title: Disrupted glutamate-glutamine cycle in acute encephalopathy with biphasic seizures and late reduced diffusion.
abstract: BACKGROUND
  Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common subtype of infectious pediatric encephalopathy in Japan. It is sometimes difficult to make an early diagnosis of AESD; excitotoxicity is postulated to be the pathogenesis based on elevated glutamine (Gln) and glutamate (Glu) complex (Glx = Glu + Gln) observed on MR spectroscopy. It is uncertain whether Gln or Glu contributes to the elevated Glx, or whether MR spectroscopy is useful for an early diagnosis.
  
  
  METHODS
  Five Japanese patients with AESD (three boys and two girls, 1 year of age) were enrolled in this study. MR spectroscopy was acquired from the frontal white matter (repetition time (TR) of 5000 ms, echo time (TE) of 30 ms) with a 1.5- or 3.0-T scanner. MR spectroscopy was performed four times for two patients, three times for one patient, and two times for two patients. Quantification of Glu and Gln was performed using LCModel.
  
  
  RESULTS
  Glu was elevated in three of four studies on days 1-4 and became normal or low afterward. Gln was normal in three studies on days 1-2, elevated in all seven studies on days 4-12, and became normal or low afterward.
  
  
  CONCLUSIONS
  These findings suggest that MR spectroscopy may be useful for an early diagnosis. Acute Glu elevation changes to subacute Gln elevation, suggesting that a disrupted Glu-Gln cycle may play an important role.
authors: Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Yachiyo, 477-96 Owadashinden, Yachiyo-shi, 276-8524, Japan. jtaka44@hotmail.co.jp.
authors: Jun-Ichi
authors: J
authors: Takanashi
authors: Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors: Masashi
authors: M
authors: Mizuguchi
authors: Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Yachiyo, 477-96 Owadashinden, Yachiyo-shi, 276-8524, Japan.
authors: Masaru
authors: M
authors: Terai
authors: Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA.
authors: A James
authors: AJ
authors: Barkovich
mesh_terms: D015415:Biomarkers / Q000097:blood; D004830:Epilepsy, Tonic-Clonic / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism* / Q000473:pathology; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D066127:White Matter / Q000378:metabolism* / Q000473:pathology
chemical_list: D015415:Biomarkers; D005973:Glutamine; D018698:Glutamic Acid
keywords: Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD); Encephalopathy; Glutamate; Glutamine; MR spectroscopy