Revascularization and aneurysm surgery: current techniques, indications, and outcome

Microsurgery Treatment as an Optimal Management of Posterior Cerebral Artery Aneurysms: A Systematic Review and Meta-Analysis

The choice of treatment of two modalities, open surgical or endovascular, in posterior cerebral artery (PCA) intracranial aneurysms must be taken based on their special characteristics. The objective of this study is to assess the potential superiority in outcomes, operative mortality, and clinical improvement after microsurgical and endovascular management repair in PCA intracranial aneurysms. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), we created this study, performing a systematic investigation on the PubMed database, with the last search carried out on June 12, 2016. The eligibility limitations were that only full text was used in the English language, and double-checking was applied. Extracted data was organized on a standard table form, including first author, publication year, general number of patients and patients at follow-up, mortality rate (with 30 days from the selecting treatment), improvement (showing postoperatively at the clinical progress (muscle strength, thinking ability, and disorientation, due to ischemic infarctions following parent vessel occlusion) for the patients of both modalities. There were eight articles that matched our study criteria. The total study population included 8,863 patients with an aneurysm, 184 (2.07%) of which had an aneurysm at the different segments of the PCA. The pooled results revealed no statistically significant difference between the two groups, in terms of mortality, but with substantial statistical results concerning clinical improvement. We concluded that the aneurysmal site and size do not influence the treatment outcome. However, clinical improvement was a statistically significant factor, demonstrating the superiority of open surgical management over endovascular treatment (EVT) for PCA aneurysms. The selection of the appropriate procedure for every case must be done based on its special characteristics.

Current Indications, Trends, and Long-Term Results of 233 Bypasses to Treat Complex Intracranial Aneurysms: A Location-Specific Analysis

BACKGROUND AND OBJECTIVES

Advances in endovascular flow diverters have led to a secular shift in the management of brain aneurysms, causing debate on current bypass indications. We therefore sought to investigate the long-term results, current indications, and trends of bypasses for brain aneurysms.

METHODS

We retrospectively reviewed bypasses performed between 2005 and 2022 to treat brain aneurysms. Demographic, clinical, and radiological data were collected till the most recent follow-up. Aneurysm occlusion and graft patency was noted on cerebral angiogram in the immediate postoperative, 3-month, and most recent follow-up periods. Clinical outcomes (modified Rankin scores) and complications were assessed at 3 month and most recent follow-up. Trends in bypass volume and graft patency were assessed in 5-year epochs. Results were dichotomized based on aneurysm location to generate location-specific results and trends.

RESULTS

Overall, 203 patients (mean age 50 years, 57% female patients) with 207 cerebral aneurysms were treated with 233 cerebral bypasses with a mean follow-up of 2 years. Fusiform morphology was the most common bypass indication. Aneurysm occlusion on immediate postoperative and final follow-up angiogram was 89% (184/207) and 96% (198/207), respectively. Graft patency rate in the immediate postoperative period and most recent follow-up was 95% (222/233) and 92% (215/233), respectively. Of 207 aneurysms, 5 (2%) recurred. Of 203 patients, 81% (165) patients had modified Rankin scores of 0-2 at the 3-month follow-up and 11 patients died (mortality 5%). Although there was a steady decrease in the bypass volume over the study period, the proportion of bypasses for recurrent aneurysms increased serially. Posterior circulation aneurysms had lower rates of aneurysm occlusion and significantly higher incidence of postoperative strokes and deaths ( P = .0035), with basilar artery aneurysms having the worst outcomes.

CONCLUSION

Bypass indications have evolved with the inception of novel flow diverters. However, they remain relevant in the cerebrovascular surgeon's armamentarium, and long-term results are excellent.

Application of surgical revascularization technique in giant aneurysm of the extracranial internal carotid artery: technical report

PURPOSE

The purpose of this study is to illustrate the diagnostic and therapeutic value and clinical significance of surgical revascularization in giant aneurysms of the extracranial internal carotid artery.

METHODS

The research team screened a group of cases of giant aneurysms of the extracranial internal carotid artery and analyzed the detailed information of the enrolled patients in terms of their basic clinical characteristics, surgical approaches and clinical prognosis.

RESULTS

All patients had a good prognosis, except for one patient who was left with only mild facial nerve palsy (grade II facial paralysis). The results demonstrate that surgical revascularization is effective and safe in the treatment of giant aneurysms of the extracranial internal carotid artery.

CONCLUSION

The significant conclusion of this study is to provide an ideal alternative treatment for the treatment of giant aneurysms of the extracranial internal carotid artery. The surgical revascularization technique is a powerful tool for vascular neurosurgeons in the management of complex cerebrovascular diseases when traditional surgical clipping or endovascular interventions encounter bottlenecks.

A Combination Technique of N-butyl-2-cyanoacrylate and Minimal Coils with Flow Control for Parent Artery Occlusion of a Giant Internal Carotid Artery Aneurysm: A Technical Note

Parent artery occlusion for large or giant internal carotid artery aneurysms remains a necessary procedure in the era of flow diverters. Endovascular parent artery occlusion is currently performed using detachable balloons or coils, which are difficult to obtain or costly. At our institution, we have devised a technique for combining n-butyl-2-cyanoacrylate and coils with flow control to solve this problem. Patients who underwent parent artery occlusion for large or giant internal carotid artery aneurysms with a follow-up period of more than 12 months were included. Imaging outcomes were evaluated for complete or incomplete aneurysmal occlusion and with or without aneurysmal shrinkage. The clinical outcome was based on changes in the modified Rankin Scale. Ten patients (ten aneurysms) were included. Their average age and average follow-up period were 68.4 years and 36 months, respectively. Complete occlusion and favorable clinical outcome were observed in all cases. The parent artery occlusion using a combination of coils and n-butyl-2-cyanoacrylate with flow control technique is effective for both imaging and clinical outcomes.

Angiographic and Clinical Outcomes of Various Techniques of Intracranial-to-Intracranial Bypass for Complex Cases with a Review of Pertinent Literature and Illustrated Cases

BACKGROUND

We sought to determine the utility of intracranial-to-intracranial bypass (IIB) surgery and the available bypass options for complex cases.

METHODS

A total of 18 IIB cases were included. Each case was classified as IIB with or without an interposition graft. The clinical and angiographic status were evaluated pre- and postoperatively and at the last follow-up. Angiographic images were analyzed and reconstructed schematically. Postoperative angiography was used to measure the bypass patency and the presence of postoperative cerebral infarction. The recipient artery occlusion time for each bypass was measured.

RESULTS

Of the 18 patients, 14 had presented with a complex intracranial aneurysm (IA), 1 with vertebrobasilar dolichoectasia, and 3 with intracranial arterial steno-occlusive disease. Ten patients had an incidentally discovered IA. Seven patients had presented with neurological deficits due to ischemia or aneurysmal mass effects. Of the 18 cases, 10 were IIBs with an interposition graft, including 4 cases of superficial temporal artery and 6 of radial artery graft bypass, and 8 were IIBs with a noninterposition graft, including 3 cases of in situ bypass, 1 case of reanastomosis, and 4 cases of reimplantation. The pre- and postoperative modified Rankin scale score did not change or improve, and all the bypasses were patent. No patient had died during the mean follow-up period of 50.0 months. The mean occlusion time of the recipient artery was 59.5 minutes. A total of 8 patients experienced postoperative cerebral infarction but all had almost recovered at discharge.

CONCLUSIONS

With proper selection of the IIB type, IIB can be a suitable treatment option for some patients with complex IAs and intracranial arterial steno-occlusive disease when extracranial-to-intracranial bypass is not feasible.

Proximal Clipping and Distal High-Flow Bypass in the Treatment of Giant/Complex Intracranial Aneurysm: An Opportunity or a Risk from a Fluid-Structural Interaction Analysis

OBJECTIVES

Conventional clipping and endovascular treatment are difficult to apply for some giant intracranial aneurysms (GIAs), and sometimes extracranial-to-intracranial (EC-IC) bypass becomes the optional choice. However, not all GIA patients can benefit from it. This study aims to recognize the underlying problems.

METHODS

We included eligible patients in our care. Then, we researched from three levels: a retrospective review of clinical data, fluid-structural analysis from two representative patient-specific models, and fluid-structural interaction analysis for idealized models to investigate the hemodynamic and biomechanical mechanisms.

RESULTS

In this article, we report nine patients with GIA who underwent EC-IC surgery. Of them, three experienced dangerous postoperative hemorrhage, and one patient died. Among these three patients, two lacked the A1 segment of the anterior cerebral artery (ACA). The numerical simulation showed that after surgery, for the patient with an unruptured aneurysm and existence of ACA, the wall deformation, wall stress, pressure, and area of the oscillatory shear index (OSI) > 0.2 were decreased by 43%, 39%, 33%, and 13%, while the patient without A1 segment having postoperative hemorrhage showed 36%, 45%, 13%, and 55% increased, respectively. Thus, we postulated a dangerous "stump phenomenon" in such conditions and further demonstrated it from idealized models with different sizes of ACA. Finally, we found a larger anastomosis angle and smaller diameter of the graft can alleviate this effect.

CONCLUSIONS

Neurosurgeon should cautiously evaluate the opportunity and risk for such patients who have aplasia of the A1 segment of ACA when making clinical decisions.

Maxillary artery utilization in subcranial-intracranial bypass procedures: a comprehensive systematic review and pooled analysis

The utilization of the internal maxillary artery (IMAX) in subcranial-intracranial bypass for revascularization in complex aneurysms, tumors, or refractory ischemia shows promise. However, robust evidence concerning its outcomes is lacking. Hence, the authors embarked on a systematic review with pooled analysis to elucidate the efficacy of this approach. We systematically searched PubMed, Embase, and Web of Science databases following PRISMA guidelines. Included articles used the IMAX as a donor vessel for revascularizing an intracranial area and reported at least one of the following outcomes: patency, complications, or clinical data. Favorable outcomes were defined as the absence of neurologic deficits or improvement in the baseline condition. Complications were considered any adverse event directly related to the procedure. Out of 418 retrieved articles, 26 were included, involving 183 patients. Among them, 119 had aneurysms, 41 experienced ischemic strokes (transient or not), 2 had arterial occlusions, and 3 had neoplasia. Furthermore, 91.8% of bypasses used radial artery grafts, and 87.9% revascularized the middle cerebral artery territory. The median average follow-up period was 12 months (0.3-53.1). The post-operation patency rate was 99% (95% CI: 97-100%; I2=0%), while the patency rate at follow-up was 82% (95% CI: 68-96%; I2=77%). Complications occurred in 21% of cases (95% CI: 9-32%; I2=58%), with no significant procedure-related mortality in 0% (95% CI: 0-2%; I2=0%). Favorable outcomes were observed in 88% of patients (95% CI: 81-96%; I2=0%), and only 3% experienced ischemia (95% CI: 0-6%; I2=0%). The subcranial-intracranial bypass with the IMAX shows excellent postoperative patency and considerable favorable clinical outcomes. While complications exist, the procedure carries a minimal risk of mortality. However, long-term patency presents heterogeneous findings, warranting additional research.

Arterial Bypass in the Treatment of Complex Middle Cerebral Artery Aneurysms: Lessons Learned from Forty Patients

OBJECTIVE

Complex middle cerebral artery (MCA) aneurysms incorporating parent or branching vessels are often not amenable to standard microsurgical clipping or endovascular embolization treatments. We aim to discuss the treatment of such aneurysms via a combination of surgical revascularization and aneurysm exclusion based on our institutional experience.

METHODS

Thirty-four patients with complex MCA aneurysms were treated with bypass and aneurysm occlusion, 5 with surgical clipping or wrapping only, and 1 with aneurysm excision and primary reanastomosis. Bypasses included superficial temporal artery (STA)-MCA, double-barrel STA-MCA, occipital artery-MCA, and external carotid artery-MCA. After bypass, aneurysms were treated by surgical clipping, Hunterian ligation, trapping, or coil embolization.

RESULTS

The average age at diagnosis was 46 years. Of the aneurysms, 67% were large and most involved the MCA bifurcation. Most bypasses performed were STA-MCA bypasses, 12 of which were double-barrel. There were 2 wound-healing complications. All but 2 of the aneurysms treated showed complete occlusion at the last follow-up. There were 3 hemorrhagic complications, 3 graft thromboses, and 4 ischemic insults. The mean follow-up was 73 months. Of patients, 83% reported stable or improved symptoms from presentation and 73% reported a functional status (Glasgow Outcome Scale score 4 or 5) at the latest available follow-up.

CONCLUSIONS

Cerebral revascularization by bypass followed by aneurysm or parent artery occlusion is an effective treatment option for complex MCA aneurysms that cannot be safely treated by standard microsurgical or endovascular techniques. Double-barrel bypass consisting of 2 STA branches to 2 MCA branches yields adequate flow replacement in most cases.

Superficial temporal artery interposition bypass for the treatment of complex intracranial aneurysms: Flexible and creative options for flow preservation bypass

PURPOSE

Flow-preservation bypass is a treatment option for complex intracranial aneurysms (IAs) that cannot be managed with microsurgical clipping or endovascular treatment. Various bypass methods are available, including interposition grafts such as the radial artery or saphenous vein. Size discrepancy, invasiveness, and procedure complexity must be considered when using interposition grafts. We describe our experience of treating complex IAs using a superficial temporal artery (STA) interposition bypass.

METHODS

We retrospectively reviewed the medical records and operative videos of all patients who were treated for complex IAs at our center from January 2009 to December 2021 using cerebral revascularization. Clinical, radiological, and surgical findings of the cases that underwent STA interposition bypass were investigated.

RESULTS

Seventy-six bypass procedures were performed of which seven (9.2%) complex IAs were managed using STA interposition bypass. Of these 5 cases were of anterior cerebral artery, 1 of middle cerebral artery, and 1 of posterior inferior cerebellar artery aneurysm. There were no postoperative ischemic complications. Revision surgery for postoperative pseudomeningocele was performed in one case. The long-term bypass patency rate was 85.7% (6 out of 7) and good long-term aneurysm control was achieved in all cases, with a mean follow-up of 64 months.

CONCLUSIONS

When treating complex IAs, creative revascularization strategies are needed in selective cases for favorable outcomes. STA interposition graft bypass which can reduce the size discrepancy between the donor and recipient may be a less invasive, flexible, and practical option for treating complex IAs.

Proximal Internal Carotid Artery Occlusion and Extracranial-Intracranial Bypass for Treatment of Fusiform and Giant Internal Carotid Artery Aneurysms

OBJECTIVE

To discuss the treatment of intracranial fusiform and giant internal carotid artery (ICA) aneurysms via revascularization based on our institutional experience.

METHODS

An institutional review board-approved retrospective analysis was performed of patients with unruptured fusiform and giant intracranial ICA aneurysms treated from November 1991 to May 2020. All patients were evaluated for extracranial-intracranial (EC-IC) bypass and ICA occlusion.

RESULTS

Thirty-eight patients were identified. Initially, patients failing preoperative balloon test occlusion were treated with superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and concurrent proximal ICA ligation. We then treated them with STA-MCA bypass, followed by staged balloon test occlusion, and, if they passed, endovascular ICA coil occlusion. We treat all surgical medically uncomplicated patients with double-barrel STA-MCA bypass and concurrent proximal ICA ligation. The mean length of follow-up was 99 months. Symptom stability or improvement was noted in 85% of patients. Bypass graft patency was 92.1%, and all surviving patients had patent bypasses at their last angiogram. Aneurysm occlusion was complete in 90.9% of patients completing proximal ICA ligation. Three patients experienced ischemic complications and 4 patients experienced hemorrhagic complications.

CONCLUSIONS

Not all fusiform intracranial ICA aneurysms require intervention, except when life-threatening rupture risk is high or symptomatic management is necessary to preserve function and quality of life. EC-IC bypass can augment the safety of proximal ICA occlusion. The rate of complete aneurysm occlusion with this treatment is 90.9%, and long-term bypass graft-related complications are rare. Perioperative stroke is a major risk, and continued evolution of treatment is required.

The surgical strategy and technical nuances of in situ side-to-side bypass for the management of complex intracranial aneurysms

Background

Despite continuous advances in microsurgical and endovascular techniques, the treatment of complex aneurysms remains challenging. Aneurysms that are dilemmatic for conventional clipping or endovascular coiling often require bypass as part of a strategy to reduce the risk of ischemic complications. In anatomically favorable sites, the intracranial-intracranial in situ bypass may be an appealing choice. This article details the surgical strategies, operative nuances, and clinical outcomes of this technique with a consecutive series in our department.

Methods

A retrospective review of a prospectively maintained neurosurgical patient database was performed to identify all patients treated with side-to-side in situ bypass from January 2016 to June 2022. In total, 12 consecutive patients, including 12 aneurysms, were identified and included in the series. The medical records, surgical videos, neuroimaging studies, and follow-up clinic notes were reviewed for every patient.

Results

Of the 12 aneurysms, there were 5 middle cerebral artery aneurysms, 4 anterior cerebral artery aneurysms, and 3 posterior inferior cerebellar artery aneurysms. The morphology of the aneurysms was fusiform in 8 patients and saccular in the remaining 4 patients. There were 3 patients presented with subarachnoid hemorrhage. The treatment modality was simple in situ bypass in 8 cases and in situ bypass combined with other modalities in 4 cases. Bypass patency was confirmed in all cases by intraoperative micro-doppler probe and (or) infrared indocyanine green (ICG) video angiography intraoperatively and with digital subtraction angiography (DSA) or computed tomography angiography (CTA) postoperatively. None of the patients developed a clinically manifested stroke due to the procedure though a callosomarginal artery was intentionally removed in one patient. The median follow-up period was 16.2 months (6-36). All patients had achieved improved or unchanged modified Rankin scale scores at the final follow-ups.

Conclusion

Cerebral revascularization technique remains an essential skill for the treatment of complex aneurysms. The in situ bypass is one of the most effective techniques to revascularize efferent territory when vital artery sacrifice or occlusion is unavoidable. The configuration of in situ bypass should be carefully tailored to each case, with consideration of variations in anatomy and pathology of the complex aneurysms.

Effect of newly developed scissors-attached micro-forceps on the recipient clamp time and occurrence of anastomotic site infarction after bypass surgery for moyamoya disease

Introduction

This study aimed to examine the effect of newly developed scissors-attached micro-forceps in superficial temporal artery-to-middle cerebral artery (STA-MCA) anastomosis for moyamoya disease (MMD).

Materials and methods

Of 179 consecutive STA-MCA anastomoses on 95 hemispheres of 71 MMD patients at the University of Fukui Hospital between 2009 and 2023, 49 anastomoses on 26 hemispheres of 21 patients were enrolled in this retrospective cohort clinical trial intraoperative indocyanine green video-angiography did not demonstrate bypass patency in three anastomoses in two patients who were excluded. Twenty-one anastomosis in 19 hemispheres of 16 patients were performed using the conventional micro-forceps (conventional group, CG), and 25 anastomoses in 22 hemispheres of 19 patients were performed using scissors-attached micro-forceps (scissors group, SG). A small infarction near the anastomotic site detected using postoperative diffusion-weighted imaging was defined as anastomotic site infarction (ASI). Factors affecting the occurrence of ASI were examined by univariate, logistic regression, and receiver operating curve (ROC) analysis.

Results

There were no significant differences in clinical parameters such as age, sex, number of sacrificed branches, number of sacrificed large branches, and number of sutures between the CG and SG. However, the clamp time and occurrence of ASI were significantly lower in the SG than in the CG. Logistic regression analysis revealed that the clamp time was the only significant factor predicting the occurrence of ASI. A receiver operating curve analysis also revealed that the clamp time significantly predicted the occurrence of ASI (area under the curve, 0.875; cutoff value, 33.2 min).

Conclusion

The newly developed scissors-attached micro-forceps could significantly reduce the clamp time and occurrence of ASI in STA-MCA anastomosis for MMD.

Endoscope-Assisted Pedicled Maxillary Artery to Middle Cerebral Artery Bypass: An Anatomic Feasibility Study

BACKGROUND

Extracranial to intracranial bypass is used to augment and/or replace the intracranial circulation for various pathologies. The superficial temporal artery is the mainstay donor for pedicled bypasses to the anterior circulation but can be limited by its variable size, low native flow rates, and potential scalp complications. Interposition grafts such as the radial artery or greater saphenous vein are alternatives but are sometimes limited by size mismatch, length needed to reach the extracranial circulation, and loss of inherent vascular elasticity. Interposition grafts between the maxillary artery (IMA) and middle cerebral artery (MCA) address these limitations.

OBJECTIVE

To explore the feasibility of harvesting the IMA through an endoscopic transnasal, transmaxillary approach to perform a direct IMA to MCA bypass.

METHODS

Combined transcranial and endoscopic endonasal dissections were performed in embalmed human cadavers to harvest the IMAs for intracranial transposition and direct anastomosis to the MCA. Donor and recipient vessel calibers were measured and recorded.

RESULTS

A total of 8 procedures were performed using the largest and distal-most branches of the IMA (the sphenopalatine branch and the descending palatine branch) as pedicled conduits to second division of middle cerebral artery (M2) recipients. The mean diameter of the IMA donors was 1.89 mm (SD ± 0.42 mm), and the mean diameter of the recipient M2 vessels was 1.90 mm (SD ± 0.46 mm).

CONCLUSION

Endoscopic harvest of the IMA using a transnasal, transmaxillary approach is a technically feasible option offering an excellent size match to the M2 divisions of the MCA and the advantages of a relatively short, pedicled donor vessel.

Clinical effect of high-flow revascularization in microsurgery combined with endoscopic endonasal surgery for skull base tumors with intracranial and extracranial involvement

Background

The objective of the study is to investigate the surgical methods and clinical effects of high-flow revascularization in microsurgery combined with endoscopic endonasal surgery for skull base tumors with intracranial and extracranial involvement.

Methods

The relationships between skull base tumors and internal carotid artery (ICA), tumor location and size, and the extent of tumor invasion were assessed. Preoperative CT perfusion (CTP), magnetic resonance (MR) perfusion-weighted imaging (PWI) (MR-PWI), and digital subtraction angiography (DSA) were performed to evaluate collateral circulation and brain tissue perfusion. Then craniotomy through the fronto-orbitozygomatic approach was performed, based on which four cases received extended middle skull base approach+Dolenc approach + Fukushima bypass type I, and six cases received extended middle skull base approach+Fukushima bypass type III. After surgery, DSA, CT angiogram (CTA), and CTP/PWI were performed to evaluate the patency of the reconstructed vessels and cerebral perfusion, and contrast-enhanced MRI to evaluate the degree of tumor resection. All patients were followed up for 6-12 months.

Results

Among the 10 cases investigated, gross total resection was achieved in 8 cases, subtotal resection in 1 case, and partial resection in 1 case, as confirmed by CT and enhanced MRI. The patency of revascularization vessels was observed using fluorescein angiography during the operation in all patients and via DSA and CTA postoperatively in nine patients. One patient underwent ventilator-assisted ventilation because of respiratory failure and failed to undergo DSA and CTA. Regarding postoperative complications, one patient developed watershed cerebral infarction on the operated side but no sequelae after drug treatment, three patients developed facial numbness, which improved after 3 months, and two patients experienced worsened diplopia. After 6 to 12 months of follow-up on the nine evaluable patients, the Glasgow Outcome Scale (GOS) was 4-5 after surgery. In addition, 6-month follow-up results showed that one patient with clival chondrosarcoma developed recurrence on contrast-enhanced MRI, while no relapse was observed in the other patients.

Conclusion

For skull base tumors with intracranial and extracranial invasion and involving the ICA, revascularization might improve the total resection rate and reduce the recurrence rate and risk of intraoperative bleeding and postoperative ischemia.

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.

Bypass Surgery Management of Complex Proximal and Distal Posterior Inferior Cerebellar Artery Aneurysms

BACKGROUND

For the complex posterior inferior cerebellar artery (PICA) aneurysms, standard microsurgical or endovascular technical options were not feasible. To determine the efficacy and outcomes of bypass surgery for complex PICA aneurysms, the authors herein review our recent surgical experience for complex PICA aneurysms.

METHODS

The authors retrospectively reviewed our experience of extracranial-intracranial bypass and intracranial-intracranial bypass surgery in treatment of proximal and distal complex PICA aneurysms at our institution from 2016 to 2020.

RESULTS

Twelve patients harboring 12 complex PICA aneurysms received bypass surgery at our institution. Seven (58.3%) patients with proximal PICA aneurysms underwent extracranial-intracranial bypass. Five (41.7%) patients with distal PICA aneurysms accepted intracranial-intracranial bypass. The postoperative symptom improvement: Of the 6 patients with preoperative hypoperfusion or ischemic of the cerebellar hemisphere, the symptom resolved in 5 patients, improved in 1 patient, of 5 patients with preoperative mass effect, the symptom resolved in 5 patients. During the follow-up period, ten patients had a modified Rankin scale (mRS) score of 0 to 1, and 1 patient had an mRS score of 2. One patient had an mRS score of 3. The long-term graft patency rate was 91.7%. All patients had no recurrence of intracranial aneurysm.

CONCLUSIONS

Base on the complexity of anatomy structure and the vascular architecture, an individualized strategy was proposed for each patient. The use of different types of bypass procedures (occipital artery-PICA end-to-end bypass, PICA-PICA end-to-end anastomosis, and/or occipital artery graft) can safely and effectively manage these complex PICA aneurysms.

Extra-intracranial bypass surgery using the orifice of maxillary artery in a patient with middle cerebral artery aneurysm. Case report and literature review

OBJECTIVE

To present the technique of extra-intracranial bypass surgery using the orifice of maxillary artery bypass, to evaluate the advantages and disadvantages of this and alternative revascularization options.

MATERIAL AND METHODS

Radial artery graft harvesting was performed at the 1st stage. Simultaneously, the second team of surgeons performed a combined (submandibular and anterior) access to the donor artery (mandibular segment of maxillary artery behind the ramus of the mandible). Craniotomy and mobilization of potential recipient arteries (M2-M3 segments of the middle cerebral artery) were performed at the 2nd stage. Distal anastomosis in end-to-side fashion was formed with M3 segment of the middle cerebral artery. At the 3rd stage, radial artery was passed through a subcutaneous tunnel in zygomatic region. The orifice of maxillary artery was resected together with distal external carotid artery (ECA) and orifice of superficial temporal artery. After transposition of ECA and orifice of maxillary artery, proximal end-to-end anastomosis was performed with radial artery. After that, the main surgical stage was performed, i.e. exclusion of M3 segment of the middle cerebral artery together with aneurysm.

RESULTS

Harvesting of mandibular segment of the maxillary artery as a donor vessel reduces the length of bypass graft to 12-14 cm since this branch is localized close to the skull base. You can also form optimal proximal end-to-end anastomosis for intracranial redirecting blood flow maxillary artery.

CONCLUSION

The described method makes it possible to form anastomosis with a short bypass graft and reduce the risk of thrombosis. This procedure is effective for cerebral bypass in patients with skull base tumors, complex aneurysms, and occlusive-stenotic lesions of carotid arteries.

Validation of the Clavien-Dindo grading system of complications for microsurgical treatment of unruptured intracranial aneurysms

OBJECTIVE

Microsurgery plays an essential role in managing unruptured intracranial aneurysms (UIAs). The Clavien-Dindo classification is a therapy-oriented grading system that rates any deviation from the normal postoperative course in five grades. In this study, the authors aimed to test the applicability of the Clavien-Dindo grade (CDG) in patients who underwent microsurgical treatment of UIAs.

METHODS

The records of patients who underwent microsurgery for UIAs (January 2013-November 2018) were retrieved from a prospective database. Complications at discharge and at short-term follow-up (3 months) were rated according to the Clavien-Dindo system. Patient outcomes were graded using the modified Rankin Scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS). A descriptive statistic was used for data analysis.

RESULTS

Overall, 156 patients underwent 157 surgeries for 201 UIAs (size range 4-42 mm). Thirty-nine patients (25%) had complex UIAs. An adverse event (CDG ≥ I) occurred in 21 patients (13.5%) by the time of discharge. Among these, 10 patients (6.4%) presented with a new neurological deficit. Significant correlations existed between a CDG ≥ I and an increase in mRS and NIHSS scores (p < 0.001). Patients treated for complex aneurysms had a significantly higher risk of developing new neurological deficits (20.5% vs 1.7%, p = 0.007). At the 3-month follow-up, a CDG ≥ I was registered in 16 patients (10.3%); none presented with a new neurological deficit. A CDG ≥ I was associated with a longer hospital length of stay (LOS) (no complication vs CDG ≥ I, 6.2 ± 3.5 days vs 9.3 ± 7.7 days, p = 0.02).

CONCLUSIONS

The CDG was applicable to patients who received microsurgery of UIAs. A significant correlation existed between CDG and outcome scales, as well as LOS. The aneurysm complexity was significantly associated with a higher risk for new neurological deficit.

Prediction of atherosclerotic changes in cavernous carotid aneurysms based on computational fluid dynamics analysis: a proof-of-concept study

PURPOSE

Recent computational fluid dynamics (CFD) studies have demonstrated the concurrence of atherosclerotic changes in regions exposed to prolonged blood residence. In this proof-of-concept study, we investigated a small but homogeneous cohort of large, cavernous carotid aneurysms (CCAs) to establish the clinical feasibility of CFD analysis in treatment planning, based on the association between pathophysiology and hemodynamics.

METHODS

This study included 15 patients with individual large CCAs. We identified calcifications, which indicated atherosclerotic changes, using the masking data of digital subtraction angiography. We conducted a CFD simulation under patient-specific inlet flow rates measured using magnetic resonance (MR) velocimetry. In the post-CFD analysis, we calculated the blood residence time ([Formula: see text]) and segmented the surface exposed to blood residence time over 1 s ([Formula: see text]). We measured the decrease in volume after flow diversion using the original time-of-flight MR angiography data.

RESULTS

Calcifications were observed in the region with [Formula: see text]. In addition, the ratio of [Formula: see text] to the surface of the aneurysmal domain exhibited a negative relationship with the rate of volume reduction at the 6- and 12-month follow-ups. Post-CFD visualization demonstrated that intra-aneurysmal swirling flow prolonged blood residence time under the condition of a small inlet flow rate, when compared to the aneurysmal volume.

CONCLUSION

The results of this study suggest the usefulness of CFD analysis for the diagnosis of atherosclerotic changes in large CCAs that may affect the therapeutic response after flow diversion.

Safety and effectiveness of high flow extracranial to intracranial saphenous vein bypass grafting in the treatment of complex intracranial aneurysms: a single-centre long-term retrospective study

Background

To summarize the safety and effectiveness of high flow extracranial to intracranial saphenous vein bypass grafting in the treatment of complex intracranial aneurysms.

Methods

The data of complex intracranial aneurysms patients for high flow extracranial to intracranial saphenous vein bypass grafting from January 2008 to January 2020 were retrospectively collected and analyzed. Eighty-two patients (31 men and 51 women) with 89 aneurysms underwent 82 saphenous vein bypass grafts followed by immediate parent vessel occlusion. The aneurysm was located at the internal carotid artery, middle cerebral artery, and basilar artery in 75, 11, and 3 cases, respectively.

Results

The patency rate of bypass grafting was 100, 100, 96.3 and 92.4% on intraoperation, on the first postoperative day, at discharge and 6 months follow-up, respectively. At discharge and 6 months follow-up, 3 and 6 patients had graft occlusions. The main postoperative complications were transient hemiparesis and hemianopsia. 3 patients died due to bypass complications and poor physical condition.

Conclusions

High flow extracranial to intracranial saphenous vein bypass grafting is safe and effective in the treatment of complex intracranial aneurysms and the saphenous vein can meet the requirements of brain blood supply. A high rate of graft patency and adequate cerebral blood flow can be achieved.

Highlights

A single-centre long-term retrospective study was conducted to assess the safety and effectiveness of high flow EC-IC saphenous vein bypass grafting in the treatment of complex intracranial aneurysms. The data of 82 patients from January 2008 to January 2020 were retrospectively collected and analysed.

We found the patency rate of bypass grafting was 100, 100, 96.3 and 92.4% on intraoperation, on the first postoperative day, at discharge and 6 months follow-up, respectively. At discharge and 6 months follow-up, 3 and 6 patients had graft occlusions.

Finally, we conclude that high flow extracranial to intracranial saphenous vein bypass grafting is safe and effective in the treatment of complex intracranial aneurysms and the selected blood supply vessels can meet the requirements of blood supply.

As far as we know, this study is one of the maximum number of cases in the treatment of complex intracranial aneurysms with saphenous vein bypass.

When Is Diagnostic Subtraction Angiography Indicated Before Clipping of Unruptured and Ruptured Intracranial Aneurysms? An International Survey of Current Practice

INTRODUCTION

The goal of this survey is to investigate the indications for preoperative digital subtraction angiography (DSA) before clipping of ruptured and unruptured intracranial aneurysms in an international panel of neurovascular specialists.

METHODS

An anonymous survey of 23 multiple-choice questions relating to indications for DSA before clipping of an intracranial aneurysm was distributed to the international panel of attendees of the European-Japanese Cerebrovascular Congress (EJCVC), which took place in Milan, Italy on 7-9 June 2018. The survey was collected during the same conference. Descriptive statistics were used to analyze the data.

RESULTS

A total of 93 surveys were distributed, and 67 (72%) completed surveys were returned by responders from 13 different countries. Eighty-five percent of all responders were neurosurgeons. For unruptured and ruptured middle cerebral artery (MCA) aneurysms without life-threatening hematoma, approximately 60% of responders perform surgery without preoperative DSA. For aneurysms in other locations than MCA, microsurgery is done without preoperative DSA in 68% of unruptured and in 73% of ruptured cases. In cases of ruptured MCA or ruptured non-MCA aneurysms with life-threatening hematoma, surgery is performed without DSA in 97% and 96% of patients, respectively. Factors which lead to preoperative DSA being performed were: aneurysmal shape (fusiform, dissecting), etiology (infectious), size (>25 mm), possible presence of perforators or efferent vessels arising from the aneurysm, intra-aneurysmal thrombus, previous treatment, location (posterior circulation and paraclinoid aneurysm) and flow-replacement bypass contemplated for final aneurysm treatment. These are all factors that qualify an aneurysm as a complex aneurysm.

CONCLUSION

There is still a high variability in the surgeons' preoperative workup regarding the indication for DSA before clipping of ruptured and unruptured intracranial aneurysms, except for ruptured aneurysms with life-threatening hematoma. There is a general consensus among cerebrovascular specialists that any angioanatomical feature indicating a complex aneurysm should lead to a more detailed workup including preoperative DSA.

Bypass Procedure Performed in the Field of a Decompressive Craniectomy in the Case of an MCA Dissecting Aneurysm: Case Report and Review of the Literature

Treatment of complex aneurysms often requires additional surgical tools including the use of the extra-intracranial (EC-IC) bypass. The following report depicts the utilization of the EC-IC bypass in treating a dissecting aneurysm several hours after a salvage emergent evacuation of an acute subdural hematoma via decompressive craniectomy (DC). Preserving the superficial temporal artery during the DC provided a donor artery for the bypass surgery.

Complete or Partial Parent Artery Sacrifice: Effect of Vessel-Occlusion Strategies on Complete Obliteration of Complex Aneurysms

OBJECTIVE/BACKGROUND

A small number of complex intracranial aneurysms are not amenable to direct clipping strategies or endovascular treatment. In these patients, parent artery sacrifice and bypass revascularization for aneurysm occlusion is an option. There are 3 strategies for parent artery sacrifice: trapping, complete occlusion of the inflow, and outflow segment; proximal occlusion of the inflow vessel; and distal occlusion of the outflow vessel(s). This study aimed to compare these techniques with regard to aneurysm occlusion rates.

METHODS

We reviewed our database for cerebral revascularization before parent artery sacrifice to treat cerebral aneurysms. We assessed aneurysm occlusion rates 3 and 12 months after surgery, outcome, and postoperative aneurysm rupture.

RESULTS

In total, 121 patients underwent parent artery sacrifice for complex aneurysms; 30% of the parent arteries were trapped, 58% proximally, and 12% distally occluded. Postoperative digital subtraction angiography revealed an aneurysm occlusion rate of 100% after trapping. Proximal occlusion led to early complete aneurysm occlusion in 71% of the cases, 21% occluded during follow-up. The complete occlusion rate was 96%, distal occlusion had an early aneurysm occlusion rate of 40%, 40% occluded during follow-up. Complete aneurysm occlusion rate was only 80%. All 3 techniques resulted in a volume reduction of more than 60% without a significant difference between the groups. The annual aneurysm rupture rate after distal parent artery sacrifice was 15%; there was no rupture after trapping or proximal parent artery sacrifice.

CONCLUSIONS

Trapping and proximal parent artery sacrifice seem to be superior to distal parent artery sacrifice regarding occlusion and rupture rates.

Development of machine learning-based preoperative predictive analytics for unruptured intracranial aneurysm surgery: a pilot study

BACKGROUND

The decision to treat unruptured intracranial aneurysms (UIAs) or not is complex and requires balancing of risk factors and scores. Machine learning (ML) algorithms have previously been effective at generating highly accurate and comprehensive individualized preoperative predictive analytics in transsphenoidal pituitary and open tumor surgery. In this pilot study, we evaluate whether ML-based prediction of clinical endpoints is feasible for microsurgical management of UIAs.

METHODS

Based on data from a prospective registry, we developed and internally validated ML models to predict neurological outcome at discharge, as well as presence of new neurological deficits and any complication at discharge. Favorable neurological outcome was defined as modified Rankin scale (mRS) 0 to 2. According to the Clavien-Dindo grading (CDG), every adverse event during the post-operative course (surgery and not surgery related) is recorded as a complication. Input variables included age; gender; aneurysm complexity, diameter, location, number, and prior treatment; prior subarachnoid hemorrhage (SAH); presence of anticoagulation, antiplatelet therapy, and hypertension; microsurgical technique and approach; and various unruptured aneurysm scoring systems (PHASES, ELAPSS, UIATS).

RESULTS

We included 156 patients (26.3% male; mean [SD] age, 51.7 [11.0] years) with UIAs: 37 (24%) of them were treated for multiple aneurysm and 39 (25%) were treated for a complex aneurysm. Poor neurological outcome (mRS ≥ 3) was seen in 12 patients (7.7%) at discharge. New neurological deficits were seen in 10 (6.4%), and any kind of complication occurred in 20 (12.8%) patients. In the internal validation cohort, area under the curve (AUC) and accuracy values of 0.63-0.77 and 0.78-0.91 were observed, respectively.

CONCLUSIONS

Application of ML enables prediction of early clinical endpoints after microsurgery for UIAs. Our pilot study lays the groundwork for development of an externally validated multicenter clinical prediction model.

A3-A3 Anastomosis in the Management of Complex Anterior Cerebral Artery Aneurysms: Experience With in Situ Bypass and Lessons Learned From Pseudoaneurysm Cases

BACKGROUND

A3-A3 side-to-side bypass is an intracranial-to-intracranial (IC-IC) revascularization option when aneurysm treatment involves occlusion of one anterior cerebral artery (ACA).

OBJECTIVE

To describe applications of A3-A3 side-to-side bypass in the management of ACA true and pseudoaneurysms along with a review of pertinent literature.

METHODS

Six consecutive patients undergoing an A3-A3 bypass as part of their aneurysm management, representing a single-surgeon experience in a 2-yr period, were included in this retrospective review of a prospectively collected database.

RESULTS

Three male and three female patients with a median (range) age of 41.5 (11-69) years representing four ruptured and two unruptured aneurysms were included. Two of the aneurysms were communicating while four were postcommunicating from which three were pseudoaneurysms. Complete aneurysm obliteration was achieved in 5/6 cases. Bypass patency was evaluated in all cases intra- and postoperatively. Good outcomes (modified Rankin Scale score ≤ 2) at follow-up were observed in 4/6 patients. An improvement in mRS scores at the most recent follow-up as compared to preoperative status was achieved in three while scores remained the same in two patients. Ischemic complications related to aneurysm treatment were observed in two patients, both of which achieved good functional recovery upon follow-up. One patient deceased postoperatively due to progression of vasospasm-related infarcts.

CONCLUSION

A3-A3 bypass in the management of true as well as pseudoaneurysms of the ACA can achieve good postoperative outcomes in selected patients. Prompt diagnosis and aggressive surgical treatment needs to be pursued if a vessel injury with pseudoaneurysm formation is suspected.

Pterygo-Maxillary Fissure as a Landmark for Localization of Internal Maxillary Artery for Use in Extracranial-Intracranial Bypass

BACKGROUND

Internal maxillary artery (IMax) is a relatively new donor vessel used in the extracranial-intracranial bypass surgery. However, unfamiliarity and relatively elaborate techniques of its harvest precluded its widespread use.

OBJECTIVE

To present a simplified technique of IMax harvest based on constant anatomical landmarks without the need of extensive skull-base drilling while providing adequate space for proximal anastomosis.

METHODS

Cadaveric dissection on 4 cadaveric heads (8 sides) was performed. Zygomatic osteotomy was performed and temporal muscle was dissected off the zygomatic process of the frontal bone and the frontal process of the zygomatic bone and reflected inferiorly into the bony gap created by the zygomatic osteotomy. Posterior wall of the maxilla (PWoM) was palpated. Following PWoM inferiorly leads to pterygo-maxillary fissure (PMF), which is a constant landmark IMax passes through.

RESULTS

IMax was localized following this technique before its entrance into PMF in every specimen. Proximal dissection was carried on to the exposed adequate length of the vessel. Depending on the relationship with the lateral pterygoid muscle, this might need to be incised to allow for identification of the IMax. After its transection, proximal stump is mobilized superiorly into the surgical field. Clinical application of this technique was demonstrated on an aneurysm case.

CONCLUSION

Using the palpation of the PWoM as a landmark for localization of PMF facilitates harvesting of IMax without need for extensive skull-base drilling and shortens the time of the surgery.

Surgical Management of Giant Intracranial Aneurysms: Overall Results of a Large Series

OBJECTIVE

To review and discuss surgical treatment options for giant intracranial aneurysms (GIAs), focusing on indications, technical aspects, and results, along with some illustrative cases.

METHODS

We reviewed the data of 82 consecutive patients surgically managed between January 2000 and December 2019 for treatment of a GIA.

RESULTS

Male sex and hemorrhage at presentation were prevalent. The average follow-up was 81.2 ± 45 months. The anterior circulation was involved in 76.8% of GIAs. If the GIA showed a clear neck, minimal atherosclerosis, or intrasaccular thrombosis, and ≤2 branches arising from the neck, it was reconstructed. This procedure was possible in 78% of cases. The technique also involved temporary clipping, remodeling, and thrombectomy, as well as fragmentation techniques. Angioarchitectural features other than these techniques underwent bypass and aneurysm trapping. Most bypasses were extracranial to intracranial and high flow. Flow capacity, collateral circulation, and availability of the donor vessel mainly affected the choice of the type of bypass. Overall, successful exclusion of the GIA was 91.4%. The need for retreatment and complication rate were 3.6% and 19.5%, respectively. A good overall outcome (modified Rankin Scale score 0-3) was achieved in 84.2% of patients, and mortality was 10%.

CONCLUSIONS

Microneurosurgical techniques still maintain a significant role for most GIAs, with a high durability and acceptable rate of morbidity and mortality. Clip reconstruction is the first-line surgical treatment option, whereas bypass is indicated in cases of planned or unplanned sacrifice of the parent artery to prevent long-term ischemic complications.

Flow Diversion for the Treatment of Petrous Internal Carotid Artery Aneurysms

Petrous internal carotid artery (ICA) aneurysms are rare and pose a unique management dilemma. They are most commonly fusiform. They are difficult to treat surgically and typically not amenable to selective aneurysmal obliteration. The advent of flow diverters, such as the Pipeline endovascular device, has offered a new approach to these historically challenging lesions. The unique utility of flow diversion in treatment of petrous ICA aneurysms is reviewed and discussed.

Cerebral revascularization for the management of complex intracranial aneurysms: a single-center experience

OBJECTIVE

Because simple intracranial aneurysms (IAs) are increasingly treated endovascularly, neurovascular surgery has become focused on complex IAs that may require deconstructive aneurysm therapy with concomitant surgical bypass. The authors describe the decision-making process concerning cerebral revascularization and present outcomes that were achieved in a large case series of complex IAs managed with cerebral revascularization and parent artery occlusion.

METHODS

The authors retrospectively reviewed the medical records, including neuroimaging studies, operative reports, and follow-up clinic notes, of all patients who were treated at the National Brain Aneurysm Center between July 1997 and June 2015 using cerebral revascularization as part of the management of an IA. They recorded the location, rupture status, and size of each IA, as well as neurological outcome using the modified Rankin Scale (mRS), aneurysm and bypass status at follow-up, and morbidity and mortality.

RESULTS

The authors identified 126 patients who underwent revascularization surgery for 126 complex, atheromatous, calcified, or previously coiled aneurysms. Ninety-seven lesions (77.0%) were unruptured, and 99 (78.6%) were located in the anterior circulation. Aneurysm size was giant (≥ 25 mm) in 101 patients, large (10-24 mm) in 9, and small (≤ 9 mm) in 16 patients. Eighty-four low-flow bypasses were performed in 83 patients (65.9%). High-flow bypass was performed in 32 patients (25.4%). Eleven patients (8.7%) underwent in situ or intracranial-intracranial bypasses. Major morbidity (mRS score 4 or 5) occurred in 2 (2.4%) low-flow cases and 3 (9.1%) high-flow cases. Mortality occurred in 2 (2.4%) low-flow cases and 2 (6.1%) high-flow cases. At the 12-month follow-up, 83 (98.8%) low-flow and 30 (93.8%) high-flow bypasses were patent. Seventy-five patients (90.4%) undergoing low-flow and 28 (84.8%) high-flow bypasses had an mRS score ≤ 2. There were no statistically significant differences in patency rates or complications between low- and high-flow bypasses.

CONCLUSIONS

When treating challenging and complex IAs, incorporating revascularization strategies into the surgical repertoire may contribute to achieving favorable outcomes. In our series, low-flow bypass combined with isolated proximal or distal parent artery occlusion was associated with a low rate of ischemic complications while providing good long-term aneurysm control, potentially supporting its wider utilization in this setting. The authors suggest that consideration should be given to managing complex IAs at high-volume centers that offer a multidisciplinary team approach and the full spectrum of surgical and endovascular treatment options to optimize patient outcomes.

Serpentine aneurysm of the posterior cerebral artery treated by internal maxillary artery bypass followed by parent artery occlusion: a case report and literature review

Serpentine aneurysms of the posterior cerebral artery (PCA) treated by the internal maxillary artery (IMA) bypass are rare. Here, the authors report the case of a 34-year-old male patient who presented with a half-year history of gradual severe headache and right-sided limb monoparesis and paresthesia lasting for 1 week. Preoperative angiograms showed a serpentine aneurysm in the left distal PCA, which was treated with internal maxillary artery-radial artery-posterior cerebral artery (IMA-RA-PCA) bypass followed by parent artery occlusion (PAO). The postoperative course was uneventful; radiological images revealed that the aneurysm disappeared, and there was good graft patency and excellent perfusion of the distal PCA territories. To the authors' knowledge, this is the first and only case of distal PCA serpentine aneurysm to be treated by IMA-RA-PCA bypass followed by proximal PAO. These findings suggest that IMA bypass surgery is a good and feasible treatment option for serpentine aneurysms of the PCA that can preserve the parent artery. Moreover, the anatomic segments of the PCA and different treatment options available for PCA serpentine aneurysms are also discussed in this study.

Occipital artery-anterior cerebral artery bypass with posterior auricular artery-middle cerebral artery bypass for stenosis of the internal carotid artery bifurcation

Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass, and STA-anterior cerebral artery (ACA) bypass, are options for direct revascularisation of anterior circulation. However, some patients don't have a suitable STA to use as a donor, so an alternative procedure must be performed. A 59-year-old, right-handed man presented with dysphasia and right-sided hemiparesis due to a transient ischaemic attack. Imaging studies revealed severe stenosis of the left internal carotid artery bifurcation. Iodoamphetamine single photon emission computed tomography demonstrated reduced cerebrovascular reserve capacity in the left hemisphere. The patient was started on antiplatelet therapy, but the ischaemic attacks persisted after one month. Thus, revascularisation of the ACA and MCA territories was considered. Digital subtraction angiography revealed prominence in the left occipital artery (OA) and posterior auricular artery (PAA), while the left STA was hypoplastic, terminating at the squamous suture level. Therefore, anastomoses were performed between both the OA and ACA and the PAA and MCA. Revascularisation was successful, and the ischaemic attacks disappeared. OA-ACA bypass, together with PAA-MCA bypass, may be effective for wide cerebral revascularisation when the STA is not available.

Massive Epistaxis from Nontraumatic Cavernous Carotid Aneurysm Treated by High-Flow Bypass and Cervical Internal Carotid Artery Ligation: A Case Report and Review of the Literature

BACKGROUND

Epistaxis is a rare presentation of the ruptured cavernous carotid aneurysm, especially the nontraumatic type. Both endovascular therapies and open surgeries have a role in the treatment with various outcomes, but the standard procedure is not well established. We report a successful high-flow bypass with cervical internal carotid artery ligation for aneurysm repair and review the related literature.

CASE DESCRIPTION

An 81-year-old man presented with massive epistaxis from the left nostril. The epistaxis was controlled by nasal packing. A saccular aneurysm of the cavernous segment of the left internal carotid artery projecting into the sphenoid sinus was revealed using computed tomography angiography. We treated this patient with high-flow bypass with ligation of the cervical internal carotid artery. Immediate postoperative computed tomography angiography showed complete disappearance of the aneurysm. Nasal packing was removed without further bleeding. No neurological deficit or complications were detected in the postoperative period.

CONCLUSIONS

In cases of massive or recurrent epistaxis without coagulopathy or nasal pathology, a cavernous carotid aneurysm should be considered. Immediate cessation of the bleeding is necessary. Flow-preservation bypass with proximal ligation of the parent artery is 1 of the effective procedures for the treatment of this condition with low morbidity.

The future of open vascular neurosurgery: perspectives on cavernous malformations, AVMs, and bypasses for complex aneurysms

Despite the erosion of microsurgical case volume because of advances in endovascular and radiosurgical therapies, indications remain for open resection of pathology and highly technical vascular repairs. Treatment risk, efficacy, and durability make open microsurgery a preferred option for cerebral cavernous malformations, arteriovenous malformations (AVMs), and many aneurysms. In this paper, a 21-year experience with 7348 cases was reviewed to identify trends in microsurgical management. Brainstem cavernous malformations (227 cases), once considered inoperable and managed conservatively, are now resected in increasing numbers through elegant skull base approaches and newly defined safe entry zones, demonstrating that microsurgical techniques can be applied in ways that generate entirely new areas of practice. Despite excellent results with microsurgery for low-grade AVMs, brain AVM management (836 cases) is being challenged by endovascular embolization and radiosurgery, as well as by randomized trials that show superior results with medical management. Reviews of ARUBA-eligible AVM patients treated at high-volume centers have demonstrated that open microsurgery with AVM resection is still better than many new techniques and less invasive approaches that are occlusive or obliterative. Although the volume of open aneurysm surgery is declining (4479 cases), complex aneurysms still require open microsurgery, often with bypass techniques. Intracranial arterial reconstructions with reimplantations, reanastomoses, in situ bypasses, and intracranial interpositional bypasses (third-generation bypasses) augment conventional extracranial-intracranial techniques (first- and second-generation bypasses) and generate innovative bypasses in deep locations, such as for anterior inferior cerebellar artery aneurysms. When conventional combinations of anastomoses and suturing techniques are reshuffled, a fourth generation of bypasses results, with eight new types of bypasses. Type 4A bypasses use in situ suturing techniques within the conventional anastomosis, whereas type 4B bypasses maintain the basic construct of reimplantations or reanastomoses but use an unconventional anastomosis. Bypass surgery (605 cases) demonstrates that open microsurgery will continue to evolve. The best neurosurgeons will be needed to tackle the complex lesions that cannot be managed with other modalities. Becoming an open vascular neurosurgeon will be intensely competitive. The microvascular practice of the future will require subspecialization, collaborative team effort, an academic medical center, regional prominence, and a large catchment population, as well as a health system that funnels patients from hospital networks outside the region. Dexterity and meticulous application of microsurgical technique will remain the fundamental skills of the open vascular neurosurgeon.

Anatomical Assessment of the Temporopolar Artery for Revascularization of Deep Recipients

BACKGROUND

Intracranial-intracranial and extracranial-intracranial bypass options for revascularization of deep cerebral recipients are limited and technically demanding.

OBJECTIVE

To assess the anatomical feasibility of using the temporopolar artery (TPA) for revascularization of the anterior cerebral artery (ACA), posterior cerebral artery (PCA), and superior cerebellar arteries (SCA).

METHODS

Orbitozygomatic craniotomy was performed bilaterally on 8 cadaveric heads. The cisternal segment of the TPA was dissected. The TPA was cut at M3-M4 junction with its proximal and distal calibers and the length of the cisternal segment measured. Feasibility of the TPA-A1-ACA, TPA-A2-ACA, TPA-SCA, and TPA-PCA bypasses were assessed.

RESULTS

A total of 17 TPAs were identified in 16 specimens. The average distal TPA caliber was 1.0 ± 0.2 mm, and the average cisternal length was 37.5 ± 9.4 mm. TPA caliber was ≥ 1.0 mm in 12 specimens (70%). The TPA-A1-ACA bypass was feasible in all specimens, whereas the TPA reached the A2-ACA, SCA, and PCA in 94% of specimens (16/17). At the point of anastomosis, the average recipient caliber was 2.5 ± 0.5 mm for A1-ACA, and 2.3 ± 0.7 mm for A2-ACA. The calibers of the SCA and PCA at the anastomosis points were 2.0 ± 0.6 mm, and 2.7 ± 0.8 mm, respectively.

CONCLUSION

The TPA-ACA, TPA-PCA, and TPA-SCA bypasses are anatomically feasible and may be used when the distal caliber of the TPA stump is optimal to provide adequate blood flow. This study lays foundations for clinical use of the TPA for ACA revascularization in well-selected cases.

Flow Diverter Therapy of a Giant Fusiform Vertebrobasilar Junction Aneurysm in a Child: Case Report

The management of giant vertebrobasilar junction (VBJ) aneurysms is extremely challenging. Flow diverter (FD) therapy has become an important alternative to treat difficult intracranial aneurysms for both open surgery and conventional endovascular therapy. Herein, we report a rare case of a giant fusiform VBJ aneurysm in a child that is successfully treated with FD therapy.

Role of botulinum neurotoxin-A in cerebral revascularization graft vasospasm prevention: current state of knowledge

Graft stenosis and occlusion remain formidable complications in cerebral revascularization procedures, which can lead to significant morbidity and mortality. Graft vasospasm can result in early postoperative graft stenosis and occlusion and is believed to be at least partially mediated through adrenergic pathways. Despite various published treatment protocols, there is no single effective spasmolytic agent. Multiple factors, including anatomical and physiological variability in revascularization conduits, patient age, and comorbidities, have been associated with graft vasospasm pathogenesis and response to spasmolytics. The ideal spasmolytic agent thus likely needs to target multiple pathways to exert a generalizable therapeutic effect. Botulinum toxin (BTX)-A is a powerful neurotoxin widely used in clinical practice for the treatment of a variety of spastic conditions. Although its commonly described paradigm of cholinergic neural transmission blockade has been widely accepted, evidence for other mechanisms of action including inhibition of adrenergic transmission have been described in animal studies. Recently, the first pilot study demonstrating clinical use of BTX-A for cerebral revascularization graft spasm prevention has been reported. In this review, the mechanistic basis and potential future clinical role of BTX-A in graft vasospasm prevention is discussed.

Cerebral Bypass Surgery for Internal Carotid Artery Occlusion, Complex Supraclinoid Carotid Artery Aneurysm, and Tumors: A Report of Four Cases

Despite growing popularity of endovascular techniques, certain subsets of patients with cerebrovascular compromise may benefit from bypass surgery. We present four cases in which pending ischemic lesion was prevented by (1) A3 resection and reanastomosis following falx meningioma removal, (2) rescue superficial temporal artery–middle cerebral artery (STA-MCA) bypass after pituitary adenoma surgery, (3) STA-MCA bypass for chronic internal carotid artery occlusion, and (4) external carotid artery-MCA bypass using radial artery grafting. Following the procedure, there were no further clinical or radiological deteriorations and long-term patency was confirmed in all four cases.

Flow diversion versus parent artery occlusion with bypass in the treatment of complex intracranial aneurysms: Immediate and short-term outcomes of the randomized trial

OBJECTIVE

We performed prospective randomized comparison of clinical and surgical outcomes of flow diversion versus PVO and bypass in patients with complex anterior circulation aneurysms.

PATIENTS AND METHODS

Open, prospective, randomized, parallel group, multicenter study of complex intracranial aneurysms treatment was conducted. Patients with complex intracranial aneurysms of anterior circulation with neck is more than 4 mm wide, dome/neck ratio is equal or less than 2:1, which is suitable for flow diversion and occlusion with bypass were included in the study. A total of 111 potential participants were enrolled since March 2015. Additional propensity score matching was performed with 40 patients in each group selected for analysis.

RESULTS

39 out of 40 patients (97.5%) from matched FD group reached good clinical outcome. In the matched bypass group acceptable outcome was achieved in 32 (80%) out of 40 patients (difference between groups p = 0.029). The morbidity and mortality rates were 15% and 5%, respectively. Difference in the rates of favorable outcomes, compared by χ2 met statistical significance (p = 0.014). The rate of complete aneurysm occlusion at 6 months was 42.5% in the FD group and 95% in surgical group (p < 0.0001). The rate of complete occlusion at 12 months was 65% in the FD group and 97.5% in surgical group. The difference between groups was still significant (p = 0.001). There were no significant differences between groups by occurrence of ischemic (p = 0.108) and hemorrhagic (p = 0.615) complications.

CONCLUSION

The study demonstrated superior clinical outcomes for endovascular flow diversion in comparison with bypass surgery in treatment of complex aneurysms. Though, both techniques grant similar percentage of major neurologic complications and comparable cure rate for cranial neuropathy. Nevertheless, flow diversion is associated with significantly lower early obliteration rate, thus possesses patient for risks of prolonged dual antiplatelet regimen and delayed rupture. Hence, it's important to stratify patient by the natural risk of aneurysm rupture prior to treatment selection.