title: Association of migraine headaches with anatomical variations of the Circle of Willis: Evidence from a meta-analysis.
abstract: BACKGROUND
  Several studies have attempted to investigate whether variations in the Circle of Willis (COW) are more common in migraine patients and whether the subsequent changes in perfusion may contribute to the pathomechanism of migraine. However, studies are not in agreement as to whether or not there is an increased prevalence of COW variations in migraineurs.
  
  
  OBJECTIVE
  To determine if migraine headaches are associated with variations in morphology of the COW.
  
  
  METHODS
  A systemic search of the major electronic databases was performed for articles studying the association of variations in the COW and migraine. Data on the prevalence of variations in patients with migraine were extracted and pooled into the meta-analysis.
  
  
  RESULTS
  A total of four articles (n=807 patients) were deemed eligible for the meta-analysis. Migraine, regardless of subtype, was found to be associated with variations in the COW (OR=2.27, 95%CI 1.53-3.38, p<0.0001). An incomplete posterior circle (OR=2.60, 95%CI 1.79-3.76, p<0.00001) was found to be more strongly associated with migraine than an incomplete anterior circle (OR=2.01, 95%CI 1.15-3.53, p=0.01). In sub-group analysis, migraine with aura was found to be associated with both an incomplete posterior (OR=3.55, 95%CI 2.25-5.59, p<0.00001) and an incomplete anterior circle (OR=2.35, 95%CI 1.20-4.62, p=0.01). Migraine without aura was found only to be associated with an incomplete posterior circle (OR=2.10, 95%CI 1.39-3.17, p=0.0004).
  
  
  CONCLUSIONS
  Migraine is associated with anatomical variations in both the anterior and posterior portions of the COW. However, larger prospective trials are needed to determine the true prevalence of variations and their pathological significance.
authors.affiliation: Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland. Electronic address: bmhenry55@gmail.com.
authors.forename: Brandon Michael
authors.initials: BM
authors.lastname: Henry
authors.affiliation: Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland.
authors.forename: Joyeeta
authors.initials: J
authors.lastname: Roy
authors.affiliation: Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland.
authors.forename: Piravin Kumar
authors.initials: PK
authors.lastname: Ramakrishnan
authors.affiliation: Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland.
authors.forename: Jens
authors.initials: J
authors.lastname: Vikse
authors.affiliation: Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland.
authors.forename: Krzysztof A
authors.initials: KA
authors.lastname: Tomaszewski
authors.affiliation: Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland.
authors.forename: Jerzy A
authors.initials: JA
authors.lastname: Walocha
mesh_terms: D002941:Circle of Willis / Q000473:pathology*; D006801:Humans; D020325:Migraine with Aura / Q000473:pathology*; D020326:Migraine without Aura / Q000473:pathology*
keywords: Cerebral arterial circle; Circle of Willis; Migraine; Willis Polygon