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

Orbitofrontal artery arising from a hairpin turn in type 1 persistent primitive olfactory artery: a possible new variant (type 6)

PURPOSE

To describe a case of a possible new variant of persistent primitive olfactory artery (PPOA).

CASE REPORT

A 93-year-old man with left hemiparesis and dysarthria underwent cranial magnetic resonance (MR) imaging and MR angiography using a 3-T scanner. MR imaging showed an acute infarction at the right precentral gyrus. MR angiography showed no steno-occlusive lesions, but the distal A1 segment of the left anterior cerebral artery (ACA) took an extreme anterior course and made a hairpin turn, connecting to the A2 segment, which is indicative of type 1 PPOA. In addition, there was a faintly visualized small artery arising from the hairpin turn. Subsequent computed tomography (CT) angiography showed that the hairpin turn had a mildly dilated arterial lumen, and an extremely tortuous orbitofrontal artery arose from the hairpin turn.

DISCUSSION

There are five types of PPOA. Type 1 is most common, and usually no arterial branch arises from the hairpin turn, except for in type 3 PPOA, which has a branch continuing to the anterior ethmoidal artery arising from the hairpin turn. Using MR and CT angiography, we diagnosed a case of type 1 PPOA associated with the orbitofrontal artery arising from a hairpin turn. A similar previously reported case was diagnosed using catheter angiography.

CONCLUSION

The present case may be a new variant (type 6) of PPOA. Because the orbitofrontal artery was relatively small in caliber and its proximal segment extremely tortuous, CT angiography had superior utility to MR angiography for demonstrating this variation.

Bilateral persistent primitive olfactory arteries associated with an accessory anterior cerebral artery

Persistent primitive olfactory artery (PPOA) is a relatively rare variation of the proximal anterior cerebral artery (ACA) that generally follows an extreme anteroinferior course and takes a hairpin turn before continuing to the A2 segment of the ACA. This variation is usually seen unilaterally, and the anterior communicating artery (ACoA) is usually long or absent. We herein report a case of bilateral persistent PPOAs associated with an accessory ACA. The length of the bilateral A1 segments was normal and the length of the ACoA was normally short. Thus, hypoplasia of the distal A1 segment is important but not necessary for the formation of the PPOA. To our knowledge, no similar cases have been reported in the relevant English language literature.

Type 4 persistent primitive olfactory artery associated with contralateral accessory middle cerebral artery arising from the fenestrated segment of the distal anterior cerebral artery

Persistent primitive olfactory artery (PPOA) is a rare variation of the proximal anterior cerebral artery (ACA) that generally follows an extreme anteroinferior course and takes a hairpin turn before continuing to the A2 segment of the ACA (type 1). There are four other types of extremely rare variations. The type 4 variation continues to the accessory middle cerebral artery (MCA) instead of the ACA. Only a few cases have been reported. We herein report a case of type 4 PPOA in which the contralateral side of the accessory MCA arose from the fenestrated segment of the distal ACA. No similar cases were found in the relevant English-language literature. For the identification of these variations on MR angiography, volume-rendering images were superior to maximum-intensity-projection images.