With interest we read the article by Pergolizzi et al. about a systematic review about the neurological manifestations of patients with COVID-19 [1]. It was concluded that SARS-CoV-2 enters the brain via ACE2-receptors, that neurological disease only rarely precedes the onset of pulmonary manifestations of a SARS-CoV-2 infection, that patients with pre-existing neurological conditions are at an increased risk of experiencing COVID-19 associated neurological abnormalities, that particularly patients with severe COVID-19 are at an increased risk of experiencing neurological disease, that drugs suppressing the immune response against SARS-CoV-2 are contraindicated for treating neurological involvement and that the neurological disease in COVID-19 patients may be easily missed [1]. We have the following comments and concerns.

The main shortcoming of the review is that it is highly speculative. There is no study available which clearly indicates that patients with pre-existing neurological disease are at an increased risk during a SARS-CoV-2 infection of developing additional neurological compromise. Entrance of SARS-CoV-2 2 to the brain via ACE2-receptors also remains unproven. There is no evidence available that particularly patients with severe infection are at an increased risk of experiencing neurological complications.

The authors do not mention a number of potential neurological manifestation of the SARS-CoV-2 infection. Central nervous system (CNS) abnormalities not included were sinus venous thrombosis, intracerebral bleeding, subarachnoid bleeding, acute, haemorrhagic, necrotic encephalopathy (AHNE), acute demyelinating encephalo-myelitis (ADEM), vasoconstriction syndrome, pituitary apoplexies’, psychosis, Parkinson’s disease, myelitis and plexitis [2-4]. Among the peripheral nervous system (PNS) abnormalities associated with SARS-CoV-2 the authors did not discuss dysgeusia, myasthenic syndrome, myositis, rhabdomyolysis and myasthenia [5].

Missing in the review is a discussion about secondary neurological compromise in COVID-19 patients due to side effects of drugs given to treat COVID-19. These drugs include chloroquine, azithromycin, steroids and others.

Overall, the review by Pergolizzi et al. has some limitations which should be met before drawing final conclusions. There is a need for prospective studies on the neurological involvement in SARS-CoV-2 infected patients. Neurological side effects of drugs given to treat COVID-19 should be included in a review about neurological disease in COVID-19.