title: The pathogenesis of Chiari I malformation and syringomyelia.
abstract: OBJECTIVE
  The pathogeneses of Chiari malformation type I and syringomyelia are incompletely understood. In this article, the authors attempt to review the current theories on the pathogeneses of Chiari I malformation and syringomyelia.
  
  
  METHODS
  A literature review for articles pertaining to Chiari I malformation or syringomyelia before August 2010 was conducted; in addition, the author's own experience in treating Chiari I malformation and syringomyelia is included.
  
  
  RESULTS
  Chiari I malformation has been defined radiographically as cerebellar tonsillar herniation or ectopia 5 mm or greater below the foramen magnum. By this narrow definition, Chiari I malformation (i.e. cerebellar tonsillar herniation or ectopia 5 mm or greater below the foramen magnum) likely encompasses a heterogeneous grouping of disorders caused by different mechanisms. Molecular and genetic studies have been helpful in furthering our understanding of Chiari I malformation.
  
  
  CONCLUSIONS
  A review of the pathogeneses of Chiari I malformation and syringomyelia is reported.
authors.affiliation: Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA. rsekula@wpahs.org
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Sekula
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Arnone
authors.forename: Christine
authors.initials: C
authors.lastname: Crocker
authors.forename: Khaled M
authors.initials: KM
authors.lastname: Aziz
authors.forename: Noam
authors.initials: N
authors.lastname: Alperin
mesh_terms: D001921:Brain / Q000473:pathology; D002640:Chiari-Frommel Syndrome / Q000209:etiology* / Q000235:genetics / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D013595:Syringomyelia / Q000209:etiology* / Q000235:genetics / Q000473:pathology*