Staged cerebral and brachiocephalic bypass in a patient with MCA and brachiocephalic steno-occlusion.

Background: Brachiocephalic steal is a rare phenomenon that may lead to hemodynamic abnormalities in the ipsilateral vertebral and carotid arteries. Current treatment includes management of vascular risk factors, endovascular stenting, and surgical management depending on the severity of symptoms. Case Information: We describe a patient with multiple vascular risk factors who presented with mild neurological symptoms and chronic right arm weakness associated with concurrent brachiocephalic steal and right MCA M1 stenosis on neuroimaging. Use of right superficial temporal artery to middle cerebral artery bypass and aorta-right subclavian bypass resulted in improved flow to the right hemisphere on quantitative magnetic resonance angiography and single-photon emission computed tomography, significantly lowering the risk of catastrophic ischemic stroke. Conclusion: Complex steal phenomena increase stroke risk. In cases of high-grade occlusion or advanced symptoms, endovascular or surgical management should be considered for optimal stroke prevention.

Blood Flow Capacity Assessment of End-to-Side Arterial Anastomosis In Vivo in Rats.

Introduction The aim of this article was to assess the flow capacity of end-to-side arterial anastomosis depending on the method of its implementation. Materials and Methods The study was conducted on 30 live Wistar rats in vivo, which were randomly divided into three groups. In each group of animals, an end-to-side microanastamosis was performed using three methods of donor artery preparation: 45 degrees (group A), 90 degrees (group B), and arteriotomy according to the "fish mouth" type (group C). The determination of flow capacity of anastomosis by measuring the blood volume flow with transonic flowmeter was performed. Results The obtained average values after the anastomosis were, respectively, 7.335 mL/s (standard deviation [SD]: 2.0771; min: 4.05; max: 10.85), 7.36 mL/s (SD: 0.836 mi: 6.15; max: 8.75), and 6.37 mL/s (SD: 1.247; min: 5.05; max: 9.05). No statistically significant difference in the blood volume flow velocity between all types of anastomoses was obtained ( p = 0.251). Conclusion The flow capacity of end-to-side arterial anastomosis does not depend on the chosen method of anastomosis.

Multi-parameter MRI-Based Machine Learning Model to Evaluate the Efficacy of STA-MCA Bypass Surgery for Moyamoya Disease: A Pilot Study.

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery represents the primary treatment for Moyamoya disease (MMD), with its efficacy contingent upon collateral vessel development. This study aimed to develop and validate a machine learning (ML) model for the non-invasive assessment of STA-MCA bypass surgery efficacy in MMD. This study enrolled 118 MMD patients undergoing STA-MCA bypass surgery. Clinical features were screened to construct a clinical model. MRI features were extracted from the middle cerebral artery supply area using 3D Slicer and employed to build five ML models using logistic regression algorithm. The combined model was developed by integrating the radiomics score (Rad-score) with the clinical features. Model performance validation was conducted using ROC curves. Platelet count (PLT) was identified as a significant clinical feature for constructing the clinical model. A total of 3404 features (851 × 4) were extracted, and 15 optimal features were selected from each MRI sequence as predictive factors. Multivariable logistic regression identified PLT and Rad-score as independent parameters used for constructing the combined model. In the testing set, the AUC of the T1WI ML model [0.84 (95% CI, 0.70-0.97)] was higher than that of the clinical model [0.66 (95% CI, 0.46-0.86)] and the combined model [0.80 (95% CI, 0.66-0.95)]. The T1WI ML model can be used to assess the postoperative efficacy of STA-MCA bypass surgery for MMD.

Indications for cerebral revascularization for moyamoya syndrome in pediatric sickle cell disease determined by Delphi methodology.

OBJECTIVE: Cerebral revascularization surgery (CRS) has been used to prevent stroke in children with sickle cell disease (SCD) and cerebral vasculopathy (e.g., moyamoya syndrome). While results suggest that it may be an effective treatment, surgical indications have not been well defined. This study sought to determine indications for offering revascularization surgery in centers with established sickle cell programs in the US. METHODS: Three sequential surveys utilizing the Delphi methodology were administered to neurosurgeons participating in the Stroke in Sickle Cell Revascularization Surgery study. Respondents were presented with clinical scenarios of patients with SCD and varying degrees of ischemic presentation and vasculopathy, and the group's agreement to offer surgical revascularization was measured. Consensus was defined as ≥ 75% similar responses. RESULTS: The response rate to all 3 surveys was 100%. Seventeen neurosurgeons from 16 different centers participated. The presence of moyamoya collaterals (MMCs) and arterial stenosis matching an ischemic distribution yielded the strongest recommendations to offer surgery. There was consensus to offer revascularization in the presence of MMCs and at least 50% arterial stenosis matching an ischemic distribution. In contrast, there was no consensus to offer revascularization with 50%-70% stenosis not matching an ischemic presentation in the absence of MMCs. The presence of the ivy sign in the distribution of the stenotic artery also contributed to the consensus to offer surgery in certain scenarios. CONCLUSIONS: There were several clinical scenarios that attained consensus to offer surgery; the strongest was moderate to severe arterial stenosis that matched the distribution of ischemic presentation in the presence of MMCs. Radiological findings of decreased cerebral flow or perfusion also facilitated attaining consensus to offer surgery. The findings of this study reflect expert opinion about questions that deserve prospective clinical research. Determination of indications for CRS can guide clinical practice and aid the design of prospective studies.

[EC-IC bypass for occlusion of the internal carotid artery]. / EC-IC-Bypass bei Verschluss der A. carotis interna.

BACKGROUND: There are barely any alternative treatment options to the drug treatment of hemodynamically caused cerebral ischemia, as in occlusion of the internal carotid artery. OBJECTIVE: For secondary prevention of an ischemic stroke due to carotid occlusion and hemodynamic instability, extracranial-intracranial (EC-IC) bypass surgery can be an important option in selected patients. MATERIAL AND METHODS: The development, study situation, indications and surgical technique for placement of an EC-IC bypass in cases of occlusion of the internal carotid artery are presented. RESULTS: With appropriate expertise and strict selection of patients, the placement of an EC-IC bypass enables stabilization of cerebral perfusion with a low rate of complications. CONCLUSION: The study situation is controversially discussed; nevertheless, surgical treatment in a specialized neurovascular center should at least be considered.

STA-MCA Double-Barrel Bypass: A Systematic Review of Technique and Single-Arm Meta-Analysis of Outcomes.

INTRODUCTION: Conventionally, one branch of the superficial temporal artery (STA) is utilized to revascularize the middle cerebral artery (MCA). However, there is the possibility of utilizing both branches of the STA when performing the bypass, characterizing the double-barrel (DB) STA-MCA bypass. Notably, a lack of studies evaluating this technique led the authors to conduct a systematic review and single-arm meta-analysis. METHODS: PubMed, Embase and Web of Science were searched systematically for publications of DB-STA-MCA bypass on November 1st, 2023. The findings were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Case reports were not included for statistical analysis purposes. RESULTS: The review included 408 patients and 534 bypasses from 34 studies. The main etiology was Moyamoya disease (64.6%), followed by cerebral ischemia (22.2%) and aneurysms (12.5%). The median of the mean follow-ups of each study was 12.8 months (range 1.5-87.9). The postoperative patency was 100%. The follow-up patency was 98% (95% CI: 96%-100%; I2 = 0%). The procedure-related mortality was 0% (95% CI: 0%-1%; I2 = 0%). Aneurysms obtained 87% (95% CI: 72%-100%; I2 = 4%) of good clinical outcomes, while Moyamoya disease yielded a rate of 70% (95% CI: 10%-100%; I2 = 97%). Ischemic complications occurred at a rate of 6% (95% CI: 2%-11%; I2 = 36%), while hemorrhagic occurred at 6% (95% CI: 1%-11%; I2 = 56%). Hyperperfusion syndrome rate was calculated as 18% (7%-30%; I2 = 55%) for Moyamoya disease. CONCLUSIONS: The procedure appears to be safe, with excellent patency rates. The clinical efficacy for ischemic and Moyamoya diseases warrants further standardized robust investigation with a broader number of patients, and aneurysm studies are required to enhance sample sizes. The main complication for the Moyamoya subgroup is hyperperfusion syndrome.

Moyamoya Disease: Advances in Diagnosis, Treatment, and Surgical Interventions.

Moyamoya disease (MMD) is a rare cerebrovascular disorder characterized by progressive narrowing of the brain's arteries, leading to an increased risk of stroke. The primary susceptibility gene, RNF213, has been identified in individuals of East Asian descent, contributing to ongoing research into potential therapeutic targets. The distinction between idiopathic MMD and secondary forms, such as Moyamoya syndrome (MMS), is discussed, focusing on associated conditions and risk factors. Surgical revascularization emerges as the mainstay of treatment, with direct, indirect, and combination bypass procedures explored. The review delves into advancements in imaging technology for diagnosis and treatment planning, emphasizing non-invasive magnetic resonance examination's role in identifying asymptomatic patients. Additionally, insights into anesthetic care and therapeutic approaches underscore the evolving understanding of this complex disease. The presented information aims to contribute to the ongoing dialogue surrounding MMD, providing a valuable resource for clinicians and researchers.

Application of individual brain connectome in chronic ischemia: mapping symptoms before and after reperfusion.

How brain functions in the distorted ischemic state before and after reperfusion is unclear. It is also uncertain whether there are any indicators within ischemic brain that could predict surgical outcomes. To alleviate these issues, we applied individual brain connectome in chronic steno-occlusive vasculopathy (CSOV) to map both ischemic symptoms and their postbypass changes. A total of 499 bypasses in 455 CSOV patients were collected and followed up for 47.8 ± 20.5 months. Using multimodal parcellation with connectivity-based and pathological distortion-independent approach, areal MR features of brain connectome were generated with three measurements of functional connectivity (FC), structural connectivity, and PageRank centrality at the single-subject level. Thirty-three machine-learning models were then trained with clinical and areal MR features to obtain acceptable classifiers for both ischemic symptoms and their postbypass changes, among which, 11 were deemed acceptable (AUC > 0.7). Notably, the FC feature-based model for long-term neurological outcomes performed very well (AUC > 0.8). Finally, a Shapley additive explanations plot was adopted to extract important individual features in acceptable models to generate "fingerprints" of brain connectome. This study not only establishes brain connectomic fingerprint databases for brain ischemia with distortion, but also provides informative insights for how brain functions before and after reperfusion.

Flow alteration surgery using a radial artery graft for recurrent ruptured vertebral artery dissecting aneurysm after stent-assisted coil embolization: A case report.

BACKGROUND: Ruptured vertebral artery dissecting aneurysm (VADA) is often treated surgically with coil embolization and sometimes recurs. We herein report a case of recurrent ruptured VADA after stent-assisted coil embolization (SAC) that was successfully treated with flow alteration surgery using a radial artery (RA) graft. CASE DESCRIPTION: A 67-year-old woman presented with headache and coma. Enhanced CT revealed subarachnoid hemorrhage due to right VADA. Since the left VA was hypoplastic, the aneurysm was treated with SAC. However, follow-up angiography revealed recurrence of the aneurysm. Additional embolization was not considered due to the small size of the recurrent lesion and the presence of a stent; therefore, flow alteration surgery was performed using a RA graft. There were no neurological deficits after surgery or recurrence. CONCLUSION: Flow alteration surgery using a RA graft is useful for recurrent VADA after SAC.

Which is a more appropriate recipient for posterior circulation bypass surgery: V3 or V2? Differences in underlying disease and lesion sites between extracranial vertebral artery dissection and atherosclerotic changes. Illustrative cases.

BACKGROUND: Revascularization for extracranial vertebral artery dissection or vertebral artery atherosclerotic occlusive lesions caused by vertebrobasilar insufficiency or posterior circulation infarction is relatively rare. When bypassing the cervical external carotid artery (ECA) or common carotid artery (CCA) using a radial artery (RA) or saphenous vein (SV) graft, it is difficult to determine whether the recipient site should be the V2 or V3 portion. OBSERVATIONS: In case 1, cervical ECA-RA-V3 bypass was performed for bilateral extracranial vertebral artery dissection with the onset of ischemia, and cervical CCA-SV-V3 bypass was added 12 days later. Nine years after surgery, the bilateral vertebral artery dissection had improved, and the patient still had a patent bypass. In case 2, cervical ECA-RA-V2 bypass was performed for arteriosclerotic bilateral extracranial vertebral artery occlusion. The bypass was patent 5 years after surgery. The postoperative course was uneventful in both patients. LESSONS: The authors present cases of posterior fossa revascularization using the vertebral artery V3 and V2 portions via skull base surgery and note that it is important to consider each patient's individual characteristics when selecting the V3 or V2 portion.

Association of Cognitive Reserve and Preoperative Cognitive Function in Patients with Adult Moyamoya Disease: A Preliminary Study.

INTRODUCTION: Many patients with moyamoya disease (MMD) exhibit cognitive decline; however, the link between cognitive reserve (CR) and cognitive function in those who have not undergone revascularization remains unexplored. We aimed to evaluate preoperative cognitive impairment in such patients and to explore the relationship between CR, measured using the Cognitive Reserve Index questionnaire (CRIq), and cognitive abilities across different domains, determined using neuropsychological tests. METHODS: Demographic, clinical, CRIq, and neuropsychological assessment data were gathered from patients with MMD who underwent preoperative cognitive functional assessments at our center during 2021-2023. These patients were categorized according to their Montreal Cognitive Assessment score. Multivariable linear regression was performed to analyze the association between CRIq score and cognitive performance, both globally and in specific domains. RESULTS: In the MMD cohort of 53 patients, 49% (n = 26) of the patients exhibited a decrease in overall cognitive performance. Individuals with cognitive dysfunction had significantly lower composite CRIq scores than those with intact cognition. Although no association between overall cognitive ability and CR was observed, independent associations emerged between CR and specific cognitive functions - language (ß = 0.56, p = 0.002), verbal memory (ß = 0.45, p = 0.001), and executive function (ß = 0.35, p = 0.03). CONCLUSION: This preliminary study revealed that expressive language, verbal memory, and executive function are linked to CR in presurgical patients with MMD, highlighting the role of CR in predicting cognitive outcomes. Further research is warranted to elucidate the combined effects of CR and other risk factors on the cognitive function of patients with MMD.

Vascular architecture characters and risk factors analysis of unstable moyamoya disease.

Background: In some MMD patients, the digital subtraction angiography (DSA) examination found, occlusion in the ipsilateral internal carotid artery or middle cerebral artery, accompanied by the formation of numerous moyamoya vessels. Conversely, the contralateral internal carotid artery or middle cerebral artery shows signs of stenosis without the presence of moyamoya vessels. Notably, cerebral perfusion studies reveal a similar or even more severe reduction in perfusion on the occluded side compared to the stenotic side. Importantly, clinical symptoms in these patients are typically attributed to ischemia caused by the stenotic side. This condition is referred to as unstable moyamoya disease (uMMD). Objective: This clinical research focuses on evaluating risk factors related to MMD and developing strategies to minimize postoperative complications. The study aims to analyze vascular characteristics and identify potential risk factors in patients with uMMD. Methods: The authors reviewed consecutive cases with complete clinical and radiological documentation of patients who underwent surgery between January 2018 and June 2023. Univariate analysis and multivariate logistic regression analysis were employed to understand the risk factors and prognosis of postoperative complications in uMMD. Results: Postoperative complications were retrospectively analyzed in 1481 patients (aged 14 to 65). Among them, 1,429 patients were assigned to the conventional treatment group, while 52 were in the unstable moyamoya disease group. The uMMD treatment group showed a significantly higher incidence of early postoperative complications such as RIND, cerebral infarction, and cerebral hemorrhage (p < 0.05). Univariate and multivariate logistic regression analyses were conducted on the postoperative complications of 52 uMMD patients. Initial symptoms of stenosis ≤50% (univariate: p = 0.008, multivariate: p = 0.015; OR [95% CI] =23.149 [1.853-289.217]) and choosing occluded side surgery (univariate: p = 0.043, multivariate: p = 0.018; OR [95% CI] =0.059 [0.006-0.617]) were identified as significant risk factors for postoperative neurological complications. Conclusion: Compared to the conventional treatment group, uMMD has higher complication rates, with vascular stenosis degree and surgical side selection identified as significant risk factors. A comprehensive understanding of preoperative clinical symptoms and vascular characteristics in moyamoya disease patients, coupled with the formulation of rational surgical plans, contributes positively to decreasing postoperative mortality and disability rates in uMMD.

Modified craniotomy procedures and virtual reality technology for accurate localization of the frontal branch of MMA in revascularization surgery.

The frontal branch of middle meningeal artery (MMA) can easily be damaged during revascularization surgery. To precise locate it and minimize its injury, we propose a set of modified craniotomy procedures combined with simple virtual reality (VR) technology based on three-dimensional (3D) Slicer simply, economically, and efficiently. Patients with Moyamoya disease (MMD) and internal carotid artery occlusion (ICAO) who received revascularization from January 2015 to December 2022 were divided into two groups based on the methods used to locate the MMA: traditional methods and precise MMA locating with VR technology. Patient demographics and clinical characteristics were analyzed to compare the preservation rates of MMA. The distances between this artery and bony anatomical landmarks were also measured to better understand its localization. There was no significant difference in baseline characteristics between the two groups. The precise MMA locating group exhibited a significantly higher preservation rate of the frontal branch of MMA (p = 0.037, 91.7% vs. 68.2%). Over 77% of patients had their frontal branch of MMA partially or completely surrounded by bony structures to varying degrees. Therefore, the combination of modified craniotomy procedures, 3D Slicer, and simple VR technology represents an economical, efficient, and operationally simple strategy.

A Practical Guide to Train the Side-to-side Anastomosis: Tips, Tricks and Technical Nuances.

BACKGROUND: Microanastomosis presents a challenge in neurosurgical procedures, requiring specialized skills. Regular practice outside the operating room is crucial. This study aims to provide a detailed description of the side-to-side anastomosis technique and analyze its advantages in preventing failures compared with other variations. METHODS: We examined the technique, characteristics, and outcomes of side-to-side bypass procedures for complex aneurysms in the anterior cerebral artery territory at our institution over the past decade. We compared our technique with those described in the literature by other groups. RESULTS: The Far East Neurosurgical Institute (FENI) technique was used in 15 patients, with 17 side-to-side anastomoses performed. The average anastomosis time was 27.5 minutes, with 100% patency in follow-up. Our technique demonstrated safety and effectiveness in treating intracranial aneurysms, yielding satisfactory short- and long-term functionality outcomes. We highlight the importance of maintaining a curvilinear arteriotomy shape, at least 3 times the diameter of the artery, and utilizing an interrupted suturing technique on the anterior wall. CONCLUSIONS: This paper presents the first comprehensive description of the side-to-side anastomosis technique, supported with images and videos for training and replicability. Our technique enhances flow dynamics and reduces the risk of acute thrombus formation. Training in simulators and microsurgery practice centers outside the operating room is essential for acquiring and refining microsurgical skills.

The Art of Cerebral Revascularization: An Illustrative Case Series of Bypass Techniques for Complex Intracranial Aneurysms.

BACKGROUND: Complex intracranial aneurysms (CIAs) comprise a subset of lesions with defiant vascular architecture, difficult access, and prior treatment. Surgical management of CIAs is often challenging and demands an assessment on a case-by-case basis. The generational evolution of bypass surgery has offered a long-standing potential for effective cerebral revascularization. Herein, we aim to illustrate a single-center experience treating CIAs. METHODS: The authors conducted a retrospective analysis of clinical records of patients treated with cerebral revascularization techniques at Hospital Nacional Dos de Mayo, Lima, Peru, during 2018-2022. Relevant data were collected, including patient history, aneurysm features on imaging, preoperative complications, the intraoperative course, aneurysm occlusion rates, bypass patency, neurological function, and postoperative complications. RESULTS: Seventeen patients (70.59% female; median age: 53 years) with 17 CIAs (64.7% saccular; 76.5% ruptured) were included. The most common clinical presentation included loss of consciousness (70.6%) and headaches (58.8%). Microsurgical treatment included first-, second-, and third-generation bypass. In 47.1% of cases, an anastomosis between the superficial temporal artery and the M3 segment was predominantly used, followed by an A3-A3 bypass (29.4%), a superficial temporal artery-M2 bypass (17.6%), and an external carotid artery to M2 bypass (5.9%). The intraoperative aneurysm rupture rate was 11.8%. Postoperative complications included ischemia (40%), cerebrospinal fluid fistulas (26.7%), and pneumonia (20%). At hospital discharge, the median Glasgow Coma Scale score was 14 (range: 10-15). At the 6-month follow-up, 82.4% of patients had a modified Rankin Scale score ≤2, bypass patency was present in all cases, and the morbidity rate was 17.6%. CONCLUSIONS: CIAs represent a spectrum of defiant vascular lesions with a poor natural history. Bypass surgery offers the potential for definitive treatment. Our case series illustrated the predominant role of cerebral revascularization of CIAs with a critical case-by-case approach to provide optimal outcomes in a limited-resource setting.

Vascular risk profile and changes of arterial hypertension after surgical revascularization in adult Moyamoya patients.

Moyamoya disease (MMD) is a rare stenoocclusive cerebral vasculopathy often treated by neurosurgical revascularization using extracranial-intracranial bypasses to prevent ischemic or hemorrhagic events. Little is known about the vascular risk profile of adult MMD patients compared to the general population. We therefore analyzed 133 adult MMD patients and compared them with data from more than 22,000 patients from the German Health Update database. Patients with MMD showed an age- and sex-adjusted increased prevalence of arterial hypertension, especially in women between 30 and 44 years and in patients of both sexes between 45 and 64 years. Diabetes mellitus was diagnosed significantly more frequently in MMD patients with increasing age, whereas the vascular risk profile in terms of obesity, nicotine and alcohol consumption was similar to that of the general population. Antihypertensive medication was changed one year after surgical revascularization in 67.5% of patients with a tendency towards dose reduction in 43.2% of all patients. After revascularization, physicians need to be aware of a high likelihood of changes in arterial hypertension and should adjust all other modifiable systemic vascular risk factors to achieve the best treatment possible.

Development of moyamoya arteriopathy following treatment of intracranial tumors: clinical and radiographic characterization.

OBJECTIVE: Moyamoya arteriopathy can develop in patients with brain tumors, particularly when associated with neurofibromatosis type 1 (NF1) or cranial irradiation. The present study aimed to analyze the clinical outcomes of moyamoya after brain tumor treatment and elucidate the effect of revascularization on brain tumors. METHODS: The authors retrospectively reviewed clinical and radiographic findings in 27 patients with brain tumors who developed moyamoya requiring revascularization surgery between January 1985 and June 2017 at a single institution. The long-term clinical and neuroimaging-based outcomes were analyzed. RESULTS: Among 27 patients, 22 patients underwent radiotherapy, and 12 patients had NF1. The mean ages at diagnosis of brain tumors and moyamoya were 4.4 years and 10.3 years, respectively. The mean interval between radiotherapy and moyamoya diagnosis was 4.0 years. The mean follow-up period after revascularization surgery was 8.5 years. Among 46 affected hemispheres in 27 patients, the patients who underwent radiotherapy (30 hemispheres in 22 patients) had a higher incidence of Suzuki stage 5 or 6 (20% [6/30] vs 0% [0/8]) and infarction (63.6% [14/22] vs 0% [0/5]) compared with patients without radiotherapy (8 hemispheres in 5 patients). After revascularization, stroke occurred in 4 patients, and 6 hemispheres showed Matsushima grade C, all of which occurred in patients with a history of radiotherapy. The residual brain tumors progressed in 4 of 21 patients (19%) after revascularization, comparable to the progression rates of brain tumors without revascularization in previous literature. CONCLUSIONS: Patients with brain tumors can develop moyamoya that exhibits characteristic clinical and radiographic features of idiopathic MMD. Moyamoya associated with cranial irradiation has a higher incidence of stroke with less capacity for revascularization, requiring thorough evaluations and timely treatment. Revascularization does not appear to have any effect on the progression of existing brain tumors.

Cerebral revascularization for complex vertebrobasilar artery dissecting aneurysms.

Vertebrobasilar artery dissecting aneurysms (VBDAs) are the most surgically challenging type of aneurysm. Cerebral revascularization is the ultimate treatment for complex VBDAs. We retrospectively analysed the characteristics, surgical outcomes and follow-up data of 21 patients who underwent cerebral revascularization to treat complex VBDAs from 2015 to 2022. According to the location of the aneurysm and the anatomic relationship between the VBDA and the PICA, VBDA patients were classified into four groups: aneurysms located at the VA with PICA involvement (10 patients), aneurysms located at the VA without PICA involvement (1 patient), aneurysms located at the basilar apex segment (1 patient) and aneurysms located at the basilar trunk segment (9 patients). A surgical algorithm for complex VBDAs was determined primarily by the location of the aneurysm, the status of the aneurysm and the ability of retrograde blood flow to reach the proximal vertebrobasilar artery. Surgical modalities for patients with aneurysms in the VA with PICA involvement included low-flow (OA-PICA) bypasses with aneurysm trapping, aneurysm excision or reconstructive clip in 8 patients and STA-PCA bypass combined with PICA preservation and aneurysm trapping in 2 patients. In patients with aneurysms in the VA without PICA involvement, aneurysm excision was performed without cerebral bypass. In patients with aneurysms in the basilar apex segment, high-flow bypass (ECA-RA-P2) with aneurysm trapping was performed. In patients with aneurysms in the basilar trunk segment, surgical modalities included high-flow bypasses (ECA-RA-P2 and LVA-RA-P2) with aneurysm trapping or proximal occlusion in 6 patients, ECA-RA-P2 bypass with partial proximal occlusion in 1 patient, ECA-RA-P2 bypass alone in 1 patient, and STA-PCA bypass with R-VA narrowing in 1 patient. Of the 21 patients, 20 experienced clinical improvement or no change, and 17 of 21 patients achieved favourable functional outcomes (mRS ≤ 2). However, one patient died of infarction and respiratory failure postoperatively. Aneurysms were completely obliterated in 13 patients, shrank in 5 patients and stabilized in 2 patients. The median follow-up period was 32.5 months. During the follow-up period, all bypasses were patent, and further clinical improvement was observed in 11 patients. Cerebral revascularization appears to be safe and effective for the treatment of complex VBDAs, and cerebral revascularization could act as a complementary treatment strategy.

Fluorescein videoangiography (FL-VAG) as a predictor of cerebral bypass patency.

Background: The fluorescein videoangiography (FL-VAG) has become a valuable adjunct tool in vascular neurosurgery. This work describes using the FL-VAG during bypass surgery and proposes a classification method for evaluating surgical results. Methods: We analyzed 26 patients with 50 cerebral bypasses from September 2018 to September 2022. We used a three grades classification method based on the pass of intravenous fluorescein through the anastomosis. Grade 1 represents the synchronous and total filling of the "T" shape ("green T″) formed by the donor and recipient vessel, Grade 2, the asynchronous filling of the anastomosis (incomplete/asynchronous "green T″), and Grade 3, a non-patent anastomosis (absence of "green T″). Results: Of the 26 patients, 8 underwent one bypass, 14 underwent double bypass, 2 underwent three bypasses, and 2 underwent four bypasses in two different interventions. The type of bypass was end-to-side anastomosis in 47 (94%) cases, internal maxillary artery to middle cerebral artery bypass with a radial artery graft (IMax-MCA anastomosis) in 2 (4%), and PICA-VA transposition in one (2%). We made 24 (48%) bypasses on the right side and 26 (52%) on the left side. After the initial surgery, thirty-nine (78%) bypasses were considered as Grade 1, 5 (10%) as Grade 2, and 6 (12%) as Grade 3. After intraoperative bypass patency assessment (IBPA), 45 (90%) of the bypasses were considered Grade 1 and remained patent on CTA. Conclusions: Using FL-VAG and a three-tier classification method is a reliable tool to predict bypass patency. It is safe, low-risk, and available worldwide.

Angiographic measurement of the superficial temporal artery for potential use in cerebral bypass surgery: a combined radiological and cadaveric study.

PURPOSE: This study aims to investigate the microsurgical anatomy of the superficial temporal artery (STA), explore the relationship between STA length and lumen diameter, and develop a reliable radiologic method for selecting STA segments for bypass surgery. METHODS: This study used 10 cadaveric dissections (20 STAs, both sides) and 20 retrospective radiological examinations (40 STAs, both sides), employing curved multiplanar reformation and flow color lookup table (CLUT) DICOM processing. Measurements included vessel lumen diameters and luminal cross-sectional thicknesses 3 mm proximal to the STA bifurcation, 3 mm distal to the frontal branch, 5 cm distal to the frontal branch, 3 mm distal to the parietal branch, and 5 cm distal to the parietal branch. The distance between the STA bifurcation and the superior zygomatic border (SZB) was also measured. In our analysis, descriptive statistics encompassed mean, standard deviation (SD), standard error, minimum and maximum values, and distributions. Comparative statistics were performed using Student's t-test, with statistical significance set at p < 0.05. RESULTS: There were no statistically significant differences between STA measurements of bifurcation distances (p = 0.88) and lumen diameters (p = 0.46) between cadavers and radiological measures. However, lumen thicknesses were larger in frontal branches than parietal branches at the seventh and eighth centimeter (p = 0.012, p = 0.039). Branches became thinner distally from the zygoma in both cadavers and radiological image measurements. CONCLUSION: The CLUT DICOM processing radiological measures provided the high-precision required to enable pre-surgical vessel selection for extracranial-intracranial bypass. The results show that STA vessel luminal diameters are sufficient (> 1 mm) for bypass surgery in the first 9 cm but gradually decrease after that. Also shown is that the choice of frontal versus parietal branches depends on individual anatomical features; therefore, careful preoperative radiological examination is critical.