Herpes Simplex Virus Type 1 Encephalitis: A Descriptive, Cross Sectional Study, 2011 - 2016, Iran

Background: Encephalitis may arise from infectious or non-infectious etiologies. Infections, predominantly viruses, are the most common causes of encephalitis. Herpes simplex virus (HSV) is the most prevalent cause of viral encephalitis in the developed countries. HSV encephalitis occurs equally in both genders and most cases are caused by HSV type 1 (HSV-1). Methods: The current descriptive, cross sectional study was conducted on patients admitted with HSV-1 encephalitis from 2011 to 2016 to Imam-Khomeini hospital complex in Tehran, Iran. The patients with clinical diagnosis of encephalitis whose cerebrospinal fluid (CSF) HSV-1 polymerase chain reaction (PCR) was positive were included. All clinical, laboratory, and imaging characteristics of patients along with their outcomes were evaluated and analyzed. Results: In the current study, of 12 cases with encephalitis manifestations and positive CSF HSV-1 PCR results, 5 were male and 7 were female with mean age of 42 years. Fever and headache were the most common complaints. Headache was more common in the cases admitted earlier (P value = 0.001). The patients were studied by brain magnetic resonance imaging (MRI) and the findings confirmed encephalitis in all the cases. Five cases had unilateral temporal lobe lesions and 6 cases had bilateral lesions. There was a clear relationship between bilateral temporal lobe lesions and higher protein level in CSF (P value = 0.001); 25% of patients (3 cases) needed stay in the intensive care unit (ICU). Three patients died and 5 patients developed disabilities. Conclusions: HSV encephalitis is a devastating disease. Clinical findings along CSF analysis and neuroimaging may result in the appropriate diagnosis. Despite appropriate treatment, undesired outcomes are common.