Extreme fenestration of the right vertebral artery: magnetic resonance angiographic demonstration

The authors describe an extreme fenestration of the right vertebral artery. This anomaly was found incidentally in a female patient undergoing MR imaging and MR angiography evaluation for severe dizziness and headache. Magnetic resonance angiography showed that the right posterior inferior cerebellar artery originated possibly extracranially and anastomosed with the terminal portion of the right vertebral artery, indicating the presence of an extremely large fenestration. This, to our knowledge, is the first report of MR angiographic demonstration of this variation. (orig.)