A parieto-occipital artery arising from ICA directly and resultant incomplete PCA.

A parieto-occipital artery arising from internal carotid artery (ICA) directly was identified in a 46-year old man. The left ICA angiograms showed that a parieto-occipital artery was arising from ICA located between posterior communicating artery (PcomA) and anterior choroidal artery (AchoA). And also, incomplete posterior cerebral artery (PCA) which had not a parieto-occipital branch was arising from prominent PcomA. AchoA arose from ICA located just distal to the anomalous origin of the parieto-occipital artery. The vertebral angiograms showed no contrast filling of left PCA. Herein, we present a very rare case which has an anomalous origin of the parieto-occipital artery and resultant incomplete PCA.