title: Late delirious behavior with 2009 H1N1 influenza: mild autoimmune-mediated encephalitis?
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.
authors.affiliation: Department of Pediatrics, Kameda Medical Center, Kamogawa, Japan. jtaka44@hotmail.co.jp
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Takanashi
authors.forename: Yukitoshi
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Imamura
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kodama
authors.forename: Akimitsu
authors.initials: A
authors.lastname: Watanabe
authors.forename: Koji
authors.initials: K
authors.lastname: Tominaga
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Muramatsu
authors.forename: A James
authors.initials: AJ
authors.lastname: Barkovich
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D001927:Brain Diseases / Q000150:complications* / Q000175:diagnosis; D002648:Child; D002652:Child Behavior; D003693:Delirium / Q000209:etiology* / Q000523:psychology; D003937:Diagnosis, Differential; D004569:Electroencephalography; D004660:Encephalitis; D005260:Female; D050031:Hashimoto Disease / Q000150:complications* / Q000175:diagnosis; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000150:complications* / Q000175:diagnosis / Q000821:virology; D008297:Male; D012189:Retrospective Studies; D013997:Time Factors