Frequency and Referral Patterns of Neural Antibody Studies During the COVID-19 Pandemic
Helena Ariño, Raquel Ruiz‐García, Beatriz Rioseras, Laura Naranjo, Eugenia Martínez‐Hernández, Albert Saiz, Francesc Graus, Josep Dalmau
Abstract
<h3>Objective</h3> To determine whether the frequency of paraneoplastic or autoimmune encephalitis antibodies examined in a referral center changed during the COVID-19 pandemic. <h3>Methods</h3> The number of patients who tested positive for neuronal or glial (neural) antibodies during pre–COVID-19 (2017–2019) and COVID-19 (2020–2021) periods was compared. The techniques used for antibody testing did not change during these periods and included a comprehensive evaluation of cell-surface and intracellular neural antibodies. The chi-square test, Spearman correlation, and Python programming language v3 were used for statistical analysis. <h3>Results</h3> Serum or CSF from 15,390 patients with suspected autoimmune or paraneoplastic encephalitis was examined. The overall positivity rate for antibodies against neural-surface antigens was similar in the prepandemic and pandemic periods (neuronal 3.2% vs 3.5%; glial 6.1 vs 5.2) with a mild single-disease increase in the pandemic period (anti-NMDAR encephalitis). By contrast, the positivity rate for antibodies against intracellular antigens was significantly increased during the pandemic period (2.8% vs 3.9%, <i>p =</i> 0.01), particularly Hu and GFAP. <h3>Discussion</h3> Our findings do not support that the COVID-19 pandemic led to a substantial increase of known or novel encephalitis mediated by antibodies against neural-surface antigens. The increase in Hu and GFAP antibodies likely reflects the progressive increased recognition of the corresponding disorders.