[]An adult case of mumps-associated encephalitis/encephalopathy successfully treated with steroid pulse therapy].

A 32-year-old-immunologically healthy woman suffered from mumps. A few days later, she was brought to our hospital because of generalized convulsions. On arrival, she developed a decorticate posture. Anti-mumps virus antibodies were detected in her serum. Elevated protein levels without pleocytosis were observed in her cerebrospinal fluid. On the basis of a diagnosis of mumps-associated encephalitis/encephalopathy, steroid pulse therapy was administered, which improve her disturbance of consciousness. She exhibited akinetic mutism, which was followed by deterioration of the frontal lobe. Single-photon emission computed tomography demonstrated decreased regional cerebral blood flow in the bilateral frontal regions. Therefore, she was suspected with frontal lobe dysfunction associated with the lesion, including the thalamus and/or brain stem. We consider that the encephalitis/encephalopathy present in this case was caused by a reversible autoimmune process triggered by mumps virus infection.