title: Human herpes 6 virus encephalitis complicating allogeneic hematopoietic stem cell transplantation.
abstract: OBJECTIVE
  To describe the presentation and management of encephalitis due to human herpes 6 virus (HHV-6) in patients who underwent allogeneic hematopoietic stem cell transplant (alloHSCT), via retrospective chart review.
  
  
  METHODS
  Of the 243 patients who underwent alloHSCT at the NIH Clinical Center during 2009 to 2011, we retrospectively analyzed 9 diagnosed with HHV-6 encephalitis post-alloHSCT.
  
  
  RESULTS
  Eight men and 1 woman (aged 19-60 years) met diagnostic criteria for study inclusion. The median time from HSCT to initial symptoms was 21 days. All patients presented with altered mental status and headaches. Seven patients had amnesia and 2 presented with fever of unknown etiology. Four patients had clinical seizures during the disease course. Brain MRI within 7 days was normal in all patients. Repeat MRI after 7 days showed hyperintensity in the limbic area in 3 patients. On initial testing, CSF analysis indicated acellularity and normal or minimally elevated protein; presence of HHV-6 was detected by PCR. After 7 days, mildly elevated protein and minimal pleocytosis were noted. Ganciclovir, foscarnet, or valganciclovir alone or in combination was initiated with subsequent improvement. Four patients remained alive at 1 year posttransplant; 2 had persistent memory deficits. Presence of encephalitis was associated with higher mortality post-alloHSCT.
  
  
  CONCLUSIONS
  High clinical suspicion and CSF PCR testing are important for early diagnosis of HHV-6 encephalitis post-HSCT. Abnormalities on brain MRI or CSF testing may be minimal and delayed. Diagnosis and management of HHV-6 encephalitis is challenging, and a larger prospective study is needed for further research.
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, USA.
authors.forename: Minal J
authors.initials: MJ
authors.lastname: Bhanushali
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Kranick
authors.forename: Alexandra F
authors.initials: AF
authors.lastname: Freeman
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Cuellar-Rodriguez
authors.forename: Minoo
authors.initials: M
authors.lastname: Battiwalla
authors.forename: Juan C
authors.initials: JC
authors.lastname: Gea-Banacloche
authors.forename: Dennis D
authors.initials: DD
authors.lastname: Hickstein
authors.forename: Steven
authors.initials: S
authors.lastname: Pavletic
authors.forename: Gary
authors.initials: G
authors.lastname: Fahle
authors.forename: Avindra
authors.initials: A
authors.lastname: Nath
mesh_terms: D000328:Adult; D000368:Aged; D000998:Antiviral Agents / Q000627:therapeutic use; D001921:Brain / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006261:Headache / Q000209:etiology; D019337:Hematologic Neoplasms / Q000150:complications / Q000628:therapy; D018380:Hematopoietic Stem Cell Transplantation / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D015654:Herpesvirus 6, Human; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D011379:Prognosis; D012189:Retrospective Studies; D019349:Roseolovirus Infections / Q000150:complications* / Q000188:drug therapy / Q000821:virology; D012640:Seizures / Q000209:etiology; D013534:Survival; D019562:Viral Load; D055815:Young Adult
chemical_list: D000998:Antiviral Agents