Recently, new evidence has emerged that the new SARS-CoV-2 coronavirus is actively affecting not only the lungs and respiratory tract but also other organs of the human body. Serious damage can also be caused to the heart, blood vessels, nerve tissues, and skin. British neurologists published in Brain magazine data that coronavirus can cause brain damage even in patients with mild symptoms of COVID-19.
Neurologists at University College London have diagnosed acute disseminated encephalomyelitis in more than 40 UK patients with COVID-19. Twelve of these patients suffered from central nervous system inflammation, ten from transient encephalopathy (brain disease). With delirium or psychosis, eight suffered a stroke, another eight suffered from nerve damage, mainly with Guillain-Barré syndrome. It is an autoimmune reaction that affects nerve cells, causes paralysis, and is fatal in 5% of cases. Due to these complications, one of the patients died at the age of 59. This inflammatory disease leads to degenerative damage to the nervous system that affects the so-called myelin sheath of nerve cells in the brain and spinal cord. The key thing scientists are now seeing is that the severity of lung disease does not always correlate with the severity of the neurological disease. Having only minor lung disease does not protect against potentially severe complications.
How does the coronavirus enter the brain?
A study by German scientists, published on the bioRxiv preprint server in June 2020, describes the various neurological manifestations of COVID-19, as well as the underlying pathophysiology. In addition, the researchers explain how coronavirus enters the brain. COVID-19 is still primarily a respiratory disease, with severe illness associated with many other ones, including central nervous system thromboembolism. The onset of neurological symptoms such as anosmia, agenesis, and headache in most patients indicates that a virus is invading the brain.
This is confirmed by the occurrence of acute disorders associated with stroke, as well as a decrease or change in consciousness in some patients with COVID-19. What’s more, many recent studies show that viral RNA is found in the brain and cerebrospinal fluid.
The new study focused on the nasopharynx and brain areas of 32 fatal COVID-19 patients with symptom tracking. After analyzing 32 autopsies, of which 29 patients tested positive for SARS-CoV-2 PCR and the remaining three were diagnosed based on signs and symptoms of COVID-19, the researchers found that four patients, or 13%, had an acute heart attack. This happened as a result of microscopic blood clots or embolism in the brain. Similar microthrombi were observed in the olfactory mucosa.
As a result of additional studies of a control group of organs, scientists came to the conclusion that the virus enters the central nervous system through the receptor fibers of the olfactory nerve, which explains the occurrence of anosmia and agenesis. The presence of tiny clots and cerebral infarctions in this area in 13% of brain samples appears to support other reports of CNS thromboembolism in patients.
The olfactory mucosa appears to be a permanent site of viral resistance and replication, as evidenced by persistently high levels of virus in this tissue for up to 53 days from the onset of the first symptoms. Scientists also speculate that the virus, present in vital centers in the brain, could exacerbate pre-existing respiratory or cardiac problems through a central mechanism.
How does the virus affect the brain?
The coronavirus can affect the nervous system in different ways, and this is not only about the loss of taste and smell. Several cases of encephalitis (inflammation of the brain), as well as Guillain-Barré syndrome, have already been described: the patient’s immune system begins to attack its own nerve cells, which leads to muscle weakness and, in severe cases, to paralysis. Doctors from the United States are concerned about reports that in New York alone, five cases of major strokes were recorded in coronavirus patients in two weeks. It should be noted that this pathology was observed in relatively young people (up to 50 years old). There were no other, pronounced symptoms of COVID-19.
According to preliminary data, as a side effect of inflammation, coronavirus can provoke blood clots in patients. As a result, this leads to an acute violation of cerebral circulation. Most of the neurological disorders are observed in patients with the severe stage of COVID-19. In such cases, neurological symptoms may persist in patients after a seemingly complete recovery from the coronavirus. Some people with COVID-19 are confused. David Hepburn, a consultant physician in the intensive care unit of the Royal Gwent Hospital in Wales, told the BBC how people go into psychosis after resuscitation amid an exacerbation of coronavirus infection. Defeating the virus is just the beginning of a long healing process. And this process can be very traumatic.
Post-resuscitation psychosis or delirium affects between a quarter and a third of all patients admitted to intensive care. However, scientists still do not know the long-term effects of delirium caused or triggered by COVID-19. Most of the physical effects in survivors resemble secondary effects of a virus present in the brain, rather than direct effects of infection. For example, a person’s immune system can fight the virus appropriately, but it can also start attacking its own cells – including brain cells and nerves. This could be due to the action of immune cells and antibodies through an inflammatory mechanism known as a cytokine storm, or through mechanisms that scientists do not yet understand.
How do you know if there is a problem?
One way to learn more is to “look into the heads” of patients using brain imaging techniques such as MRI. So far, brain imaging has revealed a number of previously unseen results, but it’s too early to use it in this pandemic. One study found patterns that include signs of inflammation and mild bleeding. They were often found in the deepest parts of the brain. Some of these results are similar to those seen in divers or altitude sickness. They may reflect an acute shortage of oxygen reaching the brain in some COVID-19 patients. However, scientists are just beginning to understand the extent to which the brain is involved in disease. Brain studies and posthumous studies of those killed by COVID-19 are limited to date.