Herpes Virus Encephalitis in Adults: Current Knowledge and Old Myths.

Herpes simplex virus (HSV) encephalitis is uncommon in clinical practice, but is frequently suspected in patients with acute alterations of consciousness. Symptoms and physical signs are nonspecific, and diagnostic confirmation typically hinges on demonstration of viral DNA in cerebrospinal fluid. Brain MRI is helpful in diagnosis and provides prognostic information. Early initiation of intravenous acyclovir is essential to optimize the patient's chances of favorable recovery. HSV encephalitis can trigger an autoimmune reaction with the possible appearance of antibodies to neuronal surface antigens. Thus, recrudescence of neurologic impairment after a treated episode of HSV encephalitis warrants consideration of secondary autoimmune encephalitis.