Pathology of moyamoya disease

Abstract

Moyamoya disease (MMD) is a cerebrovascular occlusive disease first reported by Japanese surgeons in 1957 as hypoplasia of the bilateral internal carotid arteries [1]. The entity is characterized by steno-occlusive changes at the terminal portion of the bilateral internal carotid arteries and by development of an abnormal vascular network near the arterial occlusion [2, 3]. In the criteria prepared by the Research Committee in Japan [4], instructive pathological findings are as follows: (1) intimal thickening and the resulting stenosis or occlusion of the lumen is observed in and around the terminal portion of the internal carotid artery, usually on both sides; lipid deposits are occasionally seen in the proliferating intima; (2) arteries constituting the circle of Willis, such as the anterior and the middle cerebral and the posterior communicating arteries, often show stenosis of various degrees or occlusion associated with fibrocellular thickening of the intima, waving of the internal elastic lamina, and attenuation of the media; (3) numerous small vascular channels (perforators and anastomotic branches) are observed around the circle of Willis; and (4) reticular conglomerates of small vessels are often seen in the pia mater. © 2010 Springer-Verlag Tokyo.