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Fig 4. Irregular stenosis of the left vertebral artery (VA) is shown on the left vertebral angiograms in anteroposterior (AP) (A) and lateral (B) views in patient 5. Severe stenosis of the left posterior inferior cerebral artery (PICA) orifice is also noted (arrow). Right vertebral angiogram in the lateral view shows retrograde flow through the anterior spinal artery (ASA) (C). There is minimal perfusion to right distal VA. Follow-up angiography after 9 months shows increased perfusion through the ASA at early arterial (D) and later (E) phases. Both distal VAs are connected to the ASA, and perfusion to the common trunk of the right anterior interior cerebellar artery (AICA) and PICA and left AICA is maintained by this collateral route. The left VA was completely occluded (not shown).
