Jul 9 Encephalitis

Was not there for the presentation, but am very familiar with the patient discussed.  Middle aged gentleman with 3 - 4 weeks of altered mental status, headaches, and jerky limb movements.  MRI negative, but CSF persistently abnormal with elevated WBC (all lymphos), elevated RBC, and high protein.  Rec'd an initial diagnosis of aseptic meningitis but was readmitted when symptoms worsened.  This time he improved substantially with empiric acyclovir treatment for suspected HSV encephalitis.  Some key points:

There is only 1 type of encephalitis that is readily treatable, and that is HSV-1.  Be sure to test for it - and the test of choice is PCR of spinal fluid.  Do not order "HSV serology" because you will not get the answer the patient needs.  You can check for other things like West Nile Virus or the equine encephalitis viruses, but there is not much you can do for the patient.  So if you only have a couple drops of CSF - do the HSV PCR.

There is a reseource to be aware of: the Tennessee Unexplained Encephalitis Survey (TUES) study: They will enroll your patient in an ongoing study that will test any leftover CSF and blood samples for an extensive panel of encephalitis agents. 

The IDSA has published a comprehensive practice guideline that briefly reviews the exposure risks, testing, and treatment for pretty much any cause of encephalitis.