Presence of SARS-CoV-2 in the CSF of Guillain-Barré Syndrome Patients Requires Validation.

To the Editors:

We appreciate the interest in our article[1] and the opportunity to respond to the comments. In the published report, we present a pediatric case of COVID-19-associated GBS with detection of SARS-CoV-2 in the cerebrospinal fluid (CSF). In this case, the Quick-DNA/RNA Viral MagBead (Zymo Research Corp, Irvine, CA) extraction kit on the automated KingFisher Flex Purification System (Thermo Fisher Scientific, Waltham, MA) was used for nucleic acid extraction and the Allplex nCoV-2019 kit (Seegene, Inc., Seoul, South Korea) for gene amplification. Moreover, appropriate positive, negative and internal controls were used to add confidence in the results. The multiplex real-time RT-PCR assay used in this case has a limit of detection of 4167 copies/ml and a sensitivity of 100 copies/reaction. Target genes amplified within ≤40 cycle threshold were considered detected, and the patient had a positive result for the presence of SARS-CoV-2 RNA in the CSF.

Regarding the possibility of repeating the CSF virus investigation during follow-up, we decided not to perform invasive procedures with exclusively academic purpose, as this would not change the therapeutic approach. In addition, brain magnetic resonance imaging (MRI) was normal and the patient did not show any signs of brain involvement suggestive of Bickerstaff encephalitis, such as external ophthalmoplegia or disturbance of consciousness. Respiratory muscles were not involved nor did the patient had autonomic dysfunction. The symptoms presented by the patients were explained in the article.

Finally, it is worth remembering that during the recent Zika and Chikungunya epidemics, viral RNA was also found in CSF of patients with Guillain-Barré syndrome, as well as the presence of IgM and IgG.[2] According to Parra et al,[3] arbovirus-related GBS may be caused by direct infection or parainfectious nerve damage, due to the short time between onset of infectious and neurologic symptoms. Although direct viral invasion is a less likely pathophysiologic mechanism for a disease classically defined as immune-mediated, the presence of SARS-CoV-2 RNA in CSF makes it impossible for us to rule out this hypothesis.