1.1 COVID-19 and the nervous system
COVID-19 can affect the nervous system and cause nervous system
disorders. There are three major types of neurological manifestations in
COVID-19 patients, involving the central nervous system, peripheral
nervous system, and skeletal muscles. In comparison with mild COVID-19
cases, patients with these neurological symptoms are older and more
frequently have underlying diseases, of which hypertension is the most
common [2]. In a study of 417 COVID-19 patients with mild symptoms,
85.6% and 88.0% of patients had olfactory and taste dysfunction
[3]. Previous reports have documented that neuroinvasiveness is a
common feature of CoV. Although a specific mechanism by which SARS-CoV-2
infects neural cells was not yet known, viral RNA has been detected in
the cerebrospinal fluid of COVID-19 patients. Considering the
possibility of the invasion of the nervous system by SARS-CoV-2, the
risk of its infection may be currently underestimated [4].