Persistent primitive olfactory artery associated with early bifurcated accessory anterior cerebral artery.

Five types of persistent primitive olfactory artery (PPOA), a rare variation of the proximal anterior cerebral artery (ACA), have been reported. Type 1 is most common, generally following an extreme anteroinferior course and taking a hairpin turn before continuing to the distal A2 segment of the ACA. Triple ACAs are a common variation of the A2 segment of the ACA, and a centrally located artery is called an "accessory ACA" or "median artery of the corpus callosum". This artery usually does not bifurcate or else bifurcates distally and continues to the pericallosal artery. We herein report a 74-year-old woman with type 1 PPOA and early bifurcated accessory ACA, an extremely rare combination of ACA variations, that was diagnosed using magnetic resonance angiography.