UMEM Educational Pearls

Category: Infectious Disease

Title: Herpes Encephalitis

Keywords: Encephalitis, Herpes (PubMed Search)

Posted: 9/22/2009 by Rob Rogers, MD (Updated: 12/9/2019)
Click here to contact Rob Rogers, MD

Herpes Encephalitis-When to Consider

Herpes encephalitis is a potential lethal condition with high morbidity. Obviously our job in the ED is to rule-out bacterial meningits. So, when should we consider the diagnosis of herpes encephalitis?

  • High wbc in the CSF with a negative gram stain
  • Lymphcytic predominance in the CSF
  • Altered patient and abnormal CSF
  • And, just about any of the softer "rule-out aseptic meningitis" patients

Although no great guidelines exist, consider ordering a herpes PCR when sending studies on the "rule-out meningitis" patient. What about emperically treating a patient with Acyclovir? Again, no great data. Consider treating with 10 mg/kg IV q 8 hours for patients with abnormal CSF (in addition to the Ceftriaxone/Vanc, etc.) if you are worried about them, if they are altered (or encephalopathic), and if the CSF is abnormal (elevated wbc) with a negative gram stain. Acyclovir can always be discontinued when the PCR returns negative.