Introduction: Herpes simplex virus (HSV) is the most common etiology of sporadic encephalitis and presents with an estimated mortality of 50-70%.
Objective: To describe baseline characteristics of patients with herpetic encephalitis admitted to a tertiary teaching hospital and their difference with patients with non herpetic encephalitis.
Materials and methods: Nested case control study using a retrospective cohort of patients with suspected encephalitis admitted to the Hospital Italiano de Buenos Aires (2006-2013). Adult patients included had a lumbar puncture with a positive or negative polimerase reaction for HSV. A case of herpetic encephalitis was defined as a positive polimerase reaction in spinal fluid. For each case, 5 controls were randomly selected.
Results: There were no baseline differences present between cases and controls. The only covariate associated with herpetic encephalitis was an abnormal brain magnetic resonance imaging (MRI) (OR: 5.37, IC 95% 1.42-20.38, p < 0.01). The most frecuent alterations in the MRI were extratemporal lesions or temporal ones with or without haemorrhage.
Discussion: There are no apparent baseline clinical differences between patients with or without herpetic encephalitis. A positive finding in a brain MRI should be taken into account during clinical workup.