In April 2021, a study was published in the prestigious journal Lancet that comparatively and statistically studied the history of 236 thousand people who had been diagnosed with COVID-19 and had been treated. Research has shown that one in three of these people developed a neurological or psychiatric problem six months after the illness, one in fifty had a stroke and one in eleven had severe brain dysfunction.
“How do these neurological effects relate to a viral disease that until then the medical world treated mainly as a respiratory infection, which caused pulmonary and immune problems?” This correlation is documented from the data so far and, if so, the new coronavirus or our immune system is responsible for it, which by reacting to the “invasion”, causes a catastrophic inflammation which, among other things, affects the brain. “, States Mr. Konstantinos Voumvourakis, Director-Head of the Department of Multiple Sclerosis at the Metropolitan Hospital, Professor of Neurology Neuroimmunology at EKPA.
What do we know so far?
Before SARS-CoV-2, six coronaviruses were known to infect humans. Four of them cause mild respiratory infections, while two, MERS-CoV in 2012 and SARS-CoV in 2002-03, have caused pandemics and deaths. Experimental models have found that these two coronaviruses (MERS-CoV and SARS-CoV) can invade the nervous system and cause a variety of neurological problems in both the central (CNS) and peripheral (CNS) systems.
The mechanism of coronavirus entry into the host cell
The virus, through its spike, glycoprotein S binds to the receptor of the angiotensin 2 converting enzyme (ACE2). The enzyme ACE2 is detected in many organs and systems of the body: in the nose, lungs, kidneys, liver, blood vessels, immune system and blood vessels of the brain (but not in the brain). At this stage of the infection the patients show reversibility, anosmia and taste which are reversible.
Following binding of ACE2 first to respiratory epithelial cells and then to blood vessel epithelial cells, the virus triggers a “cytokine storm”, with marked increases in interleukin-1, interleukin-6, and necrosis factor levels. High levels of these cytokines increase vascular permeability, edema, and cause extensive inflammatory lesions and hypercoagulability of the blood resulting in small and large blood clots. This combination of extensive inflammation, vascular damage and hypercoagulability leads to acute respiratory distress syndrome (ARDS), renal failure, liver damage, heart failure, myocardial infarction, multiple stroke vascular stroke.
It then causes a prolonged neuroinflammatory reaction that leads to the breakdown of brain barriers (blood-brain, meningeal) and direct entry of SARS-CoV-2 and various components of blood into the central nervous system with a possible result of seizures, stroke, encephalopathy .
Ways of infection of the central nervous system by the coronavirus
Possible ways of infection of the CNS by the coronavirus are mentioned:
-Hematogenous spread through virus particles or through macrophage monocytes
-Neurogenic dispersion through cerebral conjugates such as the olfactory, trigeminal and pneumogastric nerve.
Pandemic and neurological effects
The effects of coronavirus infection on the central and peripheral nervous system have been reported to include: neurological symptoms, neurological disorders, and late neurological manifestations.
The most common neurological symptoms are: dizziness (9%), headache (6-13%), diarrhea, hypogastric – tasteless (5-30%), hyposmia – anosmia (5-70%), myalgia (14.9%).
“The most common neurological disorders are: vascular episodes (ischemic, hemorrhagic), venous thrombosis, encephalopathy, febrile convulsions, hemorrhagic necrotic encephalitis (Weston syndrome), ADEM, myelitis, myasthenia gravis, myasthenia nervosa, M “, The doctor explains.
The most common late neurological manifestations are: Alzheimer’s disease, Parkinson’s disease, motor neurone disease, neuromuscular disorders with respiratory distress, autoimmune diseases, multiple sclerosis, optic neuromyelitis, myasthenia gravis, barren disease-syndrome.
Uncertainties and conclusions
Although the neurobiological mechanism of coronavirus activity in the brain has begun to be understood, we still do not know which of the above neurological disorders can be attributed solely to the invasion of the coronavirus into the body and which to pre-existing underlying factors, such as excessive stress, psychosomatic exhaustion and even the constant fear of illness.
In conclusion, however, and with the help of several clinical trials and meta-analyzes that either preceded or followed the research published in the Lancet, we could consider the following as facts:
The SARS-CoV-2 virus causes a strong inflammatory response with a “cytokine storm”, coagulation disorders and multiorgan failure.
The nervous system is infected by the virus with hematogenous or neurogenic spread while the direct effect on the nervous parenchyma has not been fully documented.
There are indications of both immediate and long-term disorders of physical and acquired immunity causing immune inflammatory and degenerative diseases of the nervous system.
“The COVID-19 pandemic is ongoing and information is being obtained daily at both the clinical and laboratory levels.
Physicians should be prepared for neurological complications in patients with COVID-19 both during the pandemic and later, in order to understand the natural history of SARS-CoV-2 infection and its effect. in the central and peripheral nervous system.
“Given this, it seems that the ‘post-COVID’ era will probably be accompanied by a ‘new pandemic’ of search, knowledge, and perhaps a more radical treatment of neurological diseases,” concludes Mr. Voumbourakis.
Writes:
Mr. Konstantinos Voumvourakis, Director-Head of the Multiple Sclerosis Department at the Metropolitan Hospital,
Professor of Neurology Neuroimmunology at EKPA.
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