[Spontaneous occlusion of the circle of Willis--supplementary study: analysis of the disease process and proposal of a new concept, collateral arterial syndrome].

This disorder, because of its protean manifestation, had long been controversial until Kudo advocated it as a distinctive disease apart from other apoplectiform diseases. However, exact relationship between juvenile and adult types of this disease has been rather poorly understood. As the results of this study, authors concluded that this disease consists of two parts; initial and successive. Initial part corresponds to juvenile disease process and successive to adult process. The former is the well known peculiar slowly progressive occlusive process which originates at the terminal portion of the bilateral internal carotid arteries. The latter is the disease process which develops in collateral arterial plexuses produced by initial process characterized by hemorrhagic and occlusive attacks. Both attacks, hemorrhagic and occlusive, have been believed characteristic to adult patients. But this study disclosed not a small number of patients present hemorrhagic attacks in adolescence and some of them early in juvenile age immediately after ceasing initial process. As the cause of hemorrhage, rupture of miliary aneurysms, which have been discovered in 50% of juvenile patients and 85% of adult patients by magnifying angiography (Fukuda and Yamada) was anticipated. Authors proposed a new concept: collateral arterial plexus syndrome to specify a disease process which occurs in collateral arterial plexuses and presents hemorrhagic and occlusive attacks.