A 48-year-old man with chills was admitted to our hospital. He was initially diagnosed as fever of unknown origin, which was suspected to be caused by an unidentified virus. He acutely developed disturbance of consciousness, quadriparesis and urinary disturbance. Magnetic resonance imaging of the brain showed multiple hyperintense lesions in the basal ganglia and longitudinally extended transverse myelitis on fluid-attenuated inversion recovery imaging. These lesions were without gadolinium enhancement. We finally made a diagnosis of anti-aquaporin 4 antibody positive neuromyelitis optica. His symptoms did not improve after three courses of intravenous methylpredonisolone pulse therapy (1g/day). After seven courses of double filtration plasmapheresis and successive oral predonisolone (60mg/day) therapy, his expanded disability status scale score improved from 9.5 to 6.5. Our patient developed severe neuromyelitis optica with infection-like signs as initial symptoms. Surveying autoantibodies in the early stage of leukoencephalopathies is important for the diagnosis of neuromyelitis optica because the symptoms of neuromyelitis optica vary in the acute phase, which can mimic disorders associated with acute disseminated encephalomyelitis, posterior reversible encephalopathy syndrome and multiple sclerosis. Brain magnetic resonance imaging findings also showed many patterns with or without gadolinium enhancement, which cannot always differentiate neuromyelitis optica from other leukoencephalopathies.
