Neurologic syndrome due to MERS: Is there a possibility that the virus can cross the blood-brain barrier to cause a neurological problem?

Potential neurological manifestations of COVID-19: a narrative review

Neurological manifestations are increasingly reported in a subset of COVID-19 patients. Previous infections related to coronaviruses, namely Severe Acute Respiratory Syndrome (SARS) and Middle Eastern Respiratory Syndrome (MERS) also appeared to have neurological effects on some patients. The viruses associated with COVID-19 like that of SARS enters the body via the ACE-2 receptors in the central nervous system, which causes the body to balance an immune response against potential damage to nonrenewable cells. A few rare cases of neurological sequelae of SARS and MERS have been reported. A growing body of evidence is accumulating that COVID-19, particularly in severe cases, may have neurological consequences although respiratory symptoms nearly always develop prior to neurological ones. Patients with preexisting neurological conditions may be at elevated risk for COVID-19-associated neurological symptoms. Neurological reports in COVID-19 patients have described encephalopathy, Guillain-Barré syndrome, myopathy, neuromuscular disorders, encephalitis, cephalgia, delirium, critical illness polyneuropathy, and others. Treating neurological symptoms can pose clinical challenges as drugs that suppress immune response may be contraindicated in COVID-19 patients. It is possible that in some COVID-19 patients, neurological symptoms are being overlooked or misinterpreted. To date, neurological manifestations of COVID-19 have been described largely within the disease trajectory and the long-term effects of such manifestations remain unknown.

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.

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.

Neurological diseases caused by coronavirus infection of the respiratory airways

Infections of the central nervous system (CNS) infections are critical problems for public health. They are caused by several different organisms, including the respiratory coronaviruses (CoVs). CoVs usually infect the upper respiratory tract causing the common cold. However, in infants, and in elderly and immunocompromised persons, they can also affect the lower respiratory tract causing pneumonia and various syndromes of respiratory distress. CoVs also have neuroinvasive capabilities because they can spread from the respiratory tract to the CNS. Once infection begins in the CNS cells, it can cause various CNS problems such as status epilepticus, encephalitis, and long‐term neurological disease. This neuroinvasive properties of CoVs may damage the CNS as a result of misdirected host immune response, which could be associated with autoimmunity in susceptible individuals (virus‐induced neuro‐immunopathology) or associated with viral replication directly causing damage to the CNS cells (virus‐induced neuropathology). In December 2019, a new disease named COVID‐19 emerged which is caused by CoVs. The significant clinical symptoms of COVID‐19 are related to the respiratory system, but they can also affect the CNS, causing acute cerebrovascular and intracranial infections. We describe the possible invasion routes of coronavirus in this review article, and look for the most recent findings associated with the neurological complications in the recently published literature.

Combating COVID-19 with tissue engineering: a review

The ongoing COVID-19 pandemic triggered by SARS-CoV-2 emerged from Wuhan, China, firstly in December 2019, as well spread to almost all around the world rapidly. The main reason why this disease spreads so many people in a short time is that the virus could be transmitted from an infected person to another by infected droplets. The new emergence of diseases usually may affect multiple organs; moreover, this disease is such an example. Numerous reported studies focus on acute or chronic organ damage caused by the virus. At this point, tissue engineering (TE) strategies can be used to treat the damages with its interdisciplinary approaches. Tissue engineers could design drug delivery systems, scaffolds, and especially biomaterials for the damaged tissue and organs. In this review, brief information about SARS-CoV-2, COVID-19, and epidemiology of the disease will be given at first. After that, the symptoms, the tissue damages in specific organs, and cytokine effect caused by COVID-19 will be described in detail. Finally, it will be attempted to summarize and suggest the appropriate treatments with suitable biomaterials for the damages via TE approaches. The aim of this review is to serve as a summary of currently available tissue damage treatments after COVID-19.

Neuroinvasion and Viral Reservoir in COVID-19

The new coronavirus disease 2019 (COVID-19) has a remarkably high transmissibility potential and sometimes invades the central nervous system (CNS). The study of the involvement of the nervous system in the pathogenesis of the disease is especially interesting. Currently, there are only three main theories about it: direct neuroinvasion; blood-brain barrier (BBB) crossing and nicotinic hypothesis. Because of the rapid expansion of a virus that until now was unknown, it is necessary to know the mechanisms by which severe acute respiratory syndrome (SARS)-like coronavirus (SARS-CoV-2) generates the disease. The study of the involvement of the nervous system in the pathogenesis of the disease is especially interesting, since it is the least studied question with more innovative theories that could explain not only neurological complications, but also the primary infection and the involvement of the various organs and systems.

Neurological manifestations of COVID-19, SARS and MERS

Since December 2019, the world is affected by an outbreak of a new disease named COVID-19, which is an acronym of 'coronavirus disease 2019'. Coronaviruses (CoV) were assumed to be associated with mild upper respiratory tract infections, such as common cold. This perception changed in time due to occurrence of the Severe Acute Respiratory Syndrome (SARS) caused by SARS-CoV in 2002 and the Middle East Respiratory Syndrome (MERS) caused by MERS-CoV in 2012, both inducing an epidemic severe viral pneumonia with potentially respiratory failure and numerous extra-pulmonary manifestations. The novel coronavirus, SARS-CoV-2, is likewise a causative pathogen for severe viral pneumonia with the risk of progression to respiratory failure and systemic manifestations. In this review, we will give a summary of the neurological manifestations due to SARS and MERS, as those might predict the neurological outcome in the novel COVID-19. Additionally, we provide an overview of the current knowledge concerning neurological manifestations associated with COVID-19, to the extent that literature is already available as the pandemic is still ongoing.

Should we expect neurological symptoms in the SARS-CoV-2 epidemic?

INTRODUCTION

There is growing evidence that SARS-CoV-2 can gain access to the central nervous system (CNS). We revise the literature on coronavirus infection of the CNS associated with neurological diseases.

DEVELOPMENT

Neurological symptoms were rarely reported in the SARS-CoV and MERS-CoV epidemics, although isolated cases were described. There are also reports of cases of neurological symptoms associated with CoV-OC43 and CoV-229E infection. The presence of neurological lesions, especially demyelinating lesions in the mouse hepatitis virus model, may explain the mechanisms by which coronaviruses enter the CNS, particularly those related with the immune response. This may explain the presence of coronavirus in patients with multiple sclerosis. We review the specific characteristics of SARS-CoV-2 and address the question of whether the high number of cases may be associated with greater CNS involvement.

CONCLUSION

Although neurological symptoms are not frequent in coronavirus epidemics, the high number of patients with SARS-CoV-2 infection may explain the presence of the virus in the CNS and increase the likelihood of early- or delayed-onset neurological symptoms. Follow-up of patients affected by the SARS-CoV-2 epidemic should include careful assessment of the CNS.

Should we expect neurological symptoms in the SARS-CoV-2 epidemic?

Introduction

There is growing evidence that SARS-CoV-2 can gain access to the central nervous system (CNS). We revise the literature on coronavirus infection of the CNS associated with neurological diseases.

Development

Neurological symptoms were rarely reported in the SARS-CoV and MERS-CoV epidemics, although isolated cases were described. There are also reports of cases of neurological symptoms associated with CoV-OC43 and CoV-229E infection. The presence of neurological lesions, especially demyelinating lesions in the mouse hepatitis virus model, may explain the mechanisms by which coronaviruses enter the CNS, particularly those related with the immune response. This may explain the presence of coronavirus in patients with multiple sclerosis. We review the specific characteristics of SARS-CoV-2 and address the question of whether the high number of cases may be associated with greater CNS involvement.

Conclusion

Although neurological symptoms are not frequent in coronavirus epidemics, the high number of patients with SARS-CoV-2 infection may explain the presence of the virus in the CNS and increase the likelihood of early- or delayed-onset neurological symptoms. Follow-up of patients affected by the SARS-CoV-2 epidemic should include careful assessment of the CNS.

Neurological Complications of Middle East Respiratory Syndrome Coronavirus: A Report of Two Cases and Review of the Literature

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) was first discovered in September 2012 in Saudi Arabia. Since then, it caused more than 1600 laboratory-confirmed cases and more than 580 deaths among them. The clinical course of the disease ranges from asymptomatic infection to severe lower respiratory tract illness with multiorgan involvement and death. The disease can cause pulmonary, renal, hematological, and gastrointestinal complications. In this paper, we report neurological complications of MERS-CoV in two adult patients, and we hypothesize the pathophysiology. The first patient had an intracerebral hemorrhage as a result of thrombocytopenia, disseminated intravascular coagulation, and platelet dysfunction. The second case was a case of critical illness polyneuropathy complicating a long ICU stay. In these cases, the neurological complications were secondary to systemic complications and long ICU stay. Autopsy studies are needed to further understand the pathological mechanism.