title: Conversion to symptomatic Chiari I malformation after minor head or neck trauma.
abstract: OBJECTIVE
  The Chiari I malformation is a rare disorder characterized by downward herniation of the brainstem and cerebellar tonsils through the foramen magnum. Many individuals with the Chiari I malformation do not become symptomatic until adulthood, and the factors that contribute to the onset of symptoms have not been well characterized. The purpose of this systematic chart review was to determine the incidence and validity of minor head or neck trauma as precipitating factors for the onset of symptomatic Chiari I malformation.
  
  
  METHODS
  The charts of all patients seen by the senior author (CHT) between January 1985 and July 2006 were reviewed to identify patients who had presented with symptomatic Chiari I malformation after minor head or neck trauma. Specific inclusion criteria were used to determine whether the onset of symptoms could be reliably attributed to the minor trauma.
  
  
  RESULTS
  Of the 85 patients with symptomatic Chiari I malformation seen by the senior author during this time, 11 (12.9%) had a history of minor head or neck trauma preceding the onset of symptoms. Of these, there were 3 patients (3.5%) in whom the onset of symptoms could be attributed to the trauma based on strict inclusion criteria.
  
  
  CONCLUSIONS
  Minor head or neck trauma can precipitate the onset of symptoms in a small number of previously asymptomatic patients with Chiari I malformation. Health care professionals must be aware that neurological symptoms that persist or worsen after minor head or neck trauma could indicate an underlying Chiari I malformation.
authors.affiliation: Toronto Western Research Institute, Toronto Western Hospital, Toronto, Canada.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wan
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nomura
authors.forename: Charles H
authors.initials: CH
authors.lastname: Tator
mesh_terms: D000063:Accidents, Traffic; D000293:Adolescent; D000328:Adult; D001139:Arnold-Chiari Malformation / Q000175:diagnosis* / Q000453:epidemiology / Q000601:surgery; D002170:Canada / Q000453:epidemiology; D015897:Comorbidity; D006259:Craniocerebral Trauma / Q000453:epidemiology / Q000503:physiopathology*; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019838:Neck Injuries / Q000453:epidemiology / Q000503:physiopathology*; D012189:Retrospective Studies; D055815:Young Adult