the pre-existing tinnitus group than in any of the COVID-associated tinnitus groups. While varying factors were found to contribute to tinnitus severity among the COVID-associated groups, overall, depression and/or anxiety accounted for the most variance in predicting tinnitus severity.

Discussion

The findings highlight the need to evaluate the impact of varying otologic and psychological symptoms in individuals with COVID-associated tinnitus for better patient-centered care.

NEURO-COVAX: An Italian Population-Based Study of Neurological Complications after COVID-19 Vaccinations

OBJECTIVE

In this Italian population-based study, we aimed to evaluate the neurological complications after the first and/or second dose of COVID-19 vaccines and factors potentially associated with these adverse effects.

METHODS

Our study included adults aged 18 years and older who received two vaccine doses in the vaccination hub of Novegro (Milan, Lombardy) between 7 and 16 July 2021. The NEURO-COVAX questionnaire was able to capture the neurological events, onset and duration. That data that were digitized centrally by the Lombardy region were used to match the demographic/clinical characteristics and identify a vulnerability profile. Associations between vaccine lines and the development of complications were assessed. Digital healthcare system matching was also performed to evaluate severe neurological complications (Guillain-Barrè syndrome, Bell's palsy, transverse myelitis, encephalitis) and the incidence of hospital admissions and/or the mortality rate after two doses of the vaccines.

RESULTS

The NEURO-COVAX-cohort included 19.108 vaccinated people: 15.368 with BNT162b2, 2077 with mRNA-1273, 1651 with ChAdOx1nCov-19, and 12 with Ad26.COV2.S who were subsequently excluded. Approximately 31.2% of our sample developed post-vaccination neurological complications, particularly with ChAdOx1nCov-19. A vulnerable clinical profile emerged, where over 40% of the symptomatic people showed comorbidities in their clinical histories. Defining the neurological risk profile, we found an increased risk for ChAdOx1nCov-19 of tremors (vs. BNT162b2, OR: 5.12, 95% CI: 3.51-7.48); insomnia (vs. mRNA-1273, OR: 1.87, 95% CI: 1.02-3.39); muscle spasms (vs. BNT162b2, OR: 1.62, 95% CI: 1.08-2.46); and headaches (vs. BNT162b2, OR: 1.49, 95% CI: 0.96-1.57). For mRNA-1273, there were increased risks of parethesia (vs. ChAdOx1nCov-19, OR: 2.37, 95% CI: 1.48-3.79); vertigo (vs. ChAdOx1nCov-19, OR: 1.68, 95% CI: 1.20-2.35); diplopia (vs. ChAdOx1nCov-19, OR: 1.55, 95% CI: 0.67-3.57); and sleepiness (vs. ChAdOx1nCov-19, OR: 1.28, 95% CI: 0.98-1.67). In the period that ranged from March to August 2021, no one was hospitalized and/or died of severe complications related to COVID-19 vaccinations.

DISCUSSION

This study estimates the prevalence and risk for neurological complications potentially associated with COVID-19 vaccines, thus improving the vaccination guidelines and loading in future personalized preventive medicine.

Patogenesis of tinnitus in patients with post-COVID syndrome - preliminary report

<b><br>Introduction:</b> Similarly to hearing loss and dizziness, tinnitus is a frequently reported complication of COVID-19 and remains the subject of numerous scientific reports. However, the exact impact of SARS-CoV-2 on the pathophysiology of tinnitus observed in post-COVID syndrome remains unclear. One suspected cause behind the development of vestibulocochlear symptoms is the inflammation of neural tissue triggered by SARS-CoV-2 infection.</br> <b><br>Aim:</b> The aim of this study was to analyze the results of Brainstem Auditory Evoked Potentials (BAEP) in the context of tinnitus development among patients diagnosed with post-COVID syndrome.</br> <b><br>Material and methods:</b> This retrospective study involved the analysis of BAEP test results of patients admitted to the Audiology Clinic of the Military Institute of Medicine at the National Research Institute and diagnosed with the post-COVID syndrome. The study compared the average latency values of waves I, II, III, IV, V, and intervals I-III, III-V, I-V. The statistical analysis of the obtained data was performed.</br> <b><br>Results:</b> Out of 18 patients (9 female, 9 male) with an average age of 54.22 years (9.65) diagnosed with post-COVID syndrome, tinnitus was identified in 5 individuals (27.78%). A statistically significant increase in wave V latency (5.98 vs. 5.63 [ms]; P < 0.05) and interval III-V (1.99 vs. 1.71 [ms]; P<0.05) was observed between the groups of patients with and without tinnitus.</br> <b><br>Discussion:</b> Study results analyzing BAEP changes in patients with post-COVID syndrome in the context of tinnitus are insufficient in current literature. The only available report linking post-COVID syndrome with sensorineural hearing loss demonstrated a statistically significant increase in latency values of waves III, V, and an increase in intervals I-III, III-V.</br> <b><br>Conclusions:</b> Tinnitus in patients suffering from post-COVID syndrome may be related to prolonged conduction of nerve impulses within the brainstem auditory pathway. Detailed pathophysiology of these changes requires further research.</br>.

Prevalence of New-Onset Tinnitus after COVID-19 Vaccination with Comparison to Other Vaccinations

OBJECTIVE

To investigate how often patients are diagnosed with new-onset tinnitus within 21 days after COVID-19 vaccination in comparison to after three other common vaccinations: influenza, Tdap (tetanus, diphtheria, and acellular pertussis), and polysaccharide pneumococcus.

METHODS

The TriNetX Analytics Network, a federated health research network that aggregates the de-identified electronic health record (EHR) data of over 78 million patients, was queried for patients receiving each vaccination. Instances of new-onset tinnitus within 21 days of vaccination were recorded and reported.

RESULTS

Out of 2,575,235 patients receiving a first dose of the mRNA COVID-19 vaccine without any prior tinnitus diagnosis, 0.038% (95% CI: 0.036%-0.041%) of patients had a new diagnosis of tinnitus within 21 days. There was a higher risk of a new tinnitus diagnosis after the influenza vaccine (RR: 1.95, 95% CI: 1.72-2.21), Tdap vaccine (RR: 2.36, 95% CI: 1.93-2.89), and pneumococcal vaccine (RR: 1.97, 95% CI: 1.48-2.64) than after the first dose of the COVID-19 vaccine. There was a lower risk of a new tinnitus diagnosis after the second dose of COVID-19 than after the first dose (RR: 0.80, 95% CI: 0.71-0.91).

CONCLUSION

The rate of newly diagnosed tinnitus acutely after the first dose of the COVID-19 vaccine is very low. There was a higher risk of newly diagnosed tinnitus after influenza, Tdap, and pneumococcal vaccinations than after the COVID-19 vaccine. The present findings can help to address COVID-19 vaccine hesitancy during the ongoing pandemic.

LEVEL OF EVIDENCE

Level 3 Laryngoscope, 133:1722-1725, 2023.

Endocannabinoid system components as potential neuroimmune therapeutic targets in tinnitus

Research interest in understanding tinnitus has increased severalfold in the last decade to find a cure for this auditory disorder. Hyperacusis can also accompany tinnitus, although the mechanisms involved in hyperacusis and tinnitus are different. Millions of people suffer from some degree of tinnitus with hearing loss. Tinnitus is believed to be a form of sensory epilepsy, spawning neuronal hyperactivity from the cochlear nucleus and inferior colliculus of the auditory brainstem region. Cannabis has been used for recreation, medicinal purposes, and served as an entheogen from time immemorial. With the current and increasing global medical and recreational cannabis legalization, there is renewed enthusiasm for the use of cannabinoid drugs, and the role of the endocannabinoid system (ECS) in several health disorders including tinnitus which is associated with COVID-19. The ECS signaling pathways have been proposed to affect the underlying pathophysiology of tinnitus. Cannabinoid receptors (CBRs) have been found in the auditory system, raising interest in ECS signaling in hearing and tinnitus. However, previous studies mostly in animal models of tinnitus did not investigate the involvement of CB2Rs but focused on CB1R-based responses, which suggested that CB1R ligands had no effect and may even be harmful and worsen tinnitus. With new molecular techniques and transgenic approaches used to dissect the complexity of the ECS, the role of ECS/CB2R neuroimmunological function in the auditory system and tinnitus is emerging. This perspective proposes the role of emerging neuroimmune crosstalk of the ECS in sound-sensing structures of the auditory system as a potential pharmacogenomic therapeutic target using cannabinoid CB2R ligands in tinnitus in the era of the COVID-19 pandemic.

A review of neurological side effects of COVID-19 vaccination

Following the COVID-19 virus epidemic, extensive, coordinated international research has led to the rapid development of effective vaccines. Although vaccines are now considered the best way to achieve collective safety and control mortality, due to the critical situation, these vaccines have been issued the emergency use licenses and some of their potential subsequence side effects have been overlooked. At the same time, there are many reports of side effects after getting a COVID-19 vaccine. According to these reports, vaccination can have an adverse event, especially on nervous system. The most important and common complications are cerebrovascular disorders including cerebral venous sinus thrombosis, transient ischemic attack, intracerebral hemorrhage, ischemic stroke, and demyelinating disorders including transverse myelitis, first manifestation of MS, and neuromyelitis optica. These effects are often acute and transient, but they can be severe and even fatal in a few cases. Herein, we have provided a comprehensive review of documents reporting neurological side effects of COVID-19 vaccines in international databases from 2020 to 2022 and discussed neurological disorders possibly caused by vaccination.

Analysis of Adverse Effects of COVID-19 Vaccines in Spain following Booster Dose

The present study evaluates the adverse effects of three vaccines: AstraZeneca (Vaxzevria), Pfizer/BioNTech (Comirnaty) and Moderna (Spikevax) according to the dose. From 733 participants collected, the vaccine schedule was as follows: 330 (45%) received a double dose of the AstraZeneca vaccine, 382 (52.1%) received a double dose of Pfizer, 18 (2.5%) received a heterologous prime boost and 3 (0.4%) received a single dose. Pfizer and Moderna vaccines were administered as a third dose in 70 and 121 individuals, respectively. Local and systemic reactions observed in the three vaccines were mild to moderate in severity. Only one AstraZeneca recipient (0.3%) presented a serious adverse effect: blurred vision. Adverse events were more frequent after the first dose of AstraZeneca and after the second dose of Pfizer. As the third dose, Moderna causes more adverse effects than Pfizer regardless of the type of vaccine previously administered, whereas the reactogenicity of a third dose of Pfizer is slightly higher in the group previously vaccinated with Pfizer than in that group with AstraZeneca. In short, secondary effects of the third dose of COVID-19 vaccines were similar to those after dose 2, but their frequency depends on the type of vaccine and the combinations of vaccines.

The association between SARS-CoV-2 vaccines and transverse myelitis: A review

In late 2019, the emergence of a new viral strain, later referred to as Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) took the shape of a global pandemic, affecting millions of lives and deteriorating economies around the globe. Vaccines were developed at an exceptional rate to combat the viral desolation, all of them being rolled out once they displayed sufficient safety and efficacy. However, assorted adverse events came into attention, one of them being Transverse Myelitis (TM), an infrequent, immune-mediated, focal disease of the spinal cord. This disorder can lead to severe neurological complications including autonomic, sensory, and motor deficits. The literature aims to shed light on TM and its various etiologies, specifically in line with the vaccine, and a comprehensive treatment plan. Discussing and reducing the number of vaccines related adverse events can help succor in bringing down the vaccine hesitancy and ultimately combatting the pandemic.

Acute Unilateral Peripheral Vestibulopathy After COVID-19 Vaccination: Initial Experience in a Tertiary Neurotology Center

Objective

The aim of the present study was to identify patients who developed acute unilateral peripheral vestibulopathy (AUPVP) after COVID-19 vaccination.

Methods

For this single-center, retrospective study, we screened the medical records of our tertiary interdisciplinary neurotology center for patients who had presented with AUPVP within 30 days after COVID-19 vaccination (study period: 1 June−31 December 2021). The initial diagnosis of AUPVP was based on a comprehensive bedside neurotological examination. Laboratory vestibular testing (video head impulse test, cervical and ocular vestibular evoked myogenic potentials, dynamic visual acuity, subjective visual vertical, video-oculography, caloric testing) was performed 1–5 months later.

Results

Twenty-six patients were diagnosed with AUPVP within the study period. Of those, n = 8 (31%) had developed acute vestibular symptoms within 30 days after COVID-19 vaccination (mean interval: 11.9 days, SD: 4.8, range: 6–20) and were thus included in the study. The mean age of the patients (two females, six males) was 46 years (SD: 11.7). Seven patients had received the Moderna mRNA vaccine and one the Pfizer/BioNTech mRNA vaccine. All patients displayed a horizontal(-torsional) spontaneous nystagmus toward the unaffected ear and a pathological clinical head impulse test toward the affected ear on initial clinical examination. Receptor-specific laboratory vestibular testing performed 1–5 months later revealed recovery of vestibular function in two patients, and heterogeneous lesion patterns of vestibular endorgans in the remaining six patients.

Discussion and Conclusions

The present study should raise clinicians' awareness for AUPVP after COVID-19 vaccination. The relatively high fraction of such cases among our AUPVP patients may be due to a certain selection bias at a tertiary neurotology center. Patients presenting with acute vestibular symptoms should be questioned about their vaccination status and the date of the last vaccination dose. Furthermore, cases of AUPVP occurring shortly after a COVID-19 vaccination should be reported to the health authorities to help determining a possible causal relationship.

Current Evidence in SARS-CoV-2 mRNA Vaccines and Post-Vaccination Adverse Reports: Knowns and Unknowns

The novel mRNA vaccinations against COVID-19 are gaining worldwide attention for their potential efficacy, as well as for the diagnosis of some post-vaccination-reported adverse reactions. In this state-of-the-art review article, we present the current evidence regarding mainly the diagnosis of spontaneous allergic reactions, the skin occurrences, the vascular, blood, endocrine and heart events, the respiratory reports, the gastrointestinal, hepatic and kidney events, the reproductive and pregnancy issues and the muscle events, as well as the ear, eye, neurologic and psychiatric events following mRNA vaccination against COVID-19. We further present some evidence regarding the mRNA strategies, we provide important information for side effects associated with the spike protein based LNP-mRNA vaccine and its adjuvants, as well as evidence for all the possible dangerous roles of the spike protein, and we discuss our expert opinion on the knowns and the unknowns towards the topic.