Cerebral Bypass Research Articles

Training model for the intraluminal continuous suturing technique for microvascular anastomosis

Microvascular anastomosis is a critical procedure in cerebral bypass surgeries. In some rare cases, the extraluminal interrupted technique is not optimal because the vessels are immobile and cannot be rotated, and anastomosis can be performed effectively through the intraluminal continuous suturing technique. The authors reported the application of the intraluminal continuous suturing technique in microanastomosis training with silicone tube, rat’s common iliac arteries and abdominal aorta. A silicone tube with a diameter of 1.5 mm was used to practice microanastomosis in intraluminal continuous suturing technique. Then the technique was applied in side-to-side, end-to-side anastomoses of common iliac arteries and the end-to-end abdominal aorta anastomoses of rat. The suturing time and patency rates were compared with an alternative intraluminal continuous suturing technique and one-way-up interrupted suturing technique in silicone tube and rat vessel anastomoses. The intraluminal continuous suturing technique could be gained through practicing with silicone tube, and the technique has also been demonstrated effective in side-to-side, end-to-side anastomoses of common iliac arteries of rat and the abdominal aorta end-to-end anastomoses. In all the animal experimental groups with different suturing techniques, there was no difference between the patency rates, all the immediate patency rate was 100%. There was no significant suturing time difference between the two intraluminal continuous suturing techniques, but the two intraluminal continuous suturing techniques were faster than the interrupted technique. The intraluminal continuous suturing technique described in the study could be used as an efficient method for side-to-side, end-to-side and end-to-end anastomosis, especially under the situation the posterior wall of the anastomosis could not be rotated. Proficiency of the technique could be achieved through practicing in laboratory with silicone tube and live animals.

Readmission following extracranial-intracranial bypass surgery in the United States: nationwide rates, causes, risk factors, and volume-driven outcomes.

Extracranial-intracranial (EC-IC) bypass surgery remains an important treatment option for patients with moyamoya disease (MMD), intracranial arteriosclerotic disease (ICAD) with symptomatic stenosis despite the best medical management, and complex aneurysms. The therapeutic benefit of cerebral bypass surgery depends on optimal patient selection and the minimization of periprocedural complications. The nationwide burden of readmissions and associated complications following EC-IC bypass surgery has not been previously described. Therefore, the authors sought to analyze a nationwide database to describe the national rates, causes, risk factors, complications, and morbidity associated with readmission following EC-IC bypass surgery for MMD, ICAD, and aneurysms. The Nationwide Readmissions Database (NRD) was queried for the years 2010-2014 to identify patients who had undergone EC-IC bypass for MMD, medically failed symptomatic ICAD, or unruptured aneurysms. Predictor variables included demographics, preexisting comorbidities, indication for surgery, and hospital bypass case volume. A high-volume center (HVC) was defined as one that performed 10 or more cases/year. Outcome variables included perioperative stroke, discharge disposition, length of stay, total hospital costs, and readmission (30 days, 90 days). Multivariable analysis was used to identify predictors of readmission and to study the effect of treatment at HVCs on quality outcomes. In total, 2500 patients with a mean age of 41 years were treated with EC-IC bypass surgery for MMD (63.1%), ICAD (24.5%), or unruptured aneurysms (12.4%). The 30- and 90-day readmission rates were 7.5% and 14.0%, respectively. Causes of readmission included new stroke (2.5%), wound complications (2.5%), graft failure (1.5%), and other infection (1.3%). In the multivariable analysis, risk factors for readmission included Medicaid/self-pay (OR 1.6, 95% CI 1.1-2.4, vs private insurance), comorbidity score (OR 1.2, 95% CI 1.1-1.4, per additional comorbidity), and treatment at a non-HVC (OR 1.9, 95% CI 1.1-3.0). Treatment at an HVC (17% of patients) was associated with significantly lower rates of nonroutine discharge dispositions (13.4% vs 26.7%, p = 0.004), ischemic stroke within 90 days (0.8% vs 2.9%, p = 0.03), 30-day readmission (3.9% vs 8.2%, p = 0.03), and 90-day readmission (8.6% vs 15.2%, p = 0.01). These findings were confirmed in a multivariable analysis. The authors estimate that centralization to HVCs may result in 333 fewer nonroutine discharges (50% reduction), 12,000 fewer hospital days (44% reduction), 165 fewer readmissions (43%), and a cost savings of $15.3 million (11% reduction). Readmission rates for patients after EC-IC bypass are comparable with those after other common cranial procedures and are primarily driven by preexisting comorbidities, socioeconomic status, and treatment at low-volume centers. Periprocedural complications, including stroke, graft failure, and wound complications, occurred at the expected rates, consistent with those in prior clinical series. The centralization of care may significantly reduce perioperative complications, readmissions, and hospital resource utilization.

Using swarm intelligence optimization methods for transport functions of vascular bypasses: first results and perspectives

In this paper, we consider the problem of the optimal location of the bypass graft. An electrical analogue of the cerebral vascular hemodynamic model was built, which was solved numerically using swarm intelligence methods. The optimization objective was the pressure after shunt formation in relation to the set pressure before shunting. This method was first time applied to the cerebral bypass problem, the results are in good agreement with the data of real operations.

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

BackgroundPatients 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. MethodsThis 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. ResultsGraft 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. ConclusionsBoth dobutamine and phenylephrine increased graft flow during cerebral bypass surgery, without a preference for one method over the other. Clinical trial registrationNetherlands Trial Register, NL7077 (https://www.trialregister.nl/trial/7077).

Surgical Strategies for Cerebral Revascularization in Patients with Limited Bypass Conduit Options and Unexpected Intraoperative Difficulties

Cerebral bypass procedures are complex and require substantial experience and skills and thorough preoperative planning. Cerebrovascular surgeons face increasingly complex bypass cases because most routine cases are managed by endovascular means, and because increasing numbers of patients have complex medical problems that affect available and suitable bypass conduit options. We report the cases of several patients undergoing cerebral bypass with limited bypass conduit alternatives, in whom there were unexpected intraoperative difficulties requiring complex solutions. The neurological surgery department database was reviewed to identify patients who had undergone cerebral bypass procedures during a 13-year period in whom there were limited available bypass conduits, and in whom unexpected intraoperative difficulties were encountered during cerebral bypass. Patient outcomes and graft patency were evaluated for 13 patients including 6 with ischemia, 3 with giant aneurysms, 2 with mycotic aneurysms, 1 with dissecting aneurysm, and 1 with gunshot-induced pseudoaneurysm. Median duration of follow-up was 43 months. In 12 of 13 patients, bypass graft/grafts were patent on the last computed tomography angiogram. In 1 patient, a prophylactic bypass procedure, the graft was not filling, probably because of lack of demand. Two patients died during follow-up of unrelated causes. Cerebrovascular surgeons should be versatile in dealing with patients with complex bypass. When there are limited available conduit options, we find that collaboration with other surgical specialties (e.g., plastics and vascular) is helpful. In patients in whom extreme intraoperative difficulties are expected, thorough preoperative planning with multiple backup plans should be exercised, as described in this report.

Incision Edge “Lifting Method” in Cerebral Bypass Surgery: A Novel Optional Technique for Narrow or Thin Recipient Arteries

Cerebral bypass surgery, such as the superficial temporal artery-middle cerebral artery bypass, is one of the essential procedures for cerebral revascularization. However, very narrow or thin blood vessels will increase the risk of anastomotic problems, such as occurs in Moyamoya disease. For such vessels, we have devised a "lifting method" in the recipient arteriotomy. In the present study, we have introduced this novel optional technique and evaluated its effects. The lifting method is a procedure of lifting the incision edge of a linear incision on the recipient vessel to widen the ostium. We attempted the lifting method in 23 consecutive patients (41 arteries) and, as a historical control, compared the results with those from the conventional method in 25 consecutive patients (37 arteries) for the previous 3 years. We compared patient age, years of surgical experience, recipient vessel diameter, anastomotic events, and final patency. As a subanalysis, the same evaluations were performed separately for patients with Moyamoya disease. Furthermore, the time required for the lifting procedure was measured retrospectively. The incidence of anastomotic events with the conventional method was 13.5% overall and 19% in those with Moyamoya disease. No adverse events occurred with the lifting method (P < 0.05). No statistically significant differences were found for the other factors, including final patency between the 2 groups. The time required for the lifting procedure averaged 1 minute, 15 seconds. Use of the lifting method widens and secures the ostium in a recipient vessel and greatly facilitates operability. We have found it to be a foolproof method enabling safe and reliable anastomosis even with narrow or thin vessels.

An endovascular assisted, nonocclusive cerebral bypass: a technical feasibility study in a rabbit model.

Temporary parent vessel occlusion performed to establish a high-flow interpositional bypass carries the risk of infarcts. The authors investigated the feasibility of a novel technique to establish a high-flow bypass without temporary parent vessel occlusion in order to lower the risk of ischemic complications. In 10 New Zealand white rabbits, a carotid artery side-to-end anastomosis was performed under parent artery patency with a novel endovascular balloon device. Intraoperative angiography, postoperative neurological assessments, and postoperative MRI/MRA were performed to evaluate the feasibility and safety of the novel technique. A patent anastomosis was established in 10 of 10 animals; 3 procedure-related complications occurred. No postoperative focal neurological deficits were observed. The MRI/MRA findings include no infarcts and bypass patency in 50% of the animals. The authors demonstrated the feasibility of an endovascular assisted, nonocclusive high-flow bypass. Future refinement of the device and technique in an animal model is necessary to lower the complication rate and increase patency rates.

Effectiveness of cerebral bypass revascularisation procedures in adult cerebrovascular ischaemic stroke: Looking beyond COSS – A single surgeon's experience of 7 years

Context: Adults with haemodynamic stroke secondary to cerebrovascular ischaemic events, continue to develop stroke despite optimum medical management. Aims: This study aims to identify patients with adult ischaemic stroke presenting with significant haemodynamic failure based on radiological and molecular imaging and perform Revascularisation procedure to prevent further stroke. Settings and Design: This is a retrospective database analysis of patients with CVOD requiring cerebral revasularisation procedure from 2013 to 2019. Materials and Methods: Twenty-two adult patients with age ranging from 26 to 72 years presenting with recurrent transient ischaemic attacks (TIAs) were evaluated for haemodynamic insufficiency by neuroimaging and acetazolamide challenged single-photon emission computed tomography perfusion. Those with decompensated haemodynamic insufficiency underwent cerebral revascularisation with superficial temporal artery (STA) to middle cerebral artery (MCA) bypass. Results: Of the 22 patients, in 12 patients, the procedure was done electively and in remaining 10 patients as emergency ( Conclusion: Cerebral revascularisation with STA-MCA bypass in selected patients with impending haemodynamic insufficiency results in good outcome and prevents further strokes despite continuing optimum medical therapy.

Management of Recurrent Aneurysms after Endovascular Coiling: A Fujita Experience.

Introduction:Microsurgical clipping and Endovascular coiling (EC) are both effective alternatives in the management of intracranial aneurysms. EC has been shown to be associated with the risk of recurrent aneurysm (RA) growth. Considering the minimally invasive nature of this procedure, the management of intracranial aneurysms has been skewed toward EC, especially in the developed world. In this scenario, there has been an upsurge of RAs after EC. Since the optimal management of these RAs has not been defined, they pose a unique challenge to the treating surgeons.Aims and Objectives:The aim of this study is to elucidate the optimal management of RAs after EC.Materials and Methods:Medical records of all patients who underwent surgery for RAs were reviewed from the period January 2014 to March 2019. The demographic and angiographic patterns of the patients and operative techniques and complications were studied. The outcome was dichotomized into good and bad depending on the Glasgow outcome scale (GOS).Results:There were four cases of RAs operated in our institution between the above-mentioned period. There were varied differences between the initial coiling and time to recurrences. All four patients were operated under neuromonitoring. Three underwent clipping and one patient underwent clipping with bypass. All four patients had good outcome with a GOS of 5/5.Conclusion:Operations for RAs constitute many technical challenges and require a lot of expertise. Such surgeries are recommended in high-volume centers, with sufficient experience in both clipping and cerebral bypass.

Pregnancy after direct cerebral bypass for moyamoya disease.

Moyamoya disease (MMD) disproportionately affects young to middle-aged women. The main treatment for this challenging disease is cerebral bypass surgery. Vascular neurosurgeons often need to counsel women regarding pregnancy following bypass for MMD, but there is a paucity of data. The authors set out to examine neurological and obstetric outcomes in an extensive cohort of MMD patients who had pregnancies following cerebral revascularization at the Stanford Medical Center. The authors identified all patients at their institution who underwent cerebral bypass for MMD from 1990 through 2018 and who later became pregnant. Some of these patients also had pregnancies prior to undergoing bypass surgery, and the authors examined these pregnancies as well. They performed a chart review and brief telephone survey to identify obstetric complications, transient ischemic attacks (TIAs), and strokes. Neurological and obstetric outcomes were compared to published rates. They also compared pre- and post-bypass pregnancy complication rates using logistic regression techniques. There were 71 pregnancies among 56 women whose mean age was 30.5 years. Among 59 post-bypass pregnancies, there were 5 (8%) perinatal TIAs. There were no MRI-confirmed strokes or strokes with residual deficits. Among 12 pre-bypass pregnancies, there were 3 (25%) TIAs and 2 (17%) MRI-confirmed strokes. There were no hemorrhagic complications in either group. In the generalized estimating equations analysis, performing cerebral revascularization prior to pregnancy versus after pregnancy was associated with lower odds of perinatal stroke or TIA (OR 0.15, p = 0.0061). Nine pregnancies (13%) were complicated by preeclampsia, and there was one (1%) instance of eclampsia. The overall rate of cesarean delivery was 39%. There were 2 miscarriages, both occurring in the first trimester. There were no maternal deaths. The authors present neurological and obstetric outcomes data in a large cohort of MMD patients. These data indicate that post-bypass pregnancy is accompanied by low complication rates. There were no ischemic or hemorrhagic strokes among post-bypass pregnant MMD patients. The rate of obstetric complications was low overall. The authors recommend close collaboration between the vascular neurosurgeon and the obstetrician regarding medical management, including blood pressure goals and continuation of low-dose aspirin.

Towards the numerical assessment in solving the problem of the effectiveness of vascular anastomosis in neurosurgical operations

In this study we considered the effect of formation of cerebral bypass for the real clinical case. Three configurations of vessels of the circle of Willis for the real patient was constructed in the pre-operative, post-operative and the alternative (virtual--without bypass formation) treatment cases. All calculations were carried out in the commercial software ANSYS CFX 17.2. It is shown that after installation of the bypass the stagnation zone in patient`s vessel was formed with the consequent thrombus formation that required an urgent re-operation. The changes of hemodynamic parameters (blood flow velocity, WSS and viscous dissipation energy values) before and after operation as well as after alternative treatment were analysed. For the first time, a quantitative difference in hemodynamic characteristics between cases of the real and virtual (alternative) methods of the operation was shown.

Tratamiento neuroquirúrgico de la isquemia cerebral

Introducción: El manejo actual de la isquemia cerebral aguda (IA) contempla el uso de r-tPA y terapia endovascular, mientras que en la isquemia cerebral crónica (IC) la mejor terapia aún no está definida. La revascularización cerebral microquirúrgica ha sido descrita como tratamiento alternativo para pacientes con IA y contraindicación para r-tPA o terapia endovascular, así como para pacientes con IC en quienes la terapia médica ha fracasado. Objetivo: Comunicar la experiencia inicial en cirugía de revascularización cerebral, con énfasis en la utilidad de la embolectomía microquirúrgica y del bypass cerebral como terapia de rescate en IA, así como del bypass cerebral en IC. Pacientes y Método: Serie prospectiva de 5 pacientes con isquemia cerebral tratados con cirugía de revascularización cerebral en el período 2013 a 2016. Se describe la técnica y resultados quirúrgicos, así como el estado funcional a los 3, 6 y 12 meses de seguimiento según modified Rankin Scale (mRS). Resultados: Se realizó embolectomía microquirúrgica de emergencia por IA en 3 pacientes con oclusión embólica de arteria cerebral media, bypass extra-intracraneal (EC-IC) en 1 paciente con IA secundaria a oclusión de arteria carótida interna por disección arterial y bypass cerebral combinado directo e indirecto en 1 paciente con IC secundaria a vasculopatía estenótica progresiva moyamoya-like. En los pacientes en quienes se efectuó embolectomía, se obtuvo recanalización completa en 2casos y parcial en 1 caso. En los 3 pacientes el estado funcional a 3 meses fue mRS = 3 (discapacidad moderada), mientras que a 12 meses de seguimiento en 2 casos hubo mejoría a mRS = 2 (discapacidad leve). En el paciente sometido a bypass EC-IC por IA, el estado funcional a 3, 6 y 12 meses fue mRS = 2, mRS = 1 y mRS = 0 (asintomático), respectivamente. En el paciente tratado con bypass combinado por IC, se obtuvo mejoría funcional a los 3 y 6 meses de seguimiento (mRS = 3 y mRS = 2, respectivamente), con respecto a su estado preoperatorio (mRS = 5; discapacidad severa). Conclusiones: La embolectomía microquirúrgica y el bypass cerebral son opciones terapéuticas efectivas en pacientes seleccionados con IA e IC.

Study on the relationship between post-circulatory lesions and cerebral infarction in children with ischemic moyamoya disease

Objective To explore the relationship between post-circulatory lesions and cerebral infarction in children with ischemic moyamoya disease (MMD). Methods A total of 44 children with ischemic MMD who were admitted to Department of Neurosurgery, Tianjin Medical University General Hospital from January 2010 to December 2018 were retrospectively enrolled into this study. All of them were divided into cerebral infarction group (15 cases) and non-cerebral infarction group (29 cases) according to whether they had cerebral infarction or not. Three cases were treated with encephalo-myosynangiosis (EMS), 5 cases with superficial temporal artery-middle cerebral artery anastomosis bypass (STA-MCA bypass) and 36 cases with EMS+ STA-MCA. All children were followed up by outpatient visits or telephone and were asked about the improvement of clinical symptoms and whether there were any cerebral infarction events. The outcome was assessed by the modified Rankin scale score (mRS). The clinical efficacy was compared between the 2 groups of children. The clinical factors affecting the children with cerebral infarction were further analyzed by single factor and multiple factor logistic regression. Results All 44 patients underwent successful operation. Postoperative complications occurred in 12 cases (27.3%, 12/44). There was no statistically significant difference in the incidence of complications between 2 groups [40.0% (6/15) vs. 28.7% (6/29), P=0.615]. The follow-up duration of 44 cases was 7.2±1.5 months (6-12 months). During the follow-up period, none of the children had cerebral infarction. Among the 44 cases, 35 (79.5%) had good outcomes and 9 (20.5%) had poor outcomes. There was no statistically significant difference in the favorable prognosis rate between the 2 groups [66.7% (10/15) vs. 86.3% (25/29), P=0.130]. Single factor analysis showed that MCA stenosis, PCA (posterior cerebral artery) stenosis and transient ischemic attack before operation were the influencing factors of cerebral infarction in children (all P < 0.05). Further multiple factor analysis showed that PCA stenosis was an independent risk factor for cerebral infarction in children (OR=5.465, 95% CI: 1.224-24.400, P=0.026). Conclusion In children with ischemic MMD, PCA stenosis is an independent risk factors for cerebral infarction, and whether there is cerebral infarction has no significant effect on the prognosis of those children. Key words: Moyamoya disease; Child; Factor analysis, statistical; Post-circulatory lesions; Cerebral infarction

Pregnancy After Cerebral Bypass for Moyamoya Disease

Abstract INTRODUCTION Moyamoya disease (MMD) disproportionately affects young to middle age women. Vascular neurosurgeons are often needed to counsel women regarding pregnancy following bypass for MMD, but there is a paucity of data. We set out to examine neurological and obstetric outcomes in an extensive cohort of MMD patients who had pregnancies following cerebral revascularization at the Stanford Medical Center. METHODS We identified all patients who underwent cerebral bypass for MMD and later became pregnant from 1990 through 2018. Some of these patients also had pregnancies prior to bypass, and we examined these pregnancies as well. We performed a chart review and a brief telephone survey to identify obstetric complications, transient ischemic attack (TIA), and stroke. Neurological and obstetric outcomes were compared to published rates. We also compared pre- and postbypass pregnancy complication rates using logistic regression techniques. RESULTS There were 71 pregnancies among 56 women with mean age 30.5. Among 59 postbypass pregnancies, there were 5 (8%) perinatal TIAs. There were no magnetic resonance imaging (MRI) confirmed strokes or strokes with residual deficits. Among 12 prebypass pregnancies, there were 3 (25%) TIAs and 2 (17%) MRI-confirmed strokes. There were no hemorrhagic complications in either group. In the multivariable logistic regression analysis, performing cerebral revascularization prior to pregnancy versus postpregnancy was associated with lower odds of perinatal stroke or TIA (OR 0.13, P = .007). The overall rate of cesarean delivery was 39%. CONCLUSION We present neurological and obstetric outcomes in a large cohort of MMD patients. These data indicate that postbypass pregnancy is accompanied by low complication rates. There were no ischemic or hemorrhagic strokes among postbypass, pregnant MMD patients. Obstetric complications were low overall. We recommend a close collaboration between the vascular neurosurgeon and the obstetrician regarding medical management, including blood pressure goals and continuation of aspirin.

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.

Technical Aspects and Operative Nuances Using a High-Definition 3-Dimensional Exoscope for Cerebral Bypass Surgery.

Cerebral bypass operation is a technically challenging operation that requires excellent surgical visibility and efficient ergonomics to minimize complications and maximize successful revascularization. Despite the operative microscope's utilization for the past two generations, there remains a need for continued improvement in operative visualization and surgical ergonomics. To report the positives and negatives of our initial experience using a novel 4 K high-definition (4K-HD) 3-dimensional (3D) exoscope (EX) for cranial bypass surgery. A retrospective review over 6 mo was performed of all patients who have undergone cerebral bypass surgery at a single institution using the 4K-HD 3D EX. Advantages and disadvantages of the EX and clinical outcome of the patients were assessed. A total of 5 patients underwent cerebral EC-IC bypass surgery with no EX-related complications and successful revascularization. The lightweight design of the EX allowed for easy instrument maneuverability as well as uncomplicated surgical set up in the operating room. The assistance of the cosurgeon was significantly more efficient compared to that of the operating microscope. The large monitor allowed for an immersive, collaborative, and valuable educational surgical experience. Using the EX for cerebral bypass surgery, with 3D ultra-high-definition optics, enhancements of ergonomics, and improved training, we believe that the 3D 4K-HD EX may represent the next generation of operative scopes in microneurosurgery.

Assessment of ischemic risk following intracranial-to-intracranial and extracranial-to-intracranial bypass for complex aneurysms using intraoperative Indocyanine Green-based flow analysis

Cerebral bypass is often needed for complex aneurysms requiring vessel sacrifice, yet intraoperative predictors of ischemic risk in bypass-dependent territories are limited. Indocyanine Green (ICG)-based flow analyses (ICG-BFAs; Flow 800, Carl Zeiss, Oberkochen, Germany) semi-quantitatively assess cortical perfusion, and in this work we determine the efficacy of ICG-BFA for assessing post-operative ischemic risk during cerebral bypass surgery for complex aneurysms. Retrospective clinical and pre/post-bypass intra-operative ICG-BFA data (delay and blood flow index [BFI]) on ten patients undergoing cerebral bypass for complex cerebral aneurysms requiring vessel sacrifice were collected from a single-institution prospective database and analyzed via non-parametric testing and logistic regression. Mean age was 55.9 ± 14.8 years. Pre/post-bypass delay (median 35.6 [5.1–51.3] vs. 26.0 [17.1–59.9]; p = 0.2) and BFI (median 56.1 [8.1–120.4] vs. 32.2 [3.0–147.4]; p = 0.2) did not significantly differ. Two patients (20%) developed post-operative ischemia in bypass dependent territories. Delay ratio did not differ between patients with and without post-operative ischemia (median 1.15 [0.67–1.64] vs. 0.83 [0.36–3.56]; p = 0.6), nor predict stroke risk (odds ratio = 1.1, p = 0.9). Conversely, BFI ratio was significantly lower for patients experiencing post-operative ischemia than those without ischemia (median 0.11 [0.06–0.17] vs. 0.99 [0.28–1.42]; p = 0.03). A BFI ratio <0.21 predicted the occurrence of post-operative ischemia (odds ratio = 0.02, p = 0.05). These data suggest that intraoperative ICG-BFA may help assess post-operative ischemic risk during cerebral bypass surgery for complex aneurysms requiring vessel sacrifice.

Radial Artery Fascial Flow-Through Free Flap for Complex Cerebral Revascularization: Technical Notes and Long-Term Neurologic and Radiographic Outcomes.

Surgical innovation is critical for the management of challenging cerebrovascular pathology. Flow-through free flaps are versatile composite grafts that combine viable tissue with a revascularization source. Neurosurgical experience with these flaps is limited. To provide an in-depth technical description of the radial artery fascial (and fasciocutaneous) flow-through free flap (RAFF and RAFCF, respectively) for complex cerebral revascularizations. An Institutional Review Board-approved, prospective database was retrospectively reviewed to identify patients that underwent extracranial-to-intracranial cerebral bypass with a RAFF or RAFCF. Patient demographics, underlying pathology, surgical treatment, complications, and outcomes were recorded. A total of 4 patients were treated with RAFFs or RAFCFs (average age 40 ± 8.8 yr). Two patients with progressive moyamoya disease involving multiple vascular territories with predominantly anterior cerebral artery (ACA) symptoms and flow alterations underwent combined direct ACA and indirect middle cerebral artery (MCA) bypass with a RAFF. The third patient with moyamoya disease and concomitant proximal fusiform aneurysms requiring internal carotid artery sacrifice underwent dual direct ACA and MCA bypass and indirect MCA revascularization with posterior tibial artery and RAFF grafts. The fourth patient with a large MCA bifurcation aneurysm and recurrent wound complications underwent a direct MCA bypass and complex wound reconstruction using a RAFCF. Good neurologic outcomes (Glasgow Outcomes Scale score ≥4 at discharge) were achieved in all patients. There were no perioperative surgical complications, and graft patency was confirmed on long-term follow-up. The RAFF and RAFCF are versatile grafts for complex cerebral revascularizations.

Extracranial-to-Intracranial Bypass for Refractory Vertebrobasilar Insufficiency

Vertebrobasilar insufficiency (VBI) is associated with high rates of morbidity and mortality, especially after failure of first-line medical and/or endovascular therapies. Although the optimal therapeutic strategy for refractory VBI remains unclear, surgical bypass represents a potentially life-saving treatment in this patient subset. A multi-institution retrospective database review was performed to identify patients with symptomatic refractory VBI over a 4-year period (July 2014 to July 2018). Surgical treatments, as well as clinical and neurologic outcomes were recorded. Five patients were identified with refractory VBI (average age 55 ± 11.0 years). All 5 patients had clinically significant posterior circulation strokes on presentation. Three patients underwent superficial temporal artery-to-superior cerebellar artery bypass based on significant acute perfusion mismatches or progressive strokes despite maximal medical therapy; 1 surgical patient (33%) experienced punctate perioperative strokes and there were no significant bypass related complications. Functional outcomes in the 3 surgical patients were correlated with preoperative stroke burden. The remaining 2 patients experienced rapid neurologic declines after presentation that precluded bypass, and died shortly thereafter. Refractory VBI has high morbidity, with cerebral bypass representing a safe and potentially efficacious treatment for selected patients. Long-term post-bypass outcomes are dependent on the level of irreversible preoperative neurologic injuries.

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.