Background and purpose: The cause of intracranial bleeding in moyamoya disease patients is still unknown. To identify factors that contribute to bleeding, we assessed the angiographic findings of moyamoya disease patients.
Methods: We examined angiograms obtained from 107 moyamoya patients; 70 manifested ischemic and 37 had hemorrhagic lesions. Patients with intracerebral aneurysms or both hemorrhagic and ischemic lesions in the same cerebral hemisphere were not included. Patients were divided into those <20 years of age (n=47) and those > or =20 years of age (n=60). The right and left hemispheres in each patient were individually classified as hemorrhagic, ischemic, or asymptomatic. Each hemisphere was assessed for dilatation and branch extension of the anterior choroidal artery (AChA) and posterior communicating artery (P-CoM) and for the degree of proliferation of basal moyamoya vessels. These data were then statistically analyzed for correlation with intracranial bleeding events.
Results: The degree of proliferation of basal moyamoya vessels was not statistically correlated with hemorrhagic events. On the other hand, there was a correlation between hemorrhage and dilatation and abnormal branching of the AChA. In 27 of 37 hemorrhagic hemispheres (73.0%), this artery was dilated, and its abnormal branches served as collateral supply vessels to other regions. This phenomenon was observed in 4 of 5 hemorrhagic hemispheres from young patients; it was noted in fewer than one third of ischemic and asymptomatic hemispheres from this age group. Similarly, 71.9% of hemorrhagic hemispheres from adult patients manifested AChA dilatation and branching, and the difference between hemorrhagic hemispheres and those that were ischemic or asymptomatic was statistically significant (P<0.01). Although the incidence of dilatation and abnormal branching of the P-CoM was relatively low in hemorrhagic hemispheres from adult patients (18.8%), it was significantly higher than in the ischemic and asymptomatic hemispheres from this age group. Using dilatation and abnormal branching of the AChA and/or P-CoM as assessment criteria, we obtained high specificity (86.4%) and sensitivity (84.4%) for hemorrhagic events in adult moyamoya patients.
Conclusions: In adult moyamoya patients, dilatation and abnormal branching of the AChA and/or P-CoM are strong predictors of hemorrhagic events.