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

Exploration of the risk factor for infarction after revascularization in moyamoya disease

RESULTS

Eventually, 108 consecutive patients received 174 surgeries were enrolled, experienced new or expanded infarction occured in 13 (7.47%) surgeries, which showed higher Suzuki stage on the non-operative side, more posterior cerebral artery (PCA) involvement, and more intraoperative hypotension compared to those without infarction(p < .05). The Suzuki stage on the non-operative side had the highest area under the curve (AUC) of 0.737, with a sensitivity of 0.692 and specificity of 0.783. Combination of the three factors showed better efficiency, with an AUC of 0.762, a sensitivity of 0.692, and a specificity of 0.907.

CONCLUSIONS

Revascularization was a safe option for patients with MMD, higher Suzuki stage on the non-operative side, PCA involvement, and intraoperative hypotension might be the risk factors for new or expanded infarction after revascularization in patients with MMD.

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.

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

BACKGROUND

Training in anastomosis is fundamental in neurosurgery due to the precision and dexterity required. Biological models, although realistic, present limitations such as availability, ethical concerns, and the risk of biological contamination. Synthetic models, on the other hand, offer durability and standardized conditions, although they sometimes lack anatomical realism. This study aims to evaluate and compare the efficiency of anastomosis training models in the intra-extracranial cerebral bypass procedure, identifying those characteristics that enhance optimal microsurgical skill development and participant experience.

METHODS

A neurosurgery workshop was held from March 2024 to June 2024 with 5 vascular techniques and the participation of 22 surgeons. The models tested were the human placenta, the Wistar rat, the chicken wing artery, the nasogastric feeding tube, and the UpSurgeOn Mycro simulator. The scales used to measure these models were the Main Characteristics Score and the Evaluation Score. These scores allowed us to measure, qualitatively and quantitatively, durability, anatomical similarity, variety of simulation scenarios, risk of biological contamination, ethical considerations and disadvantages with specific infrastructure.

RESULTS

The human placenta model, Wistar rat model, and UpSurgeOn model were identified as the most effective for training. The human placenta and Wistar rat models were highly regarded for anatomical realism, while the UpSurgeOn model excelled in durability and advanced simulation scenarios. Ethical and cost implications were also considered.

CONCLUSIONS

The study identifies the human placenta and UpSurgeOn models as optimal for training in intra-extracranial bypass procedures, emphasizing the need for diverse and effective training models in neurosurgery.

Pathological Findings of Donor Vessels in Bypass Surgery

(1) Background Cerebral revascularization is necessary to treat intracranial arterial stenosis caused by moyamoya disease, atherosclerosis, or large complex aneurysms. Although various donor vascular harvesting methods have been reported safe, there are no reports on the histological evaluation of donor vessels for each disease, despite the variety of diseases wherein vascular anastomosis is required. (2) Methods Pathological findings of the superficial temporal artery (STA), radial artery (RA), occipital artery (OA), and saphenous vein (SV) harvested at the institution were analyzed. Patients classified according to aneurysm, atherosclerosis, and moyamoya disease were assessed for pathological abnormalities, medical history, age, sex, smoking, and postoperative anastomosis patency. (3) Results There were 38 cases of atherosclerosis, 15 cases of moyamoya disease, and 30 cases of aneurysm in 98 donor vessels (mean age 57.2) taken after 2006. Of the 84 STA, 11 RA, 2 OA, and 1 SV arteries that were harvested, 71.4% had atherosclerosis, 11.2% had dissection, and 10.2% had inflammation. There was no significant difference in the proportion of pathological findings according to the disease. A history of hypertension is associated with atherosclerosis in donor vessels. (4) Conclusions This is the first study to histologically evaluate the pathological findings of donor vessels according to disease. The proportion of dissection findings indicative of vascular damage due to surgical manipulation was not statistically different between the different conditions.

Extracranial-Intracranial Bypass for Moyamoya Disease: The Influence of Racial and Socioeconomic Disparities on Outcomes - A National Inpatient Sample Analysis

BACKGROUND

Extracranial-intracranial (EC-IC) bypass is an established therapeutic option for Moyamoya disease (MMD). However, little is known about the effects of racial and ethnic disparities on outcomes. This study assessed trends in EC-IC bypass outcomes among MMD patients stratified by race and ethnicity.

METHODS

Utilizing the US National Inpatient Sample, we identified MMD patients undergoing EC-IC bypass between 2002 and 2020. Demographic and hospital-level data were collected. Multivariable analysis was conducted to identify independent factors associated with outcomes. Trend analysis was performed using piecewise joinpoint regression.

RESULTS

Out of 14,062 patients with MMD, 1771 underwent EC-IC bypass. Of these, 60.59% were White, 17.56% were Black, 12.36% were Asians, 8.47% were Hispanic, and 1.02% were Native Americans. Nonhome discharge was noted in 21.7% of cases, with a 6.7% death and 3.8% postoperative neurologic complications rates. EC-IC bypass was more commonly performed in Native Americans (23.38%) and Asians (17.76%). Hispanics had the longest mean length of stay (8.4 days) and lower odds of nonhome discharge compared to Whites (odds ratio: 0.64; 95% confidence interval: 0.40-1.03; P = 0.04). Patients with Medicaid, private insurance, self-payers, and insurance paid by other governments had lower odds of nonhome discharge than those with Medicare.

CONCLUSION

This study highlights racial and socioeconomic disparities in EC-IC bypass for patients with MMD. Despite these disparities, we did not find any significant difference in the quality of care. Addressing these disparities is essential for optimizing MMD outcomes.

Extracranial-Intracranial Bypass and Risk of Stroke and Death in Patients With Symptomatic Artery Occlusion: The CMOSS Randomized Clinical Trial

Importance

Prior trials of extracranial-intracranial (EC-IC) bypass surgery showed no benefit for stroke prevention in patients with atherosclerotic occlusion of the internal carotid artery (ICA) or middle cerebral artery (MCA), but there have been subsequent improvements in surgical techniques and patient selection.

Objective

To evaluate EC-IC bypass surgery in symptomatic patients with atherosclerotic occlusion of the ICA or MCA, using refined patient and operator selection.

Design, Setting, and Participants

This was a randomized, open-label, outcome assessor-blinded trial conducted at 13 centers in China. A total of 324 patients with ICA or MCA occlusion with transient ischemic attack or nondisabling ischemic stroke attributed to hemodynamic insufficiency based on computed tomography perfusion imaging were recruited between June 2013 and March 2018 (final follow-up: March 18, 2020).

Interventions

EC-IC bypass surgery plus medical therapy (surgical group; n = 161) or medical therapy alone (medical group; n = 163). Medical therapy included antiplatelet therapy and stroke risk factor control.

Main Outcomes and Measures

The primary outcome was a composite of stroke or death within 30 days or ipsilateral ischemic stroke beyond 30 days through 2 years after randomization. There were 9 secondary outcomes, including any stroke or death within 2 years and fatal stroke within 2 years.

Results

Among 330 patients who were enrolled, 324 patients were confirmed eligible (median age, 52.7 years; 257 men [79.3%]) and 309 (95.4%) completed the trial. For the surgical group vs medical group, no significant difference was found for the composite primary outcome (8.6% [13/151] vs 12.3% [19/155]; incidence difference, -3.6% [95% CI, -10.1% to 2.9%]; hazard ratio [HR], 0.71 [95% CI, 0.33-1.54]; P = .39). The 30-day risk of stroke or death was 6.2% (10/161) in the surgical group and 1.8% (3/163) in the medical group, and the risk of ipsilateral ischemic stroke beyond 30 days through 2 years was 2.0% (3/151) and 10.3% (16/155), respectively. Of the 9 prespecified secondary end points, none showed a significant difference including any stroke or death within 2 years (9.9% [15/152] vs 15.3% [24/157]; incidence difference, -5.4% [95% CI, -12.5% to 1.7%]; HR, 0.69 [95% CI, 0.34-1.39]; P = .30) and fatal stroke within 2 years (2.0% [3/150] vs 0% [0/153]; incidence difference, 1.9% [95% CI, -0.2% to 4.0%]; P = .08).

Conclusions and Relevance

Among patients with symptomatic ICA or MCA occlusion and hemodynamic insufficiency, the addition of bypass surgery to medical therapy did not significantly change the risk of the composite outcome of stroke or death within 30 days or ipsilateral ischemic stroke beyond 30 days through 2 years.

Trial Registration

ClinicalTrials.gov Identifier: NCT01758614.

The Hibiscus Model: A Feasible Cadaveric Model Using Continuous Arterial Circulation for Intracranial Bypass Training and Its Validation

OBJECTIVE

The frequency of intracranial bypass procedures has declined. Thus it is difficult for neurosurgeons to develop the necessary skills for this complex procedure. We present a perfusion-based cadaveric model to provide a realistic training experience with high anatomic and physiological fidelity, as well as instantaneous assessment of bypass patency. Validation was assessed by evaluating the educational impact and skill improvement of the participants.

METHODS

Fourteen participants attended a hands-on revascularization course with 7 cadaveric models connected to a continuous arterial circulation system pumping a red-colored solution through the entire cranial vasculature, mimicking blood circulation. The ability to perform a vascular anastomosis was evaluated initially. Further, a questionnaire on prior experience was provided. At the end of the 36-hour course, the ability to perform an intracranial bypass was reexamined and the participants completed a self-assessment questionnaire.

RESULTS

Initially, only 3 attendees were able to perform an end-to-end anastomosis within the time limit, and only 2 of these anastomoses showed adequate patency. After having accomplished the course, all participants were able to complete a patent end-to-end anastomosis within the time limit, thus demonstrating a significant improvement. Further, both overall educational gain and surgical skills were regarded as remarkable (n = 11 and n = 9).

CONCLUSIONS

Simulation-based education is considered an important aspect of medical and surgical development. The presented model is a feasible and accessible alternative to the prior models used for cerebral bypass training. This training may serve as a helpful and widely available tool to improve neurosurgeons' development irrespective of financial resources.

Influence of Patient and Technical Variables on Combined Direct and Indirect Cerebral Revascularization: Case Series

BACKGROUND

Cerebral bypass for flow augmentation is an important technique for selected neurosurgical patients, with multiple techniques used (direct, indirect, or combined).

OBJECTIVE

To assess the impact of patient and technical variables on direct and indirect bypass flow after combined revascularization.

METHODS

This was a retrospective, single-institution review of patients undergoing direct superficial temporal artery-to-middle cerebral artery bypass with indirect encephaloduro-myosynangiosis for moyamoya disease and steno-occlusive cerebrovascular disease over a 2-year period. We evaluated the effect of baseline patient characteristics, preoperative imaging characteristics, and operative variables on direct and indirect patency grades.

RESULTS

Twenty-six hemispheres (8 moyamoya disease and 18 steno-occlusive cerebrovascular disease) in 23 patients were treated with combined revascularization. The mean patient age was 53.4 ± 19.1 years. Direct bypass patency was 96%. Over a mean follow-up of 8.3 ± 5.4 months, there were 3 strokes in the treated hemispheres (11.5%). The mean modified Rankin Scale score improved from 1.3 ± 1.1 preoperatively to 0.7 ± 0.8 postoperatively. Preservation of the nondonor superficial temporal artery branch was associated with a lower direct bypass grade ( P < .01), whereas greater mean time to maximum perfusion (Tmax)> 4 and >6 seconds and mismatch volumes were associated with higher direct bypass grades ( P < .05). Tmax >4-second volume inversely predicted indirect bypass patency.

CONCLUSION

Patient and technical variables may influence the relative contributions of the direct and indirect components of combined revascularizations.

Case Report: Curative effect of OA-PICA protected bypass in severe PICA-complicated vertebral artery stenosis treatment: Results in 3 cases

Objectives

We aimed to explore the results of OA-PICA-protected bypass grafting in patients with severe stenosis of the vertebral artery combined with PICA.

Methods

Three patients with vertebral artery stenosis involving the posterior inferior cerebellar artery, treated by the Department of Neurosurgery of Henan Provincial People's Hospital from January 2018 to December 2021, were retrospectively analyzed. All the patients underwent Occipital Artery-Posterior Inferior Cerebellar Artery (OA-PICA) bypass surgery followed by elective vertebral artery stenting. Intraoperative indocyanine green fluorescence angiography (ICGA) showed patency of the bridge-vessel anastomosis. Postoperatively, the ANSYS software was used to assess the flow pressure changes and vascular shear in combination with the reviewed DSA angiogram. CTA or DSA was reviewed 1-2 years postoperatively, and the prognosis was evaluated by the modified Rankin Scale (mRS) one year postoperatively.

Results

OA-PICA bypass surgery was completed in all patients, with intraoperative ICGA showing a patent bridge anastomosis, followed by stenting of the vertebral artery, and a review of the DSA angiogram. We also employed ANSYS software evaluation of the bypass vessel, which showed stable pressure and low turnover angle, suggesting a low rate of long-term occlusion of the vessel. All patients had no procedure-related complications during their hospitalization, and were followed up for a mean of 24 months postoperatively, with a good prognosis (mRS score of 1) at 1 year postoperatively.

Conclusion

OA-PICA-protected bypass grafting is an effective treatment for patients with severe stenosis of the vertebral artery combined with PICA.

Interposition Intracranial-Intracranial Bypass Based on Anterior Cerebral Artery A1 Donor Anastomosis: Technical Advances, Outcomes, and Literature Review

BACKGROUND

The bypass technique is important for treating complex intracranial aneurysms and is infrequently performed. Intracranial-intracranial (IC-IC) bypass has shown many advantages in recent years.

OBJECTIVE

To review the techniques and outcomes of bypass based on anterior cerebral artery (ACA) A1 donor anastomosis in patients with intracranial aneurysm.

METHODS

We retrospectively reviewed the clinical and imaging data, surgical strategy, and follow-up outcomes of 7 patients treated from 2019 to 2022. Neurological function was assessed by the modified Rankin Scale (mRS). A literature review was performed using PubMed.

RESULTS

All 7 patients (3 male patients and 4 female patients; mean age, 50.4 ± 15.5 years) underwent aneurysm trapping or clipping using interposition IC-IC bypass based on ACA-A1 donor anastomosis. There were 6 middle cerebral artery (MCA) aneurysms and 1 posterior cerebral aneurysm in the series. One IC-IC bypass failed and was changed to extracranial-intracranial bypass. Three patients with MCA M1 aneurysm showed perforator-related infarction after the operation. The modified Rankin Scale score was 0 in 4 patients, 2 in 2 patients, and 1 in 1 patient. The long-term graft patency rate was 100%.

CONCLUSION

Interposition IC-IC bypass based on ACA-A1 donor anastomosis provides an effective way to achieve blood flow reconstruction in the treatment of complex aneurysms. This technique provides better caliber and volume compatibility and diminishes neck incision. Perforator-related infarction was the main complication because of involvement of the MCA M1 aneurysm location. Proximal clipping is preferred to avoid perforator-related infarction.

Evolution of open surgery for unruptured intracranial aneurysms over a fifteen year period-increased difficulty and morbidity

OBJECTIVE

The approach to intervention for unruptured intracranial aneurysms (UIAs) remains controversial. Utilization of endovascular techniques for aneurysm repair increased dramatically during the last decade. We sought to analyze recent national trends for electively treated (open and endovascular) UIAs focusing on pre-existing patient disease burden and intervention modality selection.

METHODS

The Nationwide Inpatient Sample (NIS) national database was used to identify patients with primary diagnosis codes of unruptured intracranial aneurysm between 1999 and 2014. Patients were dichotomized by intervention into endovascular or open surgical treatment. Analysis of pre-existing disease severity were calculated using the Elixhauser comorbidity index. Complications of combined peri-procedural stroke or death during admission and hospital length of stay were used as primary endpoints for comparison.

RESULTS

The percent of total UIAs treated electively with open approach decreased from more than 95 % of cases in 1999 to less than 25 % in 2014. Patients undergoing clipping were 3 years younger than those in the endovascular group (p < 0.001). The rate of primary endpoint complications (stroke and death) and length of stay for open cases saw a decrease throughout the study but remained statistically higher when compared to the endovascular group over the study period (p < 0.001). Additionally, non-neurologic complications increased over the time period for open cases. The average preoperative co-morbid disease severity for all groups treated increased over this interval. Conversely, the relative volume of endovascular cases increased but the rate of complications and average group disease remained statistically lower than the surgical clipping group (p < 0.05).

CONCLUSION

The percent of UIAs treated electively with open approach has decreased since 1999 with a concomitant increase in complication rate in particular compared to endovascular cases. However, the health characteristics of patients treated with surgical clipping show an increase in severity of pre-existing co-morbidities. Further research into factors contributing to this finding, including potential socioeconomic differences and changes in surgeon experience are needed.

Surgically treatable adult epilepsy: a changing patient population. Experience from a level 4 epilepsy center

OBJECTIVE

Invasive monitoring has long been utilized in the evaluation of patients for epilepsy surgery, providing localizing information to guide resection. Stereoelectroencephalography (SEEG) was introduced at the authors' level 4 epilepsy surgery program in 2013, with responsive neurostimulation (RNS) becoming available the following year. The authors sought to characterize patient demographics and epilepsy-related variables before and after SEEG introduction to understand whether differences emerged in their patient population. This information will be useful in understanding how SEEG, possibly in conjunction with RNS availability, may have changed practice patterns over time.

METHODS

This is a retrospective cohort study of consecutive patients who underwent surgery for epilepsy from 2006 to 2018, comprising 7 years before and 5 years after the introduction of SEEG. The authors performed univariate analyses of patient characteristics and outcomes and used generalized estimating equations logistic regression for predictive analysis.

RESULTS

A total of 178 patients were analyzed, with 109 patients in the pre-SEEG cohort and 69 patients in the post-SEEG cohort. In the post-SEEG cohort, more patients underwent invasive monitoring for suspected bilateral seizure onsets (40.6% vs 22.0%, p = 0.01) and extratemporal seizure onsets (68.1% vs 8.3%, p < 0.0001). The post-SEEG cohort had a higher proportion of patients with seizures arising from eloquent cortex (14.5% vs 0.9%, p < 0.001). Twelve patients underwent RNS insertion in the post-SEEG group versus none in the pre-SEEG group. Fewer patients underwent resection in the post-SEEG group (55.1% vs 96.3%, p < 0.0001), but there was no significant difference in rates of seizure freedom between cohorts for those patients having undergone a follow-up resection (53.1% vs 59.8%, p = 0.44).

CONCLUSIONS

These findings demonstrate that more patients with suspected bilateral, eloquent, or extratemporal epilepsy underwent invasive monitoring after adoption of SEEG. This shift occurred coincident with the adoption of RNS, both of which likely contributed to increased patient complexity. The authors conclude that their practice now considers invasive monitoring for patients who likely would not previously have been candidates for surgical investigation and subsequent intervention.

Rescue Strategy for Troublesome Situations Related to Recipient and Donor Arteries During Low-Flow Bypass Surgery

OBJECTIVE

Although technically demanding, bypass surgery is a vital part of the neurosurgical armamentarium. The aim of this article was to present representative troublesome cases related to the manipulation of donor arteries (DAs) and recipient arteries during low-flow extracranial-intracranial bypass.

METHODS

In the past 5 years, 507 low-flow bypass surgeries were performed in patients with cerebral aneurysms, moyamoya disease, and intracranial atherosclerotic stenosis. Frustrating perioperative situations were retrospectively reviewed, and 6 representative cases were described.

RESULTS

Case 1 involved repeat microanastomosis owing to occlusion of the anastomotic segment by thrombus formation. Case 2 involved repair of the DA injured by thermal energy. Case 3 involved direct repair of the DA damaged by a sharp knife. Case 4 involved repeat microanastomosis owing to avulsion of the anastomotic segment. Case 5 involved lengthening of the short DA with a nearby interposition graft. Case 6 involved use of retrograde flow via the distal segment of the DA secondary to the injury of the proximal segment of the DA. In all patients, rescue procedures were successful, and bypass flow was patent with no relevant complications.

CONCLUSIONS

The intraoperative accidents reported here were frustrating; however, all patients were safely rescued without significant sequelae. It is hoped that our experiences will help young neurosurgeons handle troublesome situations.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Constructing an Individualized Middle Cerebral Artery Model Using 3D Printing and Hydrogel for Bypass Training

The importance and complexity of cerebral bypass surgery (CBS) highlight the necessity for intense and dedicated training. Several available training models are yet to satisfy this need. In this technical note, we share the steps to construct a digital imaging and communications in medicine (DICOM)-based middle cerebral artery (MCA) model that is anatomically accurate, resembles handling properties of living tissue, and enables trainers to observe the cerebrovascular anatomy, improve and maintain microsurgical dexterity, and train in the essential steps of CBS. The internal and external molds were created from the geometry of DICOM-based MCA using Fusion 360 software (Autodesk, San Rafael, USA). They were then three-dimension (3D) printed using a polylactic acid filament. The 15% w/v solution of polyvinyl alcohol (PVA) was prepared and injected between the molds. Using five freeze-thaw cycles the solution was converted to tissue-mimicking cryo-gel. The model was then placed in a chloroform bath until the internal mold dissolved. To evaluate the accuracy of the MCA model, selected characteristics were measured and compared with the MCA mesh. The DICOM-based MCA model was produced using 3D printing that was available in the lab and the overall cost was less than $5 per model. The external mold required six and a half hours to be 3D printed, while the internal mold only required 23 minutes. Overall, the time required to 3D print the DICOM-based MCA model was just short of seven hours. The greatest statistically significant difference between the virtual MCA model and the DICOM-based MCA model was found in the length of the pre-bifurcation part of the M1 segment and the total length of the superior bifurcation trunk of M1 and superior branch of M2. The smallest statistically significant difference was found at the diameter of the inferior post-bifurcation trunk of the M1 segment and the diameter at the origin of the artery. This technical report aims to show the construction of a CBS training system involving the DICOM-based MCA model that demonstrates the shape of the vascular tree, resembles the handling/suturing properties of living tissue, and helps set up a homemade training station. We believe that our DICOM-based MCA model can serve as a valuable resource for CBS training throughout the world due to its cost-effectiveness and straightforward construction steps. Moreover, once the DICOM-based MCA model is used with our training station, it may offer an option for trainers to gain and maintain CBS skills despite limitations on time, cost, and space. This work was presented in February 2019 at the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Cerebrovascular Section Annual Meeting held in Honolulu, Hawaii.

Controversies and Advances in Adult Intracranial Bypass Surgery in 2020

Cerebral revascularization utilizing a variety of bypass techniques can provide either flow augmentation or flow replacement in the treatment of a range of intracranial pathologies, including moyamoya disease, intracranial atherosclerotic disease, and complex aneurysms that are not amenable to endovascular or simple surgical techniques. Though once routine, the publication of high-quality prospective evidence, along with the development of flow-diverting stents, has limited the indications for extracranial-to-intracranial (EC-IC) bypass. Nevertheless, advances in imaging, assessment of cerebral hemodynamics, and surgical technique have changed the risk-benefit calculus for EC-IC bypass. New variations of revascularization surgery involving multiple anastomoses, flow preserving solutions, IC-IC constructs, and posterior circulation bypasses have been pioneered for otherwise difficult to treat pathology including giant aneurysms, dolichoectasia, and medically refractory intracranial atherosclerosis. This review provides a practical update on recent advances in adult intracranial bypass surgery.

Comparative efficacy of autologous versus cadaveric saphenous vein grafts in cerebral revascularization surgery

OBJECTIVE

Cerebral bypasses are performed for the purpose of either flow augmentation for ischemic cerebrovascular disease or flow replacement for vessel sacrifice during complex aneurysm or tumor surgery. Saphenous vein grafts (SVGs) are commonly used interposition grafts. The authors of this study sought to compare the efficacy of autologous versus cadaveric SVGs in a large series of cerebral bypasses using interposition vein grafts with long-term angiographic follow-up.

METHODS

All intracranial bypass procedures performed between 2001 and 2018 were reviewed. Demographic, clinical, angiographic, and operative data were recorded and then analyzed according to SVG type.

RESULTS

A total of 308 consecutive intracranial bypasses were performed during the study period, 53 (17.2%) of which were bypasses with an interposition SVG (38 autologous, 15 cadaveric). At a median follow-up of 2.2 months (IQR 0.2-29.1), 39 (73.6%) bypasses were patent (26 [68.4%] autologous, 13 [86.7%] cadaveric, p = 0.30). Comparing autologous and cadaveric SVG recipients, there were no statistically significant differences in age (p = 0.50), sex (p > 0.99), history of smoking (p = 0.75), hypertension (p > 0.99), diabetes mellitus (p = 0.13), indication for bypass (p = 0.27), or SVG diameter (p = 0.65). While there were higher intraoperative (autologous, 100.0 ml/min, IQR 84.3-147.5; cadaveric, 80.0 ml/min, IQR 47.3-107.8; p = 0.11) and postoperative (autologous, 142.2 ml/min, IQR 76.8-160.8; cadaveric, 92.0 ml/min, IQR 69.2-132.2; p = 0.42) volumetric flow rates in the autologous SVGs compared to those in the cadaveric SVGs, the difference between the two groups did not reach statistical significance. In addition, the blood flow index, or ratio of postoperative to intraoperative blood flow, for each bypass was similar between the groups (autologous, 1.3, IQR 0.9-1.6; cadaveric, 1.5, IQR 1.0-2.3; p = 0.37). Kaplan-Meier estimates showed no difference in bypass patency rates over time between autologous and cadaveric SVGs (p = 0.58).

CONCLUSIONS

Cadaveric SVGs are a reasonable interposition graft option in cerebral revascularization surgery when autologous grafts are not available.

Cerebrovascular bypass for ruptured aneurysms: A case series

In patients with aneurysmal subarachnoid hemorrhage (aSAH) unfavorable for endovascular or traditional open surgical techniques, surgical revascularization strategies comprise one of remaining limited options. There is nonetheless a paucity of data on the safety and efficacy of bypass in aSAH. In this study, we aimed to investigate complications and outcomes in a cohort of patients with aSAH treated with bypass. A prospective single-surgeon database of consecutive patients treated for aSAH between 2013 and 2018 was retrospectively analyzed. Complications and functional status at discharge were recorded and analyzed for the patients that underwent bypass surgery. Forty patients with aSAH were treated with bypass surgery (23 extracranial-intracranial; 17 intracranial-intracranial). All-cause perioperative mortality was 13% (6 patients). At discharge and at mean 14-month follow up, respectively, 16/40 (40%) and 16/25 (64%) of patients achieved a Glasgow Outcome Score of 4-5. All-cause, in-hospital complications occurred in 28 patients (70%), of which any ischemic complication occurred in 20 patients (50%), 7 (18%) being open surgical complications. This work represents the largest modern series of bypass for aSAH to date. In cases of aSAH unfavorable for endovascular intervention or traditional open surgical techniques, bypass remains a viable option in this complex group of patients.

Contemporary trends in extracranial-intracranial bypass utilization: analysis of data from 2008 to 2016

OBJECTIVE

The impact of FDA approval of flow-diversion technology for the treatment of supraclinoid internal carotid artery aneurysms and the publication of the Carotid Occlusion Surgery Study, both of which occurred in 2011, on the utilization of extracranial-intracranial (EC-IC) bypasses is not known.

METHODS

The National Inpatient Sample (NIS) was queried for hospitalizations for EC-IC bypass performed from 2008 to 2016. Diagnoses of interest included an unruptured intracranial aneurysm (UIA), subarachnoid hemorrhage (SAH), carotid occlusive disease (COD), and moyamoya disease. The authors assessed trends in EC-IC bypass utilization for these diagnoses and the incidence of adverse discharges, defined as discharge to locations other than home, and the rate of mortality.

RESULTS

A total of 1640 EC-IC bypass procedures were performed at 558 hospitals during the study period, with 1148 procedures at 448 hospitals performed for a diagnosis of interest. The most frequent surgical indication was moyamoya disease (65.7%, n = 754), followed by COD (23.2%, n = 266), SAH (3.2%, n = 37), and a UIA (7.9%, n = 91). EC-IC bypass utilization for COD decreased from 0.21 per 100 admissions of COD in 2010 to 0.09 per 100 admissions in 2016 (p = 0.023). The frequency of adverse discharges increased during the study period from 22.3% of annual admissions in 2008 to 31.2% in 2016 (p = 0.030) when analysis was limited to procedures performed for a diagnosis of interest. Per volume, the top 5th percentile of hospitals, on average, performed 18.4 procedures (SD 13.2) per hospital during the study period, compared to 1.3 procedures (SD 1.3) that were performed in hospitals within the bottom 95th percentile. The rate of adverse discharges was higher at low-volume institutions when compared to that at high-volume institutions (33.8% vs 28.7%; p = 0.029). Over the study period, the authors noted a trend toward a reduced percentage of total surgical volume performed at high-volume hospitals (p < 0.001).

CONCLUSIONS

The authors observed a decrease in the utilization of EC-IC bypass for COD during the study period. An increase in the rate of adverse discharges was also noted, coinciding with more procedures being performed at lower-volume centers.

The cut flow index revisited: utility of intraoperative blood flow measurements in extracranial-intracranial bypass surgery for ischemic cerebrovascular disease

OBJECTIVE

In extracranial-intracranial (EC-IC) bypass surgery, the cut flow index (CFI) is the ratio of bypass flow (ml/min) to donor vessel cut flow (ml/min), and a CFI ≥ 0.5 has been shown to correlate with bypass patency. The authors sought to validate this observation in a large cohort of EC-IC bypasses for ischemic cerebrovascular disease with long-term angiographic follow-up.

METHODS

All intracranial bypass procedures performed at a single institution between 2003 and 2018 were reviewed. Demographic, clinical, angiographic, and operative data were recorded and analyzed according to bypass patency with univariate and multivariate statistical analyses.

RESULTS

A total of 278 consecutive intracranial bypasses were performed during the study period, of which 157 (56.5%) were EC-IC bypasses for ischemic cerebrovascular disease. Intraoperative blood flow measurements were available in 146 patients, and angiographic follow-up was available at a mean of 2.1 ± 2.6 years after bypass. The mean CFI was significantly higher in patients with patent bypasses (0.92 vs 0.64, p = 0.003). The bypass patency rate was 83.1% in cases with a CFI ≥ 0.5 compared with 46.4% in cases with a CFI < 0.5 (p < 0.0001). Adjusting for age, sex, diagnosis, and single versus double anastomosis, the CFI remained a significant predictor of bypass patency (p = 0.001; OR 5.8, 95% CI 2.0-19.0). A low CFI was also associated with early versus late bypass nonpatency (p = 0.008).

CONCLUSIONS

A favorable CFI portends long-term EC-IC bypass patency, while a poor CFI predicts eventual bypass nonpatency and can alert surgeons to potential problems with the donor vessel, anastomosis, or recipient bed during surgery.

Comparative Assessment of Extracranial-to-Intracranial and Intracranial-to-Intracranial In Situ Bypass for Complex Intracranial Aneurysm Treatment Based on Rupture Status: A Case Series

BACKGROUND

Comparative outcomes of extracranial-to-intracranial (EC-IC) and intracranial-to-intracranial (IC-IC) bypass for complex aneurysm treatment based on rupture status are not well described in the literature. In this study, we compare outcomes of EC-IC and IC-IC bypass for complex intracranial aneurysm treatment based on rupture status.

METHODS

A prospective neurosurgical patient database was retrospectively reviewed. Sixty-three consecutive patients with aneurysm managed with revascularization were identified between July 2014 and December 2018.

RESULTS

During the study period, 41 patients with aneurysm underwent EC-IC bypass (65%; 24 [58.5%] ruptured, 17 [41.5%] unruptured) and 22 patients with aneurysm underwent IC-IC bypass (34.9%; 13 [59.1%] ruptured, 9 [40.9%] unruptured). Graft spasm occurred in 4 patients (9.8%) in the EC-IC group (all ruptured aneurysms) and all anastomoses were patent on immediate postoperative imaging. Perioperative mortality occurred in 5 patients who underwent EC-IC bypass (12.2%; 3 ruptured, 2 unruptured) EC-IC and 2 patients who underwent IC-IC bypass (9.1%; both ruptured); (P = 0.709). Bypass-related complications occurred only in patients with ruptured aneurysm (2 [8.3%] in the EC-IC group and 0 [0%] in the IC-IC group; P = 0.285). For unruptured aneurysms, the overall complication rate was lower in IC-IC compared with the EC-IC group (P = 0.006). Modified Rankin Scale scores on discharge were significantly lower in IC-IC compared with EC-IC bypass for unruptured aneurysms (P = 0.008). There was a trend for shorter temporary occlusion and hospitalization times and overall better outcomes with IC-IC compared with EC-IC bypass.

CONCLUSIONS

Although often considered riskier than EC-IC bypass, IC-IC in situ bypass showd a favorable technical and safety profile for the treatment of complex, unruptured aneurysms.

A Survey of Microsurgical Technique for Extracranial-to-Intracranial Bypass

BACKGROUND

Extracranial-to-intracranial bypass surgery is a well-established technique that has been practiced for over 50 years. Since then, numerous technical variants have developed nationally and internationally.

OBJECTIVE

Based on a survey, to collect information on cerebrovascular bypass surgeons and their background, surgical volume, and technical steps of extracranial-to-intracranial bypasses with focus on superficial temporal artery to middle cerebral artery (STA-MCA) bypass.

METHODS

An electronic survey was distributed among bypass neurosurgeons. Responses were analyzed for national-international variations of STA-MCA bypass surgery techniques. The survey focused on the technical aspects of the surgery itself rather than patient selection or perioperative management.

RESULTS

Survey responses were collected from 51 neurosurgeons performing cerebrovascular bypass, from 11 different countries across North America, Europe, and Asia. The largest age block was early-to mid-career (66.7% aged 36-50 years). Most participating surgeons (80.40%) performed less than 20 bypasses annually, whereas a select few surgeons (3) performed more than 50 annually. The most common bypass was STA-M4 MCA bypass with a linear incision (34%) over the parietal branch (44%) and choosing an MCA recipient based on diameter (61.2%). The interrupted anastomosis technique was most common (74%).

CONCLUSIONS

The results of this electronic survey will help to identify common patterns in STA-MCA bypass surgery and will serve as a guide to other neurosurgeons to modify and improve their technique. Cerebrovascular bypass is still widely practiced, including by young neurosurgeons, who are actively learning from established masters who share their experience.

Dissection of the Superficial Temporal Artery: Significance and Performance with Bipolar Forceps

BACKGROUND

Adequate bypass harvesting of the superficial temporal artery (STA) is a standard procedure for every neurosurgeon, so mastery of techniques for its management and care is mandatory.

METHODS

Here, we report the effectiveness of using the bipolar forceps as a novel procedure.

RESULTS

This procedure improves safety, efficiency, and bleeding compared to the usual dissection.

CONCLUSIONS

In cases requiring an STA donor, this technique may be as useful as the traditional method and could become part of the neurosurgeon's armamentarium.

Pipeline Embolization Device for Treatment of Craniocervical Internal Carotid Artery Dissections: Report of 3 Cases

BACKGROUND

Dissecting pseudoaneurysms of the craniocervical circulation are uncommon, accounting for only 3% of all cerebral aneurysms. These aneurysms pose a challenge due to their location and anatomic configuration. The Pipeline Embolization Device (PED) is a flow diversion technique that successfully treats aneurysms by diverting blood flow away from the aneurysm and reconstructing the diseased parent artery by altering its hemodynamics.

CASE DESCRIPTION

We report 3 cases in which the PED was used to treat craniocervical carotid artery dissection with associated pseudoaneurysms. A single PED was used in the first case, 4 PEDs were used in the second case, and 3 PEDs and a PRECISE PRO RX carotid stent were placed in the third case. All 3 patients achieved full neurologic recovery postoperatively. Cerebral angiography performed postoperatively demonstrated revascularization, good laminar flow, and no in-stent or adjacent stenosis.

CONCLUSIONS

PED placement offers a safe and effective method of treating spontaneous or traumatic craniocervical carotid artery dissections with excellent neurologic outcomes postoperatively and complete long-term aneurysmal occlusion.