Autoimmune encephalitis concomitant with SARS-CoV-2 infection: insight from ¹⁸F-FDG PET imaging and neuronal autoantibodies

Abstract

We report the case of a 72-years-old man with concomitant autoimmune encephalitis and SARS-CoV-2 infection. Methods: Review of clinical examination, CT, PET, MRI imaging, and autoantibodies testing. Results: The patient presented subacute cerebellar syndrome and myoclonus several days after general infectious symptoms. The oropharyngeal swab test was positive for SARS-CoV-2. Brain MRI was normal. CSF testing showed normal cell counts, negative RT-qPCR and no oligoclonal banding. Brain ¹⁸F-FDG-PET showed diffuse cortical hypometabolism, associated with putaminal and cerebellum hypermetabolism, compatible with encephalitis, and especially cerebellitis. The immunological study revealed high titers of IgG autoantibodies in serum and CSF directed against the nuclei of Purkinje cells, striatal and hippocampal neurons. Search for neoplasia including whole-body ¹⁸F-FDG-PET and CT scans was negative. Treatment with steroids allowed a rapid improvement of symptoms. Conclusion: This clinical case brings arguments on the possible relationship between SARS-CoV-2 infection and autoimmune encephalitis, and on the interest of ¹⁸F-FDG-PET in such context.