Computational Fluid Dynamics in Unruptured Intracranial Aneurysms

Introduction and Objective: Intracranial aneurysm, also known as brain aneurysm, is a cerebrovascular disorder in which weakness in the wall of a cerebral artery causes a localized dilation or ballooning of the blood vessel. There is no objective way, device or tools, of predicting rupture of aneurysm so far. Computational fluid dynamics (CFDs) was proposed as a tool to identify the rupture risk. Purpose of study: To reveal the correlation of CFD findings with intraoperative microscopic findings and prove the relevance of CFDin the prediction of rupture risk and in the management of unruptured intracranial aneurysms. Subjects and Methods: A prospective cohort study was conducted inNeurosurgery department of Fujita Health University Banbuntane Hotokukai Hospital, Nagoya, Japanduring a 3?month period in 2018,from January to March, Ten patientswere diagnosed unruptured intracranial aneurysms (UIA). In diagnosis computed tomography (CT) angiogram, CFD and digital subtraction angiogram were included. Intraoperatively microscopic examination of the aneurysm wall was carried out and images recorded. The correlation between microscopic dome morphology and CFD information was performed. Results: Nine cases were found intraoperatively to have a higher risk of rupture based on the thinning of the wall. One cases had an atherosclerotic wall. All cases had low wall shear stress (WSS). In 90 % of cases Low WSS was able to predict the potency rupture risk in the near future. Conclusions: This study of CFD and its correlation with intraoperativefindings of the aneurysm suggested that low WSS of the aneurysm wall is associated with thin wall aneurysm and hence increased risk of aneurysm rupture. Thus CFD can be used to predict the risk of rupture of unruptured aneurysm and for planning of its treatment

High Flow Bypass for Cavernous Carotid Aneurysms

Introduction and objective: High flow extracranial to intracranial (HF EC–IC) cerebral revascularisation may be necessary in the management of complex skull base tumours and intracranial aneurysms. Bypass grafting can be considered high flow when a radial artery or the saphenous vein is interposed between the extracranial carotids arteries and intracranial vessels. The decision as to whether to use a low flow or high flow bypass is determined by the anticipated cerebral blood flow needed and the availability of a supply source. In this study, we have used this method to bypass for two cases of giant aneurysms of the cavernous sinus part of the ICA. Methods: Two cases of giant ICE aneurysm not amenable to clipping or coiling were taken since 2016. Patients were treated in Neurosurgery department of Fujita Health University Banbuntane Hotokukai Hospital, Nagoya, Japan. During bypass surgery, intraoperative methods were used to determine the patency of the graft artery: Doppler sonography and indocyanine green (ICG) Dual-Image Videoangiography (DIVA). Results: Two patients with symptomatic large and giant cavernous carotid aneurysms were evaluated as not amenable for clipping or endovascular treatment due to location and size of the aneurysm and associated high morbidity risk with these treatment options. In both cases radial artery graft was used for high-flow EC-MCA bypass and proximal internal carotid artery was ligated. Additionally, for high-flow bypass was performed superficial temporal artery (STA) to middle cerebral artery (MCA) bypass. DIVA, ICG and Doppler sonography were used multiple times to assess the patency of graft artery. In one case there was not complete ligation of the IC after postop DSA, the next day was performed reintervention to completely ligate IC. Postoperative course was uneventful, there were no mortality or morbidity. Follow-up showed good recovery and postoperative CT and DSA showed complete occlusion of ligated IC and patent functioning arterial graft. Conclusions: Cavernous carotid aneurysms (CCA) are rare and pose considerable challenges in management. A bypass procedure before parent artery occlusion, preferable to reduce the risks of postocclusion stroke. Intraoperative Doppler sonography and DIVA makes it easy to check the patency of the graft. DIVA is superior over Doppler or ICG in terms of better visualization of related anatomical structures