Understanding Herpes Simplex Virus Type 1 Versus Herpes Simplex Virus Type 2 Encephalitis After Neurosurgery: A Case Series and Literature Review

Abstract Background: Herpes simplex virus encephalitis (HSVE) is a rare post-operative infection that can be fatal if treatment is delayed. Herpes simplex virus type 1 (HSV-1) is a more common cause of encephalitis than herpes simplex virus type 2 (HSV-2), however, a significant overlap exists. The goal of this project was to understand the frequency and trend of HSVE after neurosurgery through a case series at our institution and in the literature with a focus on comparing HSV-1 versus HSV-2. Patients and Methods: A literature review of all published cases and case series of HSVE after neurosurgery was performed. Descriptive statistics comparing HSV-1 and HSV-2 encephalitis were computed. Data on demographics, symptoms, surgery, treatment, immunosuppression, imaging findings, steroids, and mortality were collected. Results: We identified 55 total cases of HSVE post-neurosurgery. These included 28 cases of HSV-1, 10 cases of HSV-2, and 17 cases of HSV-unspecified encephalitis. There were no differences in age, gender, symptoms, surgery, or latency between surgery and symptom onset between HSV-1 and HSV-2. Mortality was higher with HSV-1 versus HSV-2 although not statistically significant. The primary surgical indication varied substantially between HSV-1 and HSV-2. Conclusions: Herpes simplex virus encephalitis is often overlooked in the setting of encephalitis after surgery. A high index of suspicion is needed to prevent a delay in treatment.