Abstract
Introduction: The typical herpes simplex viral encephalitis (HSVE) course is an acute illness, less commonly it may present as a chronic course, mainly in children, and rarely may it be subacute. Subacute HSVE is rarely described in the literature being reported 4 times only. Case Report: We here report 2 cases of subacute HSV1 encephalitis diagnosed based on cerebrospinal fluid polymerase chain reaction and magnetic resonance imaging findings and review the literature trying to find any specific clinical, laboratory, radiologic diagnostic or prognostic criteria regarding this subacute form of HSVE. Conclusion: There is subacute form of HSVE and should be suspected with any subacute febrile illness with nonspecific cognitive impairment even in the absence of focal neurological symptoms and in cases with rapidly progressive dementia. This form has similar radiologic finding and good response to acyclovir but carry even better prognosis than that the acute HSVE.