- Department of Surgical Neurology, Research Institute for Brain and Blood Vessels Akita, Akita City, Japan
Department of Surgical Neurology, Research Institute for Brain and Blood Vessels Akita, Akita City, Japan
DOI:10.4103/2152-7806.78243Copyright: © 2011 Sámano A This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Abenamar Sámano, Ishikawa T, Moroi J, Yamashita S, Suzuki A, Yasui N. Ruptured de novo posterior communicating artery aneurysm associated with arteriosclerotic stenosis of the internal carotid artery at the supraclinoid portion. Surg Neurol Int 23-Mar-2011;2:35
How to cite this URL: Abenamar Sámano, Ishikawa T, Moroi J, Yamashita S, Suzuki A, Yasui N. Ruptured de novo posterior communicating artery aneurysm associated with arteriosclerotic stenosis of the internal carotid artery at the supraclinoid portion. Surg Neurol Int 23-Mar-2011;2:35. Available from: http://sni.wpengine.com/surgicalint_articles/ruptured-de-novo-posterior-communicating-artery-aneurysm-associated-with-arteriosclerotic-stenosis-of-the-internal-carotid-artery-at-the-supraclinoid-portion/
Background:Several de novo intracranial aneurysms have been described related to changes in hemodynamics after therapeutic occlusion of internal carotid artery (ICA); however, de novo aneurysms related to a supraclinoid arteriosclerotic stenosis of the ICA have not been described yet. Authors consider that it is important to bear in mind the possibility of developing an aneurysm in these special conditions.
Case Description:The evolution of a 62-year-old patient with subarachnoid hemorrhage, intraparenchymal frontal hematoma with some atypical circumstances that were presented together as well as the treatment he received are shown in this report. We can see this patient suffered a right thalamic hemorrhage at the age of 51 years; this condition was associated to a severe atherosclerotic stenosis of right supraclinoid ICAy. A long term had elapsed since the diagnosis of the stenosis and the discovery of a ruptured ipsilateral de novo supraclinoid internal carotid artery-posterior communicating artery (ICA-PcomA) aneurysm.
Conclusions:It seems like both conditions: the atherosclerotic supraclinoid ICA which tells of an Samano et at: Ruptured De Novo PcomA Aneurysm Associated with Arteriosclerotic Stenosis of Supraclinoid ICA. Altered vessel environment coupled to a long exposure time, hemodynamic changes, unbalance in the wall sheer stress could all of them lead to the development of the de novo aneurysm.
Keywords: Aneurysm, atherosclerosis, de novo, intracranial carotid artery, stenosis, subarachnoid hemorrhage
Aneurysms arising at the bifurcation of the posterior communicating artery (PcomA) from the internal carotid artery (ICA) are very common, comprising a quarter of all aneurysms. Variations of the circle of Willis are well known and could have a primordial role in the development of berry aneurysms associated with other risk factors such as genetics, changes in wall shear stress, smoking, hypertension and sex.[
Hemodynamic changes have been considered as one of the major reasons for de novo aneurysms.[
A 62-year-old man experienced sudden onset of severe headache, dizziness and vomiting and visited our hospital 2 hours after onset. Neurological examination revealed disturbed consciousness (Glasgow coma scale 9) with hemiparesis of the left side. He underwent CT, demonstrating subarachnoid hemorrhage (SAH) in the basal cisterns as well as a significant amount of hematoma in the right sylvian fissure and frontal lobe [
Anteroposterior view of right ICA angiography (left), lateral view of right vertebral angiography (center) and anterioposterior view of left ICA angiography (right) performed in 1999. The severely stenotic segment of right supraclinoid ICA is clearly apparent (left), along with a well-developed collateral circulation through PcomA (center). The right A1 segment remained hypoplasic while both A2 segments are filled with the flow that comes from left ICA (right)
We performed 3-dimensional CT angiography (3D-CTA), revealing the known stenotic supraclinoid segment of the ICA as well as the presence of a berry aneurysm in the right ICA-PcomA just after the stenotic segment of the ICA [
Left: pre-clipping picture. Atherosclerotic ICA (black-arrow), neck of aneurysm (yellow-arrow). The PcomA (white-arrow) and the anterior choroidal artery (green-arrow) are seen. Center: Schematic drawing of the surgical field. Right: post-clipping photograph. A well-developed PcomA is coming into the ICA
Considering that the prevalence of asymmetrical Willis’ ring could be as high as 64% in general population, it's supposed that only around the 40% of the total population would present an “ideal” Willis’ circle. This asymmetrical condition in the vessels has been described as a risk factor in the aneurysms development.[
It is well known that changes in the hemodynamic flow of ICA caused by hypoplasia or occlusive treatments when the whole ICA must be sacrificed could be directly related to intracranial aneurysms.[
Samano et at : Ruptured De Novo PcomA Aneurysm Associated with Arteriosclerotic Stenosis of Supraclinoid ICA.
These hemodynamics changes have been extensively studied lately with the computational fluid dynamics modeling systems and it has been found that in the supraclinoid ICA and in the infundibulae portion of PcomA the presence of regions of low wall shear stress (WSS) surrounded by areas of high WSS play a preponderant roll in the rise, growth and rupture of PcomA aneurysms.[
In our patient, we theorize that in the first stage the ICA's lumen was narrowed by the atherosclerotic plates, provoking the weakening of its flow giving rise to a stronger reversal flow coming from PcomA to supraclinoid ICA and the collision of both unpaired flows [
Upper: Typical flow coming from ICA (solid arrow) to PcomA (thin arrow) in the usual anatomical way. Bottom: in this patient the main flow in coming from the PcomA (solid arrow) to ICA territory and a weak flow is coming from ICA through the stenotic segment (thin arrow). The collision point of both coming flows could produce a turbulence effect that insults the walls of ICA
In conclusion, we would like to stress that when a patient with arteriosclerotic ICA occlusion and good collateral blood flow through the circle of Willis is young, as in our patient, the possibility of de novo aneurysm should be considered. Close, careful, multidisciplinary follow-up is necessary for such patients.
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