Isolated generalized myoclonus immune-mediated by SARS-CoV-2: an illustrative videotaped case

Myoclonus in the context of COVID-19 is an increasingly recognized condition. The occurrence in an ICU context in hypoxic patients, with metabolic disorders, taking several types of medication, makes difficult to establish a precise cause. Also, the implication of SARS-CoV-2 by direct invasion of the CNS or by immune-mediated phenomena is not yet clear. Currently, a dozen of cases of myoclonus as a predominant clinical manifestation, immune-mediated by SARS-Cov-2 are published. In all these cases, myoclonus was preceded by respiratory or other suggestive symptoms (e.g., anosmia) for this infection making straightforward the causal link. We describe a case of an isolated generalized myoclonus without other clinical complaints nor chest CT scan abnormalities nor SARS-CoV-2 RNA detection on nasopharyngeal swabs and on the CSF, as a para-infectious phenomenon of COVID-19 infection with excellent response to steroids perfusion. This challenging diagnosis was made upon confirmation of seroconversion (serology was negative at admission, then positive for IgM at day 6, then for both IgM and IgG at day 10) underlying that repeating serology is a diagnostic key to capture a similar findings. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10072-021-05164-8.