Neurological manifestations of COVID-19, SARS and MERS

Objective and subjective cognitive outcomes one year after COVID-19

OBJECTIVE

This study aimed to evaluate subjective cognitive, physical, and mental health symptoms as well as objective cognitive deficits in COVID-19 patients 1 year after infection.

METHODS

This was a cross-sectional study. Seventy-four patients, who contracted a SARS-CoV-2 infection in 2020, underwent an in-person neuropsychological assessment in 2021. This included standardized tests of memory, attention, and executive functions. In addition, participants also responded to scales on subjective attention deficits, mental health symptoms, and fatigue. Patients' scores were compared to published norms.

RESULTS

Patients (N = 74) had a median age of 56 years (42% female). According to the initial disease severity, they were classified as mild (outpatients, 32%), moderate (hospitalized, non-ICU-admitted, 45%), or severe (ICU-admitted, 23%). Hospitalized patients were more often affected than outpatients. In general, deficits were most common in attention (23%), followed by memory (15%) and executive functions (3%). Patients reported increased levels of fatigue (51%), anxiety (30%), distractibility in everyday situations (20%), and depression (15%). An additional analysis suggested an association between lower scores in an attention task and hyperferritinemia. As indicated by a hierarchical regression analysis, subjective distractibility was significantly predicted by current anxiety and fatigue symptoms but not by objective attention performance (final model, adj-R2 = 0.588, P < 0.001).

INTERPRETATION

One year after infection, COVID-19 patients can have frequent attention deficits and can complain about symptoms such as fatigue, anxiety, and distractibility. Anxiety and fatigue, more than objective cognitive deficits, have an impact on the patients' experienced impairments in everyday life.

Neuropathological findings in Down syndrome, Alzheimer's disease and control patients with and without SARS-COV-2: preliminary findings

The SARS-CoV-2 virus that led to COVID-19 is associated with significant and long-lasting neurologic symptoms in many patients, with an increased mortality risk for people with Alzheimer's disease (AD) and/or Down syndrome (DS). However, few studies have evaluated the neuropathological and inflammatory sequelae in postmortem brain tissue obtained from AD and people with DS with severe SARS-CoV-2 infections. We examined tau, beta-amyloid (Aβ), inflammatory markers and SARS-CoV-2 nucleoprotein in DS, AD, and healthy non-demented controls with COVID-19 and compared with non-infected brain tissue from each disease group (total n = 24). A nested ANOVA was used to determine regional effects of the COVID-19 infection on arborization of astrocytes (Sholl analysis) and percent-stained area of Iba-1 and TMEM 119. SARS-CoV-2 antibodies labeled neurons and glial cells in the frontal cortex of all subjects with COVID-19, and in the hippocampus of two of the three DS COVID-19 cases. SARS-CoV-2-related alterations were observed in peri-vascular astrocytes and microglial cells in the gray matter of the frontal cortex, hippocampus, and para-hippocampal gyrus. Bright field microscopy revealed scattered intracellular and diffuse extracellular Aβ deposits in the hippocampus of controls with confirmed SARS-CoV-2 infections. Overall, the present preliminary findings suggest that SARS-CoV-2 infections induce abnormal inflammatory responses in Down syndrome.

Development of Fluorescence-Based Assays for Key Viral Proteins in the SARS-CoV-2 Infection Process and Lifecycle

Since the appearance of SARS-CoV-2 in 2019, the ensuing COVID-19 (Corona Virus Disease 2019) pandemic has posed a significant threat to the global public health system, human health, life, and economic well-being. Researchers worldwide have devoted considerable efforts to curb its spread and development. The latest studies have identified five viral proteins, spike protein (Spike), viral main protease (3CLpro), papain-like protease (PLpro), RNA-dependent RNA polymerase (RdRp), and viral helicase (Helicase), which play crucial roles in the invasion of SARS-CoV-2 into the human body and its lifecycle. The development of novel anti-SARS-CoV-2 drugs targeting these five viral proteins holds immense promise. Therefore, the development of efficient, high-throughput screening methodologies specifically designed for these viral proteins is of utmost importance. Currently, a plethora of screening techniques exists, with fluorescence-based assays emerging as predominant contenders. In this review, we elucidate the foundational principles and methodologies underpinning fluorescence-based screening approaches directed at these pivotal viral targets, hoping to guide researchers in the judicious selection and refinement of screening strategies, thereby facilitating the discovery and development of lead compounds for anti-SARS-CoV-2 pharmaceuticals.

SARS-CoV-2 and Brain Health: New Challenges in the Era of the Pandemic

Respiratory viral infections have been found to have a negative impact on neurological functions, potentially leading to significant neurological impairment. The SARS-CoV-2 virus has precipitated a worldwide pandemic, posing a substantial threat to human lives. Growing evidence suggests that SARS-CoV-2 may severely affect the CNS and respiratory system. The current prevalence of clinical neurological issues associated with SARS-CoV-2 has raised significant concerns. However, there needs to be a more comprehensive understanding of the specific pathways by which SARS-CoV-2 enters the nervous system. Based on the available evidence, this review focuses on the clinical neurological manifestations of SARS-CoV-2 and the possible mechanisms by which SARS-CoV-2 invades the brain.

SARS-CoV-2 Bottlenecks and Tissue-Specific Adaptation in the Central Nervous System

Severe COVID-19 and post-acute sequelae of SARS-CoV-2 infection are associated with neurological complications that may be linked to direct infection of the central nervous system (CNS), but the selective pressures ruling neuroinvasion are poorly defined. Here, we assessed SARS-CoV-2 evolution in the lung versus CNS of infected mice. Higher levels of viral diversity were observed in the CNS than the lung after intranasal challenge with a high frequency of mutations in the Spike furin cleavage site (FCS). Deletion of the FCS significantly attenuated virulence after intranasal challenge, with lower viral titers and decreased morbidity compared to the wild-type virus. Intracranial inoculation of the FCS-deleted virus, however, was sufficient to restore virulence. After intracranial inoculation, both viruses established infection in the lung, but this required reversion of the FCS deletion. Cumulatively, these data suggest a critical role for the FCS in determining SARS-CoV-2 tropism and compartmentalization with possible implications for the treatment of neuroinvasive COVID-19.

Spontaneous subdural hematoma in a young COVID-19-confirmed patient without comorbidities: A case report

The majority of acute subdural hematomas are due to trauma, and cases of spontaneous subdural hematoma are rare. This report aims to provide an overview of subdural hematoma associated with COVID-19 virus. We described a case of a 22-year-old female without comorbidities and confirmed COVID-19 with spontaneous subdural hematoma on non-contrast computed tomography scan. This was the first case encountered in our hospital. There is no published cases yet in the Philippines. Mechanisms linking cerebrovascular events to COVID-19 are hypothesized. First, it has been postulated that COVID virus is neurotropic toward angiotensinogen-converting enzyme-2 receptors and it can invade and directly damage cerebral vessels. Second, entry of the virus into the cells results in marked reduction in angiotensinogen-converting enzyme-2 levels which could contribute to the development of intracranial hemorrhage. Third, COVID-19 patients usually develop a systemic hyperinflammatory syndrome characterized by fulminant hypercytokinemia which may mediate vascular remodeling and predispose to intracranial hemorrhage. COVID infection should be considered as one of the differentials in patients presenting with neurological symptom. More research needs to be performed to understand the pathogenic mechanisms behind each of these disorders and better treat such patients with suitable drugs in a timely manner.

Long-Term Effects of SARS-CoV-2 in the Brain: Clinical Consequences and Molecular Mechanisms

Numerous investigations have demonstrated significant and long-lasting neurological manifestations of COVID-19. It has been suggested that as many as four out of five patients who sustained COVID-19 will show one or several neurological symptoms that can last months after the infection has run its course. Neurological symptoms are most common in people who are less than 60 years of age, while encephalopathy is more common in those over 60. Biological mechanisms for these neurological symptoms need to be investigated and may include both direct and indirect effects of the virus on the brain and spinal cord. Individuals with Alzheimer's disease (AD) and related dementia, as well as persons with Down syndrome (DS), are especially vulnerable to COVID-19, but the biological reasons for this are not clear. Investigating the neurological consequences of COVID-19 is an urgent emerging medical need, since close to 700 million people worldwide have now had COVID-19 at least once. It is likely that there will be a new burden on healthcare and the economy dealing with the long-term neurological consequences of severe SARS-CoV-2 infections and long COVID, even in younger generations. Interestingly, neurological symptoms after an acute infection are strikingly similar to the symptoms observed after a mild traumatic brain injury (mTBI) or concussion, including dizziness, balance issues, anosmia, and headaches. The possible convergence of biological pathways involved in both will be discussed. The current review is focused on the most commonly described neurological symptoms, as well as the possible molecular mechanisms involved.

SARS-CoV-2 pandemic as a model to assess the relationship between intercurrent viral infections and disease activity in Multiple Sclerosis: A propensity score matched case-control study

INTRODUCTION

An association between intercurrent viral respiratory infections and exacerbations of Multiple Sclerosis (MS) disease activity has been proposed by several studies. Considering the rapid spread of SARS-CoV2 worldwide and the systematic effort to immediately detect all incident cases with specific diagnostic tests, the pandemic can represent an interesting experimental model to assess the relationship between viral respiratory infections and MS disease activity.

AIMS AND METHODS

In this study, we have performed a propensity score matched case-control study with a prospective clinical/MRI follow-up, on a cohort of relapsing-remitting MS (RRMS) patients who tested positive for SARS-CoV2 in the period 2020-2022, with the aim to evaluate if the SARS-CoV2 infection influences the short-term risk of disease activity. Controls (RRMS patients not exposed to SARS-CoV-2, using 2019 as the reference period) were matched 1:1 with cases for age, EDSS, sex and disease-modifying treatment (DMT) (moderate efficacy vs high efficacy). Differences in relapses, MRI disease activity and confirmed disabilty worsening (CDW) between cases in the 6 months following the SARS-CoV-2 infection, and controls in a similar 6 months reference period in 2019 were compared.

RESULTS

We identified 150 cases of SARS-CoV2 infection in the period March 2020 - March 2022, out of a total population of approximately 1500 MS patients, matched with 150 MS patients not exposed to SARS-CoV2 (controls). Mean age was 40.9 ± 12.0 years in cases and 42.0 ± 10.9 years in controls, mean EDSS was 2.54±1.36 in cases and 2.60±1.32 in controls. All patients were treated with a DMT, and a considerable proportion with a high efficacy DMT (65.3% in cases and 66% in controls), reflecting a typical real world RRMS population. 52.8% of patients in this cohort had been vaccinated with a mRNA Covid-19 vaccine. We did not observe a significant difference in relapses (4.0% cases, 5.3% controls; p = 0.774), MRI disease activity (9.3% cases, 8.0% controls; p = 0.838), CDW (5.3% cases, 6.7% controls; p = 0.782) in the 6 months after SARS-CoV-2 infection between cases and controls.

CONCLUSION

Using a propensity score matching design and including both clinical and MRI data, this study does not suggest an increased risk of MS disease activity following SARS-CoV-2 infection. All MS patients in this cohort were treated with a DMT, and a considerable number with a high efficacy DMT. These results therefore may not be applicable to untreated patients, for which the risk of increased MS disease activity after SARS-CoV-2 infection may not be excluded. A possible hypothesis explaining these results could be that SARS-CoV2 is less prone, compared to other viruses, to induce exacerbations of MS disease activity; another possible interpretation of these data might be that DMT is able to effectively suppress the increase of disease activity triggered by SARS-CoV2 infection.

How viral infections cause neuronal dysfunction: a focus on the role of microglia and astrocytes

In recent decades, a number of infectious viruses have emerged from wildlife or reemerged that pose a serious threat to global health and economies worldwide. Although many of these viruses have a specific target tissue, neurotropic viruses have evolved mechanisms to exploit weaknesses in immune defenses that eventually allow them to reach and infect cells of the central nervous system (CNS). Once in the CNS, these viruses can cause severe neuronal damage, sometimes with long-lasting, life-threatening consequences. Remarkably, the ability to enter the CNS and cause neuronal infection does not appear to determine whether a viral strain causes neurological complications. The cellular mechanisms underlying the neurological consequences of viral infection are not fully understood, but they involve neuroimmune interactions that have so far focused mainly on microglia. As the major immune cells in the brain, reactive microglia play a central role in neuroinflammation by responding directly or indirectly to viruses. Chronic reactivity of microglia leads to functions that are distinct from their beneficial roles under physiological conditions and may result in neuronal damage that contributes to the pathogenesis of various neurological diseases. However, there is increasing evidence that reactive astrocytes also play an important role in the response to viruses. In this review article, we summarize the recent contributions of microglia and astrocytes to the neurological impairments caused by viral infections. By expanding knowledge in this area, therapeutic approaches targeting immunological pathways may reduce the incidence of neurological and neurodegenerative disorders and increase the therapeutic window for neural protection.

SARS-CoV-2 infection and multi-organ system damage: A review

The SARS-CoV-2 infection causes COVID-19, which has affected approximately six hundred million people globally as of August 2022. Organs and cells harboring angiotensin-converting enzyme 2 (ACE2) surface receptors are the primary targets of the virus. However, once it enters the body through the respiratory system, the virus can spread hematogenously to infect other body organs. Therefore, COVID-19 affects many organs, causing severe and long-term complications, even after the disease has ended, thus worsening the quality of life. Although it is known that the respiratory system is most affected by the SARS-CoV-2 infection, many organs/systems are affected in the short and long term. Since the COVID-19 disease simultaneously affects many organs, redesigning diagnostic and therapy policies to fit the damaged organs is strongly recommended. Even though the pathophysiology of many problems the infection causes is unknown, the frequency of COVID-19 cases rises with age and the existence of preexisting symptoms. This study aims to update our knowledge of SARS-CoV-2 infection and multi-organ dysfunction interaction based on clinical and theoretical evidence. For this purpose, the study comprehensively elucidates the most recent studies on the effects of SARS-CoV-2 infection on multiple organs and systems, including respiratory, cardiovascular, gastrointestinal, renal, nervous, endocrine, reproductive, immune, and parts of the integumentary system. Understanding the range of atypical COVID-19 symptoms could improve disease surveillance, limit transmission, and avoid additional multi-organ-system problems.

Direct neuronal infection of SARS-CoV-2 reveals cellular and molecular pathology of chemosensory impairment of COVID-19 patients

Patients with recent pandemic coronavirus disease 19 (COVID-19) complain of neurological abnormalities in sensory functions such as smell and taste in the early stages of infection. Determining the cellular and molecular mechanism of sensory impairment is critical to understand the pathogenesis of clinical manifestations, as well as in setting therapeutic targets for sequelae and recurrence. The absence of studies utilizing proper models of human peripheral nerve hampers an understanding of COVID-19 pathogenesis. Here, we report that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) directly infects human peripheral sensory neurons, leading to molecular pathogenesis for chemosensory impairments. An in vitro system utilizing human embryonic stem cell (hESC)-derived peripheral neurons was used to model the cellular and molecular pathologies responsible for symptoms that most COVID-19 patients experience early in infection or may develop as sequelae. Peripheral neurons differentiated from hESCs expressed viral entry factor ACE2, and were directly infected with SARS-CoV-2 via ACE2. Human peripheral neurons infected with SARS-CoV-2 exhibited impaired molecular features of chemosensory function associated with abnormalities in sensory neurons of the olfactory or gustatory organs. Our results provide new insights into the pathogenesis of chemosensory dysfunction in patients with COVID-19.

Development of a novel patient-reported outcome measure to assess signs and symptoms of COVID-19

Background

Given the urgent need for vaccines and treatments for coronavirus disease 2019 (COVID-19), the Symptoms of Infection with Coronavirus-19 (SIC), a comprehensive, patient-reported outcome (PRO) measure of signs and symptoms associated with COVID-19, was developed in full alignment with current US regulatory guidance to support evaluations of vaccines and treatments in development.

Methods

An initial version of the SIC was developed to address concepts identified through a targeted literature review and consultation with experts in infectious diseases and clinicians routinely managing COVID-19 in a hospital setting. A qualitative study was conducted in sites in the United States among 31 participants aged ≥ 18 years who were English-speaking and willing and able to provide informed consent and a self-reported history by telephone or online method. The measure was refined based on additional feedback from the clinicians and three iterative rounds of combined concept elicitation and cognitive debriefing interviews conducted with patients, caregivers, and healthy volunteers.

Results

Among 39 scientific articles identified in the literature review, 35 COVID-19 signs and symptoms were reported and confirmed during interviews with clinicians, patients, and caregivers. Patients and healthy participants suggested changes for refining the draft SIC to ensure consistent interpretation and endorsed both the 24-h recall period and use of an 11-point numeric rating scale (NRS) for capturing change in symptom severity. The final version of the SIC captures the daily presence or absence of 30 symptoms and a rating of severity for 25 of the 30 symptoms using an NRS for those symptoms reported as present.

Conclusions

The SIC comprehensively addresses observations described in the literature, by clinicians, and by patients, and captures patients’ experiences with COVID-19 in a manner that minimizes complexity and facilitates completion for both patients and healthy volunteers. This measure is thus appropriate for use in clinical trials of both therapeutics and vaccines for COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41687-022-00471-w.

COVID-19 and the risk of CNS demyelinating diseases: A systematic review

Background

Viral infections are a proposed possible cause of inflammatory central nervous system (CNS) demyelinating diseases, including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). During the past 2 years, CNS demyelinating events associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have been reported, but causality is unclear.

Objective

To investigate the relationship between CNS demyelinating disease development and exacerbation with antecedent and/or concurrent SARS-CoV-2 infection.

Methods

A systematic literature review of all publications describing either a new diagnosis or relapse of CNS demyelinating diseases (MS, NMOSD, MOGAD) in association with SARS-CoV-2 infection was performed utilizing PRISMA guidelines. Descriptive statistics were used for data analysis, using a case analysis approach.

Results

Sixty-seven articles met the inclusion criteria for the study. Most of the reported cases of NMOSD (n = 13, 72.2% of reported cases) and MOGAD (n = 27, 96.5% of reported cases) were of new disease onset, presenting with typical clinical and radiographic features of these conditions, respectively. In contrast, reported MS cases varied amongst newly diagnosed cases (n = 10, 10.5% of reported cases), relapses (n = 63, 66.4%) and pseudo-relapses (n = 22, 23.2%). The median duration between COVID-19 infection and demyelinating event onset was 11.5 days (range 0–90 days) in NMOSD, 6 days (range−7 to +45 days) in MOGAD, and 13.5 days (range−21 to +180 days) in MS. Most cases received high-dose corticosteroids with a good clinical outcome.

Conclusion

Based upon available literature, the rate of CNS demyelinating events occurring in the setting of preceding or concurrent SARS-CoV-2 infection is relatively low considering the prevalence of SARS-CoV-2 infection. The clinical outcomes of new onset or relapsing MS, NMOSD, or MOGAD associated with antecedent or concurrent infection were mostly favorable. Larger prospective epidemiological studies are needed to better delineate the impact of COVID-19 on CNS demyelinating diseases.

COVID-19, cardiac involvement and cardiac rehabilitation: Insights from a rehabilitation perspective - State of the Art

Since the beginning of the pandemic, many novel coronavirus disease 2019 (COVID-19) patients have experienced multisystem involvement or become critically ill and treated in intensive care units, and even died. Among these systemic effects, cardiac involvement may have very important consequences for the patient’s prognosis and later life. Patients with COVID-19 may develop cardiac complications such as heart failure, myocarditis, pericarditis, vasculitis, acute coronary syndrome, and cardiac arrhythmias or trigger an accompanying cardiac disease. The ratio of COVID-19 cardiac involvement ranges between 7 and 28% in hospitalized patients with worse outcomes, longer stay in the intensive care unit, and a higher risk of death. Furthermore, deconditioning due to immobility and muscle involvement can be seen in post-COVID-19 patients and significant physical, cognitive and psychosocial impairments may be observed in some cases. Considering that the definition of health is “a state of complete physical, mental and social well-being”, individuals with heart involvement due to COVID-19 should be rehabilitated by evaluating all these aspects of the disease effect. In the light of the rehabilitation perspective and given the increasing number of patients with cardiac manifestations of COVID-19, in this review, we discuss the rehabilitation principles in this group of patients.

Alteration of Inflammatory Parameters and Psychological Post-Traumatic Syndrome in Long-COVID Patients

The aim of our study is to evaluate the correlation between the psychological status of patients recovered from SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) infection (long-COVID patients) and their inflammatory status. Three months after hospital discharge, ninety-three patients were recruited and categorized into two distinct populations: control and long-COVID (COrona VIrus Disease) group. Patients belonging to the control group presented with an entering diagnosis of cardiovascular, metabolic, or respiratory disease and a negative history of SARS-CoV-2 infection, whereas the long-COVID population presented with a severe SARS-CoV-2 infection treated in the sub-intensive Care Unit. Psychological evaluation was performed through the administration of the Symptom Checklist-90 (SCL90) and LDH (Lactate dehydrogenase), ferritin, CRPhs (C-high sensitivity Reactive Protein), NLR (Neutrophil-to-lymphocyte ratio), PLR (Platelet-to-lymphocyte ratio), and SII (systemic immune-inflammation index) were investigated. We highlighted that beyond the first three months after contagion, patients recovered from SARS-CoV-2 infection are characterized by the persistence of a systemic inflammatory state and are at high risk for developing somatization, depression, anxiety, and sleep disturbances. Interestingly, ferritin value was strongly correlated with sleep disorders (p < 0.05). Our study emphasizes how COVID-19 strategies for risk stratification, prognosis, and therapy management of patients should be implemented with a psychological follow-up.

A Rare Case of COVID-19-Induced Chronic Demyelinating Polyneuropathy

Chronic autoimmune demyelinating polyneuropathy (CIDP) is a rare autoimmune disorder in which the body's immune system attacks the myelin sheaths. Myelin sheaths are the fatty insulation covering and protecting the nerves, and damage to these can lead to neurological symptoms like numbness, tingling, and weakness. CIDP is a chronic disease in the Guillain-Barré syndrome spectrum. Numerous case reports of autoimmune diseases linked to coronavirus disease 2019 (COVID-19) have been seen since the onset of COVID-19 pandemic. We present one such challenging case of COVID-19-induced CIDP.

Changes in cognitive functioning after COVID-19: A systematic review and meta-analysis

Introduction

We conducted a systematic review and meta‐analysis of the cognitive effects of coronavirus disease 2019 (COVID‐19) in adults with no prior history of cognitive impairment.

Methods

Searches in Medline/Web of Science/Embase from January 1, 2020, to December 13, 2021, were performed following Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines.  A meta‐analysis of the Montreal Cognitive Assessment (MoCA) total score comparing recovered COVID‐19 and healthy controls was performed.

Results

Oof 6202 articles, 27 studies with 2049 individuals were included (mean age = 56.05 years, evaluation time ranged from the acute phase to 7 months post‐infection). Impairment in executive functions, attention, and memory were found in post‐COVID‐19 patients.  The meta‐analysis was performed with a subgroup of 290 individuals and showed a difference in MoCA score between post‐COVID‐19 patients versus controls (mean difference = −0.94, 95% confidence interval [CI] −1.59, −0.29; P = .0049).

Discussion

Patients recovered from COVID‐19 have lower general cognition compared to healthy controls up to 7 months post‐infection.

Neurographic Evidence of Inflammatory Polyneuropathies in Peri-COVID-19 Circumstances and Their Relationship With Acute Disease Severity and Inflammatory Storm

Recently, there has been increasing evidence among people infected with coronavirus disease 2019 (COVID-19) of being diagnosed with the typical acute post-infectious inflammatory polyneuroradiculopathy that was formerly known as Guillain-Barré syndrome (GBS), and it is not uncommon that some of them develop chronic inflammatory demyelinating polyneuroradiculopathy (CIDP). However, there is still a large debate and controversy about the link between COVID-19 and polyneuropathy. As a result, a multicentric retrospective cohort study was conducted in Basrah Governorate in the south of Iraq that included 2240 patients over a period of six months. Of those, 1344 patients had a history of COVID-19 in the previous year, and 1.14% of them developed inflammatory polyneuropathy, while only 0.29% (896 patients) of those with no history of COVID-19 had developed inflammatory polyneuropathy. This difference is highly significant, with a relative risk equal to six. The majority of the inflammatory polyneuropathy (44.4%) was diagnosed four to 12 weeks after the COVID-19 infection, with GBS being the most common type (72.2% of cases). Moreover, the nerve conduction velocity, the distal latency, and the amplitude of the most studied nerves were slower, more prolonged, and lower, respectively, among the COVID-19 groups compared with the non-COVID-19 group. Furthermore, there is an inverse correlation between the nerve conduction velocity in the majority of studied nerves and certain inflammatory biomarkers, such as serum ferritin, interleukin-6, and c-reactive protein. Although the occurrence of inflammatory polyneuropathy is more common among the less severe groups of COVID-19, if it occurs in the severe groups, it shows a more aggressive presentation.

SARS-CoV-2 Infects Primary Neurons from Human ACE2 Expressing Mice and Upregulates Genes Involved in the Inflammatory and Necroptotic Pathways

Transgenic mice expressing human angiotensin-converting enzyme 2 under the cytokeratin 18 promoter (K18-hACE2) have been extensively used to investigate the pathogenesis and tissue tropism of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Neuroinvasion and the replication of SARS-CoV-2 within the central nervous system (CNS) of K18-hACE2 mice is associated with increased mortality; although, the mechanisms by which this occurs remain unclear. In this study, we generated primary neuronal cultures from K18-hACE2 mice to investigate the effects of a SARS-CoV-2 infection. We also evaluated the immunological response to SARS-CoV-2 infection in the CNS of K18-hACE2 mice and mouse neuronal cultures. Our data show that neuronal cultures obtained from K18-hACE2 mice are permissive to SARS-CoV-2 infection and support productive virus replication. Furthermore, SARS-CoV-2 infection upregulated the expression of genes involved in innate immunity and inflammation, including IFN-α, ISG-15, CXCL10, CCL2, IL-6 and TNF-α, in the neurons and mouse brains. In addition, we found that SARS-CoV-2 infection of neurons and mouse brains activates the ZBP1/pMLKL-regulated necroptosis pathway. Together, our data provide insights into the neuropathogenesis of SARS-CoV-2 infection in K18-hACE2 mice.

Covid-19, nervous system pathology, and Parkinson's disease: Bench to bedside

Coronavirus disease 2019 (Covid-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is primarily regarded as a respiratory disease; however, multisystemic involvement accompanied by a variety of clinical manifestations, including neurological symptoms, are commonly observed. There is, however, little evidence supporting SARS-CoV-2 infection of central nervous system cells, and neurological symptoms for the most part appear to be due to damage mediated by hypoxic/ischemic and/or inflammatory insults. In this chapter, we report evidence on candidate neuropathological mechanisms underlying neurological manifestations in Covid-19, suggesting that while there is mostly evidence against SARS-CoV-2 entry into brain parenchymal cells as a mechanism that may trigger Parkinson's disease and parkinsonism, that there are multiple means by which the virus may cause neurological symptoms.

Neurologic complications of coronavirus and other respiratory viral infections

In humans, several respiratory viruses can have neurologic implications affecting both central and peripheral nervous system. Neurologic manifestations can be linked to viral neurotropism and/or indirect effects of the infection due to endothelitis with vascular damage and ischemia, hypercoagulation state with thrombosis and hemorrhages, systemic inflammatory response, autoimmune reactions, and other damages. Among these respiratory viruses, recent and huge attention has been given to the coronaviruses, especially the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic started in 2020. Besides the common respiratory symptoms and the lung tropism of SARS-CoV-2 (COVID-19), neurologic manifestations are not rare and often present in the severe forms of the infection. The most common acute and subacute symptoms and signs include headache, fatigue, myalgia, anosmia, ageusia, sleep disturbances, whereas clinical syndromes include mainly encephalopathy, ischemic stroke, seizures, and autoimmune peripheral neuropathies. Although the pathogenetic mechanisms of COVID-19 in the various acute neurologic manifestations are partially understood, little is known about long-term consequences of the infection. These consequences concern both the so-called long-COVID (characterized by the persistence of neurological manifestations after the resolution of the acute viral phase), and the onset of new neurological symptoms that may be linked to the previous infection.

Protective Effect of Melatonin Administration against SARS-CoV-2 Infection: A Systematic Review

Introduction: according to the World Health Organization (WHO), COVID-19 is an infectious disease caused by the SARS-CoV-2 virus, responsible for an increasing number of cases and deaths. From a preventive and therapeutic point of view, there are two concerns that affect institutions and healthcare professionals: global immunization (which is still far from being achieved) and the availability of drugs capable of preventing its consequences in the infected patient. In this sense, the role that melatonin can play is has been assessed in the recent literature. Justification and Objectives: the serious health, social and economic consequences of COVID-19 have forced an urgent search for preventive methods, such as vaccines, among others, and therapeutic methods that could be alternatives to the drugs currently used. In this sense, it must be accepted that one of the most recommended has been the administration of melatonin. The present study proposes to carry out a systematic review of its possible role in the treatment and/or prevention of COVID-19. Material and methods: a systematic review of the literature related to the prevention of COVID-19 through the administration of melatonin was carried out, following the sequence proposed by the Prisma Declaration regarding the identification and selection of documents, using the specialized health databases Trip Medical Database, Cochrane Library, PubMed, Medline Plus, BVS, Cuiden and generic databases such as Dialnet, Web of Science and Google Scholar for their retrieval. Appropriate inclusion and exclusion criteria are described for the articles assessed. The main limitation of the study has been the scarcity of works and the lack of defining a specific protocol in terms of dosage and administration schedule. Results: once the selection process was completed, and after an in-depth critical analysis, 197 papers were selected, and 40 of them were finally used. The most relevant results were: (1) melatonin prevents SARS-CoV-2 infection, (2) although much remains to be clarified, at high doses, it seems to have a coadjuvant therapeutic effect in the treatment of SARS-CoV-2 infection and (3) melatonin is effective against SARS-CoV-2 infection. Discussion: until group immunization is achieved in the population, it seems clear that we must continue to treat patients with SARS-CoV-2 infection, and, in the absence of a specific and effective antiviral therapy, it is advisable to continue researching and providing drugs that demonstrate validity based on the scientific evidence. In this regard, we believe that the available studies recommend the administration of melatonin for its anti-inflammatory, antioxidant, immunomodulatory, sleep-inducing, CD147, Mpro, p65 and MMP9 protein suppressing, nephrotoxicity-reducing and highly effective and safe effects. Conclusions: (1) melatonin has anti-inflammatory, antioxidant, immunomodulatory, and Mpro and MMP9 protein-inhibitory activity. (2) It has been shown to have a wide margin of safety. (3) The contributions reviewed make it an effective therapeutic alternative in the treatment of SARS-CoV-2 infection. (4) Further clinical trials are recommended to clearly define the administration protocol.

Role of Neuroimaging in COVID 19 Infection-A Retrospective Study

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a member of the family of coronaviruses, induces COVID-19 disease which is predominantly a respiratory illness. Several authors have reported neurological manifestations such as acute venous and arterial strokes and rarely acute disseminated encephalomyelitis, hemorrhagic posterior reversible encephalopathy syndrome, and acute inflammatory demyelinating polyneuropathy by studying magnetic resonance imaging of brain parenchymal signal abnormalities in patients with COVID-19. Owing to sparsity of literature on extrapulmonary manifestation of COVID, it is imperative to study the mechanism of neuronal invasion and manifestations of COVID-19. This study aimed to assess and correlate neurological manifestations in patients with COVID using imaging findings on computed tomography and magnetic resonance images. A retrospective observational study was conducted among 80 patients who tested positive for COVID-19 disease via a reverse transcription-polymerase chain reaction (RT-PCR) test in a tertiary care teaching institute in Pimpri, India. Most patients presented with acute arterial and venous strokes. Arterial stroke was the most prevalent finding; nearly 42.50% showed imaging findings consistent with arterial stroke; 25% patients had findings of venous stroke. Meningitis and spontaneous hemorrhage were found in 10% of cases. Rare complications such as acute disseminated encephalomyelitis comprised 7.50%, and encephalitis was found in 5%. This study highlights the need for increased neuroimaging in suspected patients to alert the treating physicians about the neurological complications. As the conventional RT-PCR and serum tests are unremarkable in the early onset of COVID-19, it is important to have a multidisciplinary approach and more neurology consultations in COVID-19 suspected patients with an emphasis on prompt neuroimaging to prevent potential life-threatening complications. To alert the attending physician about neurological involvement in patients with COVID-19, it is vital that nursing staff is aware about the neurological manifestations of COVID-19 so that they can recognize change in patients' neurological status without any undue time delay.

Neurological pathophysiology of SARS-CoV-2 and pandemic potential RNA viruses: a comparative analysis

SARS‐CoV‐2 has infected hundreds of millions of people with over four million dead, resulting in one of the worst global pandemics in recent history. Neurological symptoms associated with COVID‐19 include anosmia, ageusia, headaches, confusion, delirium, and strokes. These may manifest due to viral entry into the central nervous system (CNS) through the blood–brain barrier (BBB) by means of ill‐defined mechanisms. Here, we summarize the abilities of SARS‐CoV‐2 and other neurotropic RNA viruses, including Zika virus and Nipah virus, to cross the BBB into the CNS, highlighting the role of magnetic resonance imaging (MRI) in assessing presence and severity of brain structural changes in COVID‐19 patients. We present new insight into key mutations in SARS‐CoV‐2 variants B.1.1.7 (P681H) and B.1.617.2 (P681R), which may impact on neuropilin 1 (NRP1) binding and CNS invasion. We postulate that SARS‐CoV‐2 may infect both peripheral cells capable of crossing the BBB and brain endothelial cells to traverse the BBB and spread into the brain. COVID‐19 patients can be followed up with MRI modalities to better understand the long‐term effects of COVID‐19 on the brain.

Association of CNS demyelination and COVID-19 infection: an updated systematic review

Background

Since the declaration of COVID-19 pandemic, several case reports of demyelination of both peripheral and central nervous systems have been published. The association between CNS demyelination and viral infection has long been documented, and this link was recently reported following SARS-CoV-2 infection as well.

Objectives

In this systematic review, we aim to investigate the existing literature on CNS demyelination associated with SARS-CoV-2, and the proposed pathophysiological mechanisms.

Methods

We conducted a systematic review of articles in PubMed, SCOPUS, EMBASE, Cochrane, Google Scholar and Ovid databases, from 1 January 2020 until June 15, 2021. The following keywords were used: “COVID-19”, “SARS-CoV-2”, “demyelination”, “demyelinating disease”, “multiple sclerosis”, “neuromyelitis optica”, and “transverse myelitis”.

Results

A total of 60 articles were included in the final analysis of this systematic review and included 102 patients: 52 (51%) men and 50 (49%) women, with a median age of 46.5 years. The demyelination mimicked a variety of conditions with a picture of encephalitis/encephalomyelitis being the most common. At the same time other patterns were less frequently reported such as MS, NMOSD and even MOGAD. Longitudinally extensive transverse myelitis (LETM) was the most frequently reported pattern of spinal cord involvement.

Conclusion

A growing body of literature has shown an association between SARS‐CoV‐2 infection and the development of different types of CNS demyelination. Although causality cannot readily be inferred, this review may suggest a probable causal relationship, through a para-infectious or post-infectious immune-mediated etiology in COVID-19 patients. This relationship needs to be clarified in future research.

The comparison of fatigue, sleep quality, physical activity, quality of life, and psychological status in multiple sclerosis patients with or without COVID-19

Purpose

The study was purposed to investigate the effect of COVID-19 disease on fatigue, sleep quality, physical activity, quality of life, and psychological status in people with MS.

Methods

A total of 104 people with MS, including 46 of them with COVID-19 disease history, were enrolled in the study. All patients were evaluated with the Expanded Disability Status Scale (EDSS), Fatigue Severity Scale (FSS), Pittsburgh Sleep Quality Index (PSQI), International Physical Activity Questionnaire Short Form (IPAQ-SF), the EuroQoL Instrument (EQ-5D-3L), the Fear of COVID-19 Scale (FCV-19S) and the Coronavirus Anxiety Scale (CAS).

Results

People with MS in the COVID-19 positive group had a significantly lower IPAQ-Total score (p = 0.014). Besides, the FCV-19S scores of COVID-19 positive patients were significantly higher (p = 0.006). EQ-5D-3L Index and EQ-5D-3L VAS scores were higher in the group with COVID-19 (p₁ = 0.021, p₂ = 0.014, respectively). FCV-19S had a moderate correlation with EDSS (r = -0.362). IPAQ-Total was moderately associated with MS duration, EDSS and FSS (r₁ = -0.471, r₂ = -0.389, r₃ = -0.388, respectively). The EQ-5D-3L Index was moderately correlated with FSS (r₁ = -0.404). There was a weakly significant relationship between EQ-5D-3L Index and BMI, MS duration, PSQI and CAS (r₁ = -0.471, r₂ =-0.389, r₃ = -0.388, r₄ = -0.326, respectively). On the other hand, EQ-5D-3L was moderately associated with VAS and EDSS and PSQI (r₁ = -0.393, r₂ = -0.357, respectively).

Conclusion

COVID-19 negatively affected the people with MS's physical activity and coronavirus related fear parameters. However, the causality of this influence should be investigated in detail.

Changes of coagulation function and risk of stroke in patients with COVID-19

BACKGROUND AND PURPOSE

COVID-19 is spreading throughout the whole world as a public health issue. There is a link between the new coronavirus and changes in biochemical indicators, such as coagulation functions. Hypercoagulable state of blood caused by infections may lead to cerebrovascular diseases. More attention should be paid to patients with COVID-19, especially critically ill individuals with history of cerebrovascular disease who may have high risk of stroke.

METHODS

193 patients with COVID-19 were enrolled in the study. These patients were categorized into nonsevere (143 patients) and severe (50 patients) groups. This study evaluated laboratory tests, including routine blood tests, C-reactive protein, erythrocyte sedimentation rate, electrolytes, and coagulation functions. Furthermore, neurological function and stroke risks were evaluated in this study.

RESULTS

Compared to the nonsevere group, there were increases in white blood cells, neutrophil count, interleukin-6, erythrocyte sedimentation rate, and C-reactive protein in the severe group (p < .05). For coagulation functions, parameters like prothrombin time, international normalized ratio, activated partial thromboplastin time, thrombin time, D-dimer, and fibrin degradation products were increased significantly in the severe group (p < .01). Severe patients also demonstrated higher scores on the Framingham stroke risk profile and lower Glasgow scores (p < .05). Furthermore, significant associations were noticed between stroke risk and age, blood cell count, neutrophil count, D-dimmer, and fibrin degradation productions (p < .05).

CONCLUSIONS

Data suggested that coagulation functions were affected in patients with COVID-19. Hypercoagulable state in patients may lead to potential high risk of stroke.

Polyneuropathy following COVID-19 infection: the rehabilitation approach

A range of neurological manifestations associated with COVID-19 have been reported in the literature, but the pathogenesis of these have yet to be fully explained. The majority of cases of peripheral nervous system disease published thus far have shown a symmetrical pattern. In contrast, we describe the case of a patient with asymmetrical predominantly upper-limb sensorimotor polyneuropathy following COVID-19 infection, likely due to a multifactorial pathological process involving critical illness neuropathy, mechanical injury and inflammatory disease. His presentation, management and recovery contribute to the understanding of this complex condition and informs rehabilitation approaches.

SARS-CoV-2 Infection and Guillain-Barré Syndrome: A Review on Potential Pathogenic Mechanisms

Since December 2019, the world has been facing an outbreak of a new disease called coronavirus disease 2019 (COVID-19). The COVID-19 pandemic is caused by a novel beta-coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 infection mainly affects the respiratory system. Recently, there have been some reports of extra-respiratory symptoms such as neurological manifestations in COVID-19. According to the increasing reports of Guillain-Barré syndrome following COVID-19, we mainly focused on SARS-CoV-2 infection and Guillain-Barré syndrome in this review. We tried to explain the possibility of a relationship between SARS-CoV-2 infection and Guillain-Barré syndrome and potential pathogenic mechanisms based on current and past knowledge.

Endothelial Dysfunction in the Brain: Setting the Stage for Stroke and Other Cerebrovascular Complications of COVID-19

The Coronavirus disease 2019 (COVID)-19 pandemic has already affected millions worldwide, with a current mortality rate of 2.2%. While it is well-established that severe acute respiratory syndrome-coronavirus-2 causes upper and lower respiratory tract infections, a number of neurological sequelae have now been reported in a large proportion of cases. Additionally, the disease causes arterial and venous thromboses including pulmonary embolism, myocardial infarction, and a significant number of cerebrovascular complications. The increasing incidence of large vessel ischemic strokes as well as intracranial hemorrhages, frequently in younger individuals, and associated with increased morbidity and mortality, has raised questions as to why the brain is a major target of the disease. COVID-19 is characterized by hypercoagulability with alterations in hemostatic markers including high D-dimer levels, which are a prognosticator of poor outcome. Together with findings of fibrin-rich microthrombi, widespread extracellular fibrin deposition in affected various organs and hypercytokinemia, this suggests that COVID-19 is more than a pulmonary viral infection. Evidently, COVID-19 is a thrombo-inflammatory disease. Endothelial cells that constitute the lining of blood vessels are the primary targets of a thrombo-inflammatory response, and severe acute respiratory syndrome coronavirus 2 also directly infects endothelial cells through the ACE2 (angiotensin-converting enzyme 2) receptor. Being highly heterogeneous in their structure and function, differences in the endothelial cells may govern the susceptibility of organs to COVID-19. Here, we have explored how the unique characteristics of the cerebral endothelium may be the underlying reason for the increased rates of cerebrovascular pathology associated with COVID-19.

Postural orthostatic tachycardia syndrome (POTS) and other autonomic disorders after COVID-19 infection: a case series of 20 patients

Objective

To describe clinical features, diagnostic findings, treatments, and outcomes in patients with new-onset postural orthostatic tachycardia syndrome (POTS) and other autonomic disorders following SARS-CoV-2 infection (COVID-19).

Methods

We retrospectively reviewed medical records for patients who presented with persistent neurologic and cardiovascular complaints between April and December 2020 following COVID-19 infection.

Results

Twenty patients (70% female) were included in this study.Fifteen had POTS, 3 had neurocardiogenic syncope, and 2 had orthostatic hypotension. Six patients had abnormalities on cardiac or pulmonary testing, and 4 had elevated autoimmune or inflammatory markers. All patients were treated with non-pharmacologic therapies, and most required pharmacologic therapies. Six to 8 months after COVID-19, 17 (85%) patients had residual autonomic symptoms, with 12 (60%) unable to return to work.

Conclusions

POTS can follow COVID-19 in previously healthy patients. Appropriate diagnostic investigations and therapies are necessary to identify and treat autonomic dysfunction after COVID-19.

SARS-CoV-2 mediated neuroinflammation and the impact of COVID-19 in neurological disorders

SARS-CoV-2 is a novel coronavirus that severely affects the respiratory system, is the cause of the COVID-19 pandemic, and is projected to result in the deaths of 2 million people worldwide. Recent reports suggest that SARS-CoV-2 also affects the central nervous system along with other organs. COVID-19-associated complications are observed in older people with underlying neurological conditions like stroke, Alzheimer's disease, and Parkinson's disease. Hence, we discuss SARS-CoV-2 viral replication and its inflammation-mediated infection. This review also focuses on COVID-19 associated neurological complications in individuals with those complications as well as other groups of people. Finally, we also briefly discuss the current therapies available to treat patients, as well as ongoing available treatments and vaccines for effective cures with a special focus on the therapeutic potential of a small 5 amino acid peptide (PHSCN), ATN-161, that inhibits SARS-CoV-2 spike protein binding to both integrin α5β1 and α5β1/hACE2.

Neuroinvasion and Encephalitis Following Intranasal Inoculation of SARS-CoV-2 in K18-hACE2 Mice

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection can cause neurological disease in humans, but little is known about the pathogenesis of SARS-CoV-2 infection in the central nervous system (CNS). Herein, using K18-hACE2 mice, we demonstrate that SARS-CoV-2 neuroinvasion and encephalitis is associated with mortality in these mice. Intranasal infection of K18-hACE2 mice with 10⁵ plaque-forming units of SARS-CoV-2 resulted in 100% mortality by day 6 after infection. The highest virus titers in the lungs were observed on day 3 and declined on days 5 and 6 after infection. By contrast, very high levels of infectious virus were uniformly detected in the brains of all the animals on days 5 and 6. Onset of severe disease in infected mice correlated with peak viral levels in the brain. SARS-CoV-2-infected mice exhibited encephalitis hallmarks characterized by production of cytokines and chemokines, leukocyte infiltration, hemorrhage and neuronal cell death. SARS-CoV-2 was also found to productively infect cells within the nasal turbinate, eye and olfactory bulb, suggesting SARS-CoV-2 entry into the brain by this route after intranasal infection. Our data indicate that direct infection of CNS cells together with the induced inflammatory response in the brain resulted in the severe disease observed in SARS-CoV-2-infected K18-hACE2 mice.

Demyelinating Changes Alike to Multiple Sclerosis: A Case Report of Rare Manifestations of COVID-19

COVID-19, as a global concern and pivotal issue in the healthcare system, could have various presentations, leading to difficulty in diagnosis and management. Neuroinvasive potency, as claimed by preliminary studies, is a considerable pathogenesis. Serious neurological disorders like multiple sclerosis (MS) were out of the blue to be the first demonstration of COVID-19. This report highlights the representation of MS in a young woman, which resulted in a COVID-19 diagnosis.

Impact of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in the Nervous System: Implications of COVID-19 in Neurodegeneration

Coronavirus Disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome coronavirus-2 (SARS-CoV-2), began in December 2019, in Wuhan, China and was promptly declared as a pandemic by the World Health Organization (WHO). As an acute respiratory disease, COVID-19 uses the angiotensin-converting enzyme 2 (ACE2) receptor, which is the same receptor used by its predecessor, SARS-CoV, to enter and spread through the respiratory tract. Common symptoms of COVID-19 include fever, cough, fatigue and in a small population of patients, SARS-CoV-2 can cause several neurological symptoms. Neurological malaise may include severe manifestations, such as acute cerebrovascular disease and meningitis/encephalitis. Although there is evidence showing that coronaviruses can invade the central nervous system (CNS), studies are needed to address the invasion of SARS-CoV-2 in the CNS and to decipher the underlying neurotropic mechanisms used by SARS-CoV-2. This review summarizes current reports on the neurological manifestations of COVID-19 and addresses potential routes used by SARS-CoV-2 to invade the CNS.

Peripheral Neuropathy as a Complication of SARS-Cov-2

Previous reports have shown various neurological manifestations in about 36.4% of patients infected with SARS-Cov-2. However, peripheral neuropathy was only reported once before. A 40-year-old healthy woman presented with two weeks of cough, nasal congestion, sore throat, intermittent fevers, fatigue, and myalgia but no weakness. She tested positive for the SARS-Cov-2. Physical exam showed no neurologic deficit. Two weeks later, respiratory symptoms were improving but she developed sudden leg pain, numbness, and weakness. She described it as a "pain crisis". Neurological exam showed bilateral symmetrical, non-ascending lower extremity weakness and normal, symmetric reflexes. She had normal magnetic resonance imaging of the brain and spine, spinal fluid analysis, serum studies including creatinine kinase and C-reactive protein. She had elevated lactate dehydrogenase, low serum copper (72.9 (ref: 80.0-155.0 ug/dL)) and low vitamin B6 (14.6 (ref: 20.0-125.0 nmol/L)). A diagnosis of SARS-Cov-2-associated peripheral neuropathy was considered. We pursued empiric treatment with intravenous steroids (1000 mg methylprednisolone for three days), followed by a total of 2 g/kg of intravenous immunoglobulins (IVIG) given over five days. Pain management was done with gabapentin and ketorolac. We replaced copper and vitamin B6. Six weeks later, she reported improvement and was closer to baseline, but she endorsed residual, exertional, mild bilateral lower extremity pain, numbness, and weakness. Previous reports of treatment of SARS-Cov-2-associated neuropathy included corticosteroids and IVIG. Our patient saw the most symptomatic improvement with gabapentin. In our case, the preserved reflexes, lack of ascending pattern, sudden onset of symptoms, and normal cerebrospinal fluid (CSF) argued against Guillain-Barre syndrome. Copper deficiency can result in myelopathy but not peripheral neuropathy, so is unlikely the sole explanation. Awareness and early treatment of peripheral neuropathy in SARS-Cov-2 can result in improved clinical outcomes for patients.

Coronavirus Infection of the Central Nervous System: Animal Models in the Time of COVID-19

Naturally occurring coronaviral infections have been studied for several decades in the context of companion and production animals, and central nervous system involvement is a common finding, particularly in cats with feline infectious peritonitis (FIP). These companion and production animal coronaviruses have many similarities to recent human pandemic-associated coronaviruses such as SARS-CoV, MERS-CoV, and SARS-CoV2 (COVID-19). Neurological involvement is being increasingly recognized as an important clinical presentation in human COVID-19 patients, often associated with para-infectious processes, and potentially with direct infection within the CNS. Recent breakthroughs in the treatment of coronaviral infections in cats, including neurological FIP, have utilized antiviral drugs similar to those currently in human COVID-19 clinical trials. Differences in specific coronavirus and host factors are reflected in major variations in incidence and mechanisms of CNS coronaviral infection and pathology between species; however, broad lessons relating to treatment of coronavirus infection present within the CNS may be informative across species.