[A case of facial diplegia in associated with reactivation of herpes simplex virus type I].

A 27-year-old Japanese man developed right peripheral facial palsy after suffering from a cold and low-grade fever for 7 days. Left peripheral palsy developed 4 days later. When he visited our hospital 3 days after that, neurological examination revealed no abnormalities except peripheral facial diplegia. Cerebrospinal fluid (CSF) was normal on admission and on hospital day 12. On admission, the patient had a transient increase of serum titers of HSV type I IgM (fluorescence assay). Then, serum titers of HSV type I IgG (ELISA) continuously increased. A diagnosis of peripheral facial diplegia due to reactivation of HSV type I was made clinically and serologically. Steroid pulse therapy was performed and his facial diplegia disappeared completely after 2 weeks. This case may support the hypothesis of virus etiology of Bell's palsy, and HSV type I should be considered as one of the possible causes of facial diplegia.