Clinically mild infantile encephalopathy associated with excitotoxicity

J Neurol Sci. 2017 Feb 15:373:138-141. doi: 10.1016/j.jns.2016.12.043. Epub 2016 Dec 24.


Acute infectious encephalopathy is very frequently observed in children in East Asia including Japan. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common subtype in Japan; however, more than 40% of the patients remain unclassified into specific syndromes. To investigate the underlying pathomechanism in those with unclassified acute encephalopathy, we evaluated brain metabolism by MR spectroscopy. Among 20 patients with acute encephalopathy admitted to our hospital during January 2015 to May 2016, 12 could not be classified into specific syndromes. MR spectroscopy was performed in 8 of these 12 patients with unclassified encephalopathy. MR spectroscopy showed an increase of glutamine with a normal N-acetyl aspartate level on days 3 to 8 in three of the 8 patients, which had normalized by follow-up studies. The three patients clinically recovered completely. This study suggests that excitotoxicity may be the underlying pathomechanism in some patients with unclassified mild encephalopathy.

Keywords: Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD); Encephalopathy; Excitotoxicity; Glutamate; Glutamine; MR spectroscopy.

MeSH terms

  • Brain / diagnostic imaging*
  • Brain / metabolism*
  • Brain Diseases / diagnostic imaging*
  • Brain Diseases / drug therapy
  • Brain Diseases / metabolism*
  • Consciousness Disorders / diagnostic imaging
  • Consciousness Disorders / drug therapy
  • Consciousness Disorders / metabolism
  • Encephalitis, Viral / diagnostic imaging
  • Encephalitis, Viral / drug therapy
  • Encephalitis, Viral / metabolism
  • Female
  • Follow-Up Studies
  • Glutamic Acid / metabolism
  • Glutamine / metabolism
  • Humans
  • Infant
  • Japan
  • Magnetic Resonance Imaging
  • Magnetic Resonance Spectroscopy*
  • Male
  • Retrospective Studies
  • Roseolovirus Infections / diagnostic imaging
  • Roseolovirus Infections / drug therapy
  • Roseolovirus Infections / metabolism


  • Glutamine
  • Glutamic Acid

Supplementary concepts

  • Human Herpesvirus 6 encephalitis