Late delirious behavior with 2009 H1N1 influenza: mild autoimmune-mediated encephalitis?

Pediatrics. 2012 Apr;129(4):e1068-71. doi: 10.1542/peds.2010-3221. Epub 2012 Mar 12.

Abstract

Delirious behavior associated with influenza usually has an onset within a few days after fever and lasts <24 hours. As we encountered several patients with 2009 H1N1 influenza who presented with late-onset and long-standing delirious behavior, we retrospectively evaluated the clinical, radiologic, and laboratory features to elucidate the possible pathophysiology. This information was collected on 5 previously healthy patients (2 boys and 3 girls, aged 10-15 years) with 2009 H1N1 influenza who presented with late onset (>3 days after fever) and long-standing (>48 hours) delirious behavior. Each exhibited mild to moderate drowsiness between the episodes of delirious behavior. Electroencephalography was normal except for 1 patient with high voltage and slow activity bilaterally in the occipital regions. Brain MRI was normal. The outcome was excellent with no neurologic sequel in 4 of the 5 patients. In all 5 patients, autoantibodies against N-methyl-D-aspartate type glutamate receptor were elevated or positive in cerebrospinal fluid or serum; the autoantibody levels normalized in the 3 patients who had follow-up studies. This study indicates that 2009 H1N1 influenza has a tendency to cause late-onset and long-standing delirious behavior, at least in Japanese children. Mild autoimmune-mediated encephalitis should be considered as an underlying cause.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adolescent Behavior*
  • Brain Diseases / complications*
  • Brain Diseases / diagnosis
  • Child
  • Child Behavior*
  • Delirium / etiology*
  • Delirium / psychology
  • Diagnosis, Differential
  • Electroencephalography
  • Encephalitis
  • Female
  • Hashimoto Disease / complications*
  • Hashimoto Disease / diagnosis
  • Humans
  • Influenza A Virus, H1N1 Subtype*
  • Influenza, Human / complications*
  • Influenza, Human / diagnosis
  • Influenza, Human / virology
  • Male
  • Retrospective Studies
  • Time Factors

Supplementary concepts

  • Hashimoto's encephalitis