[Herpes simplex virus type I encephalitis with left temporal lobe lesion detected by gadolinium enhanced MRI].

A case of herpes simplex virus (type I, HSV-I) encephalitis (HSE) was reported. A 65 years old man presented acute fever and subsequently developed mental symptoms, disorientation and consciousness disturbance. HSV-I antibody titers of serum and CSF were markedly elevated, especially the elevation of IgM antibody was noticeable. MRI T1 weighted image enhanced by Gadolinium DTPA taken on the 15th day from the onset revealed a lesion in the inner side of left temporal lobe. Acyclovir therapy was administered under the diagnosis of HSE. He recovered well with the residual of moderate memory disturbance. This is a very interesting and rare case of HSE in an old patient caused by the primary infection of HSV-I. In addition, the importance of Gd enhanced MRI study to detect HSE lesion was discussed.