Concurrent basilar artery double fenestration with aneurysm and vertebral artery dissection: case report and literature review of rare cerebrovascular abnormalities.

Many disorders can cause aneurysm and/or dissection of the cerebral arteries, including fibromuscular dysplasia (FMD), connective tissue disorders, cerebral vasculitis, infection, and vascular malformations. Arterial fenestration is a rare congenital finding that can also cause aneurysms, and can rarely dissect and bleed. Treatment of aneurysm and dissection with subarachnoid hemorrhage can be very complicated, and requires case-by-case analysis of the risks and benefits of antithrombotic therapy. To the authors' knowledge, no case of double fenestration of the basilar artery has been reported. This report presents a case of concurring vertebral artery dissection and double fenestration of the basilar artery with aneurysm. The fenestration and FMD are considered possible main contributing causes of this presentation. A literature review of cerebrovascular fenestration and FMD is provided and the relationship between the 2 is considered. Lastly, the use of antithrombotic therapy in the setting of subarachnoid hemorrhage, dissection, and stent placement is discussed.