A case of acute necrotising encephalitis secondary to human herpesvirus 6 infection

In this Clinical Rounds, we present the case of a girl aged 11 months who developed acute necrotising encephalitis in the setting of human herpesvirus 6 infection, complicated by elevated intracranial pressure, seizures, and development of increased tone. This patient presented with common features of acute necrotising encephalitis including fever, seizures, altered level of consciousness, and focal neurological deficits. We discuss the investigations for acute necrotising encephalitis, which is extensive and includes serology, often showing thrombocytopenia and liver dysfunction. Cerebrospinal fluid studies can show elevated protein without pleocytosis of white blood cells. Imaging can show signal intensity changes on T2-weighted images in the bilateral thalami, basal ganglia, subcortical white matter, cerebellum, and brainstem, in addition to restricted diffusion. In this Clinical Rounds, we also highlight the importance of rapid treatment, which includes immunosuppression with corticosteroids, intravenous immunoglobulin, and plasma exchange. Finally, we discuss the poor outcomes and prognosis for patients diagnosed with acute necrotising encephalitis, with a 27% mortality rate and moderate to severe disability in 63% of survivors.