Variants in the Circle of Willis and White Matter Disease in Ecuadorian Mestizos

BACKGROUND AND PURPOSE: Studies on Whites and Asians have shown contradictory results on the association between an incomplete circle of Willis (CoW) and white matter disease (WMD). We evaluated such relationship in Ecuadorian Mestizos. METHODS: Ecuadorian Mestizos aged ≥40 years were evaluated with MRI and MRA. WMD was graded according to the modified Fazekas' scale, and the CoW was classified as complete or incomplete according to the presence or absence of one A₁ segment of the anterior cerebral artery or one or both P₁ segments of posterior cerebral arteries. RESULTS: A total of 315 persons (mean age 64.7 ± 13.4 years, 56.5% women) were prospectively enrolled over 6 months. MRAs revealed a complete CoW in 65.1%, and MRIs showed WMD in 62.5% of cases. Irrespective of age and sex, incompleteness of the CoW was not associated with a higher prevalence or severity of WMD. In contrast, age was an independent risk factor for the occurrence of WMD. CONCLUSIONS: In the Ecuadorian Mestizo population, WMD occurrence and severity do not seem to be related to incompleteness of the CoW.