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1.
World Neurosurg ; 137: 178, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31954914

RESUMO

We present the case of a 64-year-old male with a 5-day history of headaches. Magnetic resonance angiography revealed a 15 mm × 15 mm diameter aneurysm in the left middle cerebral artery arising in the region of the first branch of the middle cerebral artery-second branch of the middle cerebral artery (M2) bifurcation. Angiography revealed the lesion arose from the M2 vessel that contained a large amount of thrombus. Follow-up magnetic resonance angiography at 2 months revealed an enlargement of the lesion (16 mm × 17 mm), while a follow-up angiogram showed a decrease in the filling component of the lesion, suggesting further thrombosis. Given its rapid growth, endovascular and surgical options were considered and microsurgery was decided on. The aneurysm was accessed through the Sylvian fissure, and the M2 vessel was identified at the neck of the lesion where it entered and exited. We performed an intraaneurysmal thrombus evacuation to make the lesion clippable.1,2 We used a No. 11 blade and opened the dome away from the neck. Through this 3- to 4-mm incision, we inserted the tip of the ultrasonic aspirator device and used it to evacuate the thrombus in a circumferential fashion. This allowed for wall-to-wall apposition when deploying the aneurysm clip. A Sugita 15-mm clip (Mizuho America Inc., Los Angeles, California, USA) was used to obliterate the lesion. Both microvascular ultrasound and intraoperative angiography were used to confirm patency and flow distal to the aneurysm. In Video 1, we narrate the case and essential details of this approach. Neither Institutional Review Board nor patient consent was required to report this case with no identifiable patient information.


Assuntos
Aneurisma Intracraniano/cirurgia , Trombose Intracraniana/cirurgia , Microcirurgia/métodos , Artéria Cerebral Média/cirurgia , Procedimentos Neurocirúrgicos/métodos , Trombectomia/métodos , Angiografia Cerebral , Humanos , Aneurisma Intracraniano/diagnóstico por imagem , Trombose Intracraniana/diagnóstico por imagem , Angiografia por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Artéria Cerebral Média/diagnóstico por imagem , Instrumentos Cirúrgicos
2.
J Neurointerv Surg ; 7(7): 530-6, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24827066

RESUMO

BACKGROUND: It is thought that aneurysms evolve as the result of progressive degradation of the wall in response to abnormal hemodynamics characterized by either high or low wall shear stress (WSS). OBJECTIVE: To investigate the effects of these two different hemodynamic pathways in a series of cerebral aneurysms with known rupture sites. METHODS: Nine aneurysms in which the rupture site could be identified in three-dimensional images were analyzed. The WSS distribution was obtained from computational fluid dynamics (CFD) simulations. Internal wall stresses were computed using structural wall models under hemodynamic loads determined by the CFD models. Wall properties (thickness and stiffness) were modulated with the WSS distribution (increased or decreased in regions of high or low WSS) to test possible wall degradation pathways. Rupture probability indices (RPI) were calculated to compare different wall models. RESULTS: Most rupture sites aligned with the intrasaccular flow stream and downstream of the primary impaction zone. The model that best explained the rupture site (produced higher RPI) in eight of the nine aneurysms (89%) had thinner and stiffer walls in regions of abnormally high WSS. The remaining case (11%) was best explained by a model with thinner and stiffer walls in regions of abnormally low WSS. CONCLUSIONS: Aneurysm rupture seems to be caused by localized degradation and weakening of the wall in response to abnormal hemodynamics. Image-based computational models assuming wall thinning and stiffening in regions of abnormally high WSS were able to explain most of the observed rupture sites.


Assuntos
Aneurisma Roto/diagnóstico , Hemodinâmica , Imageamento Tridimensional/métodos , Aneurisma Intracraniano/diagnóstico , Modelos Cardiovasculares , Aneurisma Roto/fisiopatologia , Endotélio Vascular , Hemodinâmica/fisiologia , Humanos , Hidrodinâmica , Aneurisma Intracraniano/fisiopatologia
3.
Med Biol Eng Comput ; 52(10): 827-39, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25154981

RESUMO

The aim of this work was to determine whether or not Newtonian rheology assumption in image-based patient-specific computational fluid dynamics (CFD) cerebrovascular models harboring cerebral aneurysms may affect the hemodynamics characteristics, which have been previously associated with aneurysm progression and rupture. Ten patients with cerebral aneurysms with lobulations were considered. CFD models were reconstructed from 3DRA and 4DCTA images by means of region growing, deformable models, and an advancing front technique. Patient-specific FEM blood flow simulations were performed under Newtonian and Casson rheological models. Wall shear stress (WSS) maps were created and distributions were compared at the end diastole. Regions of lower WSS (lobulation) and higher WSS (neck) were identified. WSS changes in time were analyzed. Maximum, minimum and time-averaged values were calculated and statistically compared. WSS characterization remained unchanged. At high WSS regions, Casson rheology systematically produced higher WSS minimum, maximum and time-averaged values. However, those differences were not statistically significant. At low WSS regions, when averaging over all cases, the Casson model produced higher stresses, although in some cases the Newtonian model did. However, those differences were not significant either. There is no evidence that Newtonian model overestimates WSS. Differences are not statistically significant.


Assuntos
Hidrodinâmica , Imageamento Tridimensional , Aneurisma Intracraniano/fisiopatologia , Modelos Neurológicos , Reologia , Estresse Mecânico , Humanos , Fatores de Tempo , Análise de Ondaletas
4.
Int J Numer Method Biomed Eng ; 28(2): 214-28, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22548127

RESUMO

Hemodynamics is thought to be a fundamental factor in the formation, progression, and rupture of cerebral aneurysms. Understanding these mechanisms is important to improve their rupture risk assessment and treatment. In this study, we analyze the blood flow field in a growing cerebral aneurysm using experimental particle image velocimetry (PIV) and computational fluid dynamics (CFD) techniques. Patient-specific models were constructed from longitudinal 3D computed tomography angiography images acquired at 1-y intervals. Physical silicone models were constructed from the computed tomography angiography images using rapid prototyping techniques, and pulsatile flow fields were measured with PIV. Corresponding CFD models were created and run under matching flow conditions. Both flow fields were aligned, interpolated, and compared qualitatively by inspection and quantitatively by defining similarity measures between the PIV and CFD vector fields. Results showed that both flow fields were in good agreement. Specifically, both techniques provided consistent representations of the main intra-aneurysmal flow structures and their change during the geometric evolution of the aneurysm. Despite differences observed mainly in the near wall region, and the inherent limitations of each technique, the information derived is consistent and can be used to study the role of hemodynamics in the natural history of intracranial aneurysms.


Assuntos
Simulação por Computador , Hemodinâmica/fisiologia , Aneurisma Intracraniano/fisiopatologia , Modelos Cardiovasculares , Hemorreologia , Humanos , Masculino , Pessoa de Meia-Idade
5.
Int J Numer Method Biomed Eng ; 28(6-7): 801-8, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-25364852

RESUMO

Because of its ability to deal with any geometry, image-based computational fluid dynamics (CFD) has been progressively used to investigate the role of hemodynamics in the underlying mechanisms governing the natural history of cerebral aneurysms. Despite great progress in methodological developments and many studies using patient-specific data, there are still significant controversies about the precise governing processes and divergent conclusions from apparently contradictory results. Sorting out these issues requires a global vision of the state of the art and a unified approach to solving this important scientific problem. Towards this end, this paper reviews the contributions made using patient-specific CFD models to further the understanding of these mechanisms, and highlights the great potential of patient-specific computational models for clinical use in the assessment of aneurysm rupture risk and patient management.


Assuntos
Angiografia Cerebral/métodos , Circulação Cerebrovascular/fisiologia , Aneurisma Intracraniano/fisiopatologia , Simulação por Computador , Humanos , Hidrodinâmica
6.
Annu Rev Fluid Mech ; 41: 91-107, 2009 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-19784385

RESUMO

The initiation and progression of cerebral aneurysms are degenerative processes of the arterial wall driven by a complex interaction of biological and hemodynamic factors. Endothelial cells on the artery wall respond physiologically to blood-flow patterns. In normal conditions, these responses are associated with nonpathological tissue remodeling and adaptation. The combination of abnormal blood patterns and genetics predisposition could lead to the pathological formation of aneurysms. Here, we review recent progress on the basic mechanisms of aneurysm formation and evolution, with a focus on the role of hemodynamic patterns.

7.
J Eng Math ; 64(4): 367-378, 2009 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-19684874

RESUMO

Detailed knowledge of the hemodynamic conditions in normal cerebral arteries is important for a better understanding of the underlying mechanisms leading to the initiation and progression of cerebrovascular diseases. Information about the baseline values of hemodynamic variables such as wall shear stresses is necessary for comparison to pathological conditions such as in cerebral aneurysms or arterial stenoses. The purpose of this study was to compare the blood flow patterns in cerebral arteries of normal subjects determined by 4D phase-contrast magnetic resonance and image-based computational fluid dynamics techniques in order to assess their consistency and to highlight their differences. The goal was not to validate (or disprove) any of the two methodologies but rather to identify regions where disagreements are to be expected and to provide guidance when interpreting the data produced by each technique.

8.
Pediatr Neurol ; 38(2): 130-2, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18206795

RESUMO

Moyamoya disease is a rare cerebrovascular condition characterized by steno-occlusive disease of the major intracranial arteries at the base of the brain, and the appearance of innumerable, tiny, arterial collaterals that resemble a "puff of smoke." Although it has been associated with hematologic diseases such as sickle-cell disease, the association with other hemoglobinopathies is less frequently observed. We describe the association of a unique hemoglobinopathy (hemoglobin Fairfax) with beta-thalassemia and moyamoya disease in a 9-year-old girl with a history of stroke. To our knowledge, this is the first report of this unstable hemoglobin with moyamoya disease, and it emphasizes the potential for cerebral infarction due to the severe anemia of hemolytic disease.


Assuntos
Hemoglobinopatias/complicações , Hemoglobinas Anormais/metabolismo , Doença de Moyamoya/complicações , Talassemia beta/complicações , Anemia Hemolítica Congênita/etiologia , Angiografia , Isquemia Encefálica/etiologia , Artérias Carótidas/patologia , Criança , Feminino , Hemoglobinopatias/sangue , Hemoglobinopatias/patologia , Humanos , Imageamento por Ressonância Magnética , Doença de Moyamoya/sangue , Doença de Moyamoya/patologia , Acidente Vascular Cerebral/etiologia , Talassemia beta/sangue , Talassemia beta/patologia
9.
Surg Neurol ; 69(6): 627-32; discussion 632, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17976696

RESUMO

BACKGROUND: Perianeurysm edema is an uncommon complication of intracranial aneurysms, occurring mostly in giant aneurysms that suddenly thrombose. CASE DESCRIPTION: We present the first report of an unruptured, nongiant, saccular aneurysm that developed marked perianeurysm edema after embolization with Matrix2 coils. In this case, follow-up catheter angiography showed a new coil tail protruding beyond the dome of the aneurysm in the region of the most intense edema. CONCLUSIONS: We postulate that perianeurysm edema may occur after breakdown of the aneurysm wall accompanied by an inflammatory response to exposed bioactive coils. Clinicians should be aware of this potential complication and consider performing earlier surveillance angiography when this occurs to ensure that there has not been a shift in the coil mass and recurrence of the aneurysm.


Assuntos
Materiais Biocompatíveis/efeitos adversos , Edema Encefálico/etiologia , Embolização Terapêutica/efeitos adversos , Embolização Terapêutica/instrumentação , Aneurisma Intracraniano/terapia , Ácido Láctico/efeitos adversos , Ácido Poliglicólico/efeitos adversos , Adulto , Edema Encefálico/diagnóstico por imagem , Edema Encefálico/terapia , Feminino , Humanos , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Radiografia
10.
Acad Radiol ; 14(7): 804-13, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17574131

RESUMO

RATIONALE AND OBJECTIVE: The purpose of this study is to determine whether computational fluid dynamics modeling can correctly predict the location of the major intra-aneurysmal flow structures that can be identified by conventional angiography. MATERIALS AND METHODS: Patient-specific models of three cerebral aneurysms were constructed from three-dimensional rotational angiography images and computational fluid dynamic simulations performed. Using these velocity fields, contrast transport was simulated and visualizations constructed to provide a "virtual" angiogram. These models were then compared to images from high frame rate conventional angiography to compare flow structures. RESULTS: Computational fluid dynamics simulations showed three distinct flow types ranging from simple to complex. Virtual angiographic images showed good agreement with images from conventional angiography for all three aneurysms with analogous size and orientation of the inflow jet, regions of impaction, and flow type. Large intra-aneurysmal vortices and regions of outflow also corresponded between the images. CONCLUSIONS: Patient-specific image-based computational models of cerebral aneurysms can realistically reproduce the major intra-aneurysmal flow structures observed with conventional angiography. The agreement between computational models and angiographic structures is less for slower zones of recirculation later in the cardiac cycle.


Assuntos
Angiografia Cerebral/métodos , Simulação por Computador , Hemorreologia/métodos , Aneurisma Intracraniano/diagnóstico , Modelos Biológicos , Angiografia Digital/métodos , Circulação Cerebrovascular , Meios de Contraste/administração & dosagem , Humanos , Aumento da Imagem/métodos , Imageamento Tridimensional/métodos , Angiografia por Ressonância Magnética , Valor Preditivo dos Testes , Fluxo Pulsátil , Reprodutibilidade dos Testes
11.
J Comput Assist Tomogr ; 30(4): 646-8, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16845297

RESUMO

Spontaneous dissection of the internal carotid artery is an increasingly recognized condition that is readily identifiable with magnetic resonance imaging and -angiography. Early recognition of this entity is essential for optimizing medical management and avoiding potential cerebral infarction. We present a case of dissection of the internal carotid artery that occurred during magnetic resonance imaging and describe the immediate imaging characteristics.


Assuntos
Dissecação da Artéria Carótida Interna/diagnóstico , Imageamento por Ressonância Magnética , Idoso , Feminino , Humanos , Angiografia por Ressonância Magnética
12.
Acad Radiol ; 13(7): 811-21, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16777554

RESUMO

RATIONALE AND OBJECTIVES: Previous studies of aneurysm flow dynamics based on three-dimensional (3D) rotational angiography (RA) images were limited to aneurysms with a single route of blood inflow. However, aneurysms of the circle of Willis frequently involve locations with more than one source of inflow, such as aneurysms of the anterior communicating artery. The highest resolution images of cerebral vessels are from RA images, but this technique is limited to visualizing only one route of inflow at a time, leaving a significant limitation in the application of 3DRA image sets for clinical studies of patient-specific computational fluid dynamics (CFD) simulations. In this report, subject-specific models of cerebral aneurysms with multiple avenues of flow are constructed from RA images by using a novel combination of image co-registration and surface merging techniques. MATERIALS AND METHODS: RA images are obtained by means of contrast injection in each vessel that provides inflow to the aneurysm. Anatomic models are constructed independently of each of these vascular trees and fused together into a single model. The model is used to construct a finite element grid for CFD simulations of hemodynamics. RESULTS: Three examples of patient-specific models are presented: an anterior communicating artery aneurysm, a basilar tip aneurysm, and a model of an entire circle of Willis with five coincident aneurysms. The method is evaluated with a numeric phantom of an aneurysm in the anterior communicating artery. CONCLUSION: These examples show that this new technique can be used to create merged network numeric models for CFD modeling. Furthermore, intra-aneurysmal flow patterns are influenced strongly by merging of the two inflow streams. This effect decreases as distance from the merging streams increases.


Assuntos
Artérias Cerebrais/fisiopatologia , Circulação Cerebrovascular , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional , Aneurisma Intracraniano/diagnóstico , Angiografia por Ressonância Magnética/métodos , Adulto , Velocidade do Fluxo Sanguíneo , Artérias Cerebrais/patologia , Círculo Arterial do Cérebro/patologia , Círculo Arterial do Cérebro/fisiopatologia , Feminino , Humanos , Aneurisma Intracraniano/fisiopatologia , Angiografia por Ressonância Magnética/instrumentação , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Estudos Retrospectivos , Rotação
13.
Neurosurgery ; 58(4): 602-11; discussion 602-11, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16575323

RESUMO

OBJECTIVE: Embolization is an important therapeutic modality in the multidisciplinary management of arteriovenous malformations (AVM); however, prior series have reported a wide variability in overall complication rates caused by embolization (10-50% neurological deficit, 1-4% mortality). In this study, we reviewed our experience with AVM embolization and analyzed factors that might predict complications and clinical outcomes after AVM embolization. METHODS: We analyzed our combined neurovascular unit's results with AVM embolization from 1993 to 2004 for the following outcomes measures: 1) clinically significant complications, 2) technical complications without clinical sequelae, 3) discharge Glasgow Outcome Scale score, and 4) death. To determine embolization efficacy, we analyzed perioperative blood transfusion and rate of AVM obliteration. Univariate and multivariate analyses were performed for patient age, sex, history of rupture, history of seizure, associated aneurysms, AVM size, deep venous drainage, eloquent location, Spetzler-Martin grade, number of embolization stages, number of pedicles embolized, and primary treatment modality. RESULTS: Over an 11 year period, 295 embolization procedures (761 pedicles embolized) were performed in 168 patients with embolization as the primary treatment modality (n = 16) or as an adjunct to surgery (n = 124) or radiosurgery (n = 28). There were a total of 27 complications in this series, of which 11 were clinically significant (6.5% of patients, 3.7% per procedure), and 16 were technical complications (9.5% of patients, 5.4% per procedure). Excellent or good outcomes (Glasgow Outcome Scale > or = 4) were observed in 152 (90.5%) patients. Unfavorable outcomes (Glasgow Outcome Scale 1-3) as a direct result of embolization were both 3.0% at discharge and at follow-up, with a 1.2% embolization-related mortality. In the 124 surgical patients, 96.8% had complete AVM obliteration after initial resection, and 31% received perioperative transfusion (mean 1.4 units packed red blood cells per surgical patient). Predictors of unfavorable outcome caused by embolization by univariate analysis were deep venous drainage (P < 0.05), Spetzler-Martin Grade III to V (P < 0.05), and periprocedural hemorrhage (P < 0.0001) and by multivariate analysis were Spetzler-Martin III to V (odds ratio 10.6, P = 0.03) and periprocedural hemorrhage (odds ratio 17, P = 0.004). CONCLUSION: In a single-center, retrospective, nonrandomized study, 90.5% of patients had excellent or good outcomes after AVM embolization, with a complication rate lower than previously reported. Spetzler-Martin grade III to V and periprocedural hemorrhage were the most important predictive factors in determining outcome after embolization.


Assuntos
Embolização Terapêutica/efeitos adversos , Embolização Terapêutica/estatística & dados numéricos , Malformações Arteriovenosas Intracranianas/mortalidade , Malformações Arteriovenosas Intracranianas/terapia , Adolescente , Adulto , Idoso , Criança , Intervalos de Confiança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Valor Preditivo dos Testes , Estudos Retrospectivos , Resultado do Tratamento
14.
AJNR Am J Neuroradiol ; 26(10): 2550-9, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16286400

RESUMO

BACKGROUND AND PURPOSE: Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. This report describes a pilot clinical study of the association between intra-aneurysmal hemodynamic characteristics from computational fluid dynamic models and the rupture of cerebral aneurysms. METHODS: A total of 62 patient-specific models of cerebral aneurysms were constructed from 3D angiography images. Computational fluid dynamics simulations were performed under pulsatile flow conditions measured on a normal subject. The aneurysms were classified into different categories, depending on the complexity and stability of the flow pattern, the location and size of the flow impingement region, and the size of the inflow jet. The 62 models consisted of 25 ruptured and 34 unruptured aneurysms and 3 cases with unknown histories of hemorrhage. The hemodynamic features were analyzed for associations with history of rupture. RESULTS: A large variety of flow patterns was observed: 72% of ruptured aneurysms had complex or unstable flow patterns, 80% had small impingement regions, and 76% had small jet sizes. By contrast, unruptured aneurysms accounted for 73%, 82%, and 75% of aneurysms with simple stable flow patterns, large impingement regions, and large jet sizes, respectively. Aneurysms with small impingement sizes were 6.3 times more likely to have experienced rupture than those with large impingement sizes (P = .01). CONCLUSIONS: Image-based patient-specific numeric models can be constructed in an efficient manner that allows clinical studies of intra-aneurysmal hemodynamics. A simple flow characterization system was proposed, and interesting trends in the association between hemodynamic features and aneurysmal rupture were found. Simple stable patterns, large impingement regions, and jet sizes were more commonly seen with unruptured aneurysms. By contrast, ruptured aneurysms were more likely to have disturbed flow patterns, small impingement regions, and narrow jets.


Assuntos
Aneurisma Roto/fisiopatologia , Circulação Cerebrovascular/fisiologia , Aneurisma Intracraniano/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Aneurisma Roto/classificação , Artéria Carótida Interna/diagnóstico por imagem , Artéria Carótida Interna/fisiologia , Angiografia Cerebral , Feminino , Hemodinâmica/fisiologia , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Aneurisma Intracraniano/classificação , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Artéria Cerebral Média/diagnóstico por imagem , Artéria Cerebral Média/fisiologia , Projetos Piloto , Interpretação de Imagem Radiográfica Assistida por Computador , Fluxo Sanguíneo Regional/fisiologia , Fatores de Risco
15.
IEEE Trans Med Imaging ; 24(4): 457-67, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15822804

RESUMO

Hemodynamic factors are thought to be implicated in the progression and rupture of intracranial aneurysms. Current efforts aim to study the possible associations of hemodynamic characteristics such as complexity and stability of intra-aneurysmal flow patterns, size and location of the region of flow impingement with the clinical history of aneurysmal rupture. However, there are no reliable methods for measuring blood flow patterns in vivo. In this paper, an efficient methodology for patient-specific modeling and characterization of the hemodynamics in cerebral aneurysms from medical images is described. A sensitivity analysis of the hemodynamic characteristics with respect to variations of several variables over the expected physiologic range of conditions is also presented. This sensitivity analysis shows that although changes in the velocity fields can be observed, the characterization of the intra-aneurysmal flow patterns is not altered when the mean input flow, the flow division, the viscosity model, or mesh resolution are changed. It was also found that the variable that has the greater impact on the computed flow fields is the geometry of the vascular structures. We conclude that with the proposed modeling pipeline clinical studies involving large numbers cerebral aneurysms are feasible.


Assuntos
Velocidade do Fluxo Sanguíneo , Angiografia Cerebral/métodos , Imageamento Tridimensional/métodos , Aneurisma Intracraniano/diagnóstico por imagem , Aneurisma Intracraniano/fisiopatologia , Modelos Cardiovasculares , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Algoritmos , Pressão Sanguínea , Viscosidade Sanguínea , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Encéfalo/fisiopatologia , Simulação por Computador , Humanos , Aumento da Imagem/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
J Stroke Cerebrovasc Dis ; 14(2): 80-7, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-17904005

RESUMO

The recent failure of many clinical trials of neuroprotective compounds may be due in part to poor animal models of human stroke. We have developed an endovascular stroke model in nonhuman primates that is compatible with serial magnetic resonance imaging (MRI) monitoring. Using cynomologous macaques (n = 4), a microcatheter was navigated transarterially (under fluoroscopic guidance) from the femoral artery to the middle cerebral artery (MCA). The microcatheter was wedged in a branch of the MCA for 3 hours to cause focal cerebral ischemia, as verified angiographically. During occlusion and/or reperfusion, animals were scanned with MRI, and imaging findings were compared with the stained brain sections. All animals demonstrated small stroke lesions in the expected vascular territory, as seen on diffusion-weighted MRI and confirmed by postmortem examination. Reperfusion after 3 hours was confirmed angiographically (n = 2) and also by MRI (n = 4). The mean initial lesion volume, measured on the postreperfusion MRI scans, was 2.3 +/- 1.3 mL (n = 4). There was good agreement between anatomic location of the lesion on MRI and postmortem histological staining (n = 3). A "minimally invasive" primate model of focal cerebral ischemia was developed that is ideally suited to MRI studies of both acute and chronic stroke. By using serial MRI scans to measure changes in lesion size over time, we will be able to control for variability in lesion size/location. This model should prove useful as a test bed for new stroke therapies, in which noninvasive imaging findings are readily comparable to human stroke.

17.
AJNR Am J Neuroradiol ; 24(7): 1421-8, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12917140

RESUMO

BACKGROUND AND PURPOSE: Several approaches to the treatment of dissecting aneurysms of the vertebrobasilar system have been used. We evaluated our endovascular experience, which includes trapping and proximal occlusion. METHODS: Thirty-five patients with intradural vertebrobasilar dissecting aneurysms presented to our institution between 1992 and 2002. Twenty-six were treated by endovascular means and two with surgery. In the endovascular group, 14 were in a supra-posterior inferior cerebellar artery (PICA) location, and three of these extended to the vertebrobasilar junction on the initial angiogram. Ten were located in an infra-PICA location, or no antegrade flow was seen in the PICA or anterior spinal artery. Two were located at the PICA with antegrade flow preserved in the branch. Twelve lesions were treated with trapping; another 14 were initially treated with proximal occlusion techniques, two of which eventually required trapping procedures. Follow-up images were obtained within 1 year of initial treatment in 24 patients. Mean follow-up for these patients was 3.5 years. RESULTS: Initial treatments were technically successful and without complication in all 26 patients. Follow-up examinations showed complete cure in 19 of 24 patients. One patient died of global ischemia after presenting as Hunt and Hess grade 5 with subarachanoid hemorrhage. Two recurrent hemorrhages occurred in patients in the proximal occlusion group; one died, and the other underwent a trapping procedure. One patient developed contralateral vertebral dissection 24 hours after occlusion of a dissecting aneurysm of the dominant vertebral artery and died of a brain stem infarct. Another died of probable vasospasm, and the last died of an unknown cause 1 month after treatment. Two patients had recanalization despite an initial trapping procedure, both underwent further treatment. Mortality rate was 20% in the treated group (including the two patients treated surgically), with four of five deaths occurring during the initial hospital course. Mortality rate was 50% in the six patients in the untreated group who were available for follow-up. CONCLUSION: Dissecting aneurysms of the vertebrobasilar system remain high-risk lesions because of their natural history. They can be managed by endovascular methods according to aneurysm location, configuration, collateral circulation, and time of presentation. Trapping results in better prevention of rehemorrhage. Proximal occlusion can achieve occlusion without manipulation of the affected segment when more direct endovascular occlusion or stent placement cannot be performed.


Assuntos
Dissecção Aórtica/terapia , Aneurisma Intracraniano/terapia , Procedimentos Cirúrgicos Vasculares , Dissecação da Artéria Vertebral/terapia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Dissecção Aórtica/diagnóstico , Dissecção Aórtica/mortalidade , Artérias/patologia , Artérias/cirurgia , Oclusão com Balão , Cerebelo/diagnóstico por imagem , Cerebelo/patologia , Cerebelo/cirurgia , Angiografia Cerebral , Feminino , Seguimentos , Humanos , Aneurisma Intracraniano/diagnóstico , Aneurisma Intracraniano/mortalidade , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Recidiva , Estudos Retrospectivos , Hemorragia Subaracnóidea/diagnóstico , Hemorragia Subaracnóidea/mortalidade , Hemorragia Subaracnóidea/terapia , Análise de Sobrevida , Tomografia Computadorizada por Raios X , Resultado do Tratamento , Dissecação da Artéria Vertebral/diagnóstico , Dissecação da Artéria Vertebral/mortalidade
18.
Neurosurgery ; 52(4): 732-8; discussion 738-9, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12657168

RESUMO

OBJECTIVE: Intracranial residual and recurrent aneurysms can occur after surgical clipping, with risks of growth and rupture. In the past, surgical reoperation, which can be associated with higher risk than the initial operation, was the only available treatment. A combined neurovascular team that uses both surgical and endovascular therapies could maximize efficacy and outcomes while minimizing risks in these difficult cases. The indications for which surgical or endovascular treatment should be used to treat patients with residual or recurrent aneurysms, however, have not been elucidated well. We have reviewed the 10-year experience of our combined neurovascular team to determine in a retrospective manner which factors were important to treatment modality selection for patients with these residual and recurrent lesions. METHODS: From 1991 to 2001, the combined neurovascular unit at the Massachusetts General Hospital treated 25 residual and recurrent previously clipped aneurysms (15 had been clipped at other centers). Only patients in whom a clip had been placed were included in the study; patients who did not have a clip placed or whose aneurysms were wrapped or coated were excluded. The radiographic studies and clinical data were reviewed retrospectively to determine the efficacy, outcomes, and factors important to the selection of treatment strategy in these patients. RESULTS: The patients' clinical presentations were radiographic follow-up, 17 patients; rehemorrhage, 3; mass effect, 3; and thromboembolism, 2. The mean aneurysm recurrence or residual size was 11 mm (range, 4-26 mm). The mean interval until representation was 6.6 years (range, 1 wk-25 yr). Treatment consisted of: coiling, 11 patients; reclipping, 8; proximal parent vessel balloon occlusion, 2; extracranial-intracranial bypass with coil occlusion of aneurysm and parent vessel, 2; extracranial-intracranial bypass with clip trapping, 1; and extracranial-intracranial bypass with proximal clip occlusion of parent vessel, 1. The mean radiographic follow-up period was 11 months. Complete angiographic occlusion was found in 19 aneurysms (76%), at least 90% occlusion was found in 4 aneurysms (16%), intentional partial coil obliteration was found in 1 fusiform lesion (4%), and intentional retrograde flow was found in 1 fusiform lesion (4%). Clinical outcomes were excellent or good in 19 patients (76%). Twenty-one patients (84%) were neurologically the same after retreatment (13 remained neurologically intact, and 8 had preexisting neurological deficits that did not change). Three patients (12%) had new neurological deficits after retreatment, and one patient (4%) died. There were four complications of retreatment (16%), one of which was a fatal hemorrhage in a patient 1 month after intentional partial coil obliteration of a fusiform vertebrobasilar junction aneurysm. Factors important to the selection of treatment modality were recurrence or residual location (all posterior circulation lesions were treated endovascularly), lesion size (lesions larger than 10 mm were treated endovascularly or with the use of combined techniques), and aneurysm morphology (fusiform and wide-necked lesions were treated endovascularly or with the use of combined techniques). CONCLUSION: The proper selection of surgical or endovascular treatment for residual and recurrent previously clipped aneurysms can achieve excellent radiographic efficacy with low mortality. Factors important to the selection of treatment by this combined neurovascular team were posterior circulation location, aneurysm size larger than 10 mm, and fusiform morphology, which were treated endovascularly or with the use of combined techniques because of the higher surgical risk associated with these factors. For aneurysms with lower surgical risk, such as some anterior circulation aneurysms and aneurysms smaller than 10 mm, we prefer to perform a reoperation because of superior radiographic cure without compromising the outcome.


Assuntos
Embolização Terapêutica , Aneurisma Intracraniano/cirurgia , Equipe de Assistência ao Paciente , Complicações Pós-Operatórias/cirurgia , Adulto , Idoso , Angiografia Cerebral , Revascularização Cerebral , Terapia Combinada , Feminino , Seguimentos , Humanos , Aneurisma Intracraniano/diagnóstico , Aneurisma Intracraniano/mortalidade , Masculino , Pessoa de Meia-Idade , Exame Neurológico , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/mortalidade , Recidiva , Reoperação/métodos , Reoperação/mortalidade , Estudos Retrospectivos , Instrumentos Cirúrgicos , Taxa de Sobrevida
19.
J Neurosurg ; 96(2 Suppl): 162-7, 2002 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12450278

RESUMO

OBJECT: Although the pathophysiology of spinal dural arteriovenous fistulas (AVFs) has recently been elucidated, the optimal treatment strategy for these lesions has yet to be defined. Current management techniques include endovascular embolization or microsurgical obliteration. METHODS: The authors reviewed the records and angiograms of all patients with spinal dural AVFs treated at Massachusetts General Hospital over a 6-year period (1992-1998). During this period, it was intended initially to treat all patients with embolization and to reserve surgery for those in whom endovascular treatment failed or in cases in which pretreatment evaluation suggested that endovascular therapy would be ineffective or unsafe. A total of 26 patients with spinal dural AVFs were treated: there were 22 men and 4 women with a mean age of 65 years (range 39-79 years). Lesions were located in the following areas: five in foramen magnum/cervical, 13 in thoracic, five in lumbar, and three in sacral. Twenty-three (88%) of 26 patients underwent embolization and three (12%) of 23 patients underwent surgery as the primary mode of treatment. Of the 23 patients in whom embolization was performed or attempted, nine (39%) ultimately required surgery. All patients were stabilized or improved following definitive treatment, as assessed by the Aminoff-Logue scores. There was one death secondary to a myocardial infarction. CONCLUSIONS: These data demonstrate that endovascular therapy can be successful as an initial treatment for the majority of patients; however, there is a 39% failure rate, which is not observed following surgical therapy. Once a definitive therapy has been achieved using either technique virtually all patients are either stabilized or improved.


Assuntos
Malformações Vasculares do Sistema Nervoso Central/terapia , Embolização Terapêutica , Procedimentos Neurocirúrgicos , Medula Espinal/irrigação sanguínea , Adulto , Idoso , Embolização Terapêutica/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Procedimentos Neurocirúrgicos/efeitos adversos , Retratamento , Falha de Tratamento , Resultado do Tratamento
20.
Neurosurgery ; 51(1): 14-21; discussion 21-2, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12182412

RESUMO

OBJECTIVE: Posterior circulation aneurysms can be difficult lesions to treat surgically, and they have potential for high morbidity and mortality, particularly in elderly patients or those in poor neurological condition. In an effort to improve outcomes, our combined neurosurgical and neuroendovascular unit has used both surgical clipping and endovascular coiling techniques to treat posterior circulation aneurysms. Patients considered at high risk for surgery were managed with endovascular treatment. METHODS: From 1990 to 1998, 197 posterior circulation aneurysms in 189 patients were treated in our combined neurovascular unit. Of these aneurysms, 128 were ruptured, 63 were unruptured, and 6 had a distant history of rupture in patients who came to our center for delayed or repeat treatment. A total of 132 aneurysms were treated with surgical clipping (85 ruptured, 46 unruptured, and 1 with distant history of rupture) and 65 aneurysms were treated with endovascular coiling (43 ruptured, 17 unruptured, and 5 with distant history of rupture). Dissecting aneurysms of the vertebral or posteroinferior cerebellar arteries or aneurysms treated with proximal (Hunterian) occlusion were excluded from this analysis. Surgical risk was assessed using a previously described system (Massachusetts General Hospital [MGH] grade), which incorporates age, Hunt and Hess grade, size of lesion, and Fisher grade. RESULTS: Overall clinical outcomes at 1 year of follow-up were 77.2% excellent or good, 10.2% fair, 4.1% poor, and 8.6% dead. Surgical treatment resulted in 95.6% complete aneurysm occlusion and 4.4% with residual aneurysm after surgical treatment, whereas endovascular treatment resulted in 32.3% complete occlusion, 26.2% with residual aneurysm, and 41.5% with partial occlusion. In most cases, however, treatment with Guglielmi detachable coils (Boston Scientific/Target, Fremont, CA) was performed for palliation rather than complete radiographic occlusion. Outcome was closely associated with MGH grade with either treatment modality. Excellent/good outcomes were achieved in 96, 92.3, 82.9, 46.2, and 0% of surgically treated patients with MGH Grades of 0, 1, 2, 3, and 4, respectively. In comparison, excellent/good outcomes were achieved in 100, 84.2, 61.9, 0, and 50% of endovascularly treated patients with MGH Grades of 0, 1, 2, 3, and 4, respectively. CONCLUSION: A combined surgical and endovascular approach to posterior circulation aneurysms can achieve good outcomes in high-risk surgical patients treated by use of coiling techniques.


Assuntos
Aneurisma Roto/cirurgia , Cerebelo/irrigação sanguínea , Embolização Terapêutica , Aneurisma Intracraniano/cirurgia , Instrumentos Cirúrgicos , Artéria Vertebral/cirurgia , Aneurisma Roto/diagnóstico por imagem , Aneurisma Roto/mortalidade , Angiografia Cerebral , Terapia Combinada , Feminino , Seguimentos , Humanos , Aneurisma Intracraniano/diagnóstico por imagem , Aneurisma Intracraniano/mortalidade , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/diagnóstico por imagem , Complicações Pós-Operatórias/mortalidade , Complicações Pós-Operatórias/cirurgia , Reoperação , Estudos Retrospectivos , Taxa de Sobrevida , Artéria Vertebral/diagnóstico por imagem
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