Post COVID-19 disorders: is the epidemic of parkinsonism threatening the world?

Abstract

During the pandemic caused by SARS-CoV-2, the ability of this virus to infect the structures of the peripheral and central nervous system becomes increasingly clear. Damage to the nervous system is noted in almost 85% of patients who have had COVID-19, both those who have had this disease in severe form, and in patients with mild or asymptomatic course. COVID-19 worsens symptoms in patients with Parkinson's disease (PD), which potentially increases the risk of death due to pneumonia and respiratory disorders in patients with severe stages of PD. There is a concern that the COVID-19 pandemic may lead to a sharp increase in the incidence of parkinsonism, while the ability of the SARS-CoV-2 virus to cause PD is assumed. The following ways of virus penetration, including the SARS-CoV-2 virus, into the structures of the central nervous system are considered - viremia and endothelial cell damage, as well as retrograde axonal transport. The direct penetration of the COVID-19 virus into the structures of the brain may be due to a disturbance of the blood-brain barrier due to a «cytokine storm» and activation of lymphocytes, which is due to the processes of neuroinflammation. According to some of its manifestations, the extrapyramidal syndrome observed in patients with COVID-19 resembles lethargic encephalitis von Economo. However, the question of the possibility of COVID-19 causing the development of PD is extremely complex and ambiguous. The latency period between viral encephalitis and the onset of parkinsonism can reach 5 years. It is possible that the basis for the development of neurological disorders, including parkinsonism, in this category of patients is an energy deficit that leads to disruption of the functioning of neural networks (human connectome) of the human brain. Based on the currently very limited data concerning the penetration of the COVID-19 virus into the structures of the central nervous system, there is no convincing evidence of this virus causing parkinsonism. The final clarity on this issue will be provided by the results of observations on the condition of patients who have undergone COVID-19.