(Kiosk 4) Myoclonic Manifestation of Post-covid Encephalitis: A Case Report

Case Diagnosis: 63-year-old male with continuous myoclonus diagnosed with post-COVID encephalitis

Case Description or Program Description: Patient presented with seizure and loss of consciousness 2 weeks after COVID-19 infection. Examination was positive for postural tremor of the right arm. Computerized tomography (CT) scan and magnetic resonance imaging (MRI) of the brain were negative for acute pathology. He was treated with brivaracetam for focal-onset epilepsy. He subsequently developed ataxia and continuous myoclonus of the right foot, left trapezius, and left trunk. Anti-epileptics were switched to clonazepam and lacosamide. Serial electroencephalograms were negative for epileptiform discharges. Upon admission to acute rehabilitation, patient required maximal assistance for transfers and was nonambulatory. Myoclonus worsened involving head, right leg and arm despite addition of valproate. MRI brain on day 18 revealed new hyperintense lesions in cortical areas of frontoparietal, temporal and right occipital regions. Further testing included lumbar puncture, brain biopsy, labwork, and imaging which were negative for all infectious, cerebrovascular, autoimmune, and paraneoplastic processes.

Setting: Acute Rehabilitation, Hospital

Assessment/Results: Patient was diagnosed with epilepsia partialis continua secondary to COVID-19 infection. He was empirically started on IVIG and methylprednisolone and his motor symptoms started to improve. MRI brain on day 40 showed stable hyperintense lesions with decrease in size of some and increase in size of others. He completed a 4-week course of prednisone. MRI brain on day 61 revealed significant decrease in size of hyperintense lesions with no new lesions. Upon discharge, he could manage daily living and ambulation with supervision assistance.

Discussion (relevance): SARS-CoV-2 infection is an inflammatory process that damages the blood-brain barrier through release of proinflammatory cytokines causing neuroinflammation. Immune-mediated neurologic sequelae have been found including encephalitis. Timing of the patient’s significant evolving changes on MRI brain imaging and remarkable clinical improvement with steroids indicate an inflammatory etiology. Literature is limited to case reports of myoclonus and ataxia related to SARS-CoV-2 with inconsistent MRI and CSF findings. COVID-19-induced myoclonus is theorized to be from immune-mediated brainstem and cerebellar hyperexcitability through antibodies, similar to the mechanism of opsoclonus-myoclonus-ataxia syndrome.

Conclusions: Although rare, myoclonic manifestations due to encephalitis may occur in patients post SARS-CoV-2 infection. Early diagnosis and appropriate medical and rehabilitation treatments improve prognosis.