Middle Cerebral Artery Bifurcation Research Articles

Keyhole Mini-Pterional Craniotomy for Clipping of Bilateral Middle Cerebral Artery Aneurysms.

Middle cerebral artery (MCA) aneurysms remain excellent candidates for microsurgical treatment, despite proliferation of new endovascular tools. Nonetheless, patients desire less invasive options for permanent, durable treatment of their aneurysms1; this is particularly the case for those presenting without subarachnoid hemorrhage, and those with multiple aneurysms that may require several surgical approaches. Keyhole craniotomies, when properly utilized in well-selected patients, allow for minimally invasive treatment of both ruptured and unruptured cerebral aneurysms, including those harboring bilateral aneurysms which may be treated from a single approach2. Middle cerebral artery bifurcation aneurysms are ideal aneurysms for application of the keyhole concept: they reside at depth from the skull under a direct, linear path of access; obtaining early proximal control of the in-flow vessel can be accomplished with minimal further dissection at the depth of a narrow corridor; there are few perforators that require dissection; a properly placed craniotomy exposes the entire proximal sylvian fissure as well as the contralateral sylvian contents; sharp dissection of the sylvian fissure further expands the corridor which can be illuminated with lighted instruments as needed; and, conversion to a larger craniotomy can be easily performed is bailout is necessary. A relative contraindication of this approach is if both aneurysms are laterally projecting, although in experienced hands even this remains only a relative contraindication. A possible potential complication that should be prepared for is intraoperative rupture of the distal aneurysm but as demonstrated in this video, it is critical that the surgeon obtain proximal and distal control of the most distal aneurysm as would be obtained from an ipsilateral approach. In this video we demonstrate the use of this approach for bilateral unruptured MCA aneurysms, highlighting nuances for successful performance of this operation.

Fluid structure Interaction analysis for rupture risk assessment in patients with middle cerebral artery aneurysms

Accurate rupture risk assessment is essential for optimizing treatment decisions in patients with cerebral aneurysms. While computational fluid dynamics (CFD) has provided critical insights into aneurysmal hemodynamics, most analyses focus on blood flow patterns, neglecting the biomechanical properties of the aneurysm wall. To address this limitation, we applied Fluid-Structure Interaction (FSI) analysis, an integrative approach that simulates the dynamic interplay between hemodynamics and wall mechanics, offering a more comprehensive risk assessment. In this study, we used advanced FSI techniques to investigate the rupture risk of middle cerebral artery bifurcation (MCA) aneurysms, analyzing a cohort of 125 patients treated for a MCA aneurysm at Kepler University Hospital, Linz, Austria. Multivariate analysis identified two significant rupture predictors: High Equivalent Stress Area (HESA; p = 0.049), which quantifies stress distribution relative to the aneurysm surface, and Gaussian curvature (GLN; p = 0.031), which captures geometric complexity. We also introduce the HGD index, a novel composite metric combining HESA, GLN, and Maximum Wall Displacement, designed to enhance predictive accuracy. With a threshold of 0.075, the HGD index exhibited excellent diagnostic performance; in internal validation, 24 of 25 ruptured aneurysms surpassed this threshold, yielding a sensitivity of 0.96. In a 5-fold cross validation the reliability of results was confirmed. Our findings demonstrate that the HGD index provides superior rupture risk stratification compared to conventional single-parameter models, offering a more robust tool for the assessment of complex aneurysmal structures. Further multicenter studies are warranted to refine and validate the HGD index, advancing its potential for clinical application and improving patient outcomes.

In Situ M2 Bypass for Treatment of Fusiform Middle Cerebral Artery Bifurcation Aneurysm: Technical Case Instruction and Operative Video.

Fusiform middle cerebral artery (MCA) bifurcation aneurysms can be challenging to treat with standard endovascular or microsurgical techniques. The in situ side-to-side bypass technique represents an elegant revascularization option for these aneurysms when trapping becomes necessary. A man in his 50s presented for evaluation of an incidentally found fusiform, 10 mm, right MCA bifurcation aneurysm with involvement of both the inferior and superior M2 trunks. Plan was initially made for a right pterional craniotomy for trapping of the aneurysm with exclusion of the inferior M2 trunk, preservation of the superior M2 trunk, with superficial temporal artery bypass to the inferior M2 trunk. Intraoperatively, after arachnoid dissection, it became clear that the distal superior and inferior M2 branches would lie in close approximation without tension, thus superficial temporal artery-M2 bypass was deferred, and instead in situ side-to-side M2 bypass was performed. Here in our operative video, we highlight the critical steps of in situ side-to-side M2 bypass technique. We present a technical case instruction and operative video highlighting the in situ side-to-side bypass technique for treatment of a large fusiform MCA bifurcation aneurysm.

Microsurgical management of previously embolized intracranial aneurysms: A single center experience and literature review.

Endovascular treatment of intracranial aneurysms (IAs) provides less invasiveness and lower morbidity than microsurgical clipping, albeit with a long-term recurrence rate estimated at 20%. We present our single-center experience and a literature review concerning surgical clipping of recurrent previously coiled aneurysms. Retrospective analysis of nine (9) patients' data and final clinical/angiographic outcomes, who underwent surgical clipping of IAs in our center following initial endovascular treatment, over a 12-year period (2010-2022). Regarding the literature review, data were extracted from 48 studies including 969 patients with 976 aneurysms. 9 patients (5 males - 4 females) were included in the study with a mean age of 49 years. Subarachnoid hemorrhage was the initial presentation in 78% of patients. Aneurysms' most common location was the middle cerebral artery bifurcation (5/9) followed by the anterior communicating artery (3/9) and the internal carotid artery bifurcation (1/9). Indications for surgery were coil loosening, coil compaction, sac regrowth, and residual neck. Procedure-related morbidity and mortality were zero whereas complete aneurysm occlusion was achieved after surgical clipping in all cases (100%). All patients had minimal symptoms or were asymptomatic (mRS 0-1) at the final follow-up. Surgical clipping seems a feasible and safe technique for selected cases of recurrent previously coiled intracranial aneurysms. A universally accepted recurrence classification system and a guideline template for the management of such cases are needed.

Near-Wall Slow Flow Contributes to Wall Enhancement of Middle Cerebral Artery Bifurcation Aneurysms on Vessel Wall MRI.

Background: The mechanism of aneurysm wall enhancement (AWE) in middle cerebral artery (MCA) bifurcation aneurysms on vessel wall magnetic resonance imaging (VW-MRI) remains unclear. We aimed to explore the morphologically related hemodynamic mechanism for the AWE of MCA bifurcation aneurysms. Methods: Patients with unruptured MCA bifurcation aneurysms undergoing VW-MRI were enrolled. Logistic regression analyses were performed to determine the risk factors for AWE. Based on the results of retrospective analyses, bifurcation aneurysm silicone models with a specific aspect ratio (AR) were designed and underwent VW-MRI with different inlet velocities. Computational fluid dynamics (CFD) analyses were conducted on both silicone models and patients' aneurysms. Results: A total of 104 aneurysms in 95 patients (mean age 60; 34 males) were included for baseline analysis and morphological analysis. Logistic regression analysis indicated AR (OR, 5.92; 95% CI, 2.00-17.55; p = 0.001) was associated with AWE. In the high-AR group of 45 aneurysms with AWE, the aneurysm sac exhibited lower blood flow velocity, lower wall shear stress, a larger proportion of low-flow regions and higher wall enhancement values. In total, 15 silicone models were analyzed, divided into three subgroups based on neck width (4 mm, 6 mm, and 8 mm). Each subgroup contained aneurysms with five different ARs: 1.0, 1.25, 1.5, 1.75, and 2.0. In silicone models, contrast enhancement (CE) was mainly located beneath the dome of the aneurysm wall. With the same inlet velocity, CE gradually increased as the AR increased. Similarly, at the same AR, CE increased as the inlet velocity decreased. CFD demonstrated a moderate positive correlation between the near-wall enhancement index and the ratio of the low-velocity area (r = 0.6672, p < 0.001). Conclusions: The AR is associated with the AWE of MCA bifurcation aneurysms. A high AR may promote wall enhancement by causing near-wall slow flow.

Ruptured middle cerebral artery bifurcation aneurysms with concomitant intracerebral hematoma: Clinical and morphological risk factors.

The prognosis for intracerebral hematoma (ICH) following the rupture of a middle cerebral artery bifurcation (Mbif) aneurysm is poor. We compared patients with isolated diffuse subarachnoid hemorrhage (SAH) (without ICH) following Mbif aneurysm rupture to those with both SAH and ICH to evaluate clinical and morphological risk factors for ICH. A retrospective study was conducted on 112 patients with ruptured Mbif aneurysms treated between July 2016 and December 2021. We investigated age, sex, medical history (hypertension, diabetes mellitus, and smoking), rebleeding, aneurysm neck and dome size, bottleneck factor, aspect ratio, dome projection, trunk diameters and ratios, parent artery (M1) dimensions, angles between both trunks (γ1, γ2, γ3), as well as M1 length and diameter, and internal carotid artery/M1 (α) and internal carotid artery/anterior cerebral artery (β) angles. These measurements were obtained using computerized tomography angiography to assess risk factors. A total of 88 patients (78.6%) with ruptured Mbif aneurysms who met the inclusion criteria were included in the study. A total of 39 (44.3%) patients had SAH with ICH, while 49 (53.7%) patients had pure diffuse SAH. Rebleeding was significantly higher in patients with ICH (P = .02). Morphological analysis revealed that the decrease in M1 diameter and α angle, along with an increase in aneurysm size and neck, were significantly different in the ICH group (P = .025, P = .012, P = .009, and P = .005, respectively). Receiver operating characteristic curve analysis showed that a cutoff value of α = 125° had the highest diagnostic accuracy (area under the curve = 0.71), with a sensitivity of 86.26% and specificity of 68.7%. The formation of ICH following the rupture of Mbif aneurysms is associated with specific morphological parameters.

Novel Rat Model of Embolic Cerebral Ischemia Using a Radiopaque Blood Clot and a Microcatheter Under Fluoroscopy.

Conventional rat models of thromboembolic stroke do not allow control of infarct size or spontaneous recanalization. We aimed to develop a novel rat thromboembolic stroke model that ensures highly reproducible infarct sizes and locations within the MCA territory and does not require arterial ligation. Twenty male Sprague-Dawley rats and two sham-operated rats were included. A microcatheter was navigated from the caudal ventral artery to the internal carotid artery using digital subtraction angiography. A blood clot (diameter, 0.86 mm; length, 3 mm) containing zirconium dioxide was advanced in the catheter. Fluoroscopy was performed at 1, 3, 6, and 24 h after stroke model creation, and TTC staining was conducted at 24 h. Neurological deficit scores were measured. In all embolized rats, the ACA and MCA bifurcation were selective. Median operating time was 6 min. The position of the radiopaque blood clot remained unchanged for 24 h after model creation in 19/20 rats. Median infarct volume was 242 mm3 (IQR, 239-262 mm3). We present a novel rat model of highly reproducible focal infarct in only the MCA territory. Fluoroscopy effectively identified any blood clot migration. This model could contribute to the development of new thrombolytic agents.

A Complex Case of Infective Endocarditis With Systemic Complications

A 25-year-old female, with a known case of small perimembranous VSD who was started on empirical anti-tubercular drugs for suspected bilateral tubercular sacroiliitis for the last 1 month presented with persistent fever and increasing shortness of breath. Transthoracic echocardiography revealed concurrent infective endocarditis (IE) affecting the aortic and mitral valves, with small perimembranous ventricular septal defect (VSD), and severe aortic and mitral regurgitation. Repeated blood cultures did not show any growth. Empirical management with intravenous ceftriaxone and gentamicin was initiated. After completing 2 weeks of IV Gentamicin, the patient developed severe headache, vomiting, and transient loss of consciousness. MRI Head confirmed subarachnoid hemorrhage. Emergency External ventricular drain placement ameliorated intracranial pressure-related symptoms. Digital subtraction angiography identified a mycotic aneurysm at left MCA bifurcation as a complication of IE, which was successfully managed through endovascular coiling. Repeat MRI showed subsiding SAH with areas of ischemia, most probably related to cerebral vasospasm. Her blood cultures were still negative, hence shifted to Inj Vancomycin. After a few days, the patient developed a fever with a fall in GCS. Lumbar puncture confirmed bacterial meningitis, subsequently treated with intravenous meropenem. Cardiac CT was done which revealed a small perimembranous VSD along with a small ruptured Sinus of Valsalva draining in the right ventricle. After successful treatment of SAH and meningitis, the patient underwent dual valve replacement (aortic and mitral), VSD closure, and Ruptured sinus of Valsalva repair. Postoperative recovery was uneventful, and the patient was discharged on the fifth postoperative day.

Surgical Construction of Wide-Neck Bifurcation Experimental Aneurysm in an In Vivo Canine Model to Test Neurovascular Device.

Stents are increasingly used for coiling difficult aneurysms, to reduce the risk of recurrences, or to modify blood flow. Currently, available bifurcation aneurysm models are ill-suited to assess stent performance before clinical use. We designed a new animal model of wide-neck canine Y-type bifurcation aneurysm (such as middle cerebral artery (MCA) bifurcation) and previously reported one of T-type (such as basilar bifurcation). Its potential value as a training tool as well as in the evaluation of new techniques or stent or embolic agents was assessed. Seven canine aneurysms were created (three: Y-type, four: T-type). Aneurysms were followed by transfemoral cerebral angiography (TFCA) and computed tomography angiography (CTA). We performed TFCA and self-expandable stent placement for the parent artery adjoined to the aneurysmal neck in one month's follow-up. We assessed the long-term patency of the parent artery with CTA and euthanasia and got a specimen for pathologic study at six months' follow-up. In six models except one (T-type), a wide-neck bifurcation aneurysm was created successfully and they showed good long-term patency at six months' follow-up. Stent placement was technically difficult in these cases, but did not lead to aneurysm thrombosis in CTA or neointimal closure of the aneurysm neck in pathologic finding at postoperative six months later. This model may be suitable for studying the effects of endovascular treatment on aneurysm and branch occlusion rates, for preclinical testing of stents and other intravascular devices, and for training students in endovascular technique.

Microsurgical Clipping of Unruptured Middle Cerebral Artery Bifurcation Aneurysms: A Single-Center Experience.

Microsurgical clipping has traditionally been considered a standard treatment for middle cerebral artery (MCA) aneurysms. Recently, a caseload reduction related to improved endovascular treatment options has occurred in cerebrovascular neurosurgery. Therefore, studies that report the clinical and radiological outcomes after clipping are highly warranted. Patients with an unruptured MCA bifurcation aneurysm, who were surgically treated at the Department of Neurosurgery in Linz between 2002 and 2019, were included in this study. Clinical and radiological outcome parameters were evaluated for each patient. Overall, 272 patients were eligible for inclusion. Complete aneurysm occlusion was demonstrated in 266 (99.3%) of the 268 (98.5%) patients who underwent postoperative digital subtraction angiography. In six (2.2%) patients, a permanent new neurological deficit (pNND) persisted after treatment. Intraoperative aneurysm rupture was a significant factor (p = 0.0049) in the logistic regression. At the last follow-up, only two patients (0.7%) had an unfavorable outcome (mRS > 2). More recent surgeries were associated with fewer cases of pNND (p = 0.009). A transient new neurological deficit occurred in 13 patients (4.8%), with aneurysm size being a significant risk factor (p = 0.009). Surgical site infections were reported in four patients (1.5%), with patient age (p = 0.039) and time (p = 0.001) being significant factors. Two patients died (0.7%) perioperatively and two patients (0.7%) needed a retreatment in the long-term follow-up. The findings indicate that microsurgical clipping is a safe procedure with minimal need for retreatment. It achieves a high occlusion rate while maintaining a very low rate of adverse outcomes. Continuous intraoperative enhancements over time have contributed to a progressive improvement in clinical outcomes in recent years. This trend is exemplified by the absence of detectable pNND in the era of ICG angiography. Consequently, these data support the conclusion that microsurgical clipping should still be considered an appropriate treatment option for unruptured MCA bifurcation aneurysms.

Exploring the hemodynamic behavior of residual aneurysms after coiling and clipping: A computational flow dynamic analysis.

Residual intracranial aneurysms post-clipping or coiling pose a poorly established risk of rupture. Computational fluid dynamic (CFD) offers insights into hemodynamic changes following such interventions. This study aims to assess hemodynamic parameters in residual aneurysms pre- and post-treatment with surgical clips or coils using CFD. A retrospective analysis of consecutive patients between January 2015 and January 2024 was conducted. Digital subtraction angiography images were reconstructed using 3D modeling techniques, and hemodynamic parameters were analyzed with ANSYS® software. Six aneurysms were analyzed: Five unruptured and one ruptured. The aneurysms were located at the basilar apex (2), middle cerebral artery bifurcation (2), and origin of the posterior communicating artery (2). Post-treatment, there was a significant reduction in both aneurysm area (median reduction of 33.73%) and volume (median reduction of 25.3%). Five of the six cases demonstrated fewer low wall shear stress (WSS) areas, which could indicate a reduction in regions prone to thrombus formation and diminished risk of rupture. In the unruptured aneurysms, there was a median increase of 137.6% in average WSS. Notably, the only case with increased low WSS area also had the highest increase in average WSS. One basilar artery aneurysm showed increased WSS across all parameters, suggesting a higher rupture risk. The increase in average and high WSS area, along with a decrease in low WSS area, reflects a complex balance between factors of stability and rupture risk. However, a simultaneous increase in all WSS parameters may represent the highest rupture risk due to increased mechanical stress on the aneurysm wall, necessitating closer monitoring.

Defining ideal middle cerebral artery bifurcation aneurysm size for Woven EndoBridge embolization.

The Woven EndoBridge (WEB) device was approved to treat wide-necked bifurcation aneurysms. The device is designed as an intrasaccular flow disruptor covering aneurysm widths up to 10 mm. Although prior studies combined all aneurysm sizes, it is known that aneurysms behave differently in response to endovascular treatment based on their size. Therefore, the authors' objective was to identify ideal middle cerebral artery (MCA) aneurysm width and neck sizes most suitable for WEB treatment. The WorldWideWEB consortium is a large multicenter retrospective database that analyzes intracranial aneurysms treated with the WEB device. In this study, all unruptured MCA bifurcation aneurysms with available measurements were included. Cutoff values based on aneurysm width and neck in relation to aneurysm occlusion status were measured using the receiver operating characteristic (ROC) curve. Propensity score matching (PSM) was then used to compare treatment outcomes between aneurysms smaller and larger than the cutoff value for both width and neck size. The ideal cutoff values for MCA bifurcation aneurysm width and neck were 6.1 mm and 4.6 mm, respectively. On PSM, 87 matched pairs were compared based on width size (≤ 6.1 mm and > 6.1 mm), and 77 matched pairs were compared based on neck size (≤ 4.6 mm and > 4.6 mm). There was a significant difference in adequate aneurysm occlusion between aneurysms smaller and larger than those cutoff values for both widths (93% vs 76%, p = 0.0017) and neck sizes (90% vs 70%, p = 0.0026). The retreatment rate was also significantly higher for larger aneurysms in both parameters. This study shows that MCA bifurcation aneurysms ≤ 6.1 mm in width and ≤ 4.6 mm in neck size are significantly better candidates for WEB treatment, leading to improved occlusion status and reduced retreatment rate, which are important considerations when using WEB devices.

Characteristics of middle cerebral artery aneurysms treated endovascularly in a clip-favored institution.

The emergence of flow disruptors has brought a dynamic transition in the selection of treatment for middle cerebral artery (MCA) aneurysms, and the number of MCA aneurysms clipped is acceleratingly decreasing. Still, retreatment after endovascular treatment is still a dilemma, which may necessitate surgical clipping. It is all the more important to elucidate characteristics of MCA aneurysms that make clipping unfavorable. Thus, the practical characteristics of MCA aneurysms treated endovascularly in a clip-favored institution before the usage of flow disruption devices were investigated. This is a retrospective, single-center observational study. The clinical and imaging characteristics of treated MCA aneurysms from January 2012 to May 2022 were analyzed. A total of 83 aneurysms were included; 70 aneurysms (84%) were clipped, and 13 (16%) were treated endovascularly. Eighteen aneurysms (22%) were ruptured (clipping, 12; endovascular, 6). The reasons for an endovascular treatment were as follows: distal (3); subacutely ruptured with burdens of spasm (2); multiple aneurysms (6: another clipped in 3, coiled in 1, and conservatively managed in 2); no access to the operating room due to COVID-19 (1); and retreatment after coiling (1). Endovascular group aneurysms were smaller (maximum diameter 5.2 vs 7.3 mm, p < 0.01, as well as dome, neck, and height) without differences in the dome/neck and aspect (height/neck) ratios. In a subgroup analysis of 78 MCA bifurcation aneurysms, the endovascular group was still smaller (dome 4.4 vs 5.8 mm, p = 0.025; neck 2.8 vs 3.9, p = 0.03). In a limited series from a clip-favored institution before the flow disruption era, factors guided to endovascular treatments on MCA aneurysms were rather anatomical and clinical factors such as distal location, subacutely ruptured, multiple, or retreatment after coiling, than morphological factors such as dome/neck and aspect ratios albeit smaller size.

Non-invasive follow-up for intracranial aneurysms treated with contour neurovascular system-comparison of digital subtraction angiography (DSA) to magnetic resonance imaging (MRI) and spectral computed tomography angiography (CTA) in vitro.

The contour neurovascular system (CNS) is an intrasaccular flow-disrupting device designed for the treatment of intracranial wide-necked bifurcation aneurysms. Metal artifacts limit magnetic resonance imaging (MRI) accessibility after implantation. The purpose of this in vitro study was to evaluate non-invasive imaging alternatives to digital subtraction angiography (DSA). Three aneurysms of patients originally treated with CNS were three-dimensional (3D)-printed (one at the basilar tip and two at the middle cerebral artery bifurcation). CNS devices were implanted under fluoroscopic control into the 3D models. Post-implantation two-dimensional-DSA, flat panel computed tomography angiography (CTA), MRI, and spectral CTA were performed. Time of flight angiography and T1 weighted sequences showed large susceptibility artifacts at the detachment zone of the devices. A thin-sliced T2 weighted sequence in cross-sectional orientation to the aneurysm allowed visualization of the aneurysm dome, but the aneurysm neck and parent vessel could not be assessed. Focused spectral CTA, especially a 40 keV reconstruction with a metal artifact reduction algorithm (orthopedic metal artifact reduction (OMAR)), showed only minor artifacts at the detachment zone. This approach achieved a very similar result to DSA and flat panel computed tomography, enabling the assessment of the device structure, aneurysm perfusion, and parent vessel perfusion. For non-invasive follow-up of CNS, focused 40 keV CTA with OMAR seems to be a valuable option. MRI can be valuable for larger aneurysms to assess the aneurysm dome, but was not suitable for evaluating the parent vessels and aneurysm neck after CNS implantation in this study.

Flow diversion for the treatment of intracranial bifurcation aneurysms: a systematic review and meta-analysis

BackgroundFlow diversion (FD: flow diversion, flow diverter) is an endovascular treatment for many intracranial aneurysm types; however, limited reports have explored the use of FDs in bifurcation aneurysm management. We...

Flow diversion for unruptured MCA bifurcation aneurysms: comparison of p64 classic, p64 MW HPC, and p48 MW HPC flow diverter stents.

MCA bifurcation aneurysms pose treatment challenges because of the complex hemodynamics at the bifurcation and the risk of rupture. FDS implantation has been controversial and there are only limited reports. Therefore, the aim of this study was to assess the efficacy and safety of this treatment strategy using p64 MW HPC and p48 MW HPC FDSs for MCA bifurcation aneurysms, compared with the p64 classic FDS. We retrospectively analyzed our institutional database and identified all patients with saccular, non-ruptured MCA bifurcation aneurysms treated with p64 MW HPC, p48 MW HPC, or p64 classic FDS implantation alone. Aneurysms with implantation of additional devices in the same session, previous treatments, and acutely ruptured and fusiform aneurysms were excluded. A total of 79 aneurysms met the inclusion criteria: 23 receiving a p64 MW HPC, 34 receiving a p48 MW HPC, and 22 receiving a p64 classic FDS. The occlusion rate was highest for the p48 MW HPC 2 mm FDS, at 88.9% at FU2, compared with 72.2% for the p64 MW HPC and 70.6% for the p64 classic. The time to aneurysm occlusion was shortest with the p64 MW HPC, at 178.31 days. The highest retreatment rate was observed with the p48 MW HPC 3 mm. Treatment of MCA bifurcation aneurysms with a p48 MW HPC 2 mm or p64 MW HPC FDS is a safe and reliable strategy achieving high aneurysm occlusion rates - attributable to their lower porosity in relation to the parent vessel diameter as compared to the p48 MW HPC 3 mm FDS-, with reasonable morbidity and mortality.

Are There Left-Right Differences in Ruptured Middle Cerebral Artery Bifurcation Aneurysms? A Single-Center Retrospective Study and Review of the Literature.

Background The left (Lt) and right (Rt) middle cerebral artery bifurcation (MCAB) aneurysms have mostly been regarded as identical. Considering substantial Lt-Rt differences in hemispheric infarction, however, the presence of Lt-Rt differences may not be denied totally in patients with ruptured MCAB aneurysms. We herein investigated whether such Lt-Rt differences existed by a single-center retrospective study. Materials and Methods Clinical data prospectively acquired between 2011 and 2021 on 99 patients with ruptured MCAB aneurysms were analyzed. They were dichotomized based on the laterality, and demographic and outcome parameters were compared. Additionally, a literature review was conducted to elucidate possible Lt-Rt differences in the frequency of ruptured MCAB aneurysms (Rt/Lt ratio). Results Among the 99 patients, 42 had Lt and 57 had Rt ruptured MCAB aneurysms, with the Rt/Lt ratio of 1.36. Neither demographic, radiographic, nor outcome variables differed significantly between the two groups. A total of 19 studies providing information on the laterality of the ruptured MCAB were retrieved by literature search. A sum total for the Lt and Rt MCAB aneurysms was 671 and 940, making the Rt/Lt ratio of 1.40. After adding our data, a sum total for the Lt and Rt MCAB aneurysms was 713 and 997, making the Rt/Lt ratio of 1.40. Conclusion The Rt ruptured MCAB aneurysms were 1.40 times more frequent than the Lt-sided counterpart. While there may be some Lt-Rt differences in the MCA anatomy, it remains to be seen whether such anatomical differences are truly responsible for the disproportionately higher frequency of Rt MCAB aneurysms.

Coil embolization of the middle cerebral artery bifurcation aneurysms: Feasibility and durability

ObjectiveTo evaluate the feasibility and durability of coil embolization for MCAB aneurysms by analyzing clinical and radiological results. MethodsFrom January of 2008 to June of 2018, we treated a total of 1785 aneurysms using coil embolization. The aneurysms were treated by both coiling and stent-assisted coiling. Among these cases, 223 MCAB aneurysms were analyzed retrospectively. Clinical and radiological assessments were conducted at admission, after treatment, at discharge, and at last clinical follow-up. ResultsCoil embolization was performed on 223 MCAB aneurysms in 217 patients. Peri-procedural ischemic, hemorrhagic, and other complications within 30 days after coil embolization occurred at rates of 8.0 %, 8.0 %, and 2.0 %, respectively, in the ruptured group and at 2.9 %, 1.2 %, and 0 %, respectively, in the unruptured group. The overall morbidity and mortality rates associated with complications were 2.3 % and 2.0 %. The cumulative major recurrence rates were 5.1 % at 12 months, 7.1 % at 18 months, and 11.9 % at three years after coil embolization. The mean follow-up period was 33.27 ± 25.48 months. Independent risk factors for major recurrence after coil embolization for MCAB aneurysms were a ruptured aneurysm, initial incomplete occlusion, the aneurysm size, and the neck size. ConclusionCoil embolization is a good alternative treatment option for MCAB aneurysms compared to surgical clipping. Considering the risk factors for major recurrence, the follow-up angiography should continue up to three years after coil embolization.

Stent-Assisted Coil Embolization of MCA Bifurcation and Literature Review

Coil embolization of aneurysms, after more than 20 years of clinical practice shows that several conditions must be met: 1. After the necessary interval, the entire aneurysm can achieve and maintain effective hemostasis. 2. Intra-aneurysm thrombosis is the result of intra-aneurysm hemostasis induced by the coil, which must take the necessary time to form a stable and organic coil thrombus complex; 3. The homogeneity and stability of the spring-thrombus complex at the base of the aneurysm must be sufficient to ensure neoendotheliosis and re-endothelialization of the aneurysm neck. Only if the above conditions are met can the operation be successful. The advantage of stent-assisted coil embolization is that the tumor bearing vessel can be preserved. However, since the foreign body is permanently placed in the main vessel, antiplatelet drugs need to be continued after surgery in order to prevent thrombus.

The Endoscopic Transorbital Approach for Vascular Surgery: An Anterior Circulation Anatomic Study, 2-Dimensional Operative Video.

Minimally invasive endoscopic approaches in cranial base surgery have been developing in the past decades. The transorbital (TO) route is one promising alternative, yet its adequacy for intracranial vascular lesions remains unclear. The present anatomic work aimed to test the feasibility and to provide a qualitative description of the endoscopic TO approach for the anterior circulation, namely the internal carotid artery and the middle cerebral artery. Seven embalmed adult cadaveric specimens (12 sides) were used in the study. Each side was approached in 3 successive steps: (1) Superior-eyelid TO approach, with great and lesser sphenoid wing removal. (2) Removal of anterior clinoid process (ACP). (3) Removal of the lateral orbital rim. All the procedures were performed under endoscopic view. The TO approach without removing the ACP allowed to dissect the sphenoidal and lateral segments of the Sylvian fissure with an adequate identification of the middle cerebral artery bifurcation in all specimens. The removal of the ACP allowed further dissection toward the opticocarotid cistern, with the identification of the ophthalmic, posterior communicating, and the anterior choroidal arteries. The internal carotid artery bifurcation and A1 segment were also readily identified. Finally, removal of the lateral orbital rim provided a wider and more comfortable access to the above-mentioned vascular structures. According to our anatomic data, the TO approach can be used to reach the main vascular components of the anterior circulation. This opens the field for exploring its application in the treatment of vascular pathology, particularly aneurysms.