Unruptured Middle Cerebral Artery Bifurcation Research Articles

Numerical investigation of unruptured middle cerebral artery bifurcation aneurysms: influence of aspect ratio

An aneurysm is a disease condition, which is due to the pathological weakening of an arterial wall. These aneurysms are often found in various branch points and bifurcations of an artery in the cerebral circulation. Most aneurysms come to medical attention, either due to brain hemorrhages caused by rupture or found unruptured. To consider surgically invasive treatment modalities, clinicians need scientific methods such as, hemodynamic analysis to assess rupture risk. The arterial wall loses its structural integrity when wall shear stress (WSS) and other hemodynamic parameters exceed a certain threshold. In the present study, numerical simulations are carried out for unruptured middle cerebral artery (MCA) aneurysms. Three distinct representative sizes are chosen from a larger patient pool of 26 MCA aneurysms. Logically, these aneurysms represent three growth stages of any patient with similar anatomical structure. Simulations are performed to compare the three growth phases (with different aspect ratios) of an aneurysm and correlate their hemodynamic parameters. Simulations with patient specific boundary conditions reveal that, aneurysms with a higher aspect ratio (AR) correspond to an attendant decrease in both time-averaged wall shear stress (TAWSS) and spatial wall shear stress gradients (WSSG). Smaller MCAs were observed to have higher positive wall shear stress divergence (WSSD), exemplifying the tensile nature of arterial wall stretching. Present study identifies positive wall shear stress divergence (PWSSD) to be a potential biomarker for evaluating the growth of an aneurysm.

Brain aneurysm rupture during mechanical thrombectomy for large vessel occlusion: Technical case series and complication avoidance strategies.

Endovascular therapy became the mainstream treatment for patients with acute stroke due to emergent large vessel occlusion (LVO). With increasing number of interventions, it is not uncommon for incidental vascular pathologies to be found during mechanical thrombectomy. Overall, intracranial aneurysms can occur in up to 4% of the population, but previous studies suggest a slightly higher prevalence of intracranial aneurysms in stroke patients as they may share common risk factors. We report on three patients with acute stroke secondary to LVO undergoing mechanical thrombectomy with brain aneurysms incidentally discovered and discuss the potential implications and technical considerations of performing revascularization in these scenarios. In the first case, a patient treated with stent-retriever and aspiration developed a carotid-cavernous fistula without clinical repercussion. The second case illustrates an internal carotid artery posterior communicating segment aneurysm rupture with a massive subarachnoid hemorrhage. The third case exemplifies an unruptured middle cerebral artery bifurcation aneurysm related to an M2 occlusion managed with a different strategy, avoiding aneurysm rupture. Intraprocedural aneurysm rupture is a potential complication during mechanical thrombectomy, especially when anatomical challenges are present. Interventionalists should be aware of the potential risk and constraints in this setting in order to mitigate adverse events.

Correction: Efficacy and safety of endovascular therapy versus surgical clipping for patients with unruptured middle cerebral artery bifurcation aneurysms.

Correction: Efficacy and safety of endovascular therapy versus surgical clipping for patients with unruptured middle cerebral artery bifurcation aneurysms.

Efficacy and safety of endovascular therapy versus surgical clipping for patients with unruptured middle cerebral artery bifurcation aneurysms

This study aims to evaluate the efficacy and safety of endovascular therapy versus neurosurgical clipping carried out for patients with unruptured middle cerebral artery bifurcation aneurysms (MCABAs). Patients diagnosed with...

Outflow angle: a risk factor for thromboembolic complications in coil embolisation for treating unruptured middle cerebral artery bifurcation aneurysms.

Thromboembolic complications are a relevant risk in coil embolisation of cerebral aneurysms. This retrospective study aimed to assess the treatment outcomes of unruptured middle cerebral artery (MCA) bifurcation aneurysms and the predictors for thromboembolic complications based on the aneurysm morphological characteristics. We examined the following three features: inflow angle, outflow angle (OA), and bifurcation angle, formed by the aneurysm and neighbouring blood vessels. A total of 32 MCA bifurcation aneurysms were retrospectively investigated in 32 patients treated consecutively at our institute between April 2008 and March 2019. The predictors for thromboembolic complications were analysed in two groups: patients with and without thromboembolic complications. Perioperative thromboembolic complications were detected in six patients (18.8%), including two and six intra- and post-procedural thromboembolic complications, respectively; all cases were resolved. Regarding the aneurysms' morphological characteristics, the group with thromboembolic complications showed a significantly smaller OA (55.58° ± 14.05° vs. 86.04° ± 28.58°, P = 0.01) than the group without complications. Multivariate analysis revealed that smoking habits and OA < 70° were significant predictors of thromboembolic complications (smoking habits: P = 0.01, odds ratio [OR]: 6.89, 95% confidence interval [CI]: 3.78-12.62; OA < 70°: P = 0.04, OR: 3.19, 95% CI: 1.52-6.56). Our findings indicate significant pre-procedural predictors of thromboembolic complications to consider for safe treatment; clipping should be preferred to coil embolisation in high-risk patients. The method of choice should be considered in each case to allow the safe treatment of unruptured MCA aneurysms.

Microsurgical Clipping versus Advanced Endovascular Treatment of Unruptured Middle Cerebral Artery Bifurcation Aneurysms After a “Coil-First” Policy

Although intracranial aneurysms are increasingly treated endovascularly, microsurgical clipping has been the standard approach for middle cerebral artery (MCA) aneurysms. We compared microsurgical clipping and state-of-the-art endovascular treatment of unruptured MCA bifurcation aneurysms treated at a neurovascular center following a "coil-first" policy. This single-center study included 148 patients treated for 160 unruptured MCA bifurcation aneurysms. Technical success, complications, clinical outcome, and angiographic results were retrospectively compared. Microsurgical clipping was performed for 120 MCA aneurysms (75%) and endovascular treatment for 40 (25%; conventional coiling: 8, stent-assisted coiling: 16, balloon-assisted coiling: 3, and flow-disruption: 13). Technical treatment success was higher in the clipping group (100%) than in the endovascular group (92.5%, P= 0.015). Overall, complications occurred in 16.7% for clipping and in 20.0% for endovascular treatment (P= 0.631). Major ischemic stroke rates were 4.2% in the clipping group and 7.5% in the endovascular group (P= 0.414). At 6 months, a favorable outcome was obtained by 99.2% after clipping and 95.0% after endovascular treatment (P= 0.154). The 6-month complete aneurysm occlusion rates were by trend higher in the clipping group (89.2%) than in the endovascular group (75.9%, P= 0.078). Microsurgical clipping was associated with a higher technical success rate and tendentially higher complete occlusion than endovascular treatment, with no additional morbidity and similar clinical outcome. On the basis of these results, clipping proves to be the standard treatment option for MCA bifurcation aneurysms. However, endovascular treatment represents a safe and efficient alternative treatment option for patients.

Surgical treatment of unruptured middle cerebral artery bifurcation aneurysms: long-term retrospective single center study

Surgical treatment of unruptured middle cerebral artery bifurcation aneurysms: long-term retrospective single center study

Hemodynamic Features of Microsurgically Identified, Thin-Walled Regions of Unruptured Middle Cerebral Artery Aneurysms Characterized Using Computational Fluid Dynamics.

Thin-walled regions (TWRs) of aneurysm surfaces observed in microscopic surgery are thought to be vulnerable areas for growth and rupture of unruptured intracranial aneurysms (UIAs). To identify hemodynamic features of TWRs of aneurysms by using computational fluid dynamics (CFD) analyses of unruptured middle cerebral artery bifurcation (MCAB) aneurysms. Nine patients with 11 MCAB aneurysms were enrolled, and their TWRs were identified. CFD analysis was performed using 3 parameters: pressure, wall shear stress (WSS), and WSS divergence (WSSD). Each parameter was evaluated for its correspondence with TWR. Among 11 aneurysms, 15 TWRs were identified. Corresponding matches with CFD parameters (pressure, WSS, and WSSD) were 73.33, 46.67, and 86.67%, respectively. WSSD, a hemodynamic parameter that accounts for both magnitude and directionality of WSS, showed the highest correspondence. High WSSD might correspond with TWR of intracranial aneurysms, which are likely high-risk areas for rupture.

Use of a neck-bridging device for endovascular coiling of a wide-necked middle cerebral artery aneurysm

Endovascular treatment of wide-necked bifurcation intracranial aneurysms is technically challenging, often requiring adjunctive devices such as stents or balloons to maintain coil mass within the aneurysm sac. Comaneci is a...

Predictive anatomical factors for rupture in middle cerebral artery mirror bifurcation aneurysms

OBJECTIVE The aim of this study was to define predictive factors for rupture of middle cerebral artery (MCA) mirror bifurcation aneurysms. METHODS The authors retrospectively analyzed the data in patients with ruptured MCA bifurcation aneurysms with simultaneous presence of an unruptured MCA bifurcation mirror aneurysm treated in two neurosurgical centers. The following parameters were measured and analyzed with the statistical software R: neck, dome, and width of both MCA aneurysms-including neck/dome and width/neck ratios, shape of the aneurysms (regular vs irregular), inflow angle of both MCA aneurysms, and the diameters of the bilateral A1 and M1 segments and the frontal and temporal M2 trunks, as well as the bilateral diameter of the internal carotid artery (ICA). RESULTS The authors analyzed the data of 44 patients (15 male and 29 female, mean age 50.1 years). Starting from the usual significance level of 0.05, the Sidak-corrected significance level is 0.0039. The diameter of the measured vessels was statistically not significant, nor was the inflow angle. The size of the dome was highly significant (p = 0.0000069). The size of the neck (p = 0.0047940) and the width of the aneurysms (p = 0.0056902) were slightly nonsignificant at the stated significance level of 0.0039. The shape of the aneurysms was bilaterally identical in 22 cases (50%). In cases of asymmetrical presentation of the aneurysm shape, 19 (86.4%) ruptured aneurysms were irregular and 3 (13.6%) had a regular shape (p = 0.001). CONCLUSIONS In this study the authors show that the extraaneurysmal flow dynamics in mirror aneurysms are nonsignificant, and the aneurysmal geometry also does not seem to play a role as a predictor for rupture. The only predictors for rupture were size and shape of the aneurysms. It seems as though under the same conditions, one of the two aneurysms suffers changes in its wall and starts growing in a more or less stochastic manner. Newer imaging methods should enable practitioners to see which aneurysm has an unstable wall, to predict the rupture risk. At the moment one can only conclude that in cases of MCA mirror aneurysms the larger one, with or without shape irregularities, is the unstable aneurysm and that this is the one that needs to be treated.

Translucent Appearance of Middle Cerebral Artery Bifurcation Aneurysms Is Risk Factor for Intraoperative Aneurysm Rupture During Clipping.

The rupture rate of unruptured intracranial aneurysms is influenced by certain angioarchitectural and hemodynamic characteristics. Recently the translucent appearance of aneurysms was described as a possible risk factor for aneurysm rupture. In this study, we investigate the intraoperative rupture risk of surgically clipped unruptured translucent aneurysms (TAs). Clinical and radiologic data of microsurgically treated unruptured middle cerebral artery (MCA) bifurcation aneurysms between 2013 and 2015 were collected and analyzed. Aneurysms were divided into TA as defined as >90% reddish pigmentation appearance of the aneurysm wall or non-TA (NTA) according to the observation under microscope by a single neurosurgeon. Parameters were analyzed using univariate and multivariate statistical analyses. A total of 41 unruptured MCA bifurcation aneurysms were included in the analysis, and 68.2% (28/41) were defined as TA. The univariate analysis showed that aneurysm characteristics (Dmax, Wmax, height, and lower size ratio [SR]) that were small in nature were associated with TAs. TAs were associated with intraoperative rupture (28.6% vs. 0%, P= 0.04). Multivariate logistic regression analysis found that the lower SR is the independent risk factor for TAs. The results demonstrate that a lower SR correlates with TA in the MCA bifurcation and the thinner wall of the TA causes intraoperative rupture more likely. These results provide important information on the fragility of TAs and might influence the treatment decisions in unruptured MCA bifurcation aneurysms with lower SRs.

Ideal clipping methods for unruptured middle cerebral artery bifurcation aneurysms based on aneurysmal neck classification.

Endovascular coiling is widely used for many cerebral aneurysms; however, in cases of middle cerebral artery bifurcation (MCBIF) aneurysms, it is associated with a higher incidence of unfavorable outcomes compared to microsurgical clippings. In this retrospective study, we aimed to investigate the outcomes of microsurgical clipping for unruptured MCBIF aneurysms and determine the ideal clipping methods for different aneurysm subtypes. From January 2011 to December 2013, 203 aneurysms with saccular shape (<25 mm) were treated by an experienced neurosurgeon. Depending on the involvement of the aneurysmal thin wall, the aneurysm neck was classified as follows: subtype I, limited bifurcation; subtype II, progressed to M1 trunk; subtype III, progressed to M2 trunk; subtype IV, progressed to M1 and one M2 trunk; and subtype V, progressed to M1 and two M2 trunks. The clipping methods included simple, sliding, interlocking, or mixed approaches. Aneurysm clippings were accomplished without any morbidity in all cases, and seven cases had a minimal neck remnant. The following clipping methods were predominantly used: subtype I, simple (90.2%) and sliding (8.8%) (mean = 1.2 clips); subtype II, interlocking (51.4%), sliding (30.0%), mixed (15.7%), and simple (2.9%) (2.4 clips); subtype III, simple (57.5%) and sliding (42.5%) (1.5 clips); subtype IV, interlocking (64.3%) (2.1 clips), simple (10.7%), sliding (14.3%), and mixed (10.7%); and subtype V, interlocking (50.0%), sliding (35.7%), and mixed (14.3%) methods with multiple clips (2.8 clips). If an appropriate clipping method is selected according to the neck classification, satisfactory surgical obliteration can be achieved for unruptured MCBIF aneurysms without morbidity.

Microsurgical Clipping of Unruptured Middle Cerebral Artery Bifurcation Aneurysms: Incidence of and Risk Factors for Procedure-Related Complications

To report our experiences in microsurgical clipping of unruptured middle cerebral artery (MCA) bifurcation aneurysms and to evaluate the incidence of and risk factors for procedure-related complications. The study comprised 416 patients treated between March 2003 and February 2014. All patients met the following criteria: 1) microsurgical clipping of an unruptured MCA bifurcation aneurysm was performed, and 2) clinical and radiographic follow-up data were available including preoperative digital subtraction angiography. The incidence of and risk factors for procedure-related complications were retrospectively evaluated. Procedure-related complications occurred in 15 (3.6%) patients, including asymptomatic complications in 10 (2.4%) patients and symptomatic complications in 5 (1.2%) patients. Multivariate logistic regression analysis showed that posteroinferior projection of the aneurysm (odds ratio= 2.814, 95% confidence interval= 0.995-6.471, P=0.042), distance between the internal carotid artery bifurcation and the MCA bifurcation (Dt) in a linear line (odds ratio= 1.813, 95% confidence interval= 0.808-6.173, P= 0.043), and horizontal angle between the vertical line tothe base of the skull and Dt (odds ratio= 2.046, 95% confidence interval= 1.048-10.822, P= 0.048) were independent risk factors for procedure-related complications. When performing clipping of unruptured MCA bifurcation aneurysms, the procedure-related complication rate was 3.6%. Patients with MCA bifurcation aneurysms with posteroinferior projection, shorter Dt,and larger horizontal angle may be at a higher risk of procedure-related complications when performing microsurgical clipping.

The Contribution of Three-Dimensional Computerized Tomographic Angiography in the Head Positioning of the Patients with Middle Cerebral Artery Aneurysms.

Surgical intervention is a gold standard technique for ruptured and unruptured middle cerebral artery bifurcation aneurysm. Before surgical intervention it is necessary to know the three-dimensional shape, surgical position, projection and position of the aneurysm and the course of the parent artery. In a demonstrative case with middle cerebral artery aneurysm, using the OsiriX MD image processing software for DICOM images, it was demonstrated the position of the aneurysm neck, the projection of the aneurysm and the course of the M1 segment in relation with dynamic rotation and extension of the head. These dynamic videographic neuroradiological images may enhance the surgical anatomic perspective of the surgeon before the surgical intervention.

A Classification of Unruptured Middle Cerebral Artery Bifurcation Aneurysms that can Help in Choice of Clipping Technique

Middle cerebral artery (MCA) aneurysms comprise 20-25% of all intracranial aneurysms. The majority of middle cerebral artery aneurysms are treated by microsurgical clipping. Most of the classifications of aneurysms at present are based on size, location or pathology which are effective for the description but are less useful in preoperative planning and also in deciding on the technique or type of clip application. The aim of our study was to examine the morphological features of unruptured MCA bifurcation aneurysms which influence the techniques of clipping of these aneurysms and to attempt to subclassify unruptured middle cerebral artery aneurysms based on their preoperative 3D CTA and intraoperative characteristics so as to help in the intraoperative choice of technique and clip application, respectively. Preoperative 3D CT angiography and intraoperative images along with the record of technique and type of clips used for 141 unruptured MCA aneurysms operated at our center were studied retrospectively. Unruptured MCA bifurcation aneurysms could be subclassified into 5 types based on the similarities in their morphological features which influenced the techniques of clipping as recorded from their preoperative 3D CTA and intraoperative view. These types and the distinctive feature of each type are described. The various techniques of clipping are discussed based on these subgroups. The groups outlined make possible the establishment of a common technical approach to clipping within the groups. This classification, based on preoperative 3D CTA and intraoperative morphological features of the aneurysm and parent vessels, helps in the intraoperative choice of technique and type of clip application to tackle these lesions.