Table 5. Summary of studies examining circle of Willis morphology and migraine using magnetic resonance angiography.

	Anterior circle of Willis incomplete				Posterior circle of Willis incomplete
	Control	MWA	MwoA	Migraine combined	Control	MWA	MwoA	Migraine combined
Present study n = 170	13%	32%	21%	26%	41%	64%	57%	61%
Cavestro [32] n = 429	5%	9%	10%	10%	13%	35%	24%	26%
Bugnicort [31] n = 124	5%	9%	4%	6%	18%	61%	38%	49%
Schoonman [33] n = 44	17%	NR	NR	9%	67%	NR	NR	50%
Ikeda [34] n = 173	NR	NR	NR	NR	45%	81%	48%	62%

NR  =  not reported.