Does COVID-19 cause permanent damage to olfactory and gustatory function?

Recovery Patterns of COVID-19 Related Smell Disorders: An Analysis of the Available Evidence

Recently acquired olfactory dysfunction (OD) has emerged as one of hallmark manifestations of the novel Corona virus disease (COVID-19), but the evolution of its spontaneous recovery has remained inconclusive, with reports of persistence of OD beyond six months of onset. We undertook this systematic review and meta-analysis with a view to generating a pooled recovery rate of COVID-19 associated olfactory dysfunctions and attempt to examine the predictors of olfactory recovery. Systematic review and meta-analysis. A systematic search of Scopus, Google Scholar, and PubMed data bases, comprising all longitudinal studies reporting the trajectory of COVID-19 related OD was carried out. The pooled recovery rate was estimated with random-effects model, and the potential heterogeneity of the subgroup sources was analyzed using meta-regression test. After the PRISMA selection process 28 studies from 16 countries were included, with a total of 5,175 OD patients, among 11,948 COVID-19 cases. The estimated global pooled recovery rate of OD was 82.7% (95% CI, 77.46%-88.04%), with a pooled median duration of OD of 11.6 days. Only 2 out of 28 studies had recovery data beyond a period of 2 months. But no significant difference was found in the recovery rate regarding the length of follow up (P = 0.840). Studies that conducted objective olfactory assessments showed significant higher recovery rate than those with subjective assessments (P = 0.001). Although ten studies (36%) reported > 90% recovery, nine studies (32%) documented persistence of OD in > 25% of their patients. Five out of 6 studies showed that hyposmia tended to show complete recovery than anosmia. Age, co-morbidities, and intra-nasal treatments had no effects. Test of homogeneity between subgroups using the Cochran's Q test was not significant (Q = 0.69, P = 0.40). Our meta-analysis revealed high rate of early and medium term recovery of COVID-19 related OD. However, it also showed disturbing rates of persistence of OD. Anosmia tended to be predictive of residual OD than hyposmia. Age, co-morbidities, intra-nasal corticosteroid and decongestants, had no effects on OD recovery.

Taste dysfunction after COVID-19: Analysis with functional near-infrared spectroscopy

<br><b>Introduction:</b> According to official data, COVID-19 emerged in China in December 2019 and has spread worldwide since then.</br> <br><b>Aim:</b> The aim of this study was to investigate differences in functional near-infrared spectroscopy (fNIRS) recordings between convalescent COVID-19 patients and a healthy control group, which could help to clarify the pathomechanism of dysgeusia in COVID-19.</br> <br><b>Material and methods:</b> The study included 16 participants, comprised of 8 convalescent COVID-19 patients and 8 healthy controls. All participants were examined with fNIRS. The amplitude of changes in oxyhemoglobin (oxyHb) concentration in the cerebral cortex was analyzed statistically (for the test and control groups after stimulation with a taste stimulus - citric acid solution).</br> <br><b>Results:</b> The differences in the amplitude of changes in oxyHb concentration in the cerebral cortex were not statistically significant between the groups. Discussion: Using fNIRS, a strong stimulation of the visual cortex was discovered in response to the taste stimulus, consisting of large, repetitive changes in oxyHb concentration occurring in parallel with stimulation of areas of the taste cortex. This phenomenon has not, to our knowledge, been described previously in the scientific literature. The exact location of the primary taste cortex is controversial, but to date the occipital cortex has not been considered to be involved.</br> <br><b>Conclusions: No difference was observed in the dynamics of changes in oxyHb in the examined areas of the cerebral cortex between convalescent COVID-19 patients and healthy controls. However, the determination of the role of the occipital cortex in the perception of taste requires further research.</br>.

Prevalence of Chemosensitive Neurological Disorders of Smell and Taste and Association with Blood Groups in SARS-CoV-2 Patients: Cross-Sectional Study

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused a highly challenging and threatening situation worldwide. SARS-CoV-2 patients develop various clinical symptoms. The olfactory and taste dysfunctions are potential neurological manifestations among SARS-CoV-2 patients; however, their relationship with blood groups has rarely been investigated. This study aimed to investigate the prevalence of chemosensitive neurological disorders of smell and taste and their association with blood groups in SARS-CoV-2 patients. The present cross-sectional study was performed in the Department of Pathology, and Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia. A well-structured, self-administered questionnaire was designed and distributed through social media platforms. A total of 922 Saudi and non-Saudi adults aged 18 years or older participated in the study. Out of 922 participants, the number of people who had anosmia was 309 (33.5%), 211 (22.9%) had hyposmia, and 45 (4.8%) had dysosmia. Moreover, 180 (19.52%) had ageusia, 47 (5.1%) and 293 (31.8%) had hypogeusia and dysgeusia, respectively. Among all the participants, 565 (61.27%) had smell-related disorders and 520 (56.39%) participants had taste-related clinical symptoms. The occurrence of anosmia and ageusia was relatively high among females compared to males (p = 0.024). The prevalence of smell-related disorders was 25.0% (230) and taste-related disorders was 23.21% (214) among the study participants with blood group O compared to all other blood group (A, B, and AB) participants who have smell allied disorders 30.69% (283), and taste allied disorders 27.98% (258). The prevalence of chemosensitive neurological disorders involving impaired smell and taste was higher in SARS-CoV-2 patients. These clinical symptoms were common among the participants with blood group type O compared to all other ABO blood group types. The role of certain demographic characteristics was consistent throughout multiple studies, notably with female gender and young adults.

Anosmia in COVID-19 Patients: Can We Predict the Severity of Chest Manifestations?

Introduction  Anosmia is one of the common symptoms of COVID-19, the link between severity of chest infection and anosmia was investigated by few studies. Objectives  To find an association between anosmia and severity of chest infection. Methods  An analysis of patients admitted to isolation hospital of our university with confirmed polymerase chain reaction positive testing for COVID-19, between March 2021 until September 2021. We called all patients who reported anosmia during their time of illness and asked them about anosmia. We examined their chest CT. A statistical analysis was done. Results  A total of 140 patients completed the study; 65% were female and 56.4% had complete anosmia. Anosmia was significantly associated with loss of taste. Smell returned in 92.5% of anosmic patients. Duration of smell loss was ∼ 2 weeks in 40.5%. The most common symptoms associated with anosmia were running nose, sore throat, fever, and cough. Loss of smell was significantly associated with mild chest disease. 73.4% of anosmic patients had mild chest infection, 21.5% of them had moderate infection, and 5.1% had severe chest infection. Conclusion  The pattern of anosmia in COVID-19 patients has some common similarities in general; the way it starts, the associated symptoms, the time until smell returns and, the most important, the severity of chest infection. As anosmia is significantly associated with mild chest infection. the presence of anosmia could be an independent predictor of good COVID-19 outcome as reflected by a lower disease severity and less frequent ICU admissions.

Olfactory and taste dysfunction in COVID-19-incidence and recovery

Background

Olfactory and taste dysfunctions have been identified as prominent signs of COVID-19 infection. The data on its prevalence, time of onset, and recovery is highly variable.

Objective

The study was aimed at establishing the incidence of and the factors influencing smell and taste disorders in COVID-19-affected patients.

Methodology

Telephonic interviews were used to collect data on the symptoms of COVID-19-positive patients, with an emphasis on smell and taste disorders. Patients have severe disease and a history of illnesses that may affect olfaction or taste, and those unwilling to participate were excluded.

Results

A total of 1488 COVID-19-positive patients were identified. A total of 772 were included and interviewed, and their data were analysed. A total of 242 (31.3%) patients developed symptoms related to smell and/or taste. Anosmia (149) and ageusia (152) were the most common. Younger patients were more commonly affected (p = 0.0016). The presence and degree of smell symptoms and taste symptoms showed a small positive correlation (r = .234, p < .001). A strong relationship was seen with fever (r = .825, p < .001) and a significantly moderate relationship with breathing difficulty. There was no significant difference based on age or sex for the recovery of smell or taste sensations. There was a significant correlation between taste recovery and smell recovery times (p < 0.00001).

Conclusion

Smell and taste disorders, as early clinical symptoms of COVID-19, may have a diagnostic as well as a prognostic value. Treatment protocols for these patients are yet to be defined. A positive association between these symptoms and breathing difficulty was found, and we recommend COVID-19 testing and monitoring of symptoms for all patients with new-onset OTD symptoms. A combination of active enquiry about these symptoms, along with objective testing when the patients present with COVID-19 symptoms may help in better understanding of the pathophysiology and timely initiation of treatment.

Ethical considerations regarding animal experimentation

Animal experimentation is widely used around the world for the identification of the root causes of various diseases in humans and animals and for exploring treatment options. Among the several animal species, rats, mice and purpose-bred birds comprise almost 90% of the animals that are used for research purpose. However, growing awareness of the sentience of animals and their experience of pain and suffering has led to strong opposition to animal research among many scientists and the general public. In addition, the usefulness of extrapolating animal data to humans has been questioned. This has led to Ethical Committees' adoption of the 'four Rs' principles (Reduction, Refinement, Replacement and Responsibility) as a guide when making decisions regarding animal experimentation. Some of the essential considerations for humane animal experimentation are presented in this review along with the requirement for investigator training. Due to the ethical issues surrounding the use of animals in experimentation, their use is declining in those research areas where alternative in vitro or in silico methods are available. However, so far it has not been possible to dispense with experimental animals completely and further research is needed to provide a road map to robust alternatives before their use can be fully discontinued.

Tailored Approach for Persistent Olfactory Dysfunction After SARS-CoV-2 Infection: A Pilot Study

OBJECTIVE

So far, no original studies explored non-randomized, standardized protocols for COVID-19 associated olfactory dysfunction. The main objective was to determine the efficacy of a new protocol for post-COVID olfactopathy while assessing the benefit of adding adjuvant therapies to olfactory training.

METHODS

Patients suffering from long-lasting post-COVID-19 olfactory dysfunction were evaluated. A non-randomized protocol based on individual nasal endoscopy findings and patient's preferences was applied. Patients were assigned for olfactory training alone or olfactory training + adjuvant therapy. Participants performed olfactory objective and subjective evaluations at first consultation and 3 months after treatment, and results were compared.

RESULTS

A total of 47 patients were enrolled. All groups showed significant improvement in olfactory thresholds at 3-month follow-up suggesting protocol effectiveness (olfactory training group alone showed a mean threshold difference of 2.9, P < .001; Olfactory training + Topical Corticosteroid showed a mean threshold difference of 4, P = .006; Olfactory training + Topical Corticosteroid + Vitamin B complex showed a mean threshold difference of 4.4, P = .006; Olfactory training + Intranasal Vitamin A and E showed a mean threshold difference of 4.4, P < .001). Olfactory training alone showed lower mean olfactory threshold improvement, when compared to patients undergoing olfactory training + adjuvant therapy (olfactory training alone mean improvement 2.9 ± 2.3 vs olfactory training + adjuvants mean improvement 4.3 ± 2.458, P = .03).

CONCLUSIONS

This is one of the first studies to demonstrate results in the treatment of post-COVID-19 persistent olfactory impairment. A customized approach based on endoscopy findings and patient's preferences may be a valid option for the management of persistent post-COVID-19 olfactory disorder. Adjuvant therapy could be considered in addition to olfactory training, but further studies are needed in order to confirm their effectiveness in this setting.

LEVEL OF EVIDENCE

2c (outcomes research).

The Prevalence and Implications of Olfactory/Gustatory Dysfunctions among Adult COVID-19 Patients: A Retrospective Cohort Multiethnic Populations Study

(1) Background: Olfactory and gustatory dysfunctions (OGDs) was found in COVID-19 patients. Only a few studies looked into the prevalence of OGDs in the United Arab Emirates (UAE). The purpose of this study was to estimate the prevalence OGDs among multiethnic COVID-19 patients in the UAE, and its association to patients’ characteristics and disease outcomes; (2) Methods: There were 1785 COVID-19 patients included in our cohort; (3) Results: Males made up most of the study participants (86.3%). A total of 11.7% of the participants reported OGDs. Female gender and ethnicity had significantly higher symptom prevalence (p < 0.001). COVID-19 severity had a strong inverse association with OGDs (p = 0.007). Other illness outcomes, such as ICU admission, pneumonia development, and mortality, showed no correlation. Males, Asians, and patients with comorbidities all had statistically significantly lower prevalence odds. On the other hand, Emirati, Arab, and Iranian patients had a higher prevalence. COVID-19 patients with OGDs had a considerably shorter time until viral clearance than those without the symptom; (4) Conclusions: in nonsevere COVID-19, olfactory/gustatory dysfunction is common. As a result, it could be applied as a predictive sign for early disease diagnosis and prognosis.

The Prevalence and Pathophysiology of Chemical Sense Disorder Caused by the Novel Coronavirus

Emerging viral infections are a ceaseless challenge and remain a global public health concern. The world has not yet come back to normal from the devastating effects of the highly contagious and pathogenic novel coronavirus, or Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Olfactory and taste dysfunction is common in patients infected by the novel coronavirus. In light of the emergence of different coronavirus variants, it is important to update the prevalence and pathophysiology of these side effects. In this review, articles published on the prevalence of olfactory and taste dysfunction from coronavirus disease (COVID-19) and their possible pathophysiologic mechanisms have been reviewed and reported. The modulatory role of different SARS-CoV-2 variants on the chemical senses is then described. The clinical relevance of chemical sense disorder and its long-term morbidity and management is also discussed.

Evolution of neurologic symptoms in non-hospitalized COVID-19 "long haulers"

Objective

We characterized the evolution of neurologic symptoms and self‐perceived recovery of non‐hospitalized COVID‐19 “long haulers” 6–9 months after their initial Neuro‐COVID‐19 clinic evaluation.

Methods

In this follow‐up study on the first 100 patients, 50 SARS‐CoV‐2 laboratory‐positive (SARS‐CoV‐2⁺), and 50 laboratory‐negative (SARS‐CoV‐2⁻), evaluated at our Neuro‐COVID‐19 clinic between May and November 2020, patients completed phone questionnaires on their neurologic symptoms, subjective impression of recovery and quality of life.

Results

Of 52 patients who completed the study (27 SARS‐CoV‐2⁺, 25 SARS‐CoV‐2⁻) a median 14.8 (range 11–18) months after symptom onset, mean age was 42.8 years, 73% were female, and 77% were vaccinated for SARS‐CoV‐2. Overall, there was no significant change in the frequency of most neurologic symptoms between first and follow‐up evaluations, including “brain fog” (81 vs. 71%), numbness/tingling (69 vs. 65%), headache (67 vs. 54%), dizziness (50 vs. 54%), blurred vision (34 vs. 44%), tinnitus (33 vs. 42%), and fatigue (87 vs. 81%). However, dysgeusia and anosmia decreased overall (63 vs. 27%, 58 vs. 21%, both p < 0.001). Conversely, heart rate and blood pressure variation (35 vs. 56%, p = 0.01) and gastrointestinal symptoms (27 vs. 48%, p = 0.04) increased at follow‐up. Patients reported improvements in their recovery, cognitive function, and fatigue, but quality of life measures remained lower than the US normative population (p < 0.001). SARS‐CoV‐2 vaccination did not have a positive or detrimental impact on cognitive function or fatigue.

Interpretation

Non‐hospitalized COVID‐19 “long haulers” continue to experience neurologic symptoms, fatigue, and compromised quality of life 14.8 months after initial infection.

Genetically modified mice for research on human diseases: A triumph for Biotechnology or a work in progress?

Genetically modified mice are engineered as models for human diseases. These mouse models include inbred strains, mutants, gene knockouts, gene knockins, and ‘humanized’ mice. Each mouse model is engineered to mimic a specific disease based on a theory of the genetic basis of that disease. For example, to test the amyloid theory of Alzheimer’s disease, mice with amyloid precursor protein genes are engineered, and to test the tau theory, mice with tau genes are engineered. This paper discusses the importance of mouse models in basic research, drug discovery, and translational research, and examines the question of how to define the “best” mouse model of a disease. The critiques of animal models and the caveats in translating the results from animal models to the treatment of human disease are discussed. Since many diseases are heritable, multigenic, age-related and experience-dependent, resulting from multiple gene-gene and gene-environment interactions, it will be essential to develop mouse models that reflect these genetic, epigenetic and environmental factors from a developmental perspective. Such models would provide further insight into disease emergence, progression and the ability to model two-hit and multi-hit theories of disease. The summary examines the biotechnology for creating genetically modified mice which reflect these factors and how they might be used to discover new treatments for complex human diseases such as cancers, neurodevelopmental and neurodegenerative diseases.

SARS-CoV-2, COVID-19 and Parkinson’s Disease—Many Issues Need to Be Clarified—A Critical Review

Neurological manifestations during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic are of interest, regarding acute treatment and the so-called post-COVID-19 syndrome. Parkinson’s disease (PD) is one of the most common neurodegenerative movement disorders worldwide. Hence, the influence of SARS-CoV-2 and the COVID-19 syndrome on PD patients has raised many questions and produced various publications with conflicting results. We reviewed the literature, with respect to symptoms, treatment, and whether the virus itself might cause PD during the SARS-CoV-2 pandemic in SARS-CoV-2-affected symptomatic PD patients (COVID-19 syndrome). In addition, we comment on the consequences in non-symptomatic and non-affected PD patients, as well as post-COVID syndrome and its potential linkage to PD, presenting our own data from our out-patient clinic.

Evidence mapping and review of long-COVID and its underlying pathophysiological mechanism

PURPOSE

Apart from the global disease burden of acute COVID-19 disease, the health complications arising after recovery have been recognized as a long-COVID or post-COVID-19 syndrome. Evidences of long-COVID symptoms involving various organ systems are rapidly growing in literature. The objective was to perform a rapid review and evidence mapping of systemic complications and symptoms of long-COVID and underlying pathophysiological mechanisms.

METHODS

Publications reporting clinical trials, observational cohort studies, case-control studies, case-series, meta-analysis, and systematic reviews, focusing on the squeal of the disease, consequences of COVID-19 treatment/hospitalization, long-COVID, chronic COVID syndrome, and post acute COVID-19 were reviewed in detail for the narrative synthesis of frequency, duration, risk factors, and pathophysiology.

RESULTS

The review highlights that pulmonary, neuro-psychological, and cardiovascular complications are major findings in most epidemiological studies. However, dysfunctional gastrointestinal, endocrine, and metabolic health are recent findings for which underlying pathophysiological mechanisms are poorly understood. Analysis of the clinical trial landscape suggests that more than 50% of the industry-sponsored trials are focused on pulmonary symptoms. In contrast to the epidemiological trends and academic trials, cardiovascular complications are not a focus of industry-sponsored trials, suggestive of the gaps in the research efforts.

CONCLUSION

The gap in epidemiological trends and academic trials, particularly concerning cardiovascular complications not being a focus of industry-sponsored trials is suggestive of the gaps in research efforts and longer follow-up durations would help identify other long-COVID-related health issues such as reproductive health and fertility.

Wernicke Encephalopathy From Olfactory Dysfunction After COVID-19 Infection

INTRODUCTION

Coronavirus disease 2019 (COVID-19) has affected millions of people worldwide and is caused by infection from the severe acute respiratory syndrome coronavirus-2 pathogen. While COVID-19 most commonly affects the respiratory system, multiple neurological complications have been associated with this pathogen. We report a case of Wernicke encephalopathy in a young girl with poor oral intake secondary to anosmia and dysgeusia after a COVID-19 infection.

CASE REPORT

After a recent infection of COVID-19, a 15-year-old girl developed an overwhelming noxious metallic tase resulting in a 30 lb weight loss from being unable to tolerate oral foods. She presented to the hospital 3 months later with bilateral horizontal conjugate gaze palsies, up beating vertical nystagmus, difficulty with limb coordination and gait ataxia. She was found to have a thiamine level of 51 nmol/L (reference range: 70 to 180 nmol/L) and her brain magnetic resonance imaging showed fluid-attenuated inversion recovery and diffusion-weighted imaging changes in the periaqueductal gray and dorsomedial thalami suggestive of Wernicke encephalopathy. She was started on parenteral thiamine replacement and had significant neurological improvement.

CONCLUSIONS

As this pandemic continues to progress, more long-term neurological sequelae from COVID-19 such as Wernicke encephalopathy can be expected. Strong clinical suspicion for these complications is needed to allow for earlier diagnosis and faster treatment initiation.

Neurological sequelae of COVID-19: a review

Background

The COVID-19 pandemic has produced a myriad of challenges, including identifying and treating neurological sequelae.

Main body

COVID-19 can cause olfactory and respiratory dysfunction with average recovery within 1 month and a minority of patients experiencing symptoms at 8-month follow-up. Headaches are also very common (up to 93%) amongst patients with persistent COVID-19 symptoms. COVID-19 illness may also affect cognition, although results are mixed.

Conclusion

While many studies have focused on acute COVID-19 symptoms, more longitudinal studies will need to assess the neurological sequelae of the disease. Furthermore, care must be taken when attributing sequelae to COVID-19 illness and not an unrelated cause. Finally, there is concern that COVID-19 may be associated with secondary illnesses, such as Guillain–Barre, and may even contribute to the development of diseases, such as Alzheimer’s.

Post-COVID-19 Syndrome: The Persistent Symptoms at the Post-viral Stage of the Disease. A Systematic Review of the Current Data

Whilst the entire world is battling the second wave of COVID-19, a substantial proportion of patients who have suffered from the condition in the past months are reporting symptoms that last for months after recovery, i. e., long-term COVID-19 symptoms. We aimed to assess the current evidence on the long-term symptoms in COVID-19 patients. We did a systematic review on PubMed, Web of Science, EMBASE, and Google Scholar from database inception to February 15, 2021, for studies on long-term COVID-19 symptoms. We included all type of papers that reported at least one long-term COVID-19 symptom. We screened studies using a standardized data collection form and pooled data from published studies. Cohort cross-sectional, case-report, cases-series, case-control studies, and review were graded using specific quality assessment tools. Of 11,361 publications found following our initial search we assessed 218 full-text articles, of which 145 met all selection criteria. We found that 20.70% of reports on long-term COVID-19 symptoms were on abnormal lung functions, 24.13% on neurologic complaints and olfactory dysfunctions, and 55.17% on specific widespread symptoms, mainly chronic fatigue, and pain. Despite the relatively high heterogeneity of the reviewed studies, our findings highlighted that a noteworthy proportion of patients who have suffered from SARS-CoV-2 infection present a "post-COVID syndrome." The multifaceted understanding of all aspects of the COVID-19 pandemic, including these long-term symptoms, will allow us to respond to all the global health challenges, thus paving the way to a stronger public health.

The outcome of olfactory impairment in patients with otherwise paucisymptomatic coronavirus disease 2019 during the pandemic

OBJECTIVE

This study aimed to measure the duration and recovery rate of olfactory loss in patients complaining of recent smell loss as their prominent symptom during the coronavirus disease 2019 outbreak.

METHOD

This was a prospective telephone follow-up observational study of 243 participants who completed an online survey that started on 12 March 2020.

RESULTS

After a mean of 5.5 months from the loss of smell onset, 98.3 per cent of participants reported improvement with a 71.2 per cent complete recovery rate after a median of 21 days. The chance of complete recovery significantly decreased after 131 days from the onset of loss of smell (100 per cent sensitive and 97.7 per cent specific). Younger age and isolated smell loss were associated with a rapid recovery, whereas accompanying rhinological and gastrointestinal symptoms were associated with longer loss of smell duration.

CONCLUSION

Smell loss, occurring as a prominent symptom during the coronavirus disease 2019 pandemic, showed a favourable outcome. However, after 5.5 months from the onset, around 10 per cent of participants still complained of moderate or severe hyposmia.

Neurological manifestations as the predictors of severity and mortality in hospitalized individuals with COVID-19: a multicenter prospective clinical study

BACKGROUNDS

The reports of neurological symptoms are increasing in cases with coronavirus disease 2019 (COVID-19). This multi-center prospective study was conducted to determine the incidence of neurological manifestations in hospitalized cases with COVID-19 and assess these symptoms as the predictors of severity and death.

METHODS

Hospitalized males and females with COVID-19 who aged over 18 years were included in the study. They were examined by two neurologists at the time of admission. All survived cases were followed for 8 weeks after discharge and 16 weeks if their symptoms had no improvements.

RESULTS

We included 873 participants. Of eligible cases, 122 individuals (13.97%) died during hospitalization. The most common non-neurological manifestations were fever (81.1%), cough (76.1%), fatigue (36.1%), and shortness of breath (27.6%). Aging, male gender, co-morbidity, smoking, hemoptysis, chest tightness, and shortness of breath were associated with increased odds of severe cases and/or mortality. There were 561 (64.3%) cases with smell and taste dysfunctions (hyposmia: 58.6%; anosmia: 41.4%; dysguesia: 100%). They were more common among females (69.7%) and non-smokers (66.7%). Hyposmia/anosmia and dysgeusia were found to be associated with reduced odds of severe cases and mortality. Myalgia (24.8%), headaches (12.6%), and dizziness (11.9%) were other common neurological symptoms. Headaches had negative correlation with severity and death due to COVID-19 but myalgia and dizziness were not associated. The cerebrovascular events (n = 10) and status epilepticus (n = 1) were other neurological findings. The partial or full recovery of smell and taste dysfunctions was found in 95.2% after 8 weeks and 97.3% after 16 weeks. The parosmia (30.9%) and phantosmia (9.0%) were also reported during 8 weeks of follow-up. Five cases with mild headaches and 5 cases with myalgia were reported after 16 weeks of discharge. The demyelinating myelitis (n = 1) and Guillain-Barré syndrome (n = 1) were also found during follow-up.

CONCLUSION

Neurological symptoms were found to be prevalent among individuals with COVID-19 disease and should not be under-estimated during the current pandemic outbreak.

Anosmia and dysgeusia in SARS-CoV-2 infection: incidence and effects on COVID-19 severity and mortality, and the possible pathobiology mechanisms - a systematic review and meta-analysis

Background: The present study aimed to determine the global prevalence of anosmia and dysgeusia in coronavirus disease 2019 (COVID-19) patients and to assess their association with severity and mortality of COVID-19. Moreover, this study aimed to discuss the possible pathobiological mechanisms of anosmia and dysgeusia in COVID-19. Methods: Available articles from PubMed, Scopus, Web of Science, and preprint databases (MedRxiv, BioRxiv, and Researchsquare) were searched on November 10th, 2020. Data on the characteristics of the study (anosmia, dysgeusia, and COVID-19) were extracted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Newcastle-Ottawa scale was used to assess research quality. Moreover, the pooled prevalence of anosmia and dysgeusia were calculated, and the association between anosmia and dysgeusia in presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was assessed using the Z test. Results: Out of 32,142 COVID-19 patients from 107 studies, anosmia was reported in 12,038 patients with a prevalence of 38.2% (95% CI: 36.5%, 47.2%); whereas, dysgeusia was reported in 11,337 patients out of 30,901 COVID-19 patients from 101 studies, with prevalence of 36.6% (95% CI: 35.2%, 45.2%), worldwide. Furthermore, the prevalence of anosmia was 10.2-fold higher (OR: 10.21; 95% CI: 6.53, 15.96, p < 0.001) and that of dysgeusia was 8.6-fold higher (OR: 8.61; 95% CI: 5.26, 14.11, p < 0.001) in COVID-19 patients compared to those with other respiratory infections or COVID-19 like illness. To date, no study has assessed the association of anosmia and dysgeusia with severity and mortality of COVID-19. Conclusion: Anosmia and dysgeusia are prevalent in COVID-19 patients compared to those with the other non-COVID-19 respiratory infections. Several possible mechanisms have been hypothesized; however, future studies are warranted to elucidate the definitive mechanisms of anosmia and dysgeusia in COVID-19. Protocol registration: PROSPERO CRD42020223204.

Gross and Histopathology of COVID-19 With First Histology Report of Olfactory Bulb Changes

In nearly a year since the first reported cases of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a lot has been established about the virus. Correlates in regards to the biology and cellular effects of SARS-CoV-2 have brought a lot of explanations to the clinical manifestations of the disease and possible therapeutic modalities. However, despite the discoveries made, the tropism of SARS-CoV-2 has not yet been fully established, nor have all the clinical aspects of COVID-19. Herein we report the gross and histological findings in two diseased patients. Apart from the already established pulmonary and vascular changes caused by SARS-CoV-2, we report the presence of histological changes of the olfactory bulbs and frontal lobes of the brain, which may present as a correlate for COVID-19 related anosmia. The olfactory bulbs histologically showed necrotizing olfactory bulbitis. As both the olfactory bulb and frontal lobe of the cerebrum are key areas of olfaction, we believe that this tropism of SARS-CoV-2 may be key to the development of anosmia and not changes within the nasal cavity.