A 48-year-old female presented with a subarachnoid hemorrhage (SAH) due to right vertebral dissecting aneurysm. Diagnosis was made with vertebral angiogram, magnetic resonance images (MRI) and three-dimensional CT angiography (3D-CTA). These studies showed that the posterior inferior cerebellar artery (PICA) originated from the dissecting aneurysm itself. She underwent proximal occlusion of the right vertebral artery using Guglielmi detachable coils on day 28. Six months later, however, a left vertebral angiogram revealed an enlargement of the dissecting aneurysm that expanded to the PICA. This time, she underwent right occipital artery(OA)-PICA anastomosis prior to the entrapment of the dissecting aneurysm. After the OA-PICA anastomosis, MRI revealed a complete thrombosis of the dissecting aneurysm. Thrombosis of the vertebral dissecting aneurysm after a revascularization of the PICA is rare. We discuss the mechanism of thrombosis and treatment for ruptured PICA-involved dissecting aneurysm of the vertebral artery.
