title: Normocellular CSF in herpes simplex encephalitis.
abstract: BACKGROUND
  Herpes simplex virus (HSV) is the most common cause of sporadic encephalitis worldwide. The high mortality rate (70-80 %) of herpes simplex encephalitis (HSE) can be reduced to 20-30 % by antiviral therapy. However, normocellular CSF can lure physicians to look for non-infectious causes, resulting in delayed treatment. This study aimed to investigate, characterize and differentiate HSE patients, with normocellular and pleocytosis CSF, according to neuroimaging patterns, underlying disease, CSF viral load and clinical outcome. Patients with proven (by PCR positive CSF) or presumed viral infections of the CNS admitted to King Chulalongkorn Memorial Hospital between January 2002 and 2011 were analyzed.
  
  
  RESULTS
  HSV was detected in the CSF of 43 patients but only 23 patients had encephalitis. Among these 23 patients, 6 cases (26.1 %) had normal CSF WBC (<5 cells/mm(3)). One patient in this normocellular CSF group had HIV infection. Although this patient had low CD4 counts (<200 cells/mm(3)), the peripheral WBC counts showed only mild leukopenia. The CSF HSV viral load in the pleocytosis group was higher than the normocellular group, with an average of 12,200 vs 3027 copies/ml respectively. There was no correlation between the viral load and the clinical outcome. With respect to neuroimaging, 4 (66.7 %) patients in the normocellular group had unremarkable/non-specific results.
  
  
  CONCLUSIONS
  Normocellular CSF in HSE is not rare, and can be seen in normal as well as immunocompromised hosts. Clinicians should not exclude CNS infection, especially HSE, merely based on the absence of CSF pleocytosis and/or unremarkable neuroimaging study.
authors.affiliation: WHO-CC for Research and Training on Viral Zoonoses, Division of Neurology, Department of Medicine, Faculty of Medicine, Neuroscience Centre for Research and Development, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. abhinbhen@gmail.com.
authors.forename: Abhinbhen W
authors.initials: AW
authors.lastname: Saraya
authors.affiliation: WHO-CC for Research and Training on Viral Zoonoses, Division of Neurology, Department of Medicine, Faculty of Medicine, Neuroscience Centre for Research and Development, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. spwa@hotmail.com.
authors.forename: Supaporn
authors.initials: S
authors.lastname: Wacharapluesadee
authors.affiliation: WHO-CC for Research and Training on Viral Zoonoses, Division of Neurology, Department of Medicine, Faculty of Medicine, Neuroscience Centre for Research and Development, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. cakeinarak@hotmail.com.
authors.forename: Sininat
authors.initials: S
authors.lastname: Petcharat
authors.affiliation: WHO-CC for Research and Training on Viral Zoonoses, Division of Neurology, Department of Medicine, Faculty of Medicine, Neuroscience Centre for Research and Development, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. n.sittidetboripat@gmail.com.
authors.forename: Nuntaporn
authors.initials: N
authors.lastname: Sittidetboripat
authors.affiliation: WHO-CC for Research and Training on Viral Zoonoses, Division of Neurology, Department of Medicine, Faculty of Medicine, Neuroscience Centre for Research and Development, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. siriporn.ghai@gmail.com.
authors.forename: Siriporn
authors.initials: S
authors.lastname: Ghai
authors.affiliation: WHO-CC for Research and Training on Viral Zoonoses, Division of Neurology, Department of Medicine, Faculty of Medicine, Neuroscience Centre for Research and Development, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. henrywilde27@gmail.com.|Division of Infectious Disease, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand. henrywilde27@gmail.com.
authors.forename: Henry
authors.initials: H
authors.lastname: Wilde
authors.affiliation: WHO-CC for Research and Training on Viral Zoonoses, Division of Neurology, Department of Medicine, Faculty of Medicine, Neuroscience Centre for Research and Development, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. fmedthm@gmail.com.
authors.forename: Thiravat
authors.initials: T
authors.lastname: Hemachudha
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003710:Demography; D020803:Encephalitis, Herpes Simplex / Q000134:cerebrospinal fluid* / Q000150:complications / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D007964:Leukocytosis / Q000150:complications / Q000473:pathology; D008297:Male; D008875:Middle Aged; D055815:Young Adult