Abstract
Encephalitis is characterized by inflammation of brain tissue and has various infectious and noninfectious causes. CSF analysis and MRI usually reveal inflammatory changes although sometimes brain imaging may be normal. Autoimmune encephalitis is caused by antibodies against neuronal synaptic receptors, surface proteins, or intracellular proteins. In this case report, we present a 65-year-old female who presented with a fall and altered mental status. Workup for infectious etiologies was negative and MRI of the brain displayed focal restricted diffusion with corresponding T2-FLAIR hyperintensity involving gray matter structures, making the diagnosis unclear. CT perfusion of the brain demonstrated increased cerebral blood volume and cerebral blood flow in the left parietooccipital gray matter, with corresponding normal mean transit time. Following treatment failure with acyclovir, antibiotics, and steroids, the patient was found to be positive for GAD65 antibodies and diagnosed with autoimmune encephalitis. Symptoms markedly improved with plasmapheresis. Autoimmune encephalitis rarely causes restricted diffusion and this is the first case report to describe corresponding hyperperfusion on CT perfusion study.
Highlights
Encephalitis is characterized by inflammation of brain tissue, causing symptoms such as headache, fever, altered mental status, seizures, and/or focal neurologic deficits
Autoimmune encephalitis can present in both adults and children [5]
A variety of neuronal antibodies have been identified in autoimmune encephalitides
Summary
Encephalitis is characterized by inflammation of brain tissue, causing symptoms such as headache, fever, altered mental status, seizures, and/or focal neurologic deficits. CSF analysis and MRI usually reveal the findings of inflammatory changes normal findings are not uncommon. Autoimmune encephalitis is caused by antibodies against neuronal synaptic receptors and surface or intracellular proteins [1]. Clinical signs pointing to autoimmune encephalitis include subacute memory loss, psychiatric symptoms, and sleep disturbance [3]. Infectious features such as fever, vomiting, and MRI contrast enhancement are rarely seen in autoimmune encephalitis [4]. A search for autoreactive antibodies ensues in both serum and CSF [3]. MRI can range from normal to T2-FLAIR scattered hyperintensities [3]
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