Review of Viral Encephalitis Cases Seen at a Tertiary Care Center in Turkey: Focus on Herpes Simplex Type 1.

Introduction: The objective of this study was to determine the incidence of herpes simplex encephalitis (HSE), known as the most common, potentially mortal, and treatable cause of sporadic encephalitis, in a sample Turkish population.

Methods: The demographic, clinical, laboratory, imaging, electrophysiology, and polymerase chain reaction (PCR) DNA results of patients examined with a pre-diagnosis of encephalitis were retrospectively examined.

Results: A total of 68 patients were included in the study. The most common presenting symptom was altered behavior (67.6%), while temporal T2 hyperintensity was determined in the magnetic resonance imaging (MRI) of 27.9% of the patients and electroencephalography (EEG) abnormalities were determined in 66.2% of the patients. Lymphocytic pleocytosis was determined in the cerebrospinal fluid (CSF) in 35 patients. Fifty-seven patients had been diagnosed with viral encephalitis, 3 with bacterial meningitis, 3 with tuberculous meningitis, 2 with sporadic Creutzfeld-Jakob disease, 2 with acute disseminating encephalomyelitis, and 1 with Brucella encephalitis. Seven (10.2%) cases of viral encephalitis were found to be positive for herpes simplex virus (HSV) DNA by PCR.

Conclusion: Viral encephalitis is the most common cause of infectious encephalitis; however, other atypical causes should also be noted. Negative PCR results for HSV DNA should not exclude the need for antiviral therapy in patients with a strong pre-diagnosis of HSE because diagnostic modalities, including PCR, may fail in acute settings and HSE remains the sole treatable cause of infectious encephalitis.