Trends in Literature on Cerebral Bypass Surgery: A Systematic Review.

INTRODUCTION: Ever since the beginning of cerebral bypass surgery, the role of the bypass has been debated and indications have changed over the last 5 decades. This systematic literature research analysed all clinical studies on cerebral bypass that have been published from January 1959 to January 2020 for their year of publication, country of origin, citation index, role of and indication for bypass, bypass technique, revascularized territory, flow capacity, and title (for word cloud analysis per decade). METHODS: A systematic literature research was conducted using PubMed, Web of Science, EMBASE, and SCOPUS databases. All studies that have been published until January 1, 2020, were included. RESULTS: Of 6,013 identified studies, 2,585 were included in the analysis. Of these, n = 1,734 (67%) studies addressed flow-augmentation bypass and n = 701 (27%) addressed flow-preservation bypass. The most common indication reported for flow augmentation is moyamoya (n = 877, 51%), followed by atherosclerotic steno-occlusive disease (n = 753, 43%). For flow preservation, the most common indication is studies reporting on cerebral aneurysm surgery (n = 659, 94%). The increasing popularity of reporting on these bypass operations almost came to an end with the FDA approval of flow diverters for aneurysm treatment in 2011. Japan is the country with the most bypass studies (cumulatively published 933 articles), followed by the USA (630 articles) and China (232 articles). DISCUSSION/CONCLUSION: Clinical studies on cerebral bypass surgery have become increasingly popular in the past decades. Since the introduction of moyamoya as a distinct pathologic entity, Asian countries in particular have a very active community regarding this disease, with an increasing number of articles published every year. Studies on bypass for chronic steno-occlusive disease peaked in the 1980s but have remained the main focus of bypass research, particularly in many European departments. The number of reports published on these bypass operations significantly decreased after the FDA approval of flow diverters for aneurysm treatment in 2011.

Effects of dobutamine and phenylephrine on cerebral perfusion in patients undergoing cerebral bypass surgery: a randomised crossover trial.

BACKGROUND: Patients undergoing cerebral bypass surgery are prone to cerebral hypoperfusion. Currently, arterial blood pressure is often increased with vasopressors to prevent cerebral ischaemia. However, this might cause vasoconstriction of the graft and cerebral vasculature and decrease perfusion. We hypothesised that cardiac output, rather than arterial blood pressure, is essential for adequate perfusion and aimed to determine whether dobutamine administration resulted in greater graft perfusion than phenylephrine administration. METHODS: This randomised crossover study included 10 adult patients undergoing cerebral bypass surgery. Intraoperatively, patients randomly and sequentially received dobutamine to increase cardiac index or phenylephrine to increase mean arterial pressure (MAP). An increase of >10% in cardiac index or >10% in MAP was targeted, respectively. Before both interventions, a reference phase was implemented. The primary outcome was the absolute difference in graft flow between the reference and intervention phase. We compared the absolute flow difference between each intervention and constructed a random-effect linear regression model to explore treatment and carry-over effects. RESULTS: Graft flow increased with a median of 4.1 (inter-quartile range [IQR], 1.7-12.0] ml min-1) after dobutamine administration and 3.6 [IQR, 1.3-7.8] ml min-1 after phenylephrine administration (difference -0.6 ml min-1; 95% confidence interval [CI], -14.5 to 5.3; P=0.441). There was no treatment effect (0.9 ml min-1; 95% CI, 0.0-20.1; P=0.944) and no carry-over effect. CONCLUSIONS: Both dobutamine and phenylephrine increased graft flow during cerebral bypass surgery, without a preference for one method over the other. CLINICAL TRIAL REGISTRATION: Netherlands Trial Register, NL7077 (https://www.trialregister.nl/trial/7077).

Current Open Surgical Indications for Revascularization in Cerebral Ischemia.

Cerebral revascularization was pioneered half a century ago. Gradual improvements in microsurgical instrumentation and training in microsurgical techniques have allowed significant changes that improved outcomes in neurosurgery, extrapolating this knowledge to other neurosurgical diseases (brain tumor, aneurysms, and skull base tumor surgery). But the popularity of cerebral bypass procedures was followed by their decline, given the lack of clear benefit of bypass surgery in chronic cerebrovascular ischemia after the EC-IC bypass studies. Over the last couple of decades, the formidable advance of neuro-endovascular techniques for revascularization has lessened the need for application of open cerebral revascularization procedures, either for flow augmentation or flow replacement. However, there is still a select group of patients with chronic cerebral ischemia, for whom open cerebral revascularization with flow augmentation is the only treatment option available, and this will be the objective of our current review.

Diagnostic reliability of the Berlin classification for complex MCA aneurysms-usability in a series of only giant aneurysms.

BACKGROUND AND OBJECTIVE: The main challenge of bypass surgery of complex MCA aneurysms is not the selection of the bypass type but the initial decision-making of how to exclude the affected vessel segment from circulation. To this end, we have previously proposed a classification for complex MCA aneurysms based on the preoperative angiography. The current study aimed to validate this new classification and assess its diagnostic reliability using the giant aneurysm registry as an independent data set. METHODS: We reviewed the pretreatment neuroimaging of 51 patients with giant (> 2.5 cm) MCA aneurysms from 18 centers, prospectively entered into the international giant aneurysm registry. We classified the aneurysms according to our previously proposed Berlin classification for complex MCA aneurysms. To test for interrater diagnostic reliability, the data set was reviewed by four independent observers. RESULTS: We were able to classify all 51 aneurysms according to the Berlin classification for complex MCA aneurysms. Eight percent of the aneurysm were classified as type 1a, 14% as type 1b, 14% as type 2a, 24% as type 2b, 33% as type 2c, and 8% as type 3. The interrater reliability was moderate with Fleiss's Kappa of 0.419. CONCLUSION: The recently published Berlin classification for complex MCA aneurysms showed diagnostic reliability, independent of the observer when applied to the MCA aneurysms of the international giant aneurysm registry.

National trends in cerebral bypass surgery in the United States, 2002-2014.

OBJECTIVECerebral bypass procedures are microsurgical techniques to augment or restore cerebral blood flow when treating a number of brain vascular diseases including moyamoya disease, occlusive vascular disease, and cerebral aneurysms. With advances in endovascular therapy and evolving evidence-based guidelines, it has been suggested that cerebral bypass procedures are in a state of decline. Here, the authors characterize the national trends in cerebral bypass surgery in the United States from 2002 to 2014.METHODSUsing the National (Nationwide) Inpatient Sample, the authors extracted for analysis the data on all adult patients who had undergone cerebral bypass as indicated by ICD-9-CM procedure code 34.28. Indications for bypass procedures, patient demographics, healthcare costs, and regional variations are described. Results were stratified by indication for cerebral bypass including moyamoya disease, occlusive vascular disease, and cerebral aneurysms. Predictors of inpatient complications and death were evaluated using multivariable logistic regression analysis.RESULTSFrom 2002 to 2014, there was an increase in the annual number of cerebral bypass surgeries performed in the United States. This increase reflected a growth in the number of cerebral bypass procedures performed for adult moyamoya disease, whereas cases performed for occlusive vascular disease or cerebral aneurysms declined. Inpatient complication rates for cerebral bypass performed for moyamoya disease, vascular occlusive disease, and cerebral aneurysm were 13.2%, 25.1%, and 56.3%, respectively. Rates of iatrogenic stroke ranged from 3.8% to 20.4%, and mortality rates were 0.3%, 1.4%, and 7.8% for moyamoya disease, occlusive vascular disease, and cerebral aneurysms, respectively. Multivariate logistic regression confirmed that cerebral bypass for vascular occlusive disease or cerebral aneurysm is a statistically significant predictor of inpatient complications and death. Mean healthcare costs of cerebral bypass remained unchanged from 2002 to 20014 and varied with treatment indication: moyamoya disease $38,406 ± $483, vascular occlusive disease $46,618 ± $774, and aneurysm $111,753 ± $2381.CONCLUSIONSThe number of cerebral bypass surgeries performed for adult revascularization has increased in the United States from 2002 to 2014. Rising rates of surgical bypass reflect a greater proportion of surgeries performed for moyamoya disease, whereas bypasses performed for vascular occlusive disease and aneurysms are decreasing. Despite evolving indications, cerebral bypass remains an important surgical tool in the modern endovascular era and may be increasing in use. Stagnant complication rates highlight the need for continued interest in advancing available bypass techniques or technologies to improve patient outcomes.

Cerebral revascularization after the Carotid Occlusion Surgery Study: what candidates remain, and can we do better?

OBJECTIVECerebral revascularization for carotid occlusion was previously a mainstay procedure for the cerebrovascular neurosurgeon. However, the 1985 extracranial-intracranial bypass trial and subsequently the Carotid Occlusion Surgery Study (COSS) provided level 1 evidence via randomized controlled trials against bypass for symptomatic atherosclerotic carotid occlusion disease. However, in a small number of patients optimal medical therapy fails, and some patients with flow-limiting stenosis develop a perfusion-dependent neurological examination. Therefore it is necessary to further stratify patients by risk to determine who may most benefit from this intervention as well as to determine perioperative morbidity in this high-risk patient population.METHODSA retrospective review was performed of all revascularization procedures done for symptomatic atherosclerotic cerebrovascular steno-occlusive disease. All patients undergoing revascularization after the publication of the COSS in 2011 were included. Perioperative morbidity and mortality were assessed as the primary outcome to determine safety of revascularization in this high-risk population. All patients had documented hypoperfusion on hemodynamic imaging.RESULTSAt total of 35 revascularization procedures were included in this review. The most common indication was for patients with recurrent strokes, who were receiving optimal medical therapy and who suffered from cerebrovascular steno-occlusion. At 30 days only 3 perioperative ischemic events were observed, 2 of which led to no long-term neurological deficit. Immediate graft patency was good, at 94%. Long term, no further strokes or ischemic events were observed, and graft patency remained high at 95%. There were no factors associated with perioperative ischemic events in the variables that were recorded.CONCLUSIONSCerebral revascularization may be done safely at high-volume cerebrovascular centers in high-risk patients in whom optimal medical therapy has failed. Further research must be done to develop an improved methodology of risk stratification for patients with symptomatic atherosclerotic cerebrovascular steno-occlusive disease to determine which patients may benefit from intervention. Given the high risk of recurrent stroke in certain patients, and the fact that patients fail medical therapy, surgical revascularization may provide the best method to ensure good long-term outcomes with manageable up-front risks.

Cerebral Bypass Surgery: Level of Evidence and Grade of Recommendation.

BACKGROUND AND AIMS: Cerebral bypasses are categorized according to function (flow augmentation or flow preservation) and to characteristics: direct, indirect or combined bypass, extra-to-intracranial or intra-to-intracranial bypass, and high-, moderate- or low-capacity bypass. We critically summarize the current state of evidence and grades of recommendation for cerebral bypass surgery. METHODS: The current indications for cerebral bypass are discussed depending on the function of the bypass (flow preservation or augmentation) and analyzed according to level of evidence criteria. RESULTS: Flow-preservation bypass plays an important role in managing complex intracranial aneurysms (level of evidence 4; grade of recommendation C). Flow-preservation bypass is currently only very rarely indicated in the treatment of cerebral tumors involving major cerebral arteries (level of evidence 5; grade of recommendation D). The trend has evolved in favor of partial resection and radiotherapy. To preserve the flow, the bypass is always a direct bypass.Flow-augmentation bypass is currently recommended for Moyamoya patients with ischemic symptoms and compromised hemodynamics (level of evidence 4; grade of recommendation C) and patients with hemorrhagic onset (level of evidence 1B; grade of recommendation A). Flow-augmentation bypass is currently not recommended for patients with recently symptomatic carotid artery occlusion, even in the setting of compromised cerebral hemodynamics (level of evidence 1A; grade of recommendation A), but may be considered in patients with hemodynamic failure and recurrent medically refractory symptoms as a final resort (level of evidence 5; grade of recommendation D). CONCLUSIONS: The results of recent randomized clinical trials narrow the indication for cerebral bypass in the setting of ischemic cerebrovascular disease. However, cerebral bypass is still very useful for managing complex intracranial aneurysms (not amenable to selective clipping or endovascular therapies) and is the only treatment option for managing symptomatic patients with Moyamoya vasculopathy and impaired brain hemodynamics.

Role of Indocyanine Green Videoangiography in Identification of Donor and Recipient Arteries in Cerebral Bypass Surgery.

The identification and preparation of a very good quality donor artery is a crucial step in every superficial temporal artery to middle cerebral artery (STA-MCA) bypass.For flow-preservation bypass performed for trapping of complex MCA aneurysms, the key element is the correct target of the recipient artery. When a cortical recipient artery (M4 segment of the MCA) is selected, this vessel must be a terminal branch of the artery whose sacrifice is necessary for definitive aneurysmal treatment.In this chapter we report on two techniques for (1) intraoperative mapping and preparation of good quality STA branch as the donor artery for STA-MCA bypass (mostly in the case the frontal branch of the STA needs to be used) and (2) selective identification of the correct superficial (M4 cortical) "recipient" artery in flow-preservation STA-MCA bypass performed for managing complex MCA aneurysms.Both techniques are based on the use of microscope-integrated indocyanine green videoangiography (ICG-VA), an intraoperative tool allowing observation and real-time assessment of blood flow in large and small vessels, with distinct evaluation of arterial, capillary, and venous phases.The two techniques contribute, respectively, to (1) reduce the risk of erroneous identification or injury of the donor artery in STA-MCA bypass procedures and (2) eliminate the risk of erroneous revascularization of a non-involved arterial territory in flow-preservation bypass surgery for managing complex MCA aneurysms.

Universal Bypass for Treatment of Symptomatic Moyamoya Disease or Moyamoya Syndrome. Analysis of a Personal Case Series on Behalf of the Italian Moyamoya Association.

BACKGROUND: Moyamoya (MM) is a very rare cerebrovascular disease, particularly in Caucasians. We describe the results of an Italian case series where the mainstay of treatment was a bypass or a combined approach. METHODS: An analysis of a prospectively collected database was carried out. The main objective was to investigate (1) the risk of perioperative stroke and surgical complications, (2) the risk of new ischemic events, and (3) the risk of new hemorrhages at follow-up (mean follow-up: 2.2 years). RESULTS: Between January 2011 and January 2015 we carried out 34 bypasses in 23 patients with MM (15 MM disease, 5 unilateral MM, 3 MM syndrome); mean age was 34 (range:1-57). The mortality and definitive morbidity rates were 0 %. Two patients suffered from transient aphasia and one developed partial palsy of the facial nerve. Five of the 12 patients with preoperative fixed deficits improved. No patient with preoperative ischemia experienced new ischemic symptoms. Rebleeding occurred in 1 of the 11 patients with a hemorrhagic presentation (9 %). CONCLUSIONS: The bypass/combined approach to MM appears to have a favorable risk profile and preventive effectiveness, particularly on TIAs and ischemic stroke.

A novel training model for superficial temporal artery (STA)- middle cerebral artery (MCA) anastomosis using microsurgical techniques.

OBJECTIVE: To create a reusable and inexpensive training model with technological tools that simulates cerebral bypass surgery and a sensor system that provides tactile feedback to the surgeon. Furthermore, we aimed to evaluate the anastomotic stability and contribution to the surgeon's learning curve. METHODS: We created a superficial temporal artery (STA)-middle cerebral artery (MCA) bypass simulation model using chicken and turkey brachial arteries. A cranium model was printed with a three-dimensional printer for craniotomy and cerebral parenchyma was created by pouring silicone into the cranial mold. A blood flow simulation system was also prepared. Pressure-sensitive sensors were placed on parenchyma, and tactile conditioning was performed via audible warning from the sensors. 24 anastomosis were performed with different sutures and hand tools. Anastomosis completion times and durability and the number of touches and pressures applied to the parenchyma were recorded. The stability of the anastomoses was evaluated by increasing the pressure in the blood flow simulation system, so usefulness of the training model was evaluated. RESULTS: The time required for anastomosis completion decreased as the number of practices (p < 0.05). As the number of practices increased, the number of parenchymal touches decreased (p < 0.05). CONCLUSIONS: With practice, the time required for anastomosis completion and number of parenchymal touches decreased. Thus, the model is useful, inexpensive, reusable, easily accessible and contributes to the surgeon's learning curve. Our model with pressure-sensitive sensors can be used for microsurgery practice, enabling the surgeons to gain tactile conditioning and evaluate anastomotic stability and leakage.

First-generation bypass surgery for a giant fusiform aneurysm of the middle cerebral artery: an illustrative case and surgical video.

Giant fusiform aneurysms of the middle cerebral artery (MCA) are complex and rare vascular lesions with a poor natural history and challenging treatment decision-making. We report the case of a 46-year-old male with a history of chronic hypertension and a transient ischemic attack who presented with left-sided hemiparesis. A cerebral angiotomography revealed an unruptured giant fusiform aneurysm in the M2 segment of the right MCA. After carefully evaluating the procedure's risks and benefits with the patient, he underwent a low-flow bypass surgery. An anastomosis between the superficial temporal artery and the M3 segment was performed with proximal clipping of the M2 segment. The postoperative course was uneventful, with preserved bypass patency. At follow-up, the patient was neurologically intact. This report illustrates the nuances and operative techniques for treating a giant fusiform aneurysm of the M2 segment that accounted for a preserved bypass patency and optimal patient neurological recovery.

Advancing Neurosurgical Skills: A Comparative Study of Training Models for Intra-Extracranial Cerebral Bypass.

BACKGROUND: Training in anastomosis is fundamental in neurosurgery due to the precision and dexterity required. Biological models, although realistic, present limitations such as availability, ethical concerns, and the risk of biological contamination. Synthetic models, on the other hand, offer durability and standardized conditions, although they sometimes lack anatomical realism. This study aims to evaluate and compare the efficiency of anastomosis training models in the intra-extracranial cerebral bypass procedure, identifying those characteristics that enhance optimal microsurgical skill development and participant experience. METHODS: A neurosurgery workshop was held from March 2024 to June 2024 with 5 vascular techniques and the participation of 22 surgeons. The models tested were the human placenta, the Wistar rat, the chicken wing artery, the nasogastric feeding tube, and the UpSurgeOn Mycro simulator. The scales used to measure these models were the Main Characteristics Score and the Evaluation Score. These scores allowed us to measure, qualitatively and quantitatively, durability, anatomical similarity, variety of simulation scenarios, risk of biological contamination, ethical considerations and disadvantages with specific infrastructure. RESULTS: The human placenta model, Wistar rat model, and UpSurgeOn model were identified as the most effective for training. The human placenta and Wistar rat models were highly regarded for anatomical realism, while the UpSurgeOn model excelled in durability and advanced simulation scenarios. Ethical and cost implications were also considered. CONCLUSIONS: The study identifies the human placenta and UpSurgeOn models as optimal for training in intra-extracranial bypass procedures, emphasizing the need for diverse and effective training models in neurosurgery.

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.

A narrative review of techniques for surgical revascularization of the extracranial vertebral artery in vertebrobasilar insufficiency.

Vertebrobasilar insufficiency is a condition characterized by poor blood flow through the posterior circulation of the brain, which supplies the brainstem, thalamus, hippocampus, cerebellum, occipital lobes, and medial temporal lobes. Narrowing or occlusion of the vertebral arteries may be result in a range of neurological symptoms, including dizziness, imbalance, dysarthria, and even stroke. If symptomatic patients fail medical management, revascularization of the vertebral artery should be considered. Restoration of blood flow may involve transluminal balloon angioplasty or stent placement; however, certain cases may still require surgical intervention. The complexity of surgical revascularization of the vertebral artery requires careful consideration of skull base and neck anatomy. This review article will focus on bypass of the vertebral artery in the setting of ischemic pathology, describing the technique, anatomical nuances, steps involved in preoperative planning, and postoperative management.

Frontotemporal Approach for Infectious Aneurysm Trapping and Superficial Temporal Artery-Middle Cerebral Artery Bypass.

Although neurotropic, the varicella-zoster virus (VZV) is a rare cause of mycotic cerebral aneurysms. As with other mycotic aneurysms, medical management can provide complete resolution. Surgery for refractory aneurysms can be complicated by vessel friability and complex morphologies requiring excision and revascularization. In Video 1, we present key steps in the surgical management of a previously ruptured and growing fusiform mycotic cerebral aneurysm. A 58-year-old woman with a history of neuromyelitis optica resulting in lower-extremity paraplegia and chronic immunosuppression presented elsewhere with a Hunt and Hess 2 and Fisher grade 3 subarachnoid and intraparenchymal hemorrhage. Initial angiography demonstrated a 3-mm right distal middle cerebral artery fusiform aneurysm. Because of a recent shingles episode and cerebrospinal fluid studies consistent with a viral cause (glucose 26, protein 166, lymphocytes 64%), acyclovir and steroid therapy was commenced. She was transferred to our institution after serial angiography demonstrated aneurysm growth to 7 mm over 1 week. On arrival, she was neurologically intact except for her baseline lower-extremity weakness. To address the lesion, she underwent a superficial temporal artery-to-middle cerebral artery direct bypass, followed by clip trapping and microsurgical excision of the diseased arterial segment. Pathologic analysis confirmed the presence of VZV in the aneurysm walls. Postoperatively, she was at her neurologic baseline and was discharged 2 weeks later. Immediate and 5-month postoperative vascular imaging demonstrated bypass patency and no residual aneurysm. Similar to other mycotic aneurysms, VZV-associated cerebral aneurysms refractory to medical management can be safely treated with definitive excision and revascularization in selected patients.

Rethinking Cerebral Bypass Surgery.

Despite the evolution of indications, cerebral bypass remains an important treatment for selected patients with moyamoya disease, steno-occlusive cerebrovascular disease, complex aneurysms, and tumors. Ongoing advancements in patient selection and recent strategic, technical, and technological innovations are facilitating more tailored constructs with lower complication rates and continue to reshape the field. The consolidation of cerebral bypass to specialized centers will likely continue as the complexity of both the pathologies requiring treatment and the revascularization constructs performed increases.

A Posterior Communicating Segment Aneurysm of the Supraclinoid Internal Carotid Artery Treated with an Extracranial to Intracranial Bypass and Trapping.

Surgical treatment of giant aneurysms often poses significant challenges. Endovascular techniques have evolved exponentially over the last decades, and most of these complex aneurysms can be treated with flow-diverting techniques; however, successful obliteration of all giant aneurysms is not always possible with endovascular flow-diverting techniques. Although the need for microsurgical intervention has undoubtedly diminished, a versatile-thinking surgeon should keep in mind that obliteration of these aneurysms combined with revascularizing the distal circulation via extracranial-intracranial bypass techniques can provide a potentially life-long durable solution. The key to curing these pathologies is to utilize interdisciplinary decision making with a robust knowledge of the pros and cons of different treatment approaches. Herein, we present a case of a giant posterior communicating segment aneurysm of the left supraclinoid internal carotid artery (ICA), which was treated by obliteration ( Fig. 1 ). Extradural anterior clinoidectomy was used to provide exposure of the supraclinoidal ICA proximal to the aneurysm, and revascularization of the distal circulation was achieved with a common carotid artery to M2-superior trunk bypass using a radial artery interposition graft ( Fig. 2 ). The patient was a 62-year-old female who presented with vision loss in her left eye but was otherwise neurologically intact. She had a history of two unsuccessful flow-diverting stent placement attempts 2 months prior to this surgery. Postoperatively, the patient woke up without any deficits, with her left eye vision partially recovered and ultimately returning to normal at 1-year follow-up. Computed tomography (CT) angiography at a 1-year follow-up showed complete obliteration of the aneurysm and successful revascularization of the distal circulation. The link to the video can be found at: https://youtu.be/DsIuIJJj1l4 .

The changing landscape of cerebral revascularization surgery: A United Kingdom experience.

Objective: We describe the chronological trends in cerebral revascularization surgery through a single-surgeon experience; and we review whether in the context of giant and fusiform cerebral aneurysms, flow-diverting stents have impacted on the use of cerebral revascularization surgery. Methods: We review our single institution prospectively collected database of cerebral revascularization procedures between 2006 and 2018. Comparing this to our database of flow-diverting endovascular stent procedures, we compare the treatment of fusiform and giant aneurysms. We describe patient demographics, procedural incidence, complications, and outcomes. Results: Between 2006 and 2018, 50 cerebral revascularization procedures were performed. The incidence of cerebral revascularization surgery is declining. In the context of giant/fusiform aneurysm treatment, the decline in cerebral revascularization is accompanied by a rise in the use of flow-diverting endovascular stents. Thirty cerebral revascularizations were performed for moyamoya disease and 11 for giant/fusiform aneurysm. Four (14%) direct bypass grafts occluded without neurological sequela. Other morbidity included hydrocephalus (2%), transient ischemic attacks (2%), and ischemic stroke (2%). There was one procedure-related mortality (2%). Flow-diverting stents were inserted for seven fusiform and seven giant aneurysms. Comparing the treatment of giant/fusiform aneurysms, there was no significant difference in morbidity and mortality between cerebral revascularization and flow-diverting endovascular stents. Conclusion: We conclude that with the decline in the incidence of cerebral revascularization surgery, there is a need for centralization of services to allow high standards and outcomes to be maintained.

Gross Total Resection of a Recurrent in-and-around Cavernous Sinus Meningioma through a Combined Transcavernous Anterior and Middle Infratemporal Fossa Approach with Extracranial-Intracranial Bypass.

Objectives The study aims to describe surgical management of an invasive cavernous sinus meningioma with a combination of several skull base approaches and bypass surgery. Design This study is an operative video. Results Resection of the recurrent skull base meningioma is still challenging, especially if the tumor involves or encases the carotid artery. Cerebral bypass surgery is an essential adjunct in the armamentarium of skull base surgery when vessel reconstruction is required. In this paper, we describe our experience of successful treatment of an invasive recurrent skull base meningioma, which involved the entire cavernous sinus and the internal carotid artery. A 46-year-old woman presented with a 2-year history of gradually worsening left-sided exophthalmos and visual impairment. The patient had previously undergone two craniotomies for resection of the left-sided spheno-orbital meningioma. Pathological diagnosis was chordoid meningioma, which is classified as an intermediate-grade meningioma. The second surgery had been performed for a rapid tumor regrowth 6 months after the first surgery. The patient lost her left-side vision after the second surgery. Aggressive tumor regrowth was confirmed with extension into the left orbit, infratemporal fossa, and cavernous sinus with engulfment of the carotid artery. A balloon occlusion test revealed intolerance of the left internal carotid artery occlusion. Considering the patient's age, tumor behavior, and intolerance of the carotid artery of the lesion side, we scheduled gross total resection of the tumor with vessel reconstruction. Conclusion Although cerebral bypass surgery is a technically challenging procedure, it plays an important role in the surgical management of the complex vessel-engulfing tumor. The link to the video can be found at https://youtu.be/GCmpxK3hW18 .

Effectiveness of pharmacologic interventions for prevention of cerebral hyperperfusion syndrome following bypass surgery.

BACKGROUND: Cerebral hyperperfusion syndrome (CHS) following bypass surgery is a major cause of neurological morbidity and mortality. However, data regarding its prevention have not been assorted until date. OBJECTIVE: The objective of this study was to review the literature and evaluate whether any conclusion can be drawn regarding the effectiveness of any measure on preventing bypass-related CHS. METHODS: We systematically reviewed PubMed and Cochrane Library from September 2008 to September 2018 to collect data regarding the effectiveness of pharmacologic interventions on the refers to pretreatment (PRE) of bypass-related CHS. We categorized interventions regarding their class of drugs and their combinations and calculated overall pooled estimates of proportions of CHS development through random-effects meta-analysis of proportions. RESULTS: Our search yielded 649 studies, of which 23 fulfilled inclusion criteria. Meta-analysis included 23 studies/2,041 cases. In Group A (blood pressure [BP] control), 202 out of 1,174 pretreated cases developed CHS (23.3% pooled estimate; 95% confidence interval [CI]: 9.9-39.4), Group B (BP control + free radical scavenger [FRS]) 10/263 (0.3%; 95% CI: 0.0-14.1), Group C (BP control + antiplatelet) 22/204 (10.3%; 95% CI: 5.1-16.7), and Group D (BP control + postoperative sedation) 29/400 (6.8%; 95% CI: 4.4-9.6)]. CONCLUSIONS: BP control alone has not been proven effective in preventing CHS. However, BP control along with either a FRS or an antiplatelet agent or postoperative sedation seems to reduce the incidence of CHS.