An unpleasant souvenir from COVID-19: symptoms of the nervous system

Today, our greatest interest and concern is post-COVID neurological symptoms, that is, nervous system symptoms that persist for many months after infection with the SARS-CoV-2 virus. Since they concern a significant percentage of patients, this increases our concern about the situation of Polish patients requiring neurologist care. Access to doctors in this specialty is currently difficult, and those responsible for the healthcare system in Poland need to take urgent action. As the Polish Neurological Society, we call for increased spending both on the development of neurological personnel and on the diagnosis and treatment of diseases of the nervous system,” continues Prof. PhD. doctor Alina Kulakovskaya.

Long-term effects of the pandemic

The COVID-19 pandemic, declared in March 2020, was an event that shook not only the health system, but also the entire economic and social life. We encountered a pandemic situation for the first time; no one knew what awaited us, which caused justifiable fear. The stress associated with contracting an unknown disease was so severe that it could lead to various neurological and mental complications, such as mood disorders or cognitive impairment, including: impairment of memory and concentration. However, it quickly became clear that these were not the only neurological symptoms accompanying the infection.

According to a study conducted by the European Academy of Neurology, acute neurological disorders associated with COVID-19 include encephalopathy, stroke, headaches, loss of smell and peripheral nerve diseases. Risk factors for the development of acute neurological disorders in COVID-19 include: older age, male gender and the presence of previous neurological diseases. In patients hospitalized with severe COVID-19, the occurrence of acute neurological impairment is associated with an almost 6-fold increased risk of death during hospitalization. The question also arises – do the neurological symptoms disappear when the infection disappears or do they become a problem for a longer period of time?

SARS-CoV-2 virus and the nervous system

The above data led scientists to wonder whether the SARS-CoV-2 virus enters the nervous system, and if so, by what route. In general, coronaviruses are not neurotropic viruses, but primarily infect the respiratory system. On the other hand, it is known that ACE-2 receptors, which are targeted by the SARS-CoV-2 virus, are also found on glial cells in the brain and neurons in the spinal cord.

“There are currently several different hypotheses regarding the entry of the virus into the brain and cerebrospinal fluid, but the evidence for its presence in these places is still very limited. However, we know that there are certain immunological changes (i.e., increases in specific antibodies) that occur in the cerebrospinal fluid of patients with COVID-19 that are absent in healthy people. However, it has not yet been established whether these changes are the result of the presence of the virus in the CNS or its fragments, such as the S protein, which at some point in the viral life cycle breaks away from the virus and functions independently. According to one hypothesis, the accumulation of protein S in the nervous system can cause the onset of post-COVID syndrome,” explains Professor Alina Kulakovskaya.

Post-COVID neurological symptoms

Post-COVID refers to long-term health effects, lasting more than 3 months, associated with infection with the SARS-CoV-2 virus. There are many possible post-COVID symptoms, including: chronic fatigue syndrome, smell disturbances, memory problems, cough, gastrointestinal disturbances, dysautonomia (i.e. disturbances in the functioning of the autonomic nervous system, which can cause, among other things, increased heart rate, changes in blood pressure, problems with thermoregulation, excessive sweating or sexual dysfunction), exercise intolerance and mental disorders. Therefore, many of them involve the nervous system, and it is concerning that post-COVID syndrome occurs in a significant percentage of patients.

A large American study involving almost 240,000 people. of patients after infection with the SARS-CoV-2 virus showed that 34% of patients had a neurological or psychiatric diagnosis within 6 months of infection with COVID-19, and in people with severe COVID requiring hospitalization, this figure reached 46%. The results of this study were published in the prestigious journal Lancet Psychiatry (2021; 8(5): 416-427). In continuation of this study, also published in the journal Lancet Psychiatry (2022; 9(10): 815-827), which already included a group of almost 1 million 200 thousand people. In post-COVID patients, it was shown that the risk of cognitive deficits (brain fog), dementia, psychosis and epilepsy at 2 years in the post-COVID group was still higher than in the control group.

“This is very alarming data and indicates that there is likely to be an even greater increase in the number of patients requiring neurologist care in the near future, even greater than that driven solely by demographic trends. In Poland, the number of neurologists is insufficient compared to the needs, as are the costs and investments in neurology. For several years now, we, as a PTS, have been calling for an urgent increase in spending on the development of neurological personnel, as well as on the diagnosis and treatment of diseases of the nervous system, and to carry out the necessary organizational changes. The data from the above-mentioned studies are another important argument in favor of introducing changes as quickly as possible to avoid a collapse in neurological care,” the professor emphasizes. Alina Kulakovskaya.

SARS-CoV-2 virus and smell disorders

By far the most common neurological complication of COVID-19 is a loss of smell, affecting up to 60% of people with the infection. These disorders include a complete loss of smell (anosmia), a decreased ability to smell (hyposmia), or a disorder in which the patient perceives different odors as completely different from how they actually smell (parosmia).

What causes these disorders? As it seems today, the SARS-CoV-2 coronavirus attacks the so-called supporting cells that make up the olfactory epithelium and support the functioning of olfactory neurons, facilitating their reception of olfactory stimuli. This means that the coronavirus usually does not damage neurons directly, but rather destroys supporting cells that have the ability to regenerate. Therefore, in most patients, smell disturbances are transient and disappear after a maximum of 6 weeks.

“Unfortunately, in approximately 10% of patients, smell impairment resulting from COVID-19 is permanent. In these people, the virus could cause molecular damage inside the cells that form the olfactory epithelium, and thus permanently disrupt the functioning of the olfactory receptors and sense of smell,” says the professor. Alina Kulakovskaya.

In addition to smell disturbances, infection with the SARS-CoV-2 virus can have other long-term and serious health consequences, such as:

• immunological changes in the cerebrospinal fluid of patients that are absent in healthy people;

• damage to the blood-brain barrier;

• formation of microthrombi, including in the vessels of the brain;

• a “cytokine storm” that can affect neurotransmission in the brain, which can lead to: depression, chronic fatigue, anhedonia (i.e. loss of the ability to feel pleasure) and pain. These are typical post-COVID symptoms.

Challenges facing Polish neurology

The president-elect of the Polish Neurological Society adds that the COVID-19 pandemic has been a huge challenge for the entire medical community, but Polish neurologists have coped well with this difficult situation by supporting patients and participating in various scientific research and educational initiatives.

“The pandemic and widespread post-COVID syndrome show how important neuroscience plays in modern medicine. We believe that neurology should be, along with cardiology and oncology, a third strategic area in the Polish healthcare system. The number of patients with diseases of the nervous system continues to grow, primarily due to the aging of our society. In November, the month that marks National Older People’s Day, it is worth remembering that according to the Central Statistics Office, people over 60 currently make up 28% of our society, and the same number is predicted to be the same in 2050. like 40%. This means rapidly growing systemic problems facing Polish neurology and the need to take urgent and comprehensive measures to improve the situation of patients with diseases of the nervous system,” the expert notes.