Frequency and Referral Patterns of Neural Antibody Studies During the COVID-19 Pandemic: Experience From an Autoimmune Neurology Center.

OBJECTIVE: To determine whether the frequency of paraneoplastic or autoimmune encephalitis antibodies examined in a referral center changed during the COVID-19 pandemic. METHODS: 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. RESULTS: 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%, p = 0.01), particularly Hu and GFAP. DISCUSSION: 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.

Neuroimmune disorders in COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the aetiologic agent of the coronavirus disease 2019 (COVID-19), is now rapidly disseminating throughout the world with 147,443,848 cases reported so far. Around 30-80% of cases (depending on COVID-19 severity) are reported to have neurological manifestations including anosmia, stroke, and encephalopathy. In addition, some patients have recognised autoimmune neurological disorders, including both central (limbic and brainstem encephalitis, acute disseminated encephalomyelitis [ADEM], and myelitis) and peripheral diseases (Guillain-Barré and Miller Fisher syndrome). We systematically describe data from 133 reported series on the Neurology and Neuropsychiatry of COVID-19 blog ( https://blogs.bmj.com/jnnp/2020/05/01/the-neurology-and-neuropsychiatry-of-covid-19/ ) providing a comprehensive overview concerning the diagnosis, and treatment of patients with neurological immune-mediated complications of SARS-CoV-2. In most cases the latency to neurological disorder was highly variable and the immunological or other mechanisms involved were unclear. Despite specific neuronal or ganglioside antibodies only being identified in 10, many had apparent responses to immunotherapies. Although the proportion of patients experiencing immune-mediated neurological disorders is small, the total number is likely to be underestimated. The early recognition and improvement seen with use of immunomodulatory treatment, even in those without identified autoantibodies, makes delayed or missed diagnoses risk the potential for long-term disability, including the emerging challenge of post-acute COVID-19 sequelae (PACS). Finally, potential issues regarding the use of immunotherapies in patients with pre-existent neuro-immunological disorders are also discussed.