Middle Cerebral Artery Bifurcation Research Articles

Study of Typical Ruptured and Unruptured Intracranial Aneurysms Based on Fluid–Structure Interaction

Most intracranial aneurysms (IAs) will be abnormal bulges on the walls of intracranial arteries that result from the dynamic interaction of geometric morphology, hemodynamics, and pathophysiology. Hemodynamics plays a key role in the origin, development, and rupture of IAs. In the past, hemodynamic studies of IAs were mostly based on the rigid wall hypothesis of computational fluid dynamics, and the influence of arterial wall deformation was ignored. We used fluid-structure interaction (FSI) to study the features of ruptured aneurysms, because it can solve this problem very well and the simulation will be more realistic. A total of 12 IAs, 8 ruptured and 4 unruptured, at the middle cerebral artery bifurcation were studied using FSI to better identify the characteristics of ruptured IAs. We studied the differences in the hemodynamic parameters, including the flow pattern, wall shear stress (WSS), oscillatory shear index (OSI), and displacement and deformation of the arterial wall. Ruptured IAs had a larger low WSS area and more complex, concentrated, and unstable flow. Also, the OSI was higher. In addition, the displacement deformation area at the ruptured IA was more concentrated and larger. A large aspect ratio; a large height/width ratio; complex, unstable, and concentrated flow patterns with small impact areas; a large low WSS region; large WSS fluctuation, high OSI; and large displacement of the aneurysm dome could be risk factors associated with aneurysm rupture. If similar cases are encountered when simulation is used in the clinic, priority should be given to diagnosis and treatment.

Abstract Number ‐ 141: Microemboli Monitoring After Intrasaccular Flow Disruption: Single‐center Experience

Introduction The management of wide‐necked bifurcation aneurysms can be challenging due to multiple factors. Intrasaccular flow disruption with the Woven EndoBridge (WEB) has demonstrated a safe and effective profile. Current microemboli data after the WEB device placement is non‐existent. We evaluated the rate of embolic signals (MES) after WEB device implantation. Methods We performed a retrospective analysis of a prospectively maintained database including patients who underwent WEB device implantation for the treatment of unruptured intracranial aneurysms between 2021 and 2022. Variables studied included patient demographics, modified Rankin Scale (mRS) before and 3 months post‐treatment, comorbidities, aneurysm characteristics, platelet inhibition tests, and activated clotting time. All patients were on aspirin and a P2Y12 inhibitor and had therapeutic levels on platelet aggregation assays. Intraoperative heparin was given in all cases to keep a therapeutic ACT. P2Y12 drugs were stopped after the procedure. In all patients, MES monitoring was performed in the immediate postoperative period and >12 hours after the procedure. Results 34 patients with 34 aneurysms were analyzed. Mean age was 67.4 years and 85% were females. Mean aneurysm size was 13.1 ± 2.0 mm and mean neck size 4.4 ± 1.5 mm. Locations were middle cerebral artery bifurcation and M1‐M2 segment (n = 13), basilar artery tip (n = 10), anterior communicating artery (n = 8), internal carotid artery terminus (n = 2) and pericallosal artery (n = 1). A single WEB was implanted in 100% of the cases. MES were negative in all cases. 3‐month mRS remained stable or improved in all cases. No procedure‐related complications were seen. Conclusions Our findings reinforce the safety profile of intrasaccular flow disruption. These findings differ from a previous analysis of unruptured aneurysms in our institution where a 7.7% incidence of MES was reported after endovascular treatment of unruptured aneurysms with primary or assisted coiling.

Abstract Number ‐ 245: Machine Learning‐Enabled Detection of Unruptured Cerebral Aneurysms Improves Detection Rates and Clinical Care

Introduction Unruptured cerebral aneurysms (UCAs) have a relatively low prevalence of approximately 3%, but detection can prevent devastating consequences of subarachnoid hemorrhage. Here, we assess the performance of a machine‐learning (ML) algorithm to identify UCAs and determine whether routine use of the algorithm would have improved detection rates and patient care. Methods From a prospectively maintained multi‐center registry across 8 certified stroke centers (1 comprehensive, 7 primary), we identified patients who underwent CT angiogram for evaluation of stroke from 3/14/21 – 11/31/21. An FDA‐cleared convolutional deep neural network (Viz ANEURYSM, Viz.ai, Inc.) trained to identify UCAs at least 4mm analyzed the images. Ground truth was provided by independent expert neuroradiology read. The primary outcome was rate of UCAs detected by the ML algorithm but not detected or addressed in the clinical radiology report or clinical notes, which was determined by two independent researchers. Results Among 1191 CT angiogram scans performed during the study period, 49 were flagged by the ML algorithm as possibly demonstrating an UCA, of which 26 cases were confirmed as true positive (PPV 53%).The most common locations included posterior communicating artery (22%), followed by MCA bifurcation (19%). Of these cases, 9 (35%) were not noted in the clinical radiology report or clinical notes, with a median size of 4.2 mm [IQR 3–7.5 mm], and 22 (85%) were not referred for follow up, with median size of 5 mm [IQR 3.7‐11.3 mm]. Of the 22 cases not referred for follow up, 13 (59%) had been noted in the radiology report. 46% (6/13) of the detected but not referred cases had a diameter greater than 10mm. Conclusions UCAs of sizes and intra‐dural locations that may warrant treatment are frequently missed or not followed up in routine clinical care. An ML algorithm that flags studies and notifies clinicians may minimize missed treatment opportunities.

Abstract Number ‐ 67: A case of Carotid blowout syndrome, case report, and review.

Introduction Carotid blowout syndrome (CBS) is a potentially fatal carotid artery rupture. It is an unforeseen complication during mechanical thrombectomy that can be catastrophic without timely diagnosis and intervention. CBS develops when a damaged arterial wall cannot sustain its integrity, especially in patients who have undergone surgery or radiotherapy due to cancer. Carotid blowout syndrome is classified as threatened (type1), impending (type2), and acute (type3). Endovascular techniques have emerged as preferable alternatives to surgical ligation for treatment of CBS. Previous systemic reviews and meta‐analyses demonstrated that both coil embolization and stent grafting may be safe treatment options for CBS. This case study aims to show that early detection and endovascular management with transient distal balloon occlusion and stenting are lifesaving measures. Methods Case‐report Results Case presentation: 60‐year‐old male with past medical history of lung cancer s/p chemotherapy and radiation, hypertension, and methamphetamine abuse presented with left‐sided weakness and dysarthria, onset was 2 hours prior to arrival, his NIHSS was 11, CT head was negative for hemorrhage, CT angiogram of head and neck showed tandem occlusion of right ICA and right MCA bifurcation, he was in window for intravascular thrombolysis without contraindication, so he received Alteplase, he was brought into Angio‐suite for mechanical thrombectomy, On Right CCA injection there was complete occlusion of Right ICA with TICI‐0 flow, distal branches of Right ACA and MCA were not visualized. Mechanical thrombectomy was done on Right ICA and Right MCA. During clot retrieval, flow arrest was achieved by inflating the balloon guide with diluted contrast. Post thrombectomy there was extravasation around the right CCA and ICA, so the balloon guide was reinflated to have a florist around the catheter and hemostasis in the right ICA, two carotid stents were deployed sequentially with rapid exchange technique with overlapping technique, an endovascular graft was introduced and deployed at mid cervical segment at the point of leak and dissection. Post mechanical thrombectomy, TICI‐3 flow in the right ICA, and MCA were achieved, the patient was discharged to rehab in a stable condition on dual antiplatelet regimen. Conclusions CBS is a rare complication during mechanical thrombectomy, early and aggressive intervention in CBS is crucial to prevent devastating consequences, Transient balloon occlusion distal to the carotid blowout of the ICA is a reasonable technique for completing endovascular management with stenting.

Abstract TMP14: Machine Learning-Enabled Detection Of Unruptured Cerebral Aneurysms Improves Detection Rates And Clinical Care

Background: Unruptured cerebral aneurysms (UCAs) have a relatively low prevalence of approximately 3%, but detection can prevent devastating consequences of subarachnoid hemorrhage. Here, we assess the performance of a machine-learning (ML) algorithm to identify UCAs and determine whether routine use of the algorithm would have improved detection rates and patient care. Methods: From a prospectively maintained multi-center registry across 8 certified stroke centers (1 comprehensive, 7 primary), we identified patients who underwent CT angiogram for evaluation of stroke from 3/14/21 - 11/31/21. A convolutional deep neural network (Viz.AI) trained to identify UCAs > 2mm analyzed the images. Ground truth was provided by independent expert neuroradiology read. The primary outcome was rate of UCAs detected by the ML algorithm but not detected or addressed in the clinical radiology report or clinical notes, which was determined by two independent researchers. Results: Among 1191 CT angiogram scans performed during the study period, 110 were flagged by the ML algorithm as possibly demonstrating an UCA, of which 36 cases were confirmed as true positive (PPV 33%). The most common locations included posterior communicating artery (22%), followed by MCA bifurcation (19%). Of these cases, 13 (26%) were not noted in the clinical radiology report or clinical notes, with a median size of 3 mm [IQR 2.7-4.4 mm], and 28 (78%) were not referred for follow up, with median size of 4.3 mm [IQR 3-9 mm]. Of the 28 cases not referred for follow up, 15 (54%) had been noted in the radiology report. 40% (6/15) of the detected but not referred cases had a diameter greater than 10mm. Conclusion: UCAs of sizes and intra-dural locations that may warrant treatment are frequently missed in routine clinical care. An ML algorithm that flags studies and notifies clinicians may minimize missed treatment opportunities.

Abstract TP29: Nurse-led Acute Stroke Process Promotes Advocacy And Treatment Times: A Case Series

Background: Reperfusion therapies for acute ischemic strokes are highly time sensitive. Centers across the world have implemented various approaches in treating these patients when presenting to the ED using multidisciplinary team approaches, straight-to-CT, and straight-to-angio suite. Several studies recently published the efficiency of an ED nurse-led stroke process on improving timeliness and decreasing door-to-treatment times. Purpose: Little to no literature has focused on how a stroke RN leading a stroke alert process serves as a patient advocate to assist the decision-making process. Methods: Our CSC built a stroke program using a multidisciplinary team, parallel workflow approach led by a Stroke Responder, filled by a neuroscience RN specially trained to lead the acute stroke process. This case series exemplifies how the Stroke Responder influenced the decision-making process in 2 stroke alerts. Case Study 1: A 60-year old high-profile public figure presented to the ED with mild aphasia. With a low NIHSS, some providers may be reluctant to offer thrombolysis based off risk vs benefit. In this patient’s case, mild aphasia was debilitating to life and career. The stroke RN emphasized this resulting in the patient receiving thrombolysis and making a full recovery to baseline. Case Study 2: For an incoming stroke alert on a 90+ year old, the stroke RN received pertinent patient information and a family contact number from EMS via telemedicine. The stroke RN was able to confirm information with family and transferred call to neurologist for consent of thrombolysis prior to patient arrival. Patient was transferred straight-to-CT upon arrival, administered the thrombolytic within 12 min, and subsequently taken for mechanical thrombectomy in the right MCA bifurcation when procedure was aborted due to NIHSS from 13 to 3. Conclusion: Highly specialized neuroscience nurses assigned to lead a stroke alert process benefit the patient beyond providing effective care coordination and assisting the neurologist with assessments. They can help drive the decision-making process resulting in higher treatment rates and faster door-to-treatment times.

Double stent-retriever as the first-line approach in mechanical thrombectomy: a randomized in vitro evaluation

BackgroundA repeated number of passes during mechanical thrombectomy leads to worse clinical outcomes in acute ischemic stroke. Initial experiences with the simultaneous double stent-retriever (double-SR) technique as the first-line treatment...

Flow Diversion as Destination Treatment of Intracranial Mycotic Aneurysms: A Retrospective Case Series.

Mycotic aneurysms represent a rare type of intracranial aneurysm. Treatment options usually consist of coiling, clipping, or liquid embolization. Data regarding outcomes after flow diversion of mycotic aneurysms are sparse. To present a single-center case series regarding our experience with FD as definitive treatment for ruptured mycotic aneurysms initially treated with coil embolization. We retrospectively reviewed a prospectively maintained database of all cerebrovascular procedures performed at a single institution between 2017 and 2021 for cases that used FD for the management of intracranial mycotic aneurysms. Prospectively collected data included patient demographics, medical history, rupture status, aneurysm morphology, aneurysm location, and periprocedural complications. The main outcomes included neurological examination and radiographic occlusion rate on cerebral digital subtraction angiography. Three patients with 4 ruptured mycotic aneurysms that were initially treated with coil embolization were identified that required retreatment. The aneurysms were located along the middle cerebral artery bifurcation (n = 2), posterior cerebral artery P1/2 junction (n = 1), and basilar artery apex (n = 1), which all demonstrated recurrence after initial coil embolization. Successful retreatment using flow diverting stents was performed in all 3 patients. At the last angiographic follow-up, all aneurysms demonstrated complete occlusion. No patients suffered new periprocedural complications or neurological deficits after FD. Flow-diverting stents may be an effective treatment option for intracranial mycotic aneurysms that are refractory to previous endovascular coiling. Future studies are warranted to establish the associated long-term safety and clinical efficacy.

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.

Predicting the growth of middle cerebral artery bifurcation aneurysms using differences in the bifurcation angle and inflow coefficient.

Growing intracranial aneurysms (IAs) are prone to rupture. Previous cross-sectional studies using postrupture morphology have shown the morphological or hemodynamic features related to IA rupture. Yet, which morphological or hemodynamic differences of the prerupture status can predict the growth and rupture of smaller IAs remains unknown. The purpose of this longitudinal study was to investigate the effects of morphological features and the hemodynamic environment on the growth of IAs at middle cerebral artery (MCA) bifurcations during the follow-up period. One hundred two patients with MCA M1-2 bifurcation saccular IAs who underwent follow-up for more than 2 years at the authors' institutions between 2011 and 2019 were retrospectively identified. During the follow-up period, cases involving growth of MCA IAs were assigned to the event group, and those with MCA IAs unchanged in size were assigned to the control group. The morphological parameters examined were aneurysmal neck length, dome height, aspect ratio and volume, M1 and M2 diameters and their ratio, and angle configurations among M1, M2, and the aneurysm. Hemodynamic parameters were flow rate and wall shear stress in M1, M2, and the aneurysm, including the aneurysmal inflow rate coefficient (AIRC), defined as the ratio of the aneurysmal inflow rate to the M1 flow rate. Those parameters were compared statistically between the two groups. Correlations between morphological and hemodynamic parameters were also examined. Eighty-three of 102 patients were included: 25 with growing MCA IAs (event group) and 58 with stable MCA IAs (control group). The median patient age at initial diagnosis was 66.9 (IQR 59.8-72.3) years. The median follow-up period was 48.5 (IQR 36.5-65.6) months. Both patient age and the AIRC were significant independent predictors of the growth of MCA IAs. Moreover, the AIRC was strongly correlated with sharper bifurcation and inflow angles, as well as wider inclination angles between the M1 and M2 arteries. The AIRC was a significant independent predictor of the growth of MCA IAs. Sharper bifurcation and inflow angles and wider inclination angles between the M1 and M2 arteries were correlated with the AIRC. MCA IAs with such a bifurcation configuration are more prone to grow and rupture.

Y‐Stent–Assisted Coiling of Wide‐Necked Intracranial Aneurysms With the Neuroform Atlas Stent System

Background Endovascular management of wide‐necked bifurcation aneurysms poses a therapeutic challenge, as coiling often requires the use of multiple adjunctive stent constructs to achieve successful embolization without compromising parent vessel integrity. The Neuroform Atlas Stent System is a novel low‐profile, intraluminal remodeling device. The study aims to investigate the safety and efficacy of Y‐stent–assisted coiling configuration constructs using the next generation stent for aneurysm coil embolization. Methods Subjects undergoing Y‐stent–assisted coiling in the ATLAS IDE (Safety and Effectiveness of the Treatment of Wide Neck, Saccular Intracranial Aneurysms with the Neuroform Atlas Stent System Investigational Device Exception) trial were identified for subgroup analysis. Enrollment in the trial was not stratified on the basis of the procedural stenting technique used. The primary efficacy end point was complete aneurysm occlusion (Raymond–Roy class 1) on 12‐month angiography, in the absence of re‐treatment or parent artery stenosis (>50%) at the target location. The primary safety end point was any major stroke or ipsilateral stroke or neurological death within 12 months. Adjudication of the primary end points was performed by an independent imaging core laboratory and the clinical events committee. Results A total of 60 subjects were identified. The mean age was 59, and 28.3% were men. The median aneurysm size was 6.7 mm, with a median neck size of 4.3 mm. Frequently reported aneurysm locations included the basilar apex (56.7%), anterior communicating artery (20.0%), and middle cerebral artery bifurcation (11.7%). The composite primary efficacy end point was achieved in 81.1% of subjects. Overall, 1.7% of subjects experienced a primary safety endpoint of major ipsilateral stroke or neurological death. Conclusion In the ATLAS IDE aneurysm cohort premarket approval study, Y‐stent–assisted coiling with Neuroform demonstrated high rates of complete aneurysm occlusion at 12 months, with low rates of morbidity.

Trends of Expanding Indications of Woven EndoBridge Devices for the Treatment of Intracranial Aneurysms: ASystematic Review and Meta-analysis.

Woven EndoBridge (WEB) was introduced for the endovascular therapy of wide-neck intracranial aneurysms. The safety and efficacy have been evaluated through several meta-analyses. However, these reviews did not cover the expanding indications in detail. Therefore, we aimed to show the changing trends for intracranial aneurysm treatment using the WEB device. Asystematic review and meta-analysis was conducted with PubMed, Embase, and Cochrane databases. We searched for studies that reported baseline characteristics of aneurysms and the WEB devices, which had treated more than 20aneurysms consecutively. The pooled proportions of aneurysm indications and used WEB device types were obtained. To evaluate the changing indications for the treated aneurysm size, including the neck diameter, atrend line and linear regression model was measured. A total of 27cohorts were included encompassing 1831aneurysms treated with the WEB. Atotal of 86% were used in the four major locations as on-label indications (middle cerebral artery bifurcation; 34%, anterior communicating artery; 26%, basilar tip; 18%, internal carotid artery terminus; 7%). Among off-label indications, the most common location was the posterior communicating artery (8%), followed by the anterior cerebral artery including the pericallosal artery (6%). The median aneurysm size and neck diameter was 7 mm and 4.6 mm, respectively. The WEB device has been used for the treatment of smaller aneurysms than the initial indication. Also, the proportion for ruptured aneurysm treatment was increased up to 15%. The mechanical and technical development of the WEB resulted in expanding the indications for the treatment of intracranial aneurysms. The off-label indications accounted for 14% in total and an increasing number of small aneurysms are treated with WEB devices. Moreover, the proportion for ruptured aneurysm treatment was currently increased up to 14% more than in the beginning.

Pipeline embolization of complex, wide-necked middle cerebral artery bifurcation aneurysms: A single-center experience.

To evaluate the performance of Pipeline Embolization Device (PED) in complex, wide-necked middle cerebral artery (MCA) bifurcation aneurysms. We performed a retrospective review of patients treated with PED for complex, wide-necked MCA bifurcation aneurysms between August 2016 and March 2021. In addition to demographic data, we collected aneurysmal neck width, dome-to-neck ratio, complications, and clinical and angiographic follow-up. The embolization degree of aneurysms was evaluated by O'Kelly-Marotta (OKM) grading scale, and the prognosis was assessed with the modified Rankin Scale (mRS). From August 2016 to March 2021, a total of 46 patients with 49 MCA bifurcation aneurysms in our center were enrolled, of whom all received PEDs successfully. The O'Kelly-Marotta (OKM) grading showed that post-procedure 15 patients (32.6%) were grade C, another 8 patients (17.4%) were grade D. Aneurysms with small remnant or complete occlusion were 50%, symptomatic ischemic events occurred in 3 (6.5%), and bleeding events in 1 (2.2%). 41 patients underwent a 6-month angiography follow-up, in which 7 patients (17.1%) remained OKM grade C and 30 patients (73.2%) achieved OKM grade D. Complete occlusion and small remnant aneurysms were up to 90.3%. 40 (97.6%) patients' mRS scores were 0, and 1 (2.4%) patient was 2. No new bleeding and ischemic events occurred during the 6-month. The Pipeline Embolization Device provides a safe and effective treatment alternative for complex, wide-necked MCA aneurysms. A larger number with longer-term follow-up data is needed for further verification.

The pCONUS2 and pCONUS2 HPC Neck Bridging Devices

IntroductionBifurcation aneurysms represent an ongoing endovascular challenge with a variety of techniques and devices designed to address them. We present our multicenter series of the pCONUS2 and pCONUS2 HPC devices when treating bifurcation aneurysms.MethodsWe performed a retrospective review of our prospectively maintained databases at 3 tertiary neurointerventional centers to identify all patients who underwent coil embolization with the pCONUS2 or pCONUS2 HPC device between February 2015 and August 2021. We recorded baseline demographics, aneurysm data, complications, immediate and delayed angiographic results.ResultsWe identified 55 patients with 56 aneurysms, median age 63 years (range 42–78 years), 67.3% female (n = 37). The commonest aneurysm location was the MCA bifurcation (n = 40, 71.4%). Average dome height was 8.9 ± 4.2 mm (range 3.2–21.5 mm), average neck width 6.4 ± 2.5 mm (range 2.6–14 mm), and average aspect ratio 1.3 ± 0.6 (range 0.5–3.3). The pCONUS2 was used in 64.3% and the pCONUS2 HPC in 35.7%. The procedural technical success rate was 98.2%. Intraoperative complications occurred in 5 cases (8.9%), 4 of which were related to the coils with partial thrombus formation on the pCONUS2 HPC seen in 1 case that was resolved with heparin. In relation to the procedure and treatment of the aneurysm the overall permanent morbidity was 1.8% (n = 1/55) and mortality 0%. Delayed angiographic follow-up (48 aneurysms) at median 12 months postprocedure (range 3–36 months) demonstrated adequate occlusion of 83.4% of aneurysms.ConclusionThe pCONUS2 and pCONUS2 HPC devices carry a high technical success rate, low complication and retreatment rate, and good rates of adequate occlusion. Larger prospective confirmatory studies are required.

Outcome of microsurgical clipping of ruptured intracranial aneurysms: An early experience

Introduction: Rupture of intracranial aneurysm is a catastrophic event with a mortality rate of 25% to 50%. Despite recent advances in endovascular techniques, microsurgical clipping is the standard modality of treatment due to its relative low cost and feasibility. We prospectively analyzed the cases of microsurgically clipped aneurysms with an aim to evaluate the overall outcome and the pretreatment variables predicting outcomes. Materials and methods: This is the prospective study of 15 consecutive microsurgical clippings of ruptured intracranial aneurysms conducted in the Department of Neurosurgery at College of Medical Sciences Teaching Hospital, Chitwan, Nepal from April 2018 to March 2020. Patients were followed up for at least three months and assessed according to modified Rankin Scale (mRS). Results: The mean age of patients was 55.47 years with female predominance. The most common location of aneurysms was Middle cerebral artery bifurcation (53%). Favorable outcome (mRS score 1 to 3) was achieved in 60% of patients whereas 40% had unfavorable outcome (mRS score 4 to 6). Poor Hunt and Hess at presentation and presence of vasospasm/infarction were associated with poor outcome. Overall mortality rate was 27%. Three patients required VP shunt whereas three patients each had vasospasm/Delayed ischemic neurological deficit (DIND) and intra-operative rupture. Conclusion: Microsurgical clipping of aneurysms is a standard treatment modality with good results despite recent advances in endovascular techniques. Favorable outcome can be achieved in patients with good Hunt and Hess grade at presentation and without clinical vasospasm/DIND.

Deterioration of non-lesional side evoked potential during unilateral single unruptured intracranial aneurysm clipping: incidental finding or true warning signal?

To investigate patients presenting non-lesional side evoked potential (EP) deterioration without lesional side EP change during unruptured intracranial aneurysm (UIA) clipping surgery. This single-center, retrospective study included patients who underwent single UIA clipping with intraoperative neuromonitoring between March 2017 and December 2021. For targeting lateralized surgery group, we included the UIAs located in middle cerebral artery bifurcation, middle cerebral artery, anterior choroidal artery, and internal carotid artery. Motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) were measured during surgery. Postoperative neurologic deficits (PNDs) were defined using the modified Rankin Scale. A total of 315 patients were enrolled. Twenty-seven patients (8.6%) presented with deterioration of one or more EPs. Nine patients showed non-lesional side EP deterioration first without lesional side EP change. Five patients showed only non-lesional side EP deterioration and did not present PNDs or radiologic complications. Three patients showed non-lesional side EP deterioration followed by bilateral EP warnings, one of which had PND due to postoperative subarachnoid hemorrhage. The other two patients had no PND but showed postoperative cerebral vasospasm. This study provides a basis for decisions regarding the firstly appeared non-lesional side EP deterioration without lesional side EP change during unilateral UIA clipping. Further studies with larger sample sizes are needed to generalize these findings.

Vortex formation and associated aneurysmogenic transverse rotational shear stress near the apex of wide-angle cerebral bifurcations.

Aneurysm formation preferentially occurs at the site of wide-angle cerebral arterial bifurcations, which were recently shown to have a high longitudinal positive wall shear stress (WSS) gradient that promotes aneurysm formation. The authors sought to explore the other components of the hemodynamic environment that are altered with increasing bifurcation angle in the apical region and the effects of these components on WSS patterns on the vessel wall that may modulate aneurysm genesis and progression. Parametric models of symmetrical and asymmetrical bifurcations were created with increasing bifurcation angles (45°-240°), and 3D rotational angiography models of 13 middle cerebral artery (MCA) bifurcations (7 aneurysmal, 6 controls) were analyzed using computational fluid dynamics. For aneurysmal bifurcations, the aneurysm was digitally removed to uncover hemodynamics at the apex. WSS vectors along cross-sectional planes distal to the bifurcation apex were decomposed as orthogonal projections to the cut plane into longitudinal and transverse (tangential to the cross-sectional plane) components. Transverse rotational WSS (TRWSS) and TRWSS gradients (TRWSSGs) were sampled and evaluated at the apex and immediately distal from the apex. In parametric models, increased bifurcation angle was associated with transverse flow vortex formation with emergence of an associated apical high TRWSS with highly aneurysmogenic positive TRWSSGs. While TRWSS decayed rapidly away from the apex in narrow-angle bifurcations, it remained greatly elevated for many radii downstream in aneurysm-prone wider bifurcations. In asymmetrical bifurcations, TRWSS was higher on the aneurysm-prone daughter vessel associated with the wider angle. Patient-derived models with aneurysmal bifurcations had wider angles (149.33° ± 12.56° vs 98.17° ± 8.67°, p < 0.001), with significantly higher maximum TRWSS (1.37 ± 0.67 vs 0.48 ± 0.23 Pa, p = 0.01) and TRWSSG (1.78 ± 0.92 vs 0.76 ± 0.50 Pa/mm, p = 0.03) compared to control nonaneurysmal bifurcations. Wider vascular bifurcations are associated with a novel and to the authors' knowledge previously undescribed transverse component rotational wall shear stress associated with a positive (aneurysmogenic) spatial gradient. The resulting hemodynamic insult, demonstrated in both parametric models and patient-based anatomy, is noted to decay rapidly away from the protection of the medial pad in healthy narrow-angle bifurcations but remain elevated distally downstream of wide-angle aneurysm-prone bifurcations. This TRWSS serves as a new contribution to the hemodynamic environment favoring aneurysm formation and progression at wide cerebral bifurcations and may have clinical implications favoring interventions that reduce bifurcation angle.

Aneurysm presence at the anterior communicating artery bifurcation is associated with caliber tapering of the A1 segment.

Vessel tapering results in blood flow acceleration at downstream bifurcations (firehose nozzle effect), induces hemodynamics predisposing to aneurysm initiation, and has been associated with middle cerebral artery (MCA) aneurysm presence and rupture status. The authors sought to determine if vessel caliber tapering is a generalizable predisposing factor by evaluating upstream A1 segment profiles in association with aneurysm presence in the anterior communicating artery (ACoA) complex, the most prevalent cerebral aneurysm location associated with a high rupture risk. Three-dimensional rotational angiographic studies were analyzed for 68 patients with ACoA aneurysms, 37 nonaneurysmal contralaterals, and 53 healthy bilateral controls (211 samples total). A1 segments were determined to be dominant, codominant, or nondominant based on flow and size. Equidistant cross-sectional orthogonal cuts were generated along the A1 centerline, and cross-sectional area (CSA) was evaluated proximally and distally, using intensity-invariant edge detection filtering. The relative tapering of the A1 segment was evaluated as the tapering ratio (distal/proximal CSA). Computational fluid dynamics was simulated on ACoA parametric models with and without tapering. Aneurysms occurred predominantly on dominant (79%) and codominant (17%) A1 segments. A1 segments leading to unruptured ACoA aneurysms had significantly greater tapering compared to nonaneurysmal contralaterals (0.69 ± 0.13 vs 0.80 ± 0.17, p = 0.001) and healthy controls (0.69 ± 0.13 vs 0.83 ± 0.16, p < 0.001), regardless of dominance labeling. There was no statistically significant difference in tapering values between contralateral A1 and healthy A1 controls (0.80 ± 0.17 vs 0.83 ± 0.16, p = 0.56). Hemodynamically, A1 segment tapering induces high focal pressure, high wall shear stress, and high velocity at the ACoA bifurcation. Aneurysmal, but not contralateral or healthy control, A1 segments demonstrated significant progressive vascular tapering, which is associated with aneurysmogenic hemodynamic conditions at the ACoA complex. Demonstration of the upstream tapering effect in the communicating ACoA segment is consistent with its prior detection in the noncommunicating MCA bifurcation, which together form more than 50% of intracranial aneurysms. The mechanistic characterization of this upstream vascular tapering phenomenon is warranted to understand its clinical relevance and devise potential therapeutic strategies.

Comparing treatment outcomes of various intracranial bifurcation aneurysms locations using the Woven EndoBridge (WEB) device

BackgroundThe Woven EndoBridge (WEB) device has Food and Drug Administration approval for treatment of wide-necked intracranial bifurcation aneurysms. The WEB device has been shown to result in adequate occlusion in...