title: Nationwide Incidence of Acquired Central Nervous System Demyelination in Icelandic Children.
abstract: BACKGROUND
  Recognizing acquired demyelinating syndromes and multiple sclerosis is important to commence early treatment. The objective of this study was to describe the incidence of acquired demyelinating syndromes and multiple sclerosis among the entire Icelandic pediatric population according to recently promoted criteria.
  
  
  METHODS
  The study included all children in Iceland (<18 years) with acquired demyelinating syndromes and multiple sclerosis from 1990 to 2009 with a minimum of 5-year follow-up. Clinical data were gathered and radiological images reviewed. The cohort included all patients with acquired demyelinating syndromes and multiple sclerosis in the Icelandic pediatric population.
  
  
  RESULTS
  Eighteen patients with acquired demyelinating syndromes and multiple sclerosis were included, the total annual incidence being 1.15/100,000 (acquired demyelinating syndromes 1.02 and multiple sclerosis 0.45/100,000). The median age at diagnosis was 14.25 years (range 1.25-17.5 years). Thirteen patients were initially diagnosed with clinically isolated syndrome, two had acute disseminated encephalomyelitis, two had multiple sclerosis, and one had neuromyelitis optica. Seven children were diagnosed with multiple sclerosis; three patients with clinically isolated syndrome developed multiple sclerosis after the age of 18 and were not included in the multiple sclerosis group. The gender ratio was equal. Of the nine girls, seven were diagnosed with clinically isolated syndrome. Most patients (11 of 18) were diagnosed during the period January through March. Oligoclonal bands in cerebrospinal fluid were exclusively found in patients with multiple sclerosis and clinically isolated syndrome and 13 of 14 available magnetic resonance images revealed clear abnormalities.
  
  
  CONCLUSIONS
  The annual incidence of acquired demyelinating syndromes and multiple sclerosis in Iceland was 1.15/100,000 children. The risk of progression from clinically isolated syndrome to multiple sclerosis was high. There was no female preponderance.
authors.affiliation: Faculty of Medicine, University of Iceland, Reykjavík, Iceland.
authors.forename: Brynjar Thor
authors.initials: BT
authors.lastname: Gudbjornsson
authors.affiliation: Faculty of Medicine, University of Iceland, Reykjavík, Iceland; Children's Hospital Iceland, Landspítali - University Hospital Iceland, Reykjavík, Iceland.
authors.forename: Ásgeir
authors.initials: Á
authors.lastname: Haraldsson
authors.affiliation: Department of Diagnostic Imaging, Landspítali - University Hospital Iceland, Reykjavík, Iceland.
authors.forename: Hildur
authors.initials: H
authors.lastname: Einarsdóttir
authors.affiliation: Faculty of Medicine, University of Iceland, Reykjavík, Iceland; Children's Hospital Iceland, Landspítali - University Hospital Iceland, Reykjavík, Iceland. Electronic address: olitho@landspitali.is.
authors.forename: Ólafur
authors.initials: Ó
authors.lastname: Thorarensen
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003711:Demyelinating Diseases / Q000453:epidemiology*; D004673:Encephalomyelitis, Acute Disseminated / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D015994:Incidence; D007223:Infant; D008297:Male; D009103:Multiple Sclerosis / Q000453:epidemiology; D009188:Myelitis, Transverse / Q000453:epidemiology; D009471:Neuromyelitis Optica / Q000453:epidemiology
keywords: ADEM; CIS; acquired demyelinating syndrome; children; multiple sclerosis; transverse myelitis