Post COVID anti-NMDAR Encephalitis in an adolescent girl

Anti-NMDAR encephalitis is a neuro-inflammatory disorder caused by antibodies targeting neurons in the central nervous system. Certain viruses break immune tolerance of neuronal proteins and increase the permeability of blood brain barrier (BBB) to antibodies resulting in post infectious autoimmunity. We report a case about a 13 years old girl diagnosed as a case of anti-NMDAR encephalitis, who presented with psychiatric symptoms followed by abnormal movements and encephalopathy, with later development of autonomic instability with tachycardia and blood pressure at 98th centile. Her thyroid profile initially showed hyperthyroidism with negative anti-thyroid antibodies with subsequent normalization without anti-thyroid drug. Her SARS-CoV-2 IgM was positive despite being asymptomatic that had induced autoimmunity in central nervous system and caused transient thyroiditis. She poorly responded to first tier immune therapy (methylprednisolone pulse & plasmapheresis) but there was remarkable response to second tier immune therapy with Rituximab with prompt attainment of ambulation and self care.