Herpes simplex virus encephalitis: Clinical manifestations, diagnosis and outcome in 106 adult patients

Background: Herpes simplex virus (HSV) is one of the most common causes of sporadic encephalitis worldwide. Objective: We aimed to determine clinical characteristics and prognosis of HSV encephalitis (HSVE) cases reviewed retrospectively from several collaborating centers. Study design: We searched hospital archives of the last 10 years for patients with HSVE diagnosis, i.e. clinical presentation compatible with encephalitis and brain involvement on magnetic resonance imaging (MRI) and/or detection of HSV DNA in the cerebrospinal fluid by polymerase chain reaction (PCR). Clinical characteristics were noted and patients were phone-interviewed. HSVE cases were grouped and analyzed as proven and probable, based on virological confirmation by PCR. Univariate and multivariate analyses were used to determine factors associated with prognosis. Results: A total of 106 patients (63 males and 43 females; mean age, 44 years; range, 18-83 years) were included. Most common symptoms were changes in mental status, fever, headache, and seizure. HSV PCR was positive in 69% of patients tested, while brain involvement was detected on MRI in 95%. Acyclovir was started mostly within five days of main symptom and continued for >= 14 days. Case fatality rate was 8%, while 69% of patients recovered with sequelae. Favorable prognosis was observed in 73% of patients. Multivariate analysis identified the duration of disease before hospital admission (odds ratio (OR) = 1.24) and the extent of brain involvement on MRI at the time of admission (OR = 37.22) as two independent risk factors associated with poor prognosis. Conclusions: Although HSVE fatality regressed considerably with acyclovir treatment, many patients survive with sequelae. Our results emphasize the importance of early diagnosis and prompt treatment of HSVE.