Note marked progressive narrowing of the V4 segments has developed bilaterally, crossing the PICA origins. Changes are worse on the right. No vasospasm in the anterior circulation. Close inspection reveals a small aneurysm at the junction of the right PICA and vertebral artery. Likely diagnosis is dissecting aneurysm of vertebral / PICA junction - bilateral dissections, major differential diagnosis is dissection of PICA origin and vasospasm explaining the vertebral stenoses.