Electrophysiological features and outcomes of post-infectious myoclonus-ataxia syndrome: a case report and literature review.

backgroundMyoclonus has become one of the neurological manifestations associated with coronavirus disease 2019 (COVID-19); however, the origin and pathophysiological mechanism remained uncertain. CASE PRESENTATION: A rare case of myoclonus-ataxia syndrome associated with COVID-19 was presented. A 52-year-old Asian woman exhibited generalized myoclonus, ataxia, nystagmus, and dysarthria two weeks after a fever episode, which deteriorated rapidly within a few days. Electromyography (EMG) revealed synchronized bursts in both hands concurrent with myoclonic jerks. The absence of somatosensory evoked potential and lack of correlation between electromyography (EEG) and EMG suggested a subcortical origin of the myoclonus. A post-infectious immune-mediated process was considered the most likely mechanism, given the latency from fever to myoclonus onset, and the absence of other possible etiologies. Treatment with intravenous methylprednisolone led to notable improvement and a good outcome at the two-month follow-up.

conclusionMyoclonus arising from subcortical structures can be associated with COVID-19. Early aggressive immunotherapy is important for a favorable outcome. Review of similar cases along with our report suggests COVID-19-associated myoclonus-ataxia as a distinct syndrome warranting prompt diagnosis and treatment.