抄録
Two cases of moyamoya disease accompanied by an aneurysm were reported. One case had an aneurysm located within the middle cerebral artery proximate to the carotid bifurcation. Another had one located within the plexal portion of the anterior choroidal artery. Moyamoya disease can be defined as progressive arterial occlusive changes due to intimal fibrous thickening. In the aneurysm within the circle of Willis, clipping can be performed to prevent subarachnoid hemorrhage, but a major concern in clipping of the aneurysm is narrowing of the parent artery. In the aneurysm within the moyamoya vessels, this aneurysm can be expected to disappear spontaneously.
