Cerebral Aneurysms Research Papers - Academia.edu (original) (raw)

Usually blood is modeled as a Newtonian fluid, neglecting its shear-thinning behavior, when calculating the blood flow in cerebral arteries and intracranial aneurysms. Treatment with flow diverting devices leads to much slower and more constant flows inside the aneurysm sack, thus the accuracy of the Newtonian model had to be reviewed. We measured the viscosity at different shear rates and used the results for a Carreau Yasuda model. We then used Comsol Multiphysics to model a bend cerebral parent vessel with a side wall aneurysm and calculate the velocity of the blood stream using both viscosity models. Against the first intuition the Newtonian model overestimates the effect of the flow diverting stent. Using the Carreau Yasuda model the velocities behind the device are about 4% to 6% higher.

- by and +2
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- Computational Fluid Dynamics (CFD) modelling and simulation, Blood Flow, Endovascular Neurosurgery, Cerebral Aneurysms

Background: El vasoespasmo cerebral como complicación de hemorragia subaracnoidea genera un alto impacto en morbilidad, estancia, costos y mortalidad hospitalarias. Objective: Determinar las concentraciones séricas de óxido nítrico ON) y malondialdehído (MDA) en pacientes con hemorragia subaracnoidea y su relación con el vasoespasmo cerebral. Method: Se realizó un estudio observacional, descriptivo, longitudinal, de cohorte, prospectivo. Se incluyeron un total de 52 pacientes, los cuales se dividieron en 2 grupos: 1) pacientes con hemorragia subaracnoidea (n=26), 2) pacientes sanos (n=26). Se realizó un análisis estadístico mediante la prueba de ANOVA, X2 y un modelo de regresión de Cox. Results: Observamos un incremento de las concentraciones séricas del ON en la fase aguda de la hemorragia y en el estadio subagudo se observó un descenso por debajo de la concentración sérica de los controles. El MDA mostró un comportamiento similar observando un incremento de la fase aguda y posteriormente un descenso gradual sin llegar a la concentración del grupo control con diferencias significativas. Conclusions: Nuestros resultados demuestran que las concentraciones séricas de ON y MDA incrementan significativamente durante la fase aguda de la HSA y disminuyen durante su evolución, no se encontró una asociación con el desarrollo de vasoespasmo.

- by Cervantes-González J.A.
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- Subarachnoid hemorrhage, Cerebral Aneurysms
- by Sherif Rashad
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- Neuroscience, Neurosurgery, Endovascular Neurosurgery, Cerebral Aneurysms

Objectives: To look at the early results of Intracranial
flow diverting stents in the treatment of both
unruptured and ruptured Intracranial Cerebral Aneurysms.
Design: Retrospective review of all cerebral aneurysms
treated with flow diverting stents.
Subjects: 47 patients who presented to our hospital
between 2008 and 2010 with aneurysms presenting
technical difficulties for conventional coil treatment
or clipping were treated with flow-diverting stents,
either with or without coils.
Methods: Retrospective review of intracranial stent
database, case notes, angiography data and outpatient
follow up was done. Retrospective review of
intracranial stent database, case notes, angiography
data and outpatient follow up was done. Glasgow
outcome scale (GOS) was noted at pre-treatment,
3 months and 6 months. Technical complications,
immediate angiography outcome, clinical complications,
follow up 6 months angiography and clinical
outcome at 3 and 6 months will be presented where
available.
Results: 47 patients aged between 28 and 79 years
were treated (average 49.5 yr); 13 were men and 34
were women.
Angiographic follow-up at 6 months was available
in 27 patients. 16 presented with SAH and the rest
were unruptured mostly symptomatic aneurysms.
There were 4 deaths. Six patients had peri-procedural
strokes and one had a 3rd nerve palsy. The
majority of the surviving 43 patients made a good
recovery with a GOS of 5.
Conclusions: Flow-diverting stents are a promising
addition to the endovascular interventional specialists’
armamentarium in treating difficult aneurysms unsuitable
for traditional coiling or clipping. There are
significant risks of infarction and haemorrhage. Periprocedural
management is multi-disciplinary and is
vital for optimal outcome. The early results are
encouraging but long-term follow up and further
studies are advised to investigate its long term efficacy.

- by DR AVINASH HARIDAS
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- Cerebral Aneurysms

Objective: Numerous studies have suggested a relationship between delayed occlusion of intracranial aneurysms treated with the Pipeline Embolization Device (PED) and the presence of an incorporated branch. However, in some cases, flow diversion may still be the preferred treatment option. This study sought to determine whether geometric factors pertaining to relative size and angulation of branch vessel(s) can be measured in a reliable fashion and whether they are related to occlusion rates. Methods: Eighty aneurysms treated at a single neurovascular center from November 2008 to June 2014 were identified. Two blinded raters prospectively reviewed the imaging performed at the time of the procedure and measured the following geometric variables: inflow jet/incorporated branch direction angle and branch artery/ parent artery ratio. Delayed occlu-sion was defined as the absence of complete aneurysmal occlusion at one year. Analysis was performed using logistic regression and intra-class correlation coefficient (ICC). Results: Twenty-four (30%) aneurysms with 28 incorporated branches were identified. A trend toward higher inflow jet/ incorporated branch direction angle was found in the group of aneurysms demonstrating delayed occlusion when compared to the group with complete occlusion. ICC revealed high correlation. Overall lower one-year occlusion rates of 53% versus 73% for aneurysms with and without incorporated branches, respectively, were also noted. Conclusions: The presence of an incorporated branch conferred a 20% absolute risk increase for delayed aneurysmal occlusion. Incorporated branches with a larger angle between the inflow jet and the incorporated branch direction exhibited a trend toward lower occlusion rates. This might be further investigated using a multicenter approach in conjunction with other potentially relevant clinical and angiographic variables.

- by Akli Zetchi and +1
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- Neurosurgery, Neuroradiology, Cerebrovascular diseases, Interventional Neuroradiology

Endovascular treatment of brain aneurysms with flow diverter device can be technically difficult. Obtaining distal access through the wide neck of a large or giant aneurysm may be challenging and sometimes the microcatheter needs to be looped inside the aneurysm. However, the inability to resolve this loop and to straighten the microcatheter can preclude flow diverter placement. This brief report presents four cases of large/giant aneurysms treated with flow diverter device, in which our innovative stent-retriever anchor technique was used to obtain the distal access of the parent artery. All procedures were technically successful, and no complications were recorded.

- by Vessel Plus and +1
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- Endovascular Therapy, Endovascular Neurosurgery, Cerebral Aneurysms, Endovascular Surgery

Many new endovascular devices have been used under the guidance of the International Subarachnoid Aneurysm Trial (ISAT). Clipping still offers higher occlusion rates, and its technique continues to evolve, resulting in smaller exposures and reduced manipulation to brain tissue. We sought to evaluate the routine use of the minisphenoidal approach to manage intracranial aneurysms in a high-volume institution. We retrospectively reviewed our database of aneurysm patients from October 2013 to May 2016. Data were originally collected prospectively. The minisphenoidal approach has been progressively replacing the pterional approach for managing aneurysms in our department. Occlusion rates for ruptured and unruptured aneurysms were analyzed using late follow-up angiograms. Functional outcome assessment and the impact on quality of life were also measured. We performed 124 minisphenoidal craniotomies in 117 patients to clip 147 aneurysms. Patient mean age was 53.9 years. Seventy patients (5...

- by Daniel D Cavalcanti
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- Neurosurgery, Magnetic Resonance Imaging, Quality of life, Adolescent

Blood blister-like aneurysms (BBA) are rare aneurysms arising mainly from the anterior wall of the internal carotid artery (ICA) its supraclinoid segment (C6). The aneurism BBA usually forms a as small, consisting only of adventiva, bulge of the artery wall. Often these aneurysms lack aneurysmal neck, which is typical for saccular ones. All of those factors result in susceptibility to rupture causing subarachnoid haemorrhage (SAH) and difficulty in diagnosing and treatment.
The presented case series sums up the treatment of seven BBA cases operated in the Neurosurgery Department of Medical University of Gdansk between 1997 and 2012. All described patients were admitted due to SAH and all underwent surgery. The aneurysms were treated by means of neck clipping technique, applied with or without covering it by a muscular muff or a piece of gauze (wrapping). One case was treated by wrapping only.
Most of treated BBA cases were middle aged women. The results of treatment were unsuccessful in the majority of patients (6/7; 85.7%), three of them died, the other three became disabled and one patient was discharged in a good condition.
The outcome after surgical treatment of BBA is poor. Morphological distinctiveness of these aneurysms significantly complicates their efficient securing. Uneventful prognosis can be achieved in younger patients, with lower scores in Hunt-Hess or Fisher scale.

- by Przemyslaw M Waszak
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- Neurosurgery, Vascular neurology, Cerebral Aneurysms
- by Sotiris Veranis
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- Medicine, Cerebral Aneurysms
- by Adelia Sequeira
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- Mathematics, Computer Science, Optimal Control, Computational Fluid Dynamics

Three dimensional (3D) printed models represent innovative tools in anatomy teaching and surgical planning. The present study aimed at generating 3D skull models incorporating middle cerebral artery (MCA) aneurysms and in assessing their anatomical accuracy and utility as training and preoperative planning tools. Two aneurysm models were generated. Initially, a full skull (model A) and subsequently a half skull (model B) using white polyactic acid (PLA) filament incorporating two arterial networks with hard black PLA filament (in model A) and a softer semitransparent filament (in model B). The models were based on computed tomographic angiography (CTA) of a female patient suffering from bilateral unruptured middle cerebral aneurysms. Model A, a high contrast model, was designed for anatomical illustration purposes. Model B was designed to allow for clipping simulations. The anatomical accuracy of the two models compared to CTA was assessed by measuring their dimensions at the neck, proximal, distal branches and fundus, using an electronic micrometer. The utility of the models for the comprehension of the underlying anatomy, pathology and preoperative planning was evaluated by means of online questionnaires following clipping simulations conducted by neurosurgery residents and specialized neurosurgeons. Of the two 3D printed models generated, model B (clipping model) showed the highest degree of anatomical accuracy. The results of the online survey on the utility of the proposed models indicate that the majority of participants accepted the innovation with positive responses and approve the use of 3D printed aneurysm models for preoperative planning and resident training.

- by Sotiris Veranis
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- Cerebral Aneurysms
- by Marticela Cabeza-Morales
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- Neurology, Neurosurgery, Cerebral Aneurysms
- by Sujoy Banik
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- Neuroanesthesia, Cerebral Aneurysms, Avm and Aneurysm Surgery, Intracranial Volume

Several advances have been made in Data Assimilation techniques applied to blood flow modeling. Typically, idealized boundary conditions, only verified in straight parts of the vessel, are assumed. We present a general approach, based on a Dirichlet boundary control problem, that may potentially be used in different parts of the arterial system. The relevance of this method appears when computational reconstructions of the 3D domains, prone to be considered sufficiently extended, are either not possible, or desirable, due to computational costs. Based on taking a fully unknown velocity profile as the control, the approach uses a discretize then optimize methodology to solve the control problem numerically. The methodology is applied to a realistic 3D geometry representing a brain aneurysm. The results show that this DA approach may be preferable to a pressure control strategy, and that it can significantly improve the accuracy associated to typical solutions obtained using idealized velocity profiles.

- by Telma Guerra and +1
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- Optimal Control, Computational Fluid Dynamics, Data Assimilation, Mathematical Modelling

We carry out high-resolution laboratory experiments
and numerical simulations to investigate the dynamics
of unsteady vortex formation across the neck of an anatomic
in vitro model of an intracranial aneurysm. A transparent
acrylic replica of the aneurysm is manufactured and attached
to a pulse duplicator system in the laboratory. Time-resolved
three-dimensional three-component velocity measurements
are obtained inside the aneurysm sac under physiologic
pulsatile conditions. High-resolution numerical simulations
are also carried out under conditions replicating as closely as
possible those of the laboratory experiment. Comparison of
the measured and computed flow fields shows very good
agreement in terms of instantaneous velocity fields and threedimensional
coherent structures. Both experiments and
numerical simulations show that a well-defined vortical
structure is formed near the proximal neck at early systole.
This vortical structure is advected by the flow across the
aneurysm neck and impinges on the distal wall. The results
underscore the complexity of aneurysm hemodynamics and
point to the need for integrating high-resolution, timeresolved
three-dimensional experimental and computational
techniques. The current work emphasizes the importance of
vortex formation phenomena at aneurysmal necks and
reinforces the findings of previous computational work and
recent clinical studies pointing to links between flow pulsatility
and aneurysm growth and rupture.

- by Trung Le
- •
- Cerebral Aneurysms

Intracranial aneurysms carry risk of rupture with life threatening consequences. Hemodynamic forces are considered to be the key in cerebral aneurysm rupture. Notably, the hemodynamic analysis requires precise characterization of intra-aneurysmal blood velocity field, raising the need to develop novel measurement techniques. This study aims to assess the performance of speckle-based x-ray phase contrast particle imaging velocimetry (PIV) for velocity field mapping of a pulsatile blood flow in a patient specific aneurysm model without contrast agent. Porcine blood was used in a blood circulation loop including the aneurysm model, which was imaged using the synchrotron x-ray phase contrast imaging (PCI) at an optimum phase propagation distance. X-ray images were processed to improve speckle characteristics for PIV analysis. A computational fluid dynamic (CFD) model was developed for simulation of the blood velocity field and compared to the x-ray PCI-PIV measurements. The CFD model and x-ray PCI-PIV measurements showed similar intra-aneurysmal blood flow structures although the velocity magnitudes were generally higher in CFD model. Contrary to CFD model, x-ray PCI-PIV measurements revealed formation of blood cell stagnation at the aneurysm dome at low blood flow rate, cushioning upon the blood flow shear force. Synchrotron x-ray PCI-PIV offers potential for hemodynamic analysis in patient specific cerebral aneurysm models without contrast agent.

- by Mohammad Izadifar
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- 3D printing, Cardiovascular Imaging, Cerebral Aneurysms

The development of the frozen elephant trunk (FET) technique for a simplified treatment of complex lesions of the thoracic aorta originated as an evolution of the classic elephant trunk technique, described for the first time by Borst et al. [1] in 1983. Novel technologies and standardization of the surgical approach produced a progressive improvement of early and late outcomes. Most of the time and for specific indications, FET procedure allows physicians to treat lesions involving extensive portions of the thoracic aorta in one single step. Spinal cord injury remains one of the main complications of this procedure, even though spinal protection strategies have led to better results. We hereby report our opinions and recommendations based on our experience started in 2007.

- by Vessel Plus and +1
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- Aortic valve repair, Abdominal Aortic Aneurysms, Aortic Disease, Aortic Dissection
- by Rupendra Bahadur Adhikari
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- Neurosurgery, Nepal, Headache, CT scanning
- by Ahmed Mohamadin
- •
- Biochemistry, Neuroscience, Neurosurgery, Natural Products Chemistry

BACKGROUND AND PURPOSE: Flow diversion with the Pipeline Embolization Device is increasingly used for endovascular treatment of intracranial aneurysms due to high reported obliteration rates and low associated morbidity. While obliteration of covered branches in the anterior circulation is generally asymptomatic, this has not been studied within the posterior circulation. The aim of this study was to
evaluate the association between branch coverage and occlusion, as well as associated ischemic events in a cohort of patients with posterior circulation aneurysms treated with the Pipeline Embolization Device.
MATERIALS AND METHODS: A retrospective review of prospectively maintained databases at 8 academic institutions from 2009 to 2016
was performed to identify patients with posterior circulation aneurysms treated with the Pipeline Embolization Device. Branch coverage following placement was evaluated, including the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and posterior cerebral artery. If the Pipeline Embolization Device crossed the ostia of the contralateral vertebral artery, its long-term patency was assessed as well.
RESULTS: A cohort of 129 consecutive patients underwent treatment of 131 posterior circulation aneurysms with the Pipeline Embolization
Device. Adjunctive coiling was used in 40 (31.0%) procedures. One or more branches were covered in 103 (79.8%) procedures. At a median
follow-up of 11 months, 11% were occluded, most frequently the vertebral artery (34.8%). Branch obliteration was most common among asymptomatic aneurysms (P .001). Ischemic complications occurred in 29 (22.5%) procedures. On multivariable analysis, there was no significant difference in ischemic complications in cases in which a branch was covered (P .24) or occluded (P .16).
CONCLUSIONS: There was a low occlusion incidence in end arteries following branch coverage at last follow-up. The incidence was
higher in the posterior cerebral artery and vertebral artery where collateral supply is high. Branch occlusion was not associated with a
significant increase in ischemic complications.

- by Adam A Dmytriw and +2
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- Neurosurgery, Cerebrovascular diseases, Interventional Neuroradiology, Cerebral Aneurysms

Giant aneurysms are challenging lesions with unacceptable high rates of aneurysm recanalization and rerupture following embolization. Reliable in vivo models are urgently needed to test the performance of new more efficient endovascular... more

- by Gerhard Sommer
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- Neuroscience, Cognitive Science, Computational Fluid Dynamics, Biomechanics

Flow diversion with the Pipeline Embolization Device is increasingly used for endovascular treatment of intracranial aneurysms due to high reported obliteration rates and low associated morbidity. While obliteration of covered branches in the anterior circulation is generally asymptomatic, this has not been studied within the posterior circulation. The aim of this study was to evaluate the association between branch coverage and occlusion, as well as associated ischemic events in a cohort of patients with posterior circulation aneurysms treated with the Pipeline Embolization Device. A retrospective review of prospectively maintained databases at 8 academic institutions from 2009 to 2016 was performed to identify patients with posterior circulation aneurysms treated with the Pipeline Embolization Device. Branch coverage following placement was evaluated, including the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and posterior ...

Rupture risk assessment for intracranial aneurysms remains challenging, and risk factors, including wall shear stress, are discussed controversially. The primary purpose of the presented challenge was to determine how consistently aneurysm rupture status and rupture site could be identified on the basis of computational fluid dynamics. Two geometrically similar MCA aneurysms were selected, 1 ruptured, 1 unruptured. Participating computational fluid dynamics groups were blinded as to which case was ruptured. Participants were provided with digitally segmented lumen geometries and, for this phase of the challenge, were free to choose their own flow rates, blood rheologies, and so forth. Participants were asked to report which case had ruptured and the likely site of rupture. In parallel, lumen geometries were provided to a group of neurosurgeons for their predictions of rupture status and site. Of 26 participating computational fluid dynamics groups, 21 (81%) correctly identified the ...

- by Yildirim Suzen
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- Mechanical Engineering, Biomechanical Engineering, Biomedical Engineering, Humans
- by Rupendra Bahadur Adhikari
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- Neurosurgery, Neuroimaging, Japan, Skull Base Surgery

- by Simona Hodis
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- Mechanical Engineering, Biomechanical Engineering, Biomedical Engineering, Humans
- by Ahmed Mohamadin
- •
- Biochemistry, Neuroscience, Neurosurgery, Natural Products Chemistry
- by Ahmed A Elberry
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- Biochemistry, Neuroscience, Neurosurgery, Natural Products Chemistry
- by Ahmed A Elberry
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- Biochemistry, Neuroscience, Neurosurgery, Natural Products Chemistry

- by Nicolas Aristokleous and +2
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- Clinical Sciences, Cerebral Aneurysms, Neurosciences
- by Trung Le
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- Engineering, Humans, Computer Simulation, Cerebral Aneurysms

The role of hemodynamics in the growth of intracranial aneurysms is not completely clear. We present a hemodynamic study with two adjacent unruptured aneurysms arising from one parent artery but growing in different ways. This study aimed to investigate whether there were differences in hemodynamic characteristics between the two growing aneurysms. A 62-year-old female patient presented with six unruptured intracranial aneurysms. Catheter angiography at 6-month intervals revealed that two aneurysms located adjacently at the right posterior inferior cerebellar artery were growing over a 1-year period. Three-dimensional aneurysm geometries were acquired via rotational angiography. Computational fluid dynamic simulations were conducted on the 3D aneurysm geometries under patient-specific pulsatile flow conditions that were measured by magnetic resonance velocimetry. The proximal multilobular aneurysm demonstrated high flow and physiological levels of wall shear stress (WSS) in the regi...

- by Kenichi Funamoto and +1
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- Humans, Cerebellum, Hemodynamics, Female

Autosomal dominant polycystic kidney disease (ADPKD) is a common single gene hereditary disorder characterized by progressive development of bilateral renal cysts eventually leading to chronic kidney disease and an array of extrarenal abnormalities including intracranial aneurysm (ICAN). While the association of ICAN with ADPKD is undisputed, its management is not standardized. Conflicting data about the benefits of screening to the efficacy of different treatment modalities have not helped establish any opinion. We report three such cases managed surgically at Hiroshima University Hospital and discuss and review the literature regarding ADPKD and ICAN. Decision for surgical management of these cases were multifactorial and not exclusively because of ADPKD. There is a lack of sufficient randomized data on these topics and until such results are available, neurosurgeons are likely to resort to bit-part data and weigh the risk-benefit factor in individual patients and proceed accordingly.

- by Rupendra Bahadur Adhikari
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- Neurosurgery, Neuroimaging, Japan, Skull Base Surgery

We report the case of a 30-year-old hypertensive phenotypically female that was brought to our Acute and Emergency department obtunded with a Glasgow Coma Scale of 4/15. She developed acute subarachnoid rebleed, 43 days after the first one because of left posterior communicating artery non-traumatic saccular aneurysmal rupture. She had primary amenorrhea, poor secondary sexual characteristics, hypertension, and long- standing unexplained hypokalemia. Her work-up uncovered the presence of 46-XX karyotyping and 17-hydroylase deficiency. The pertinent medical literature does not mention an association between intracranial Berry aneurysmal formation and congenital adrenal hyperplasia due to 17-hydroxylase deficiency. To the best of our knowledge, this is the first-ever reported case.