title: Prevalence of head trauma in patients with difficult headache: the North Norway Headache Study.
abstract: OBJECTIVE
  To test whether chronic headache (>3 days/week) is more prevalent than episodic headache (<3 days/week) in patients with a previous history of significant head trauma.
  
  
  METHODS
  We included 903 consecutive patients referred to a specialist center for headache during a period of 2 years. As the main parameter, we selected self-reported history of previous significant head trauma defined as loss of consciousness or hospitalization due to head trauma.
  
  
  RESULTS
  One hundred eighty-nine out of 903 patients with difficult headache referred to a neurologist had a previous history of head trauma (21%). We identified 297 patients with headache 3 days or more per week (33%). Of these patients with chronic headache, 68 (23%) reported previous significant head trauma compared with 121/714 (17%) in other patients with headache (P =.18). Shorter length of education was associated with chronic headache; however, age, sex, or specific headache syndromes such as migraine or tension headache were not related to chronicity.
  
  
  CONCLUSIONS
  Although the incidence of previous head trauma was prevalent in this highly selected group of patients with headache, such a history was not a predictor of chronicity.
authors.affiliation: Department of Neurology, Tromsø University Hospital and University of Tromsø, Norway.
authors.forename: Svein Ivar
authors.initials: SI
authors.lastname: Bekkelund
authors.forename: Rolf
authors.initials: R
authors.lastname: Salvesen
mesh_terms: D002908:Chronic Disease; D006259:Craniocerebral Trauma / Q000145:classification / Q000150:complications* / Q000453:epidemiology*; D006261:Headache / Q000209:etiology*; D020773:Headache Disorders / Q000209:etiology; D006801:Humans; D015994:Incidence; D009664:Norway / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies