Duplication of the vertebral artery: report of two cases and review of the literature.

Duplication of the vertebral artery is rare. We report two cases in which it was an incidental finding. In the first, duplication of the right vertebral artery was demonstrated by magnetic resonance angiography (MRA) and conventional angiography. The second patient had duplication of the right vertebral artery demonstrated by MRA. We discuss the origin of this abnormality, its radiological implications and its potential clinical significance are discussed.