Dissecting the Circle of Willis-Migraine connection: A review.

Abstract

Objective: Anatomical variations in the Circle of Willis (CoW) may mediate the prevalence of migraines with aura (MWA) and without aura (MWoA) in patients. The aim of this review is to describe and evaluate contrasting studies to clarify the current understanding of this association within the literature.

Methods: A comprehensive search across PubMed, Google Scholar, and the Cochrane Library resulted in 10 relevant studies that met our selection criteria and examined the association between the CoW and migraine prevalence.

Results: Conflicting results were reported across the prospective and retrospective studies, which varied among different populations and the inclusion classification of CoW variants. Studies that evaluated posterior CoW variations repeatedly reported differential associations between migraines with aura (MWA) and without aura (MWoA), thus revealing a significant association only with the former. Two mechanisms of actions were hypothesized to be attributed to such associations; one hypothesized a resultant cerebral hypovascularization, whilst the other emphasized the role of shear stress in associated small arteries.

Discussion: While some studies reported significant associations between specific CoW variations and migraines, particularly with the posterior CoW variations and MWA, conflicting evidence emphasizes the necessity for further investigations to provide a greater understanding between CoW variations and different migraine subtypes. A consensus calls for future studies to include larger samples over various ethnic populations to overcome the biases encountered within the current field of literature.