Neurochemical Biomarkers in patients with COVID-19

The limited data available on CSF analysis in patients with COVID-19 prompted us to conduct a large-scale multicenter study on behalf of the German Society for CSF Diagnostics and Clinical Neurochemistry (DGLN), taking into account a wide range of parameters, including white blood cell count (WCC) in CSF and cytology, quantitative and qualitative detection of intrathecal IgG, IgM and IgA synthesis, markers of blood CSF barrier (BCB) dysfunction, total protein, lactate, glucose and SARS-CoV-2 CSF polymerase chain reaction (PCR), antibody indices (AI), autoantibody findings and cytokine levels. CSF findings from 150 lumbar punctures in 127 patients with PCR-proven COVID-19 and neurologic symptoms showed that direct CNS infection with SARS-CoV-2 appears to be rare. The major findings were BCB dysfunction in the absence of intrathecal inflammation consistent with cerebrospinal endotheliopathy and a decrease in CSF flow rate. Cytokine levels were frequently elevated in CSF (often in association with BCB dysfunction) and serum. Persistent BCB dysfunction and elevated cytokine levels may contribute to both acute symptoms and ''long COVID.'' Further analysis of COVID-19 patients with longitudinal data is warranted.