title: Neurological manifestations of influenza infection in children and adults: results of a National British Surveillance Study.
abstract: BACKGROUND
  The emergence of influenza A(H1N1) 2009 was met with increased reports of associated neurological manifestations. We aimed to describe neurological manifestations of influenza in adults and children in the United Kingdom that presented at this time.
  
  
  METHODS
  A 2-year surveillance study was undertaken through the British adult and pediatric neurological surveillance units from February 2011. Patients were included if they met clinical case definitions within 1 month of proven influenza infection.
  
  
  RESULTS
  Twenty-five cases were identified: 21 (84%) in children and 4 (16%) in adults. Six (29%) children had preexisting neurological disorders. Polymerase chain reaction of respiratory secretions identified influenza A in 21 (81%; 20 of which [95%] were H1N1) and influenza B in 4 (15%). Twelve children had encephalopathy (1 with movement disorder), 8 had encephalitis, and 1 had meningoencephalitis. Two adults had encephalopathy with movement disorder, 1 had encephalitis, and 1 had Guillain-Barré syndrome. Seven individuals (6 children) had specific acute encephalopathy syndromes (4 acute necrotizing encephalopathy, 1 acute infantile encephalopathy predominantly affecting the frontal lobes, 1 hemorrhagic shock and encephalopathy, 1 acute hemorrhagic leukoencephalopathy). Twenty (80%) required intensive care, 17 (68%) had poor outcome, and 4 (16%) died.
  
  
  CONCLUSIONS
  This surveillance study described a cohort of adults and children with neurological manifestations of influenza. The majority were due to H1N1. More children than adults were identified; many children had specific encephalopathy syndromes with poor outcomes. None had been vaccinated, although 8 (32%) had indications for this. A modified classification system is proposed based on our data and the increasing spectrum of recognized acute encephalopathy syndromes.
authors.affiliation: Institute of Infection and Global Health, University of Liverpool.
authors.forename: Anu
authors.initials: A
authors.lastname: Goenka
authors.forename: Benedict D
authors.initials: BD
authors.lastname: Michael
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ledger
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Hart
authors.forename: Michael
authors.initials: M
authors.lastname: Absoud
authors.forename: Gabriel
authors.initials: G
authors.lastname: Chow
authors.forename: James
authors.initials: J
authors.lastname: Lilleker
authors.forename: Michael
authors.initials: M
authors.lastname: Lunn
authors.forename: David
authors.initials: D
authors.lastname: McKee
authors.forename: Deirdre
authors.initials: D
authors.lastname: Peake
authors.forename: Karen
authors.initials: K
authors.lastname: Pysden
authors.forename: Mark
authors.initials: M
authors.lastname: Roberts
authors.forename: Enitan D
authors.initials: ED
authors.lastname: Carrol
authors.forename: Ming
authors.initials: M
authors.lastname: Lim
authors.forename: Shivaram
authors.initials: S
authors.lastname: Avula
authors.forename: Tom
authors.initials: T
authors.lastname: Solomon
authors.forename: Rachel
authors.initials: R
authors.lastname: Kneen
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000473:pathology; D002493:Central Nervous System Diseases / Q000453:epidemiology / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification; D009981:Influenza B virus / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D006113:United Kingdom / Q000453:epidemiology
keywords: H1N1; classification; encephalopathy; influenza; surveillance