SYSTEMIC VASCULAR CHANGES IN SPONTANEOUS OCCLUSION OF THE CIRCLE OF WILLIS

Background and Purpose: We examined the presence of systemic etiologic factors causing vascular changes in so-called "spontaneous occlusion of the circle of Willis" (cerebrovascular moyamoya disease) to determine whether extracranial, as well as intracranial, vessels are involved in this disease. Methods: Histopathologic examination and morphometric analysis of the extracranial vessels were performed in 13 patients with this disease. Results: The histopathologic findings of the extracranial vessels were as follows: 1) advanced intimal fibrous thickening similar to that of the intracranial vessels; and 2) characteristic intimal fibrous nodular thickening, which may indicate organization of mural thrombi, at the proximal portions of the pulmonary arteries in three of 13 patients. Morphometric analysis revealed significant intimal thickening of the pulmonary arteries (p < 0.05), renal arteries (p < 0.05), and pancreatic arteries (p < 0.01) in patients with this disease as compared with age- and sex-matched control patients. Conclusions: On the basis of these findings, it is highly likely that this disease has systemic etiologic factors, as well as focal etiologic factors, that work to create vascular change in both the intracranial and extracranial vessels.