From: res4w@galen.med.Virginia.EDU (Robert E. Schmieg)
Subject: Re: herpes virus
Organization: University of Virginia
Distribution: world 
Date: Fri, 20 Nov 1992 18:24:15 GMT

   Yes, the herpesvirus family can infect the brain.

The different herpesviruses that can cause viral meningitis
(inflammation of the membranes covering the brain) or
encephalitis (inflammation of the brain matter), along with
the common clinical syndrome <>, include:
   herpes simplex, types 1 and 2 (HSV-1, HSV-2)
   	 HSV-1 <cold sores>
         HSV-2 <genital herpes>
   varicella-zoster (VZV)
         <chickenpox, shingles>
   Epstein-Barr (EBV) 
         <infectious mononucleosis>
   cytomegalovirus (CMV)
         <cytomegalic inclusion disease>

A few definitions:
viral meningitis - "a benign, self-limited illness with
clinical signs of headache, fever, and meningeal inflammation"
synonyms: aseptic meningitis, serous meningitis

viral encephalitis - "more severe illness in which fever,
headache, and meningeal inflammation are complicated by
depression of the state of consciousness, seizures, and/or
focal neurologic deficits suggesting inflammation within the
parenchyma of the brain"
synonym: meningoencephalitis

encephalomyelitis - encephalitis with signs of spinal cord
involvement


   The damage caused to the central nervous system (CNS)
depends upon the type of clinical infection and the specific
virus.

   Herpesviruses show no seasonal distribution. 

   I will restrict the following to encephalitis, as it is the
most severe and potentially lethal manifestation of central
nervous system infection by the family of herpesviruses.
The estimated incidence of herpesvirus encephalitis is from
1000 to 2000 per year in the United States.

HSV-1
=====
most common cause of localized herpesvirus encephalitis
past history of cold sores, etc. does NOT help in ruling out
   or suggesting this diagnosis
dx is suggested by temporal lobe signs & severity of
   encephalitis
can seldom be isolated from blood or CSF
early definitive diagnosis still requires a brain biopsy
all age groups can be affected, but 3rd & 4th decades are
   lower rates; see in children, young adults (15-30), and older
patients (50+) most commonly
in neonates: panencephalitis
in adults: encephalitis with localization in the temporal and
   frontal lobes initially, often with marked asymmetry
tx: acyclovir, vidarabine
prognosis: depends upon timing of institution of specific
   therapy; the early the better.  Mortality rates of
   untreated HSV-1 encephalitis are about 70%, which can be 
   reduced to about 30% with specific therapy
about 50% of survivors have neurological impairment, ranging
   from motor & sensory deficits, aphasia, and Korsakoff's
   psychosis.  Level of consciousness at time of institution
   of therapy is a major determinant of long-term prognosis.

HSV-2
====
rare for encephalitis to occur in adults
onset of HSV-2 infection may coincide with appearance of
   genital lesions
HSV-2 can be isolated from CSF or blood
in neonates: causes generalized and severe encephalitis,
   occurs in up to 50% of neonates delivered vaginally in women
   with primary HSV-2 infection; risk to infant is lower if
   mother has recurrent HSV-2 lesions at time of delivery

VZV
===
overt CNS infection is very rare, but fairly severe when it
   happens.
in immunosuppressed patients: can cause multifocal
   encephalitis with lots of sharply circumscribed lesions
tx: no proven specific treatment that I know of, but usually
   these pts are started on acyclovir
prognosis: mortality rate less than 10%, permanent sequelae
   rare; this may not hold true for pts with underlying cancer
   or immunosuppression

References:
Johnson, RT.  Herpes Simplex Encephalitis /and/ Viral
Meningitis and Encephalitis, in Cecil Textbook of Medicine,
17th ed., 1985.

Moore, JH.  The Nervous System, in Robbins Pathologic Basis of
Disease, 4th ed., 1989.