title: Neurologic manifestations and complications of pandemic influenza A H1N1 in Malaysian children: what have we learnt from the ordeal?
abstract: BACKGROUND
  In 2009, pandemic influenza A H1N1 emerged in Mexico and subsequently spread worldwide. In Malaysia, there were more than a thousand of confirmed cases among children. The general clinical characteristics of these children have been well-published. However, the description of neurologic complications is scarce.
  
  
  OBJECTIVE
  This study aims to describe the characteristics of neurologic manifestations and complications in a national paediatric cohort with pandemic influenza A H1N1.
  
  
  METHODS
  During the pandemic, children (12 years or less) admitted for novel influenza A H1N1 in 68 Malaysian public hospitals, were prospectively enrolled into national database. The clinical, laboratory and neuro-imaging data for children with neurologic manifestations, hospitalized from 15th June 2009 till 30th November 2009, was reviewed.
  
  
  RESULTS
  Of 1244 children with influenza A H1N1 during the study period, 103 (8.3%) presented with influenza-related neurological manifestations. The mean age of our study cohort was 4.2 years (SD: 3.3 years). Sixty percent of them were males. Sixty-nine (66.9%) were diagnosed as febrile seizures, 16 (15.5%) as breakthrough seizures with underlying epilepsy, 14 (13.6%) as influenza-associated encephalopathy or encephalitis (IAE) and 4 (3.9%) as acute necrotizing encephalopathy of childhood (ANEC). All 4 available CSF specimens were negative for influenza viral PCR. Among 14 children with brain-imaging done, 9 were abnormal (2: cerebral oedema, 4: ANEC and 3: other findings). There were four deaths and three cases with permanent neurological sequelae.
  
  
  CONCLUSIONS
  About one-tenth of children with pandemic influenza A H1N1 presented with neurologic complications. The most common diagnosis was febrile seizures. One-fifth of those children with neurologic presentation had IAE or ANEC, which carried higher mortality and morbidity. This large national study provides us useful data to better manage children with neurologic complications in the future pandemic influenza outbreaks.
authors.affiliation: Institute of Paediatrics, Hospital Kuala Lumpur, Kuala Lumpur, Malaysia.
authors.forename: Hussain Imam
authors.initials: HI
authors.lastname: Muhammad Ismail
authors.affiliation: Department of Paediatrics, Hospital Pulau Pinang, Malaysia. Electronic address: cmteh1976@yahoo.com.
authors.forename: Chee Ming
authors.initials: CM
authors.lastname: Teh
authors.affiliation: Clinical Research Center, Ministry of Health, Malaysia.
authors.forename: Yin Leng
authors.initials: YL
authors.lastname: Lee
mesh_terms: D001927:Brain Diseases / Q000453:epidemiology / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000150:complications* / Q000453:epidemiology; D008296:Malaysia / Q000453:epidemiology; D008297:Male; D058873:Pandemics
keywords: Children; Encephalopathy; H1N1; Influenza A; Neurologic complications; Pandemic; Seizures