Developmental anomalies of the distal vertebral artery and posterior inferior cerebellar artery: diagnosis by CT angiography and literature review

The aim of this study was to identify variations in the anatomy of the distal vertebral artery (VA) and posterior inferior cerebellar artery (PICA) with computed tomography (CT) angiography. CT angiography was performed at two hospitals. And the results were analyzed for VA anomalies. Seven of the 3067 patients who received brain CT angiography in first hospital had seven intracranial VA fenestrations. Twelve of 546 patients who received CT angiography of intracranial and extracranial vessels in second hospital had 16 anatomical variations of the V3 segment. Two fenestrations of the V3 segment, three C1 origins of the PICA, seven aberrant VAs with an intradural course at the C2 level without a normal VA, and four aberrant VAs with an intradural course at the C2 level with a normal VA were observed. Seventeen of the 314 patients who received cervical CT angiography in second hospital had 21 anatomical variations of the VA. Two fenestrations of the V3 segment, six C1 origins of the PICA, three C2 origins of the PICA, one VA origin of the occipital artery, one fenestration of the V4 segment, five aberrant VAs with an intradural course at the C2 level without a normal VA, and three aberrant VAs with an intradural course at the C2 level with a normal VA were observed. A certain number of anatomical variants of the distal VA and PICA may reflect variations in size and connections of the lateral or posterior spinal artery.