Cerebrospinal fluid cytokines in COVID-19: a review and meta-analysis.

INTRODUCTION: Neurological involvement can occur in patients with SARS-CoV-2 infections, resulting in coronavirus disease 2019 (COVID-19). Cytokine alterations are associated with neurological symptoms in COVID-19. We performed a review of cytokines in the cerebrospinal fluid (CSF) of patients with COVID-19. METHODS: Two reviewers independently searched PubMed for all relevant articles published prior to November 11, 2022. Active SARS-CoV-2 infection and CSF cytokine analyses were required for inclusion. RESULTS: Three-hundred forty-six patients with COVID-19 and 356 controls from 28 studies were included. SARS-CoV-2 PCR was positive in the CSF of 0.9% (3/337) of patients with COVID-19. Thirty-seven different cytokines were elevated in the CSF of patients with COVID-19 when compared to controls and the standards set forth by individual assays used in each study. Of the 37 cytokines, IL-6 and IL-8 were most commonly elevated. CSF IL-6 is elevated in 60%, and CSF IL-8 is elevated in 51% of patients with COVID-19. CONCLUSION: Levels of several inflammatory cytokines are elevated in the CSF of patients with COVID-19, and SARS-CoV-2 PCR is often not isolated in the CSF of patients with COVID-19. Many patients with COVID-19 have neurological symptoms and given the cytokine elevations in the absence of detectable viral RNA in cerebrospinal fluid; further study of the CSF cytokine profiles and pathogenesis of neurological symptoms in COVID-19 is needed.