Aspirin interruption before neurosurgical interventions: A controversial problem.

Aspirin is widely used for primary or secondary prevention of ischemic events. At the same time, chronic aspirin consumption can affect blood clot formation during surgical intervention and increase intraoperative blood loss. This is especially important for high-risk surgery, including neurosurgery. Current European Society of Cardiology guidelines recommend aspirin interruption for at least 7 d before neurosurgical intervention, but this suggestion is not supported by clinical evidence. This narrative review presents evidence that challenges the necessity for aspirin interruption in neurosurgical patients, describes options for aspirin effect monitoring and the clinical implication of these methods, and summarizes current clinical data on bleeding risk associated with chronic aspirin therapy in neurosurgical patients, including brain tumor surgery, cerebrovascular procedures, and spinal surgery.

Application of virtual and mixed reality for 3D visualization in intracranial aneurysm surgery planning: a systematic review.

Background: Precise preoperative anatomical visualization and understanding of an intracranial aneurysm (IA) are fundamental for surgical planning and increased intraoperative confidence. Application of virtual reality (VR) and mixed reality (MR), thus three-dimensional (3D) visualization of IAs could be significant in surgical planning. Authors provide an up-to-date overview of VR and MR applied to IA surgery, with specific focus on tailoring of the surgical treatment. Methods: A systematic analysis of the literature was performed in accordance with the PRISMA guidelines. Pubmed, and Embase were searched to identify studies reporting use of MR and VR 3D visualization in IA surgery during the last 25 years. Type and number of IAs, category of input scan, visualization techniques (screen, glasses or head set), inclusion of haptic feedback, tested population (residents, fellows, attending neurosurgeons), and aim of the study (surgical planning/rehearsal, neurosurgical training, methodological validation) were noted. Results: Twenty-eight studies were included. Eighteen studies (64.3%) applied VR, and 10 (35.7%) used MR. A positive impact on surgical planning was documented by 19 studies (67.9%): 17 studies (60.7%) chose the tailoring of the surgical approach as primary outcome of the analysis. A more precise anatomical visualization and understanding with VR and MR was endorsed by all included studies (100%). Conclusion: Application of VR and MR to perioperative 3D visualization of IAs allowed an improved understanding of the patient-specific anatomy and surgical preparation. This review describes a tendency to utilize mostly VR-platforms, with the primary goals of a more accurate anatomical understanding, surgical planning and rehearsal.

Neurointerventional Radiology: History, Present and Future.

Neurointerventional Radiology (NIR), encompassing neuroendovascular surgery, endovascular neurosurgery, and interventional neurology, is an innovative and rapidly evolving multidisciplinary specialty focused on minimally invasive therapies for a wide range of neurological disorders. This review provides a comprehensive overview of NIR, discussing the three routes into the field, highlighting their distinct training paradigms, and emphasizing the importance of unified approaches through organizations like the Society of Neurointerventional Surgery (SNIS). The paper explores the benefits of co-managed care and its potential to improve patient outcomes, as well as the role of interdisciplinary collaboration and cross-disciplinary integration in advancing the field. We discuss the various contributions of neurosurgery, radiology, and neurology to cerebrovascular surgery, aiming to inform and educate those interested in pursuing a career in neurointervention. Additionally, the review examines the adoption of innovative technologies such as robotic-assisted techniques and artificial intelligence in NIR, and their implications for patient care and the future of the specialty. By presenting a comprehensive analysis of the field of neurointervention, we hope to inspire those considering a career in this exciting and rapidly advancing specialty, and underscore the importance of interdisciplinary collaboration in shaping its future.

Paraclinoid aneurysms clipping through an extradural sphenoid ridge keyhole approach.

BACKGROUND: Paraclinoid aneurysms represent a challenge for neurosurgeons due to the anatomical complexity of this region. Then, innovative techniques such as the extradural sphenoid ridge approach are suitable for a safe microsurgical clipping. METHOD: A description of the surgical technique was made by the senior author, a vascular neurosurgeon experienced with the use of this approach in the management of paraclinoid aneurysms exemplified through a clinical case. CONCLUSION: Microsurgical clipping through an extradural sphenoid ridge keyhole approach for small and midsize paraclinoid aneurysms is an excellent treatment modality with good clinical and surgical results.

Neuromonitoring Identifies Occlusion of Femoral Artery in STA-MCA Bypass Procedure: A Case Report.

Intraoperative neurophysiological monitoring (IONM) is a technique used to assess the somatosensory and gross motor systems during surgery. While it is primarily used to detect and prevent surgically induced nervous system trauma, it can also detect and prevent injury to the nervous system that is the result of other causes such as trauma or ischemia that occur outside of the operative field as a result of malpositioning or other problematic physiologic states. We present a case study where a neuromonitoring alert altered the surgical procedure, though the alert was not correlated to the site of surgery. A 69-year-old male with a history of bilateral moyamoya disease and a left middle cerebral artery infarct underwent a right-sided STA-MCA bypass and encephaloduroarteriosynangiosis (EDAS) with multimodal IONM. During the procedure, the patient experienced a loss of motor evoked potential (MEP) recordings in the right lower extremity. Blood pressure was elevated, which temporarily restored the potentials, but they were lost again after the angiography team attempted to place an arterial line in the right femoral artery. The operation was truncated out of concern for left hemispheric ischemia, and it was later discovered that the patient had an acute right external iliac artery occlusion caused by a fresh thrombus in the common femoral artery causing complete paralysis of the limb. This case highlights the importance of heeding IONM alerts and evaluating for systemic causes if the alert is not thought to be of surgical etiology. IONM can detect adverse systemic neurological sequelae that is not necessarily surgically induced.

Dolichoectatic vertebrobasilar aneurysms: a systematic review and meta-analysis of management strategies and outcomes.

OBJECTIVE: The aim of this study was to describe the efficacy, clinical outcomes, and complications of open cerebrovascular surgery, endovascular surgery, and conservative management of dolichoectatic vertebrobasilar aneurysms (DVBAs). METHODS: Relevant articles were retrieved from PubMed, Scopus, Web of Science, and Cochrane databases according to PRISMA guidelines. A meta-analysis was conducted for clinical presentation, treatment protocols, and clinical outcomes-good (improved or stable clinical status) or poor (deteriorated clinical status or death)-and mortality rates. RESULTS: The 9 identified articles described 41 cases (27.5%) of open cerebrovascular surgery, 61 endovascular procedures (40.9%), and 47 cases (31.5%) of conservative management for DVBAs. The total cohort had a good outcome rate of 51.9% (95% CI 28.3%-74.6%), a poor outcome rate of 45.5% (95% CI 23.0%-70.1%), and a mortality rate of 22.3% (95% CI 11.8%-38.0%). The treatment groups had comparable good clinical outcome rates (open cerebrovascular surgery group: 24.7% [95% CI 2.9%-78.2%]; endovascular surgery group: 69.0% [95% CI 28.7%-92.5%]; conservative management group: 57.7% [95% CI 13.0%-92.5%]; p = 0.19) and poor outcome rates (open vascular surgery group: 75.3% [95% CI 21.8%-97.1%]; endovascular surgery group: 27.2% [95% CI 5.6%-0.70.2%]; conservative management group: 39.9% [95% CI 9.1%-81.6%]; p = 0.15). The treatment groups also had comparable mortality rates (open vascular surgery group: 39.5% [95% CI 11.4%-76.8%]; endovascular surgery group: 15.8% [95% CI 4.4%-43.0%]; conservative management group: 19.2% [95% CI 6.8%-43.5%]; p = 0.23). CONCLUSIONS: The current study of DVBAs illustrated poor outcomes and high mortality rates regardless of the treatment modality. The subgroup analysis showed heterogeneity among the subgroups and advice for personalized management.

Complementary role of Indocyanine green video angiography, dual-image video angiography and flow-800.

BACKGROUND: Visualization of cerebral vessels, their branches and the surrounding structures are essential during cerebrovascular surgery. Indocyanine green dye-based video angiography is a commonly used technique in cerebrovascular surgery. This paper aims to analyze the real-time imaging of ICG-AG, DIVA, and the use of ICG-VA with Flow 800 to compare their usefulness in surgery. METHODS: Intraoperative real-time identification of vascular and surrounding structures in twenty nine anterior circulation aneurysms and three posterior circulation aneurysm clipping, one STA-MCA bypass, and two carotid endarterectomies were performed in patients using ICG-VA alone, DIVA, ICG-VA with Flow 800 to analyze and compare each of these methods in details. RESULTS: ICG-VA and DIVA couldn't visualize perforators in twenty-three cases of cerebral aneurysms clipping when used alone. Compared to that by adding Flow 800 perforators were easily visualized. In three cases, occlusion of perforators after clip application was visualized by DIVA and solved by repositioning surgical clips. In one STA-MCA bypass surgery, adequate blood flow to cortical branches of MCA (M4) from STA branches was assessed with ICG-VA, DIVA, and the use of ICG-VA with Flow 800 color mapping. ICG-VA, DIVA, and Flow 800 observed the lack of blood flow and fluttering atherosclerotic plaques in carotid endarterectomy. In one case of basilar tip aneurysm, we used ICG-VA with Flow 800; the intensity diagram drawn after determining regions of interest showed that there was no flow within the aneurysm sac after clipping. CONCLUSION: In real-time surgery, a multimodal approach using ICG-VA, DIVA, and ICG-VA with Flow 800 colour mapping can serve as useful tools for better visualization of vascular and surrounding structures. The benefits of flow 800 color mapping, such as determining regions of interest, intensity diagrams, and color-coded images, outweigh the advantages over the ICG-VA and DIVA in the visualization of critical vascular anatomy in humans during surgical procedures.

Transpetrosal Approach to a Ruptured Distal Basilar Perforating Artery Aneurysm.

Basilar perforating artery aneurysms are rare and underreported vascular anomalies in the cerebrovascular literature. Various open and endovascular treatment approaches can be employed to treat these aneurysms based on several patient- and aneurysm-specific factors. Some authors have even advocated for conservative, nonoperative management. Here, we report a case of a ruptured distal basilar perforating artery aneurysm secured by an open transpetrosal approach. A 67-year-old male presented to our institution with a Hunt-Hess grade 2, modified Fisher grade 3 subarachnoid hemorrhage (SAH). Initial cerebral digital subtraction angiography (DSA) did not identify an intracranial aneurysm or other vascular lesions. However, the patient had a re-rupture event several days after presentation. DSA at this time revealed a posteriorly projecting distal basilar perforating artery aneurysm. Initial attempts with endovascular coil embolization were unsuccessful. Thus, an open transpetrosal approach was taken to gain access to the middle and distal basilar trunk to secure the aneurysm. This case underscores the unpredictability of basilar perforating artery aneurysms and the challenges encountered when considering active treatment. We demonstrate an open surgical approach with an intraoperative video for definitive management after failed attempted endovascular treatment.

Is it time to rethink microsurgical training for the treatment of intracranial aneurysms in Australia?

BACKGROUND: Case volume and complexity for microsurgical treatment of cerebral aneurysms have changed due to the growing use of endovascular therapy in clinical practice. The authors sought to quantify the clinical exposure of Australian neurosurgery trainees to cerebral aneurysm microsurgery. METHODS: This observational, retrospective cross-sectional study examined the Australian National Hospital Morbidity database for all admissions related to microsurgical and endovascular treatment of aneurysmal subarachnoid haemorrhage (aSAH) and unruptured intracranial aneurysms (UIAs) for the years 2008 to 2018. Procedural volumes were compared with neurosurgical trainee figures to investigate the rate of procedural exposure relative to the neurosurgical workforce. RESULTS: A total of 8,874 (41.6%) microsurgical procedures (3,662 for aSAH, 5,212 for UIAs), and 12,481 (58.4%) endovascular procedures (6,018 for aSAH, 6,463 for UIAs) were performed. Trainee exposure to microsurgery in aSAH declined from 9.1 to 7.3 cases per trainee per annum (mean 7.7), with case complexity confined mostly to simple anterior circulation aneurysms. There are significant state-by-state differences in the preferred treatment modality for aSAH. During the same study period, the number of microsurgical cases for UIAs increased (from 8.9 to 13.5 cases per trainee per annum, mean 11.0). Significantly more endovascular procedures are performed than microsurgery (10.7 to 17.0, mean 12.7 cases, for aSAH; 8.0 to 21.5, mean 13.7 cases, for UIAs). CONCLUSIONS: Trainee exposure to open aneurysm surgery for aSAH have significantly declined in both case volume and complexity. There is an overall increase in the number of surgeries for elective aneurysms, but this varies widely from state-to-state.

Dual Microscope Indocyanine Green Video Angiography and Endoscopic Review to Treat Intracranial Aneurysm: A Review of the Literature Regarding a Case.

The use of the indocyanine green video angiography (ICG-VA) both endoscope and microscope has become popular in recent decades thanks to the safety, efficacy, and added value that they have provided for cerebrovascular surgery. The dual use of these technologies is considered complementary and has helped cerebrovascular surgeons in decision-making, especially for aneurysm clipping surgery; however, its use has been described for both aneurysm surgery, resection of arteriovenous malformations, or even for bypass surgeries. We conducted a review of the literature with the MeSH terms "microscope indocyanine green video angiography (mICG-VA)," "endoscopic review," AND/OR "intracranial aneurysm." A total of 97 articles that included these terms were selected after a primary review to select a total of 26 articles for the final review. We also present a case to exemplify its use, in which we use both technological tools for the description of the aneurysm, as well as for decision-making at the time of clipping and for reclipping. Both tools, both the use of the endoscope and the mICG-VA, have helped decision-making in neurovascular surgery. A considerable clip replacement rate has been described with the use of these technologies, which has helped to reduce the complications associated with poor clipping. One of the main advantages of their usefulness is that they are tools for intraoperative use, which is why they have shown superiority compared to digital subtraction angiography, which takes longer to use and has a higher risk of complications associated with the contrast medium. On the other hand, a very low rate of complications has been described with the use of the endoscope and mICG-VA, which is why they are considered safe tools to use. In some cases, mention has been made of the use of one or the other technology; however, we consider that its dual use provides more information about the status of the clip, its anatomy, its relationship with other vascular structures, and the complete occlusion of the aneurysm. We consider that the use of both technologies is complementary, so in case of having them both should be used, since both the endoscope and the mICG-VA provide additional and useful information.

Segmentation techniques of brain arteriovenous malformations for 3D visualization: a systematic review.

BACKGROUND: Visualization, analysis and characterization of the angioarchitecture of a brain arteriovenous malformation (bAVM) present crucial steps for understanding and management of these complex lesions. Three-dimensional (3D) segmentation and 3D visualization of bAVMs play hereby a significant role. We performed a systematic review regarding currently available 3D segmentation and visualization techniques for bAVMs. METHODS: PubMed, Embase and Google Scholar were searched to identify studies reporting 3D segmentation techniques applied to bAVM characterization. Category of input scan, segmentation (automatic, semiautomatic, manual), time needed for segmentation and 3D visualization techniques were noted. RESULTS: Thirty-three studies were included. Thirteen (39%) used MRI as baseline imaging modality, 9 used DSA (27%), and 7 used CT (21%). Segmentation through automatic algorithms was used in 20 (61%), semiautomatic segmentation in 6 (18%), and manual segmentation in 7 (21%) studies. Median automatic segmentation time was 10 min (IQR 33), semiautomatic 25 min (IQR 73). Manual segmentation time was reported in only one study, with the mean of 5-10 min. Thirty-two (97%) studies used screens to visualize the 3D segmentations outcomes and 1 (3%) study utilized a heads-up display (HUD). Integration with mixed reality was used in 4 studies (12%). CONCLUSIONS: A golden standard for 3D visualization of bAVMs does not exist. This review describes a tendency over time to base segmentation on algorithms trained with machine learning. Unsupervised fuzzy-based algorithms thereby stand out as potential preferred strategy. Continued efforts will be necessary to improve algorithms, integrate complete hemodynamic assessment and find innovative tools for tridimensional visualization.

Brain Arteriovenous Malformations: Status of Open Surgery after A Randomized Trial of Unruptured Brain Arteriovenous Malformations.

The results of "A Randomized Trial of Unruptured Brain Arteriovenous Malformations" (ARUBA) suggested that observation alone resulted in less morbidity and mortality than intervention for these lesions. These findings generated significant controversy throughout the cerebrovascular community and resulted in several subsequent studies investigating the role of microsurgical resection on ARUBA-eligible patients. Herein, we provide a brief overview of the ARUBA trial, its subsequent criticisms, the resultant publications challenging the findings in ARUBA, and discuss the available data regarding the effect ARUBA has had on arteriovenous malformation (AVM) treatments.

Cerebrovascular Anatomy: Laboratory Research, Education, Innovations, and Future Directions.

Over the past century, major advances in the field of cerebrovascular anatomic research have transformed the craft of cerebrovascular surgery into a modern art. A thorough anatomic understanding of the complex cerebrovascular anatomy is crucial to a successful surgical procedure. Despite clear descriptions of the anatomic "norms" and "variations" in the existing literature, research on this topic is far from diminishing. This article reviews the roots, early and contemporary evolution, and status of the cerebrovascular and skull base anatomic research field and its various aspects and limitations. It also discusses the different areas amenable to potential improvement and future directions.

Academics versus the Internet: Evaluating the readability of patient education materials for cerebrovascular conditions from major academic centers.

Background: Health literacy profoundly impacts patient outcomes as patients with decreased health literacy are less likely to understand their illness and adhere to treatment regimens. Patient education materials supplement in-person patient education, especially in cerebrovascular diseases that may require a multidisciplinary care team. This study aims to assess the readability of online patient education materials related to cerebrovascular diseases and to contrast the readability of those materials produced by academic institutions with those of non-academic sources. Methods: The readability of online patient education materials was analyzed using Flesch-Kincaid Grade Level (FKGL) and Flesch Reading Ease (FRE) assessments. Readability of academic-based online patient education materials was compared to nonacademic online patient education materials. Online patient education materials from 20 academic institutions and five sources from the web were included in the analysis. Results: Overall median FKGL for neurovascular-related patient online education documents was 11.9 (95% CI: 10.8-13.1), reflecting that they are written at a 12th grade level, while the median FRE was 40.6 (95% CI: 34.1-47.1), indicating a rating as "difficult" to read. When comparing academic-based online patient education materials to other internet sources, there was no significant difference in FRE and FKGL scores (P = 0.63 and P = 0.26 for FKGL and FRE, respectively). Conclusion: This study demonstrates that online patient education materials pertaining to cerebrovascular diseases from major academic centers and other nonacademic internet sites are difficult to understand and written at levels significantly higher than that recommended by national agencies. Both academic and nonacademic sources reflect this finding equally. Further study and implementation are warranted to investigate how improvements can be made.

Surgical Treatment of Large and Giant Anterior Cerebral Artery Aneurysms in the Endovascular Era: Analysis of Large Clinical Series.

OBJECTIVE: Analysis of results of surgical treatment of 112 patients with large and giant anterior cerebral artery (ACA) aneurysms. METHODS: This is the largest clinical series of large and giant ACA aneurysms ever reported. Retrospective analysis of medical charts, radiographic studies, and intraoperative videos was performed. Univariate and multivariate analysis of relations among 3 types of outcomes (complete aneurysm occlusion, ischemic complications, and clinical outcomes) and predicting factors was performed. RESULTS: Most aneurysms were communicant (84.8%). Aneurysms of the A1 segment and distal segments (A2-A5) were encountered rarely. Complete aneurysm occlusion (class I) was shown in 95 cases (90.5%). In 4 patients, only exploration and wrapping were performed because of severe atherosclerosis and chronic intraluminal thrombi. Partial occlusion (class III) was shown in 2 patients, and neck residual (class II) in 4 patients. Cerebral ischemia developed in 29 patients postoperatively. Occlusion or injury of the A1 segment and anterior communicating artery perforators and recurrent branch of Heubner were the most common reason for ischemic complications. At follow-up, 97 patients (86.6%) had favorable outcomes. Ten patients (8.9%) had unfavorable outcomes because of postoperative complications. CONCLUSIONS: Microsurgery provides effective and relatively safe occlusion of complex ACA aneurysms. Direct clipping can be applied in most cases independent of their precise location. In certain cases, alternative methods can be safely used. According to multivariate analysis, giant aneurysm size, aneurysm-related mass effect, involvement of large arterial branches in the aneurysm wall, and intraoperative complications were significant predicting factors for ischemic complications.

Characteristics and Management of Dilated Mastoid Emissary Veins: A Case Report and Literature Review.

INTRODUCTION: The mastoid emissary vein (MEV) describes a transosseous connection between the sigmoid dural venous sinus and the suboccipital venous plexus. In cases of outflow stenosis or malformation, the MEV may become dilated and a source of pulsatile tinnitus (PT) amenable to treatment. We describe a case of PT secondary to MEV treated successfully via endovascular coil embolization and conduct a systematic review of the literature. METHODS: We performed a systematic review without meta-analysis of studies involving management of dilated MEV on January 14, 2022, and describe a case of PT secondary to an enlarged MEV treated via coil embolization. RESULTS: A total of 13 studies were selected for full review. Reports identified MEV presenting as PT in 60% (12 of 20) of cases, intraoperative hemorrhage in mastoid surgery in 15% (3 of 20), a compressive scalp mass in 10% (2 of 20), and thrombophlebitis, facial swelling, or an incidental finding in 5% (1 of 20) each. Forty-five percent (9 of 20) underwent treatment, with all experiencing symptom resolution or improvement. Surgery included transvenous coil embolization in 33.3% (3 of 9), flap reconstruction in 22.2% (2 of 9), and surgical packing, ligation, and thrombectomy in 11.1% (1 of 9) each. Dilated MEV was reported concurrently with impeded drainage pathways in 35% (7 of 20) of reports. CONCLUSIONS: Dilated MEV has been reported as an etiology of pulsatile tinnitus and appears amenable to treatment via open and endovascular means. Endovascular coil embolization appears to offer effective symptom resolution, however, available literature exists only in case reports and small series. Further investigation is highly warranted.

Computer vision coaching microsurgical laboratory training: PRIME (Proficiency Index in Microsurgical Education) proof of concept.

Computer vision (CV) feedback could be aimed as a constant tutor to guide ones proficiency during microsurgical practice in controlled environments. Five neurosurgeons with different levels of microsurgical expertise performed simulated vessel dissection and micro-suture in an ex vivo model for posterior computer analysis of recorded videos. A computer program called PRIME (Proficiency Index of Microsurgical Education) used in this research recognized color-labeled surgical instruments, from downloading videos into a platform, with a range of motion greater than 3 mm, for objective evaluation of number of right and left hand movements. A proficiency index of 0 to 1 was pre-established in order to evaluate continuous training improvement. PRIME computer program captured all hand movements executed by participants, except for small tremors or inconsistencies that have a range of motion inferior to 3 mm. Number of left and right hand movements were graphically expressed in order to guide more objective and efficacious training for each trainee, without requiring body sensors and cameras around the operating table. Participants with previous microsurgical experience showed improvement from 0.2 to 0.6 (p < 0.05), while novices had no improvement. Proficiency index set by CV was suggested, in a self-challenge and self-coaching manner. PRIME would offer the capability of constant laboratory microsurgical practice feedback under CV guidance, opening a new window for oriented training without a tutor or specific apparatus regarding all levels of microsurgical proficiency. Prospective, large data study is needed to confirm this hypothesis.

The Fluorescent Patient: An Unusual Effect of Fluorescein Angiography.

Although fluorescein is widely used for intraoperative angiography, some of its side effects remain obscure. In this report, we present the case of a 41-year-old patient with chronic ischemia caused by moyamoya syndrome who underwent bypass revascularization with intraoperative fluorescein angiography (FA). Immediately after the surgery, the patient presented homogeneous fluorescence of the entire skin. We discuss this curious phenomenon as well as other side effects that may arise due to FA.

Augmented Reality Fluorescence Imaging in Cerebrovascular Surgery: A Single-Center Experience with Thirty-Nine Cases.

BACKGROUND: Several intraoperative imaging methods exist in cerebrovascular surgery to visualize and analyze the vascular anatomy flow. A new method based on multispectral fluorescence (MFL) imaging of indocyanine green (ICG) video angiography (VA) allows real-time, augmented reality (AR) visualization of blood flow superimposed on white-light microscopic images. We describe our single-center experience using MFL AR in cerebrovascular surgery. METHODS: Case descriptions are provided of cerebrovascular surgery with intraoperative use of MFL AR images performed at our institution from June 2018 to April 2020. MFL superimposes the blood flow in real time on white-light microscopic images. We used MFL AR imaging as well as standard ICG-VA visualization and intraoperative digital subtraction angiography (DSA) as a control. RESULTS: A total of 39 cases (33 aneurysm clippings, 4 arteriovenous malformations, and 2 external carotid-internal carotid bypass surgeries), were performed using MFL technology-based AR visualization of ICG. MFL AR imaging and DSA showed a high correlation concerning aneurysm occlusion and vessel patency. In arteriovenous malformation resection surgery, MFL AR imaging facilitated early identification of the feeding arteries and draining veins. Because of increased sensitivity of MFL AR, a reduced dose of ICG could be used, allowing repeated intraoperative imaging. There were no postoperative complications, side effects, or technical problems related to the use of MFL AR imaging. CONCLUSIONS: MFL AR is an easy-to-use adjunct in cerebrovascular surgery and shows a high correlation with intraoperative DSA. No interruption of the surgery is necessary because MFL AR images of the blood flow are superimposed in real time on white-light microscopic images.