Coronavirus disease 2019 poses a global challenge to healthcare and society in the early 21 st century. We report neuropathological changes in 52 patients aged between 22 years and 88 years (median 58 years) who were infected with the CoV-2 coronavirus. Patients died under various circumstances and had various pre-existing diseases. The inclusion criteria for this study were: positive result for the nasopharyngeal swab for SARS-CoV-2 RNA, diagnosis of pneumonia of SARS-CoV-2 or nucleoproteins of SARS-CoV-2 in pulmonary tissue confirmed by immunohistochemical methods (IHC). Samples from all brain structures and lung specimens were taken for histopathological examinations. Brain and pulmonary samples were stained typically with histological and immunohistochemical methods and small tissue fragments were examined with the transmission electron microscope (TEM). The light and electron microscopy examination confirmed the numerous neuropathological changes in the brains of the patients infected with the CoV-2. Many of these changes were caused by pre-existing diseases of patients and/or by necessary treatment. However, vascular lesions and the inflammatory process seem to be characteristic of the CoV-2 infection. In all of the structures of 52 brains of patients, damage of the vessel walls and morphological feature of the damage to the blood-brain barrier were observed. Lymphocytic and microglial infiltrates, both perivascular and diffuse, were also observed. Hence, the brain changes due to COVID-19 infection, could be called COVID-19 cerebral angiopathy with diffuse inflammation.

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Introduction: Adult neurogenesis includes proliferation and differentiation of progenitor cells as well as their migration and maturation. In the adult human brain, two neurogenic regions, the hippocampal dentate gyrus (DG) and the subventricular zone (SVZ) of lateral ventricles, have been identified. In the dentate gyrus, three types of transcriptionally active cells and in the subventricular zone, four types of transcriptionally active cells, including GFAP-positive neural stem cells (NSCs), have been differentiated. Material and methods: The aim of the study was to identify and compare density of neurogenic cells between two study groups of patients (7 men, 7 women, mean age 70 ± 6.03) with ischemic stroke and with hemorrhage (6 men, 2 women, mean age 64.75 ± 12.23) and the control group of patients (6 men, 2 women, mean age 64 ± 10.95) free of neuropathologic changes who died suddenly within less than 10 min. Results: In both groups, in the hippocampal dentate gyrus and in the subventricular zone of lateral ventricles, the presence of single GFAP-positive neural stem cells and the transcriptionally active cells labelled with phosphorylated histone H3 Ser-10 (p-Histone H3 Ser-10)/neural progenitor cells (NPCs), was observed. The quantitative analysis of cells with p-Histone H3 Ser-10 expression in the hippocampal DG revealed significant differences between the hemorrhage and control groups (p = 0.001, test t). However, in the SVZ, it showed a statistically significant decrease in the density of transcriptionally active cells in the group of patients with ischemic stroke (p = 0.001, test t). A distinct decrease in the density of transcriptionally active cells, proportional to the length of the patients' hospitalization, was observed. Conclusions: Hypoxia belongs to pathomechanic factors responsible for ischemic stroke, which can induce neurogenesis. However, hypoxia along with ischemia and other factors implicated in ischemic stroke, such as the patient's age or duration of ischemia can have a decisive influence on the decrease in the density of transcriptionally active cells in this pathologic process.

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with the onset of neurological and psychiatric symptoms during and after the acute phase of illness. Inflammation and hypoxia induced by SARS-CoV-2 affect brain regions essential for fine motor function, learning, memory, and emotional responses. The mechanisms of these central nervous system symptoms remain largely unknown. While looking for the causes of neurological deficits, we conducted a study on how SARS-CoV-2 affects neurogenesis. In this study, we compared a control group with a group of patients diagnosed with COVID-19. Analysis of the expression of neurogenesis markers showed a decrease in the density of neuronal progenitor cells and newborn neurons in the SARS-CoV-2 group. Analysis of COVID-19 patients revealed increased microglial activation compared with the control group. The unfavorable effect of the inflammatory process in the brain associated with COVID-19 disease increases the concentration of cytokines that negatively affect adult human neurogenesis.

We describe a case of 52-year-old woman with a medical history of Crohn's disease presented abrupt fever, asymmetrical multiple cranial nerve palsies and focal neurological symptoms localized to the brainstem. The patient was initially diagnosed with ischaemic stroke, because of acute clinical course and results of neuroimaging. Cerebrospinal fluid analysis revealed mild infection with negative Gram staining and culture. Final diagnosis of Listeria monocytogenes brainstem infection (rhombencephalitis) was set up on the basis of further clinical course and positive blood cultures. Listerial rhombencephalitis should be kept in mind in immunocompromised adult patients who develop fever, asymmetrical multiple cranial nerve palsies and focal neurological symptoms localized to the brainstem even without typical neuroimaging, cerebrospinal fluid findings and negative cultures. Early diagnosis and adequate antibiotic treatment is of crucial importance.