Imaging Spectrum of Viral and Autoimmune Encephalitis: A Case Series

Encephalitis refers to an acute, diffuse inflammatory process affecting the brain. Viral encephalitis being the most important cause. Imaging of patients with viral encephalitis reveals edema in the affected brain parenchyma with possible diffusion restriction in the acute phase probably due to cytotoxic edema. Depending on the virus grey and white matter of the brain may be involved or a distinct site may be involved such as temporal lobes in HSV encephalitis. Viral encephalitis has a predilection for young and elderly. HSV encephalitis is the most commonly diagnosed viral encephalitis in developing countries. ADEM is an important differential diagnosis to be considered which tends to involve the white matter and the distribution is usually asymmetric. In the present case series we have presented HIV, Herpes, Rota virus, Japanese encephalitis virus manifestations of viral and autoimmune encephalitis. Both herpes and Japanese encephalitis are haemorrhagic encephalitis with a fulminant clinical course. Autoimmune-mediated encephalitis can be distinguished by its association with autoantibodies and by certain recognizable features on MR imaging, which include cerebellar degeneration, striatal encephalitis, brain stem encephalitis, and leukoencephalopathy. The purpose of this montage is to ensure that the clinician includes the specific virus and autoimmuneetiology in the differential diagnosis.