Clinical Significance of Intracranial Aneurysms in Adult Moyamoya Disease.

Objective: We present the relationship between an aneurysm in adult moyamoya disease (MMD) patients and a future stroke event.

Methods: One hundred forty-seven aneurysms were found in 118 adult MMD patients. To find risk factors for future hemorrhagic and ischemic stroke, Kaplan-Meier and Cox-regression analyses were performed on clinical and radiologic factors. In addition to the anatomical classification method based on the circle of Willis, aneurysms occurring in the collateral pathway were analyzed by reflecting the hemodynamic changes in MMD.

Results: The initial clinical presentations are divided into ischemia (n = 53, 44.9%), hemorrhage (n = 51, 43.2%), and asymptomatic (n = 14, 11.9%). The mean size of the aneurysms was 2.9 ± 1.67 mm. Thirty-four aneurysms were treated with coil (n = 24) and glue embolization (n = 10). One hundred thirteen aneurysms were conservatively managed. All of aneurysms did not cause recurrent hemorrhagic strokes by aneurysm rupture. The mean follow-up period duration was 78.3 ± 58.9 months. The overall estimated rate of hemorrhage was 10.5%/hemisphere at 5 years and 18.2%/hemisphere at 10 years after the initial angiography. The overall estimated rate of infarction was 2.8%/hemisphere at 5 years and 4.5%/hemisphere at 10 years after the initial angiography. A Cox regression analysis revealed that a collateral pathway aneurysm is a significant risk factor for hemorrhagic stroke (P = 0.045, hazard ratio = 2.366). However, less hemorrhaging occurred in MMD patients with hypertension (P = 0.018, hazard ratio = 0.364).

Conclusions: The presence of a collateral pathway aneurysm appears to reflect the hemodynamic stress exerted on the cerebral hemispheres of MMD patients, suggesting an increased risk of future hemorrhagic strokes.