Rapid de novo Formation of a Large Aneurysm in a Patient with Fibromuscular Dysplasia

OBJECTIVE: The authors report the first case of intracranial fibromuscular dysplasia (FMD) presenting with rapid de novo formation of an unruptured large vertebral artery (VA) fusiform aneurysm. CASE PRESENTATION: A 41-year-old man presented with left hemiparesis. He had a giant thrombosed aneurysm at the basilar artery-superior cerebellar artery (BA-SCA) junction and a left extracranial VA aneurysm. A de novo VA fusiform aneurysm developed during a 1-month interval following the first session of intravascular coil embolization for the BA-SCA aneurysm. Stress on the fragile artery due to FMD during micro-catheterization may have caused the de novo aneurysm. An anomalous aortic origin of the left VA may also have played a role in the formation of the large de novo aneurysm and extracranial VA aneurysm. We performed overlapping stent-assisted coil embolization for the VA fusiform aneurysm using an Enterprise VRDs, and coil embolization for the BA-SCA thrombosed aneurysm using the stent-assisted technique with an Enterprise stent. Both aneurysms remained occluded for 7 years. CONCLUSION: We concluded micro-catheterization to be the cause of the large de novo aneurysm. This case emphasizes the importance of carefully performing intravascular interventional procedures for patients with FMD.