Neurological consequences of COVID-19.

In December 2019, cases of pneumonia caused by infection with the previously unknown severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), leading to coronavirus disease 2019 (COVID-19), were identified. Typical manifestations of COVID-19 are fever, cough, fatigue and dyspnoea. Initially, it was thought that the mechanism of action of SARS-CoV-2 was only associated with respiratory tract invasion, but it was later revealed that the infection might involve many other organs and systems, including the central and peripheral nervous systems. Neurological complications associated with SARS-CoV-2 infection include encephalopathy, encephalitis, meningitis, acute disseminated encephalomyelitis (ADEM), ischaemic and haemorrhagic stroke and cerebral venous sinus thrombosis. In cases of peripheral nervous system involvement, smell and taste disorders, myopathy or the signs and symptoms of Guillain‒Barré syndrome are observed. The most common early neurological complications, particularly during the first year of the epidemic, were anosmia and taste disorders, which, according to some studies, occurred in over 80 percent of patients with COVID-19. The proportion of patients with serious neurological manifestations was small compared to the global number of patients, but the numbers of SARS-CoV-2 infections and critical patients increased substantially. The experience from 2 years of the pandemic has shown that approximately 13% of infected patients suffer from severe neurological complications. The relationship between SARS-CoV-2 and the nervous system is not only a cause of neurological complications in previously healthy individuals but also directly and indirectly affects the courses of many nervous system diseases.