Two successfully treated adult cases of intra-ventricular hemorrhage (IVH) accompanied with middle cerebral artery (MCA) occlusion, moyamoya phenomenon, pseudoaneurysm at the peripheral portion of the dilatated anterior choroidal artery (AchA) and choroid plexus angioma are reported in the paper.
In each case, CT scan on admission revealed IVH with a small intracerebral hematoma (ICH) adjacent to the trigonal portion of the right lateral ventricle; and an initial right carotid angiogram showed occlusion at the proximal portion of the right MCA with moyamoya vessels around it and angiomatous shadow at the trigonal portion of the right lateral ventricle. In the first follow up angiogram (14 days after onset in Case 1 and 21 days after in Case 2) an aneurysm appeared at the peripheral portion of the dilatated AchA in each case and had grown larger by the time of the second follow up angiogram (49 days after onset in Case 1 and 40 days after in Case 2). In each case, surgery was performed and both the aneurysm and the angiomatous mass were removed. Histologically the former was diagnosed as a pseudo-aneurysm and the latter was diagnosed as an AVM.
Recently many cases of aneurysms associated with moyamoya diseases and moyamoya-like disease have been reported. Moyamoya phenomenon is not specific to moyamoya disease. Arterial occlusion due to various causes, i. e., arteriosclerosis, radiation, tumor, neurofibromatosis, and spontaneous occlusion, may cause the formation of moyamoya vessels as a collateral pathway.
In the literature, 27 cases (including our two cases) of moyamoya phenomenon associated with MCA occlusion have been reported. Of the 27 cases, 16 presented intracranial hemorrhage (IVH:11 cases, ICH: three cases, SAH: two cases). Of these 16 cases, seven had intracranial aneurysms, and in six of these aneurysms were located within the moyamoya vessels. All of the six cases presented IVH. These cases seemed to be similar to moyamoya disease associated with aneurysms located within the moyamoya vessels.
We considered our two cases as follow: Moyamoya vessels associated with spontaneous MCA occlusion seemed to be formed as a collateral pathway. Dilatation of the AchA developed as a collateral pathway and a feeding artery to the choroid plexus angioma. ICH and IVH occurred due to rupture of the dilatated fragile wall of the moyamoya vessels and a pseudoaneurysm was formed at the site of the ICH. Choroid plexus angioma may have facilitated an increase in blood flow of the AchA and participated in the rupture.
As to the treatment of such cases, EC-IC bypass surgery in addition to removal of the aneurysm has been reported. But the effect of EC-IC bypass has not been elucidated clearly and should be investigated carefully in the future.