Risk Profile In Extracranial/Intracranial Bypass Surgery—The Role of Antiplatelet Agents, Disease Pathology, and Surgical Technique In 168 Direct Revascularization Procedures

Management of Patients undergoing Elective Craniotomy under Antiplatelet or Anticoagulation Therapy: An International Survey of Practice

BACKGROUND

 The literature concerning the management of antiplatelet (AP) and anticoagulation (AC) medication in the perioperative phase of craniotomy remains scarce. The aim of this international survey was to investigate the current practice among neurosurgeons regarding their perioperative management of AP and AC medication.

METHODS

 We distributed an online survey to neurosurgeons worldwide with questions concerning their perioperative practice with AP and AC medication in patients undergoing craniotomy. Descriptive statistics were performed.

RESULTS

 A total of 130 replies were registered. The majority of responders practice neurosurgery in Europe (79%) or high-income countries (79%). Responders reported in 58.9 and 48.8% to have institutional guidelines for the perioperative management of AP and AC medication. Preoperative interruption time was reported heterogeneously for the different types of AP and AC medication with 40.4% of responders interrupting aspirin (ASA) for 4 to 6 days and 45.7% interrupting clopidogrel for 6 to 8 days. Around half of the responders considered ASA safe to be continued or resumed within 3 days for bypass (55%) or vascular (49%) surgery, but only few for skull base or other tumor craniotomies in general (14 and 26%, respectively). Three quarters of the responders (74%) did not consider AC safe to be continued or resumed early (within 3 days) for any kind of craniotomy. ASA was considered to have the lowest risk of bleeding. Nearly all responders (93%) agreed that more evidence is needed concerning AP and AC management in neurosurgery.

CONCLUSION

 Worldwide, the perioperative management of AP and AC medication is very heterogeneous among neurosurgeons.

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.

Efficacy and Safety of Extracranial-Intracranial Bypass Surgery for Posterior Circulation Aneurysms: A Systematic Review and Single-Arm Meta-Analysis

OBJECTIVE

Treating complex posterior circulation aneurysms poses challenges, and extracranial to intracranial (EC-IC) bypass techniques are potential therapeutic options. However, the safety and efficacy of this approach for posterior circulation aneurysms remain unclear. The study's objective was to assess the safety and efficacy of EC-IC bypass in these aneurysms.

METHODS

Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we conducted a systematic review on EC-IC revascularization for posterior circulation aneurysms. Included studies had at least 4 patients and reported data on mortality, patency, complications, or clinical outcomes. Favorable clinical outcomes were defined as modified Rankin Scale below 3 or Glasgow Outcome Scale above 3, and complications were any issues related to the bypass procedure.

RESULTS

From 3036 articles reviewed, 22 studies involving 196 patients who underwent 210 EC-IC bypass procedures for posterior circulation aneurysms were selected. The median follow-up period of 14 studies was 31.66 months (6-61 months). Final follow-up indicated a high bypass patency rate of 96% [95% confidence interval [CI]: 91%-100%; I2 = 12%], with a mortality rate of 5% [95% CI: 1%-9%; I2 = 0%]. Additionally, 83% [95% CI: 70%-96%; I2 = 77%] of patients showed good outcomes at the last follow-up. Complications were observed in 40% [95% CI: 26%-55%; I2 = 80%]. Heterogeneity was associated with specific studies.

CONCLUSIONS

EC-IC bypass procedures are a viable treatment option for posterior circulation aneurysms, with high bypass patency rates and favorable clinical outcomes. However, complications, especially neurological deficits, exist. Open revascularization remains essential for neurovascular surgeons dealing with complex aneurysms.

Is medical management useful in Moyamoya disease?

Moyamoya disease (MMD), characterized by progressive internal carotid artery stenosis and collateral vessel formation, prompts cerebral perfusion complications and is stratified into idiopathic and Moyamoya syndrome subtypes. A multifaceted approach toward MMD management addresses cerebral infarctions through revascularization surgery and adjunctive medical therapy, while also navigating risks such as intracranial hemorrhage and cerebral infarction resulting from arterial stenosis and fragile collateral vessels. Addressing antithrombotic management reveals a potential role for treatments like antiplatelet agents and anticoagulants, despite the ambiguous contribution of thrombosis to MMD-related infarctions and the critical balance between preventing ischemic events and averting hemorrhagic complications. Transcranial doppler has proven useful in thromboembolic detection, despite persisting challenges concerning the efficacy and safety of antithrombotic treatments. Furthermore, antihypertensive interventions aim to manage blood pressure meticulously, especially during intracerebral hemorrhage, with recommendations and protocols varying based on the patient's hypertension status. Additionally, lipid-lowering therapeutic strategies, particularly employing statins, are appraised for their possible beneficial role in MMD management, even as comprehensive data from disease-specific clinical trials remains elusive. Comprehensive guidelines and protocols to navigate the multifaceted therapeutic avenues for MMD, while maintaining a delicate balance between efficacy and safety, warrant further meticulous research and development. This protocol manuscript seeks to elucidate the various aspects and challenges imbued in managing and navigating through the complex landscape of MMD treatment.

Extracranial-Intracranial Cerebral Revascularization for Atherosclerotic Vessel Occlusion: An Updated Systematic Review of the Literature

BACKGROUND

Atherosclerotic steno-occlusive cerebrovascular disease includes extracranial carotid occlusive and intracranial atherosclerotic disease. Despite the negative findings in Carotid Occlusion Surgery Study (COSS), many large centers continue to report favorable results for revascularization surgery in select groups of patients. The aim of our study was to perform an updated systematic review to investigate the role of revascularization surgery for atherosclerotic steno-occlusive patients in the modern era.

METHODS

Five independent reviewers performed Preferred Reporting Items for Systematic Reviews and Meta-Analyses-guided literature searches in October 2022 to identify articles reporting clinical outcomes in adult patients undergoing bypass for atherosclerotic steno-occlusive disease. Primary endpoints used were perioperative and long-term ischemic strokes, intracerebral hemorrhage, bypass patency, and favorable clinical outcomes. Study quality was evaluated with Newcastle-Ottawa, JADAD, and the Oxford Center for Evidence-Based Medicine scales.

RESULTS

A total of 6709 articles were identified in the initial search. Of these articles, 50 met the inclusion criteria and were included in the systematic review. A notable increase in the proportion of articles published over the past 10 years was observed. There were 6046 total patients with 4447 bypasses performed over the period from 1978 to 2022. The average length of follow-up was 2.75 ± 2.71 years. The average Newcastle-Ottawa was 6.23 out of 9 stars. There was a significant difference in perioperative stroke (odds ratio [OR], 0.65 [0.48-0.87]; P = 0.004), long-term ischemia (OR, 0.32 [0.23-0.44]; P < 0.0001), overall ischemia (OR, 0.36 [0.28-0.44]; P < 0.0001), and favorable outcomes (OR, 3.63 [2.84-4.64]; P < 0.0001) when comparing pre-COSS to post-COSS time frames in favor of post-COSS.

CONCLUSIONS

Based on a systematic review of 50 articles, the existing literature indicates that long-term stroke rates and favorable outcomes for surgical revascularization for steno-occlusive disease have improved over time and are lower than previously reported. Improved patient selection, perioperative care, and surgical techniques may contribute to improved outcomes.

European Stroke Organisation (ESO) Guidelines on Moyamoya angiopathy: Endorsed by Vascular European Reference Network (VASCERN)

The European Stroke Organisation (ESO) guidelines on Moyamoya Angiopathy (MMA), developed according to ESO standard operating procedure and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology, were compiled to assist clinicians in managing patients with MMA in their decision making. A working group involving neurologists, neurosurgeons, a geneticist and methodologists identified nine relevant clinical questions, performed systematic literature reviews and, whenever possible, meta-analyses. Quality assessment of the available evidence was made with specific recommendations. In the absence of sufficient evidence to provide recommendations, Expert Consensus Statements were formulated. Based on low quality evidence from one RCT, we recommend direct bypass surgery in adult patients with haemorrhagic presentation. For ischaemic adult patients and children, we suggest revascularization surgery using direct or combined technique rather than indirect, in the presence of haemodynamic impairment and with an interval of 6–12 weeks between the last cerebrovascular event and surgery. In the absence of robust trial, an Expert Consensus was reached recommending long-term antiplatelet therapy in non-haemorrhagic MMA, as it may reduce risk of embolic stroke. We also agreed on the utility of performing pre- and post- operative haemodynamic and posterior cerebral artery assessment. There were insufficient data to recommend systematic variant screening of RNF213 p.R4810K. Additionally, we suggest that long-term MMA neuroimaging follow up may guide therapeutic decision making by assessing the disease progression. We believe that this guideline, which is the first comprehensive European guideline on MMA management using GRADE methods will assist clinicians to choose the most effective management strategy for MMA.

Risks and benefits of continuation and discontinuation of aspirin in elective craniotomies: a systematic review and pooled-analysis

BACKGROUND/AIM

Discontinuation of aspirin (ASA) prior to elective craniotomies is common practice. However, patients treated with ASA for secondary prevention bear a higher risk for thromboembolic complications. Aim of this systematic review is to investigate the risks and benefits of perioperative continuation and discontinuation of ASA in elective craniotomies.

METHODS

PubMed and Embase databases were searched. Inclusion criteria were retro- and prospective studies, reporting hemorrhagic and thromboembolic complications in patients in whom ASA was either continued or discontinued perioperatively in elective craniotomies. We excluded shunt operations and emergency cases. The MINORS (Methodological index for non-randomized studies) score was used to quantify the methodological quality of the eligible studies.

RESULTS

Out of 523 publications, 7 met the eligibility criteria (cumulative cohort of 646 patients). The mean MINORS score for the comparative studies was 18.7/24 (± SD 2.07, range: 17-22) and 9/16 for the unique non-comparative study, indicating an overall weak methodological quality of the included studies. 57.1% of the patients underwent craniotomy for intra- and extra-axial tumor removal, 39.0% for bypass surgery and 3.9% for neurovascular lesions (other than bypass). In 31.0% of the cases, ASA was prescribed for primary and in 69.0% for secondary prevention. ASA was continued perioperatively in 61.8% and discontinued in 38.2% of the cases. The hemorrhagic complication rate was 3% (95% CI [0.01-0.05]) in the ASA continuation group (Con-Group) and 3% (95% CI [0.01-0.09]) in the discontinuation group (Disc-Group) (p = 0.9). The rate of thromboembolic events in the Con-Group was 3% (95% CI [0.01-0.06]) in comparison to 6% (95% CI [0.02-0.14]) in the Disc-Group (p = 0.1).

CONCLUSION

Perioperative continuation of ASA in elective craniotomies does not seem to be associated with an increased hemorrhagic risk. The potential beneficial effect of ASA continuation on thromboembolic events needs to be further investigated in patients under ASA for secondary prevention.

Complementary Tools in Cerebral Bypass Surgery

Cerebral revascularization surgery has been advanced by the refinement of several adjunctive tools. These tools include perioperative blood thinners, intraoperative spasmolytic agents, electrophysiological monitoring, and methods for assessing bypass patency or marking arteriotomies. Despite the array of options, the proper usage and comparative advantages of different complements in cerebral bypass have not been well-cataloged elsewhere. In this literature review, we describe the appropriate usage, benefits, and limitations of various bypass adjuncts. Understanding these adjuncts can help surgeons ensure that they receive reliable intraoperative information about bypass function and minimize the risk of serious complications. Overall, this review provides a succinct reference for neurosurgeons on various cerebrovascular bypass adjuncts.

Moyamoya Disease-Standards and Advances in Revascularization Procedure and Peri-operative Management

Moyamoya disease (MMD) is a chronic, occlusive cerebrovascular disease with unknown etiology characterized by progressive stenosis at the terminal portion of the internal carotid artery and the abnormal vascular network formation at the base of the brain. Superficial temporal artery-middle cerebral artery (STA-MCA) bypass is a preferred surgical procedure for ischemic-onset MMD patients by improving cerebral blood flow. Recent evidence further indicates that flow-augmentation bypass has a potential role for preventing re-bleeding in hemorrhagic-onset MMD patients. Based on such cumulative evidence, there is a worldwide increase in the number of MMD patients undergoing bypass surgery, thus thorough understanding of the basic pathology of MMD including peri-operative hemodynamics is critical for avoiding surgical complications. The author sought to demonstrate the standard surgical procedure of STA-MCA bypass with indirect pial synangiosis for adult MMD patients and its pitfall in the early postoperative period, introducing the characteristic peri-operative hemodynamic condition of adult MMD after surgery, such as local cerebral hyperperfusion and intrinsic hemodynamic ischemia caused by watershed shift phenomenon.

Imaging Pattern and the Mechanisms of Postoperative Infarction After Indirect Revascularization in Patients with Moyamoya Disease

OBJECTIVE

To develop preventive strategies against postoperative infarction after indirect revascularization surgery in patients with moyamoya disease (MMD), we evaluated clinical information, with a specific focus on the imaging pattern of postoperative infarction.

METHODS

We retrospectively evaluated 421 surgical procedures performed in 354 (262 pediatric and 159 adult) patients with MMD from April 1991 to March 2021 at our institute. In addition to clinical information, raw images of postoperative infarction were collected and categorized into subtypes by the location of the infarction.

RESULTS

Symptomatic and asymptomatic postoperative infarction occurred in 47 and 12 patients (11.1% and 2.6%), respectively, and more than half (51.7%) of these cases of postoperative infarction occurred immediately or the day after the surgery. Cortical infarction around the craniotomy site was the most frequent pattern observed (50/59, 84.8%), and some of these cases seemed to occur under local compression from epidural or subdural hematomas (15/50, 30.0%). Ipsilateral white matter infarctions located in the watershed area (9/59, 15.3%) and contralateral infarctions (3/59, 5.1%) were also observed. Four patients (1.0%) showed sudden occlusions of ipsilateral or contralateral large intracranial arteries immediately after surgery. Postoperative infarction caused permanent neurologic deficits in 7 patients (1.7%), and all included the cortex outside the craniotomy site.

CONCLUSIONS

Local cortical irritation, hemodynamic fluctuation, and thromboembolic events were suggested as possible mechanisms of postoperative infarction after indirect revascularization in patients with MMD. Minimizing cortical irritation, maintaining adequate cerebral blood flow, and perioperative antiplatelet agents might decrease the incidence of postoperative infarction.

Flow-augmentation bypass for moyamoya disease

Moyamoya disease (MMD) is a chronic, occlusive cerebrovascular disease with unknown etiology, which is characterized by progressive steno-occlusive changes at the terminal portion of the internal carotid artery and an abnormal vascular network formation at the base of the brain. MMD has an intrinsic temporal nature to attempt a gradual conversion of the vascular supply for the brain from intracranial/internal carotid (IC) system to extracranial/external carotid (EC) system, so called "IC-EC conversion." Compatible cerebrovascular angio-architecture could be found in association with a variety of conditions such as neuro-fibromatosis type-1, Down's syndrome and cranial irradiation, which is called as moyamoya syndrome, akin/quasi MMD, or secondary MMD. Diagnosis of moyamoya vasculopathy, either idiopathic or secondary, is clinically important because flow-augmentation bypass is markedly beneficial for this entity to prevent cerebral ischemic attack by improving cerebral blood flow. Moreover, recent evidence indicated that flow-augmentation bypass could prevent re-bleeding in hemorrhagic MMD patients. Based on these backgrounds, there is a worldwide increase in the number of MMD patients undergoing bypass surgery. We sought to demonstrate our standard surgical procedure of superficial temporal artery-middle cerebral artery bypass with indirect pial synangiosis for MMD and its technical pitfall. We also discuss the intrinsic peri-operative hemodynamics of MMD after bypass surgery, including local cerebral hyper-perfusion and characteristic hemodynamic ischemia caused by watershed shift phenomenon. The aim of this review article is to understand the basic pathology of MMD, which is essential for complication avoidance while conducting flow-augmentation bypass for MMD.

Occipital artery to p3 segment of posterior inferior cerebellar artery bypass in treating a complex fusiform aneurysm

We provide a case report of a 58-year-old man who presented with a ruptured fusiform dissecting aneurysm located at the junction of the vertebral artery and posterior inferior cerebellar artery (PICA). Due to the lesion's complexity, a two-step approach was planned for revascularisation of PICA using the occipital artery (OA) prior to coiling embolisation. An end-to-side OA-PICA bypass was performed with implantation at the caudal loop of the p3 PICA segment. Fifteen days after the procedure, the aneurysm underwent stent-assisted coiling for successful obliteration of the aneurysm. The patient tolerated this procedure well and now at 1.5 years of follow-up remains free from any neurological deficits (modified Rankin Score 0). This case report illustrates one of the unique scenarios where both the vascular territory involved and morphological features of the aneurysm prohibited the use of more conventional means, necessitating the use of an arterial bypass graft for successful treatment of this lesion. As open vascular surgery is becoming less common in the age of endovascular coiling, our article uniquely reports on the combined use of both endovascular and microsurgical techniques to treat a complex aneurysm of the posterior circulation.

Paradoxical association of symptomatic cerebral edema with local hypoperfusion caused by the 'watershed shift' after revascularization surgery for adult moyamoya disease: a case report

Superficial temporal artery–middle cerebral artery anastomosis is generally considered as an effective method in improving damage associated with intracerebral occlusions in moyamoya disease. Hemodynamic changes caused by revascularization are the cause of many postoperative complications. Of the 186 consecutive surgeries for moyamoya disease at our hospital from 2015, we herein presented one case of adult-onset moyamoya disease that manifested symptomatic local cerebral edema and local hypoperfusion caused by the ‘watershed shift’. A 67-year-old woman presented with limb numbness on the right side and underwent superficial temporal artery–middle cerebral artery anastomosis, resulting in neurological dysfunction and the formation of a reversible high-signal lesion at left frontotemporal lobes on T2-weighted images along with a decrease in perfusion values on ¹²³I N-isopropyl-p-iodoamphetamine single-photon emission computed tomography, while the anastomotic vessel was patent on magnetic resonance angiography. This phenomenon of hypoperfusion area (left frontotemporal lobe) remote to anastomotic site (left temporal lobe area) led to the diagnosis of the ‘watershed shift’ phenomenon. In light of the hypoperfusion induced by ‘watershed shift’, the patient was treated with fluid replacement. With the gradual recovery of perfusion, the patient presented significantly improvement both on the magnetic resonance imaging findings and neurological symptoms. In conclusion, regional cerebral edema with hypoperfusion, possibly due to cerebral ischemia and the ‘watershed shift’ phenomenon, may be another novel entity that needs to be considered as a potential complication after extracranial–intracranial bypass for moyamoya disease.

Predictive factors for acute thrombogenesis occurring immediately after bypass procedure for moyamoya disease

Extracranial-to-intracranial (EC-IC) bypass surgery is an effective treatment for patients with moyamoya disease and other conditions. Some patients with moyamoya disease have a risk of acute thrombogenesis at the anastomotic site just after bypass surgery. The purpose of this study was to study risk factors of acute thrombogenesis and determine effective countermeasures. This study included 48 patients (66 EC-IC bypass procedures) with moyamoya disease and 52 controls (54 procedures) without moyamoya disease. The development of acute thrombogenesis was compared between the moyamoya disease and control groups. In the moyamoya disease group, clinical and radiological characteristics were assessed with respect to acute thrombogenesis. In the patients with acute thrombogenesis, causes of technical problems were retrospectively examined. The incidence of acute thrombogenesis was significantly higher in the moyamoya disease group than those in the control group. In the moyamoya disease group, acute thrombogenesis was observed in seven patients. In the moyamoya disease group, the magnetic resonance angiography (MRA) scores were significantly higher in patients with acute thrombogenesis than those in the patients without acute thrombogenesis. In the multivariate analysis, the predictive factor of acute thrombogenesis in moyamoya disease was a high MRA score (odds ratio, 2.336; p = 0.009). During EC-IC bypass surgery for moyamoya disease, acute thrombogenesis should be considered to obtain a high patency rate, particularly in patients with high MRA scores. Acute thrombogenesis will not influence morbidity if proper countermeasures are followed; therefore, the prediction and recognition of white thrombus are important for a successful bypass surgery.

Single Vessel Double Anastomosis for Flow Augmentation – A Novel Technique for Direct Extracranial to Intracranial Bypass Surgery

BACKGROUND

A double anastomosis using a single superficial temporal artery (STA) donor branch for both a proximal side-to-side (S2S) and a distal end-to-side anastomosis is a novel direct bypass technique for use in selected patients necessitating flow augmentation.

OBJECTIVE

To describe the single-vessel double anastomosis (SVDA) technique, including its indications, advantages, and limitations, in addition to reporting our cases series of patients who underwent a SVDA bypass surgery.

METHODS

Patients undergoing a SVDA bypass at a single institution between January 2010 and February 2016 were retrospectively reviewed. Intraoperative flow data was collected, including STA cut-flow, bypass flows, and cut flow index (CFI). Bypass patency was assessed by cerebral angiography and quantitative magnetic resonance angiography with noninvasive optimal vessel analysis. Adverse events occurring during the hospital stay and clinical status at last follow up was recorded.

RESULTS

Seven patients underwent SVDA bypass. Mean follow-up was 14.5 mo. Initial CFI for the S2S bypasses averaged 0.56 ± 0.25 and CFI after the SVDA averaged 1.15 ± 0.24. There was a statistically significant average difference in CFI before and after the SVDA bypass (p < .013). Thirteen bypasses (93%) were patent postoperatively, and remained patent at last follow up. Four patients experienced various postoperative complications. None of the patients had a new stroke since hospital discharge.

CONCLUSION

SVDA is a novel technique that can be advantageous for selected cases of extracranial-to-intracranial bypass. Expertise in bypass procedures is a necessary prerequisite. Graft patency rates and complications appear comparable to other bypass techniques.

Efficacy of STA-MCA bypass surgery in moyamoya angiopathy: long-term follow-up of the Caucasian Krupp Hospital cohort with 81 procedures

BACKGROUND

Despite the consensus on the efficacy of revascularizing surgery in moyamoya angiopathy (MA) in Asia, the indication in Caucasian moyamoya patients is controversially discussed.

OBJECTIVE

The efficacy of revascularizing surgery in adult European patients with MA should be clarified.

METHODS

This study retrospectively analyzed the rate of further strokes and hemorrhages as well as MRI and Duplex ultrasound features during long-term follow up after STA-MCA bypass.

RESULTS

Eighty-one STA-MCA bypass procedures in 54 patients with MA operated in one single German institution were analyzed. All 54 patients (100%) were Caucasians. After two diffusion restricted spots in MRI perioperatively (2.5%) and short-lasting symptoms directly after surgery, no patient experienced further new symptoms related to stroke or hemorrhages nor no new gliotic scars or microbleeds on MRI for 38.2 months. Duplex ultrasound 3 months after surgery documented bypass patency in 100% and sonographic sign for good relevance of the bypass in 96.2%. In addition, the diameter of the donor vessel had increased in 89.9% as an indicator for the relevance of the bypass. Semi-quantitative analysis of perfusion changes in the operated hemispheres demonstrated an increase in perfusion in the MCA territory in 56 of 74 (75.7%) hemispheres 36.7 months after surgery. In MRA images, a reduction of typical moyamoya collaterals was found in 65 of 79 hemispheres (82.3%) after a mean of 37.2 months.

CONCLUSION

Direct STA-MCA bypass is an effective therapy in Caucasian patients with hemodynamically compromised MA.

Intracranial Hemorrhage After Superficial Temporal Artery-Middle Cerebral Artery Direct Anastomosis for Adults with Moyamoya Disease

BACKGROUND

Intracranial hemorrhage, such as intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and intraventricular hemorrhage (IVH), is an extremely rare complication after surgical revascularization for moyamoya disease (MMD). However, the incidence, timing, prognosis, possible mechanism, and prevention are not well known.

METHODS

Adult patients with MMD who underwent direct bypass or combined bypass and experienced ICH, SAH, or IVH within 7 days postoperatively were enrolled in this study. The medical records and radiologic findings of these patients, together with their intraoperative video recordings, were reviewed retrospectively.

RESULTS

Direct superficial temporal artery (STA)-middle cerebral artery (MCA) bypass or combined bypass was performed for 222 hemispheres in 193 adult patients with MMD between January 2001 and December 2016. Intracranial hemorrhage occurred perioperatively in 8 hemispheres (3.6%) in 8 patients. The hemorrhages developed immediately after STA-MCA direct anastomosis during surgery in 3 patients. Hemorrhage on computed tomography and neurologic deterioration were also observed immediately postoperatively in 2 patients and during the postoperative period in 3 patients. Although 4 patients received medical management, neurosurgical treatment was needed in the other 4 patients. One patient died, and 6 patients were left with moderate or severe disabilities.

CONCLUSIONS

Intracranial hemorrhage (ICH, IVH, or SAH) after direct bypass for adult patients with MMD is an extremely rare but fatal complication. Although these hemorrhages can be associated with hyperperfusion syndrome, no effective prevention has been established.

Graft Occlusion and Graft Size Changes in Complex Internal Carotid Artery Aneurysm Treated by Extracranial to Intracranial Bypass Using High-Flow Grafts with Therapeutic Internal Carotid Artery Occlusion

BACKGROUND

Although the extracranial-to-intracranial high-flow bypass (EC-IC HFB) continues to be indispensable for complex aneurysms, the risk factors for the graft occlusion and whether the graft size changes after the bypass have not been well established.

OBJECTIVE

To evaluate the risk factors for the graft occlusion and to confirm whether graft diameters changed over time.

METHODS

The data of 75 patients who suffered from complex internal carotid artery (ICA) aneurysms and were treated by EC-IC HFB using radial artery graft (RAG) or saphenous vein graft (SVG) with therapeutic ICA occlusion were evaluated. Clinical and radiological characteristics were compared in patients with and without the graft occlusion by the log-rank test. Graft diameters measured preoperatively, postoperatively, at 6 months, and at 1 year were compared by paired t-test.

RESULTS

During a follow-up period (median 26.2 months), graft occlusions were seen in 4 patients (5.3%), and these were the SVGs. Only SVG was related to graft occlusion (P < .001). There was a significant increase with time in RAG diameters (preoperative, 3.1 ± 0.41 mm; postoperative, 3.6 ± 0.65 mm; 6 months, 4.3 ± 1.0 mm; 1 year, 4.4 ± 1.0 mm), while there were no significant diameter changes in SVGs.

CONCLUSION

The present study showed that the SVG was related to the graft occlusion and RAGs gradually enlarged. Unless Allen test is negative, RAG may be better to be used as a graft in EC-IC HFB if therapeutic ICA occlusion is needed.

In situ administration of abciximab for thrombus resolution during intracranial bypass surgery: case report

Abciximab is a glycoprotein IIb/IIIa receptor antagonist that functions to prevent platelet aggregation, thus reducing thrombus initiation and propagation. It has been widely used during percutaneous endovascular interventions, such as aneurysm coil embolization, angioplasty, atherectomy, and stent placement, as both a preventative and a salvage therapy. The use of abciximab in cardiac and neurosurgical procedures has been associated with a reduced incidence of ischemic complications and a decreased need for repeated intervention. In these settings, abciximab has been delivered transarterially via a microcatheter or infused intravenously for systemic administration. The authors describe novel in situ delivery of abciximab as an agent to dissolve "white clots," which are composed primarily of platelets, during an intracranial superficial temporal artery to middle cerebral artery bypass in a 28-year-old woman with severe intracranial occlusive disease. Abciximab was able to resolve multiple platelet-based clots after unsuccessful attempts with conventional clot dispersal techniques, such as heparinized saline, tissue plasminogen activator, mechanical passage of a wire through the vessel lumen, and multiple takedowns and re-anastomosis. After abciximab was administered, patency was demonstrated intraoperatively using indocyanine green dye and confirmed postoperatively at 1 and 10 months via CT angiography. The in situ use of abciximab as an agent to disperse a thrombus during intracranial bypass surgery is novel and has not previously been described in the literature, and serves as an additional tool during intracranial vessel bypass surgery.

Long-Term Outcome After Conservative Treatment and Direct Bypass Surgery of Moyamoya Disease at Late Suzuki Stage

OBJECTIVE

To investigate the long-term outcomes after conservative and direct surgical treatment for patients with moyamoya disease (MMD) at late Suzuki stage.

METHODS

We retrospectively reviewed 82 patients (164 hemispheres) with MMD at late Suzuki stage at Beijing Tiantan Hospital. Clinical features, radiologic findings, and outcomes were analyzed.

RESULTS

The mean age at diagnosis was 36.4 ± 11.7 years. The distribution of the initial Suzuki stage of MMD was as follows: stage 4, n = 113; stage 5, n = 45; stage 6, n = 6, posterior cerebral artery involvement was observed in 41 hemispheres (25.0%). The incidence of postoperative stroke (<48 hours) was 6.7%. During the average follow-up of 55.1 ± 16.2 months, including postoperative and follow-up strokes, 7 of 75 conservatively treated hemispheres (9.3%) and 9 of 89 surgically treated patients (10.1%) experienced a stroke event; there was no statistical significance in the Kaplan-Meier curve of stroke incidence between the surgical group and conservative group (log-rank test, P = 0.848). However, the rate of perfusion improvement in direct bypass surgically treated patients was higher than in those conservatively treated patients 3 months after discharge (P < 0.05).

CONCLUSIONS

Although direct bypass surgery was shown to effectively improve the cerebral perfusion in patients with MMD at late Suzuki stage, compared with conservative treatment, it did not reduce the risk of recurrent stroke. Further study is needed to determine whether direct bypass surgery is effective in patients with MMD at late Suzuki stage.

Progress on Complications of Direct Bypass for Moyamoya Disease

Moyamoya disease (MMD) involves progressive occlusion of the intracranial internal carotid artery resulting in formation of moyamoya-like vessels at the base of the brain. It can be characterized by hemorrhage or ischemia. Direct vascular bypass is the main and most effective treatment of MMD. However, patients with MMD differ from those with normal cerebral vessels. MMD patients have unstable intracranial artery hemodynamics and a poor blood flow reserve; therefore, during the direct bypass of superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis, perioperative risk factors and anesthesia can affect the hemodynamics of these patients. When brain tissue cannot tolerate a high blood flow rate, it becomes prone to hyperperfusion syndrome, which leads to neurological function defects and can even cause intracranial hemorrhage in severe cases. The brain tissue is prone to infarction when hemodynamic equilibrium is affected. In addition, bypass vessels become susceptible to occlusion or atrophy when blood resistance increases. Even compression of the temporalis affects bypass vessels. Because the STA is used in MMD surgery, the scalp becomes ischemic and is likely to develop necrosis and infection. These complications of MMD surgery are difficult to manage and are not well understood. To date, no systematic studies of the complications that occur after direct bypass in MMD have been performed, and reported complications are hidden among various case studies; therefore, this paper presents a review and summary of the literature in PubMed on the complications of direct bypass in MMD.