title: Clinical characteristics of acute encephalopathy of obscure origin: a biphasic clinical course is a common feature.
abstract: OBJECTIVE
  To evaluate the clinical characteristics of acute encephalopathy of obscure origin (AE).
  
  
  METHODS
  We examined clinical, imaging, and laboratory findings in children with AE. Specific subtypes of AE such as Reye's syndrome (RS), acute necrotizing encephalopathy (ANE), hemorrhagic shock and encephalopathy (HSE), acute encephalitis with refractory, repetitive partial seizures (AERRPS), and hemiconvulsion-hemiplegia syndrome (HH) were diagnosed. Other AE patients were regarded as non-specific subtype.
  
  
  RESULTS
  Nineteen patients were identified; specific AEs in 14 and non-specific AE in 5. Patients with RS, ANE, HSE frequently showed neuroimaging abnormalities (9/9) and significant elevation of liver enzymes (7/9) within 2 days after onset. Prognoses were extremely poor; early death in 6 and severe neurological sequelae in 3. Two of the 3 HH patients and 4 of the 5 non-specific AE patients showed biphasic clinical courses (AEBC); consciousness levels transiently improved following initial seizures and were exacerbated at the fourth to sixth days. In AEBC, neuroimaging abnormalities were rarely observed during the acute phase (1/5) but were detectable at clinical exacerbation. They rarely showed severely abnormal elevation in liver enzymes (1/6) and resulted in mild to moderate neurological sequelae (6/6).
  
  
  CONCLUSIONS
  A biphasic clinical course is a common feature in HH and non-specific AE.
authors.affiliation: Division of Child Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, Yonago, Japan. maegaki@grape.med.tottori-u.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Maegaki
authors.forename: A
authors.initials: A
authors.lastname: Kondo
authors.forename: R
authors.initials: R
authors.lastname: Okamoto
authors.forename: T
authors.initials: T
authors.lastname: Inoue
authors.forename: K
authors.initials: K
authors.lastname: Konishi
authors.forename: A
authors.initials: A
authors.lastname: Hayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Tsuji
authors.forename: S
authors.initials: S
authors.lastname: Fujii
authors.forename: K
authors.initials: K
authors.lastname: Ohno
mesh_terms: D000208:Acute Disease; D001921:Brain / Q000002:abnormalities* / Q000473:pathology; D001927:Brain Diseases / Q000145:classification / Q000175:diagnosis* / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D003952:Diagnostic Imaging; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007223:Infant; D008099:Liver / Q000201:enzymology; D008297:Male; D012189:Retrospective Studies; D013997:Time Factors