Accessory posterior cerebral artery as a duplicate anterior choroidal artery.

Purpose: Anatomical variations in the anterior choroidal artery (AChA) and/or the posterior cerebral artery (PCA) are rare. Hyperplastic AChA is an anatomical variant supplying both the AChA area and the PCA area. In accessory PCA, a hyperplastic AChA supplies part of the PCA territory. To our knowledge, there are no previous reports of accessory PCA associated with duplicated AChAs.

Methods: We report a case of accessory PCA as a duplicated AChA associated with contralateral accessory middle cerebral artery, diagnosed by digital subtraction angiography.

Results: A 34-year-old man visited our hospital because of headache and neck pain. Magnetic resonance imaging showed flow voids around the left medial temporal lobe. Magnetic resonance angiography showed vascular structures in the left PCA. Left internal carotid angiography revealed the accessory PCA supplying not only the AChA (plexal segment) territory but also part of the PCA (anterior and posterior temporal arteries) territory. Three-dimensional rotational angiography revealed a tiny branch proximal to accessory PCA. Careful assessment revealed that the tiny branch perfused the left AChA (cisternal segment) territory. Therefore, we made a diagnosis of duplicated AChAs. Right internal carotid angiography also showed the accessory middle cerebral artery originating from the anterior cerebral artery (proximal A1 segment).

Conclusion: Careful imaging assessment is important to identify the rare anatomical variations seen in this case, in which three-dimensional rotational angiography was useful and provided a better understanding of the vascular structure, including tiny vessels.