Abstract
It is the purpose of this paper to discuss differences between intracranial aneurysms associated with Moyamoya disease and usual saccular aneurysms. Thirty six published cases of bilateral Moyamoya disease with 42 intracranial aneurysms, including a case of the authors, were reviewed. Ten cases of unilateral Moyamoya disease with 14 intracranial aneurysms and 5 cases of unidentified Moyamoya disease with 7 intracranial aneurysms, in which it remained unknown whether the Moyamoya vessel was unilateral or bilateral, are also being referred to. The predominant symptoms of the 36 cases were classified the hemorrhagic type (79%), ischemic type (12%), and others (9%). Incidence of the hemorrhagic type was higher than in the general Moyamoya disease (P<0.05). Of the 42 intracranial aneurysms in the 36 cases, 2 aneurysms (5%) in 1 case (3%) were fusiform and the others were all saccular or spherical. They were located, except for 1 unknown case in a major artery in 24 cases, or 59%, and the peripheral artery in 17 cases, or 41%. This high incidence of peripheral artery aneurysm might be characteristic of the Moyamoya disease. The 24 major artery aneurysms were present in the carotid system in 37.5% and in the vertebro-basilar system in 62.5%, showing a predominance in the posterior circulation (P<0.001). The carotid aneurysms occurred more frequently in the C2-4 portion of the internal carotid artery than in the C1 portion. The vertebrobasilar aneurysms had a markedly higher occurrence in the top portion of the basilar artery. The 17 peripheral artery aneurysms were located in the basal ganglia or its surrounding area (82%) and in an anastomotic vessel, except in the basal ganglia area (18%). The size of the peripheral artery aneurysm was significantly smaller than that of the major artery aneurysm (P<0.005). The peripheral artery aneurysms showed a tendency either to an increase or a decrease in size; they sometimes disappeared or bled. Of the 3 peripheral artery aneurysms which were examined histologically, 2 were reported to be true aneurysms and 1 false. No fundamental differences were found between the intracranial aneurysms associated with the bilateral Moyamoya disease and those with the unilateral and unidentified Moyamoya disease.
