The COVID-19 vaccine offers hope to overcome the pandemic. Unfortunately, scientists are starting to see another problem. The neurological symptoms are most often associated with the respiratory system, but not always. Some patients transmit the virus but theoretically show no symptoms. However, they have, for example, an olfactory disorder, which they sometimes do not notice themselves. These are the only symptoms then. In addition, it is clearer that there are people who have beaten the coronavirus but have not recovered. Many of them experience severe neurological disorders.
Doctors are increasingly reporting that some patients infected with the coronavirus experience symptoms from the nervous system. High fever, cough, and shortness of breath are just basic symptoms of COVID-19 disease caused by the coronavirus. The most common indication that SARS-CoV-2 attacked directly the peripheral nervous system is a loss of taste or smell, but there are other symptoms as well. It turns out that the coronavirus affects not only the lungs and the heart, but is also responsible for pathological changes taking place in the brain. What are the most common neurological disorders reported?
How COVID-19 affects the brain and the nervous system
The SARS-CoV-2 coronavirus infection most often causes several respiratory symptoms, but it is not the only risk for patients. The interference of the coronavirus with the nervous system was indicated by one of the less common symptoms of the infection – weakening of the sense of smell and taste. This symptom may indicate an attack by a virus in the central nervous system.
For now, scientists are concluding preliminary studies and comparisons of this virus to the earlier SARS-CoV-1, which caused a minor pandemic in 2003. The two viruses are very similar, and both cause some neurological symptoms. SARS-CoV-2 most likely enters the brain through the nose, specifically through the nerve fibers in its mucosa. The effect of coronavirus entry into the brain is neurological symptoms, not only headaches and dizziness, fatigue or loss or disturbance of smell or taste, but also possible stroke or delirium. Unfortunately, it turns out that people who have overcome the coronavirus infection also experience neurological complications. And they are often serious complications that require specialist treatment. A small number of patients can get serious brain damage. Many convalescents, including those who have been infected with COVID-19 asymptomatically, develop the syndrome of chronic fatigue, concentration disorders, memory, and other cognitive function disorders. These particular complications after COVID-19 relate to the ability to meaningfully interact with the world.
There remains a group of neurological symptoms that appear after contracting the infection.
Many convalescents, including those who have had the infection asymptomatically, develop a syndrome of chronic fatigue, concentration disorders, memory disorders, and other cognitive functions. Headaches, dizziness, and neuralgia may also persist for a long time.
What neurological diseases can SARS-CoV-2 cause?
There are many indications that COVID-19 damages other important centers in the brain, including those responsible for breathing, in some patients. These neurological consequences of the disease may explain the occurrence of sudden seizures, loss of consciousness, encephalopathy, and acroparesthesia, i.e. tingling, numbness, and stinging of the limbs, or respiratory failure in people who have had COVID-19 without severe symptoms and are not at risk. If breathing problems are caused not by changes in the lungs but in the brain, the use of a respirator is not an effective solution. There are some examples of such diseases, divided by the type of signs.
- Acute COVID-19 symptoms resemble any generalized infection. Symptoms of encephalopathy appear in sleepiness, impaired consciousness, headaches, nausea, and vomiting. In this context, meningitis and encephalitis may also occur as a direct consequence of viral invasion into the central nervous system.
- There are also sub-acute symptoms occurring at different times after the onset of the infection. These include, first of all, olfactory and taste disorders, which are common and affect even 70-80% of patients. The olfactory nerves are then attacked by the virus and migrated to the structures of the central nervous system. These symptoms are very specific and many patients experience a loss of smell and taste, even without symptoms of an obvious infection in the respiratory tract.
- Some autoimmune syndromes have also been described, where the presence of the virus provokes the immune system and, through antigenic similarity, the structures of the nervous system are affected and damaged. These are demyelinating syndromes, such as, for example, ADEM syndrome (acute disseminated encephalomyelitis), as well as damage to the peripheral nervous system in the form of Guillain-Barre syndrome, which means acute inflammatory demyelinating polyradiculoneuropathy.
- There is also a whole list of delayed symptoms. These signs include nonspecific ailments, memory impairment and disturbances in higher mental functions, a state of breakdown, mental slowness. There is even talk of the aging process of the brain after severe covid infection when it comes to deep states of brain hypoxia. Fatigue syndrome also appears. Many people feel weakness, low exercise tolerance, which is associated with respiratory dysfunction, but also with peripheral nerves damage. Pain syndromes, i.e. neuralgia, neuropathies, as an expression of secondary damage to the nervous system, also come to the surface.
- One complication that can happen in the context of COVID-19 at any time from the onset of the infection is stroke. A suffering person has increased blood clotting, which causes embolism, blood clotting in small vessels, and strokes of various etiology. At the beginning of the epidemic, this affected a few percent of patients, but these rates are unfortunately rising due to the prevalence of infection and its overlapping with comorbidities that are themselves a risk factor for stroke.
Much is still unknown about the neurological symptoms of COVID-19, so research on the subject, which is still ongoing, will be key to clarifying this issue.