Intracranial Aneurysms in Adult Moyamoya Disease

The prevalence of aneurysm formation in adults with moyamoya disease (MMD) is approximately 14%, and it represents a major potential hemorrhagic risk. We aimed to study the characteristics of intracranial aneurysms occurring in patients with MMD. We retrospectively reviewed our 10-year experience of patients with intracranial aneurysms and a diagnosis of MMD at our hospital. Imaging studies and clinical records of 211 patients who were admitted to our hospital between January 2007 and December 2016 and were diagnosed with MMD were retrospectively reviewed. Patients were divided into 2 groups: 1) MMD without intracranial aneurysms and 2) MMD with intracranial aneurysms. The 2 groups were compared using statistical analysis. Angiographic findings and clinical features of MMD-associated aneurysms were reviewed. There were significant differences between the 2 groups, including age and clinical presentation. Among all enrolled patients (N = 132), 11 aneurysms were discovered in 11 patients. Prevalence of intracranial aneurysms in patients with MMD was 8.3%, and the rupture rate of these aneurysms was 63.6%. We classified the 10 MMD-associated aneurysms (excluding 1 incidentally found paraclinoid aneurysm) as follows: 4 dissecting aneurysms or pseudoaneurysms and 6 hemodynamic true aneurysms. MMD-associated intracranial aneurysms frequently occur in patients presenting with hemorrhagic MMD and are associated with an extremely high rate of rupture. Long-standing hemodynamic stress as well as pathologic and anatomic factors might contribute to the formation of an aneurysm.