Propensity-adjusted cost analysis of radial versus femoral access for neuroendovascular procedures.

BACKGROUND: Transradial artery (TRA) access for neuroendovascular procedures is associated with fewer complications than transfemoral artery (TFA) access. This study compares hospital costs associated with TRA access to those associated with TFA access for neurointerventions. METHODS: Elective neuroendovascular procedures at a single center were retrospectively analyzed from October 1, 2018 to May 31, 2019. Hospital costs for each procedure were obtained from the hospital financial department. The primary outcome was the difference in the mean hospital costs after propensity adjustment between patients who underwent TRA compared with TFA access. RESULTS: Of the 338 elective procedures included, 63 (19%) were performed through TRA versus 275 (81%) through TFA access. Diagnostic procedures were more common in the TRA cohort (51 of 63, 81%) compared with the TFA cohort (197 of 275, 72%), but the difference was not significant (p=0.48). The TRA cohort had a shorter length of hospital stay (mean (SD) 0.3 (0.5) days) compared with the TFA cohort (mean 0.7 (1.3) days; p=0.02) and lower hospital costs (mean $12 968 ($6518) compared with the TFA cohort (mean $17 150 ($10 946); p=0.004). After propensity adjustment for age, sex, symptoms, angiographic findings, procedure type, sheath size, and catheter size, TRA access was associated with a mean hospital cost of $2514 less than that for TFA access (95% CI -$4931 to -$97; p=0.04). CONCLUSION: Neuroendovascular procedures performed through TRA access are associated with lower hospital costs than TFA procedures. The lower cost is likely due to a decreased length of hospital stay for TRA.

Perspective review on applications of optics in cerebral endovascular neurosurgery.

Cerebral endovascular neurosurgery has transformed the way we manage cerebrovascular disease. Several landmark trials have demonstrated the effectiveness of endovascular techniques leading to continued technological development and applications for various diseases. The utilization of optical technologies and devices is already underway in the field of endovascular neurosurgery. We discuss the contemporary paradigms, challenges, and current optical applications for the most common cerebrovascular diseases: carotid atherosclerotic disease, cerebral aneurysms, intracranial atherosclerosis, and dural arteriovenous fistulas. We also describe needs-based opportunities for future optical applications, with the goal of providing researchers a sense of where we feel optical technologies could impact the way we manage cerebral disease.

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

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

Outcomes after carotid endarterectomy among elderly dual Medicare-Medicaid-eligible patients.

OBJECTIVE: To determine whether patients who are dual eligible for Medicare and Medicaid benefits have outcomes after carotid endarterectomy (CEA) that are comparable to the outcomes of those eligible for Medicare alone. METHODS: The study cohort included fee-for-service Medicare beneficiaries ≥65 years of age who underwent CEA (ICD-9-CM code 38.12) between 2003 and 2010. Beneficiaries with ≥1 month of Medicaid coverage were considered dual eligible. We fit mixed models to assess the relationship between coverage (dual eligible vs Medicare only) and outcomes over time after adjustment for demographic and clinical characteristics. RESULTS: There were 53,773 dual-eligible and 452,182 Medicare-only beneficiaries hospitalized for CEA. The percentage of dual-eligible patients receiving CEA increased from 10.1% in 2003 to 11.5% in 2010, with no change in geographic distribution across the country. In adjusted analyses, dual-eligible vs Medicare-only beneficiaries had a higher rate of 30-day ischemic stroke or death; higher in-hospital, 30-day, and 1-year all-cause mortality; and higher 30-day all-cause readmission. Relative annual reductions in outcomes from 2003 to 2010 ranged from 2% to 5%, but there was no significant interaction between dual-eligible status and time. CONCLUSIONS: Dual-eligible beneficiaries had worse outcomes than those eligible for Medicare alone. Additional work is necessary to understand the reasons for this difference.

Predictors of Surgical Site Infection After Nonemergent Craniotomy: A Nationwide Readmission Database Analysis.

OBJECTIVE: Surgical site infections (SSIs) carry significant patient morbidity and mortality and are a major source of readmissions after craniotomy. Because of their deleterious effects on health care outcomes and costs, identifying modifiable risk factors holds tremendous value. However, because SSIs after craniotomy are rare and most existing data comprise single-institution studies with small sample sizes, many are likely underpowered to discern for such factors. The objective of this study was to use a large hetereogenous patient sample to determine SSI incidence after nonemergent craniotomy and identify factors associated with readmission and subsequent need for wound washout. METHODS: We used the 2010-2014 Nationwide Readmissions Database cohorts to discern for factors predictive of SSI and washout. RESULTS: We identified 93,920 nonemergent craniotomies. There were 2079 cases of SSI (2.2%) and 835 reoperations for washout (0.89%) within 30 days of index admission and there were 2761 cases of SSI (3.6%) and 1220 reoperations for washout (1.58%) within 90 days. Several factors were predictive of SSI in multivariate analysis, including tumor operations, external ventricular drain (EVD), age, length of stay, diabetes, discharge to an intermediate-care facility, insurance type, and hospital bed size. Many of these factors were similarly implicated in reoperation for washout. CONCLUSIONS: SSI incidence in neurosurgery is low and most readmissions occur within 30 days. Several factors predicted SSI after craniotomy, including operations for tumor, younger age, hospitalization length, diabetes, discharge to institutional care, larger hospital bed size, Medicaid insurance, and presence of an EVD. Diabetes and EVD placement may represent modifiable factors that could be explored in subsequent prospective studies for their associations with cranial SSIs.

The Utility of Routine Intensive Care Admission for Patients Undergoing Intracranial Neurosurgical Procedures: A Systematic Review.

BACKGROUND: Patients who have undergone intracranial neurosurgical procedures have traditionally been admitted to an intensive care unit (ICU) for close postoperative neurological observation. The purpose of this study was to systematically review the evidence for routine ICU admission in patients undergoing intracranial neurosurgical procedures and to evaluate the safety of alternative postoperative pathways. METHODS: We were interested in identifying studies that examined selected patients who presented for elective, non-emergent intracranial surgery whose postoperative outcomes were compared as a function of ICU versus non-ICU admission. A systematic review was performed in July 2016 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist of the Medline database. The search strategy was created based on the following key words: "craniotomy," "neurosurgical procedure," and "intensive care unit." RESULTS: The nine articles that satisfied the inclusion criteria yielded a total of 2227 patients. Of these patients, 879 were observed in a non-ICU setting. The most frequent diagnoses were supratentorial brain tumors, followed by patients with cerebrovascular diseases and infratentorial brain tumors. Three percent (30/879) of the patients originally assigned to floor or intermediate care status were transferred to the ICU. The most frequently observed neurological complications leading to ICU transfer were delayed postoperative neurological recovery, seizures, worsening of neurological deficits, hemiparesis, and cranial nerves deficits. CONCLUSION: Our systematic review demonstrates that routine postoperative ICU admission may not benefit carefully selected patients who have undergone elective intracranial neurosurgical procedures. In addition, limiting routine ICU admission may result in significant cost savings.

Emerging Technologies in Flow Diverters and Stents for Cerebrovascular Diseases.

PURPOSE OF REVIEW: Stents and flow diverters have revolutionized the treatment of cerebrovascular disease. Guglielmi coils, flexible microcatheters, and first-generation intracranial stents, such as Neuroform (Stryker Neurovascular) and Enterprise stents (Codman/DePuy-Synthes), have paved the way for the development of the Pipeline Embolization Device (PED) (ev3/Covidien/Medtronic) and other endovascular approaches. RECENT FINDINGS: This review discusses the historical development of flow diverter technologies from the PED to similar devices, such as the Surpass stent (Stryker Neurovascular), the Flow-Redirection Endoluminal Device (FRED; MicroVention, Inc.), the SILK stent (Balt Extrusion), and the p64 Flow Modulation Device (Phenox). In addition, the potential use of drug-eluting stents and various bioresorbable scaffolds (e.g., poly-L-lactic acid, magnesium), new developments in stent material (e.g., thin-film nitinol), design (e.g., biocompatible polymers, embedded microcircuitry, flow models), and potential applications for flow diverters will be considered. Endovascular treatment of cerebrovascular disease is rapidly advancing via continued development of new technology.

4D flow MRI assessment of extracranial-intracranial bypass: qualitative and quantitative evaluation of the hemodynamics.

INTRODUCTION: Our aim was to assess the feasibility of using time-resolved 3D phase-contrast (4D flow) MRI to characterize extracranial-intracranial (EC-IC) bypass. METHODS: We enrolled 32 patients who underwent EC-IC bypass (15 men, 17 women; mean age 66.4 years). In all, 16 underwent radial artery graft (RAG) bypass and 16 underwent superficial temporal artery (STA) bypass. 4D flow MRI, time-of-flight (TOF) magnetic resonance angiography (MRA), and computed tomography angiography (CTA) were performed. Bypass patency, flow direction, and blood flow volume (BFV) of each artery were determined by 4D flow MRI. Arterial diameters were measured by TOF-MRA and CTA. We compared RAG and STA bypasses by evaluating the flow direction and BFV of each artery. We evaluated the correlation between arterial diameters (measured by CTA or MRA) and the BFV and the detectability of flow direction (measured by 4D flow MRI) of each artery. RESULTS: 4D flow MRI confirmed the patency of each bypass artery. Flow direction of the M1 segment of the middle cerebral artery and BFV in the bypass artery differed between RAG and STA groups (p < 0.01). BFV in the bypass slightly correlated with the diameters on CTA (p < 0.05, R (2) = 0.287). Of the 29 arteries in the circle of Willis, nine were not depicted on 4D flow MRI. Cutoff values for arterial diameters on CTA and TOF-MRA for detecting the artery on 4D flow MRI were 2.4 and 1.8 mm, respectively. CONCLUSION: 4D flow MRI provided unique information for characterizing EC-IC bypasses, although this detectability is limited when addressing small arteries with slow flow.

Cranial neurosurgical 30-day readmissions by clinical indication.

OBJECT: Postsurgical readmissions are common and vary by procedure. They are significant drivers of increased expenditures in the health care system. Reducing readmissions is a national priority that has summoned significant effort and resources. Before the impact of quality improvement efforts can be measured, baseline procedure-related 30-day all-cause readmission rates are needed. The objects of this study were to determine population-level, 30-day, all-cause readmission rates for cranial neurosurgery and identify factors associated with readmission. METHODS: The authors identified patient discharge records for cranial neurosurgery and their 30-day all-cause readmissions using the Agency for Healthcare Research and Quality (AHRQ) State Inpatient Databases for California, Florida, and New York. Patients were categorized into 4 groups representing procedure indication based on ICD-9-CM diagnosis codes. Logistic regression models were developed to identify patient characteristics associated with readmissions. The main outcome measure was unplanned inpatient admission within 30 days of discharge. RESULTS: A total of 43,356 patients underwent cranial neurosurgery for neoplasm (44.23%), seizure (2.80%), vascular conditions (26.04%), and trauma (26.93%). Inpatient mortality was highest for vascular admissions (19.30%) and lowest for neoplasm admissions (1.87%; p < 0.001). Thirty-day readmissions were 17.27% for the neoplasm group, 13.89% for the seizure group, 23.89% for the vascular group, and 19.82% for the trauma group (p < 0.001). Significant predictors of 30-day readmission for neoplasm were Medicaid payer (OR 1.33, 95% CI 1.15-1.54) and fluid/electrolyte disorder (OR 1.44, 95% CI 1.29-1.62); for seizure, male sex (OR 1.74, 95% CI 1.17-2.60) and index admission through the emergency department (OR 2.22, 95% CI 1.45-3.43); for vascular, Medicare payer (OR 1.21, 95% CI 1.05-1.39) and renal failure (OR 1.52, 95% CI 1.29-1.80); and for trauma, congestive heart failure (OR 1.44, 95% CI 1.16-1.80) and coagulopathy (OR 1.51, 95% CI 1.25-1.84). Many readmissions had primary diagnoses identified by the AHRQ as potentially preventable. CONCLUSIONS: The frequency of 30-day readmission rates for patients undergoing cranial neurosurgery varied by diagnosis between 14% and 24%. Important patient characteristics and comorbidities that were associated with an increased readmission risk were identified. Some hospital-level characteristics appeared to be associated with a decreased readmission risk. These baseline readmission rates can be used to inform future efforts in quality improvement and readmission reduction.

Peripheral occlusive disease may provide the highest hospital margins despite rising costs.

OBJECTIVE: The objective of this study was to review vascular surgical financial trends in a tertiary care setting and to evaluate the impact of a vascular program within a health care system in the face of lower reimbursements and rising costs. METHODS: With use of Current Procedural Terminology codes and diagnosis-related groups, vascular categories of aortic disease, cerebrovascular disease, and peripheral occlusive disease (POCD) were identified at an academic tertiary health care center. Hospital margins were calculated for each of the defined categories by Health Quest cost accounting data cross-walked with Current Procedural Terminology codes, date of service, and admitting physician for each year from 2010 to 2012. RESULTS: All categories realized volume growth and a positive margin for the hospital. In comparison of 2010 and 2012, aortic cases showed an overall volume growth of 19%, revenue increase of 31%, and cost increase of 54%, resulting in an overall margin decrease of 7%. Cerebrovascular cases showed a 30% increase in volume growth, revenue increase of 13%, and cost increase of 5%, resulting in a margin increase of 18%. POCD cases showed overall volume growth of 35%, revenue increase of 37%, cost increase of 54%, and a margin increase of 15%. The margin for POCD exceeded the margin for aortic and cerebrovascular cases combined by 77%. CONCLUSIONS: In evaluating a vascular program's fiscal viability, volume-driven POCD was the only category producing growing hospital margins in the face of significant cost increases.

Worse outcomes for patients undergoing brain tumor and cerebrovascular procedures following the ACGME resident duty-hour restrictions.

OBJECT: On July 1, 2003, the Accreditation Council for Graduate Medical Education (ACGME) implemented duty-hour restrictions for resident physicians due to concerns for patient and resident safety. Though duty-hour restrictions have increased resident quality of life, studies have shown mixed results with respect to patient outcomes. In this study, the authors have evaluated the effect of duty-hour restrictions on morbidity, mortality, length of stay, and charges in patients who underwent brain tumor and cerebrovascular procedures. METHODS: The Nationwide Inpatient Sample was used to evaluate the effect of duty-hour restrictions on complications, mortality, length of stay, and charges by comparing the pre-reform (2000-2002) and post-reform (2005-2008) periods. Outcomes were compared between nonteaching and teaching hospitals using a difference-in-differences (DID) method. RESULTS: A total of 90,648 patients were included in the analysis. The overall complication rate was 11.7%, with the rates not significantly differing between the pre- and post-duty hour eras (p = 0.26). Examination of hospital teaching status revealed that complication rates decreased in nonteaching hospitals (12.1% vs 10.4%, p = 0.0004) and remained stable in teaching institutions (11.8% vs 11.9%, p = 0.73) in the post-reform era. Multivariate analysis demonstrated a significantly higher complication risk in teaching institutions (OR 1.33 [95% CI 1.11-1.59], p = 0.0022), with no significant change in nonteaching hospitals (OR 1.11 [95% CI 0.91-1.37], p = 0.31). A DID analysis to compare the magnitude in change between teaching and nonteaching institutions revealed that teaching hospitals had a significantly greater increase in complications during the post-reform era than nonteaching hospitals (p = 0.040). The overall mortality rate was 3.0%, with a significant decrease occurring in the post-reform era in both nonteaching (5.0% vs 3.2%, p < 0.0001) and teaching (3.2% vs 2.3%, p < 0.0001) hospitals. DID analysis to compare the changes in mortality between groups did not reveal a significant difference (p = 0.40). The mean length of stay for all patients was 8.7 days, with hospital stay decreasing from 9.2 days to 8.3 days in the post-reform era (p < 0.0001). The DID analysis revealed a greater length of stay decrease in nonteaching hospitals than teaching institutions, which approached significance (p = 0.055). Patient charges significantly increased in the post-reform era for all patients, increasing from $70,900 to $96,100 (p < 0.0001). The DID analysis did not reveal a significant difference between the changes in charges between teaching and nonteaching hospitals (p = 0.17). CONCLUSIONS: The implementation of duty-hour restrictions correlated with an increased risk of postoperative complications for patients undergoing brain tumor and cerebrovascular neurosurgical procedures. Duty-hour reform may therefore be associated with worse patient outcomes, contrary to its intended purpose. Due to the critical condition of many neurosurgical patients, this patient population is most sensitive and likely to be negatively affected by proposed future increased restrictions.

Disability in Italian neurosurgical patients: validity of the 12-item World Health Organization Disability Assessment Schedule.

The aim of the study was to assess factor structure, internal consistency and validity of the Italian version of the World Health Organization Disability Assessment Schedule 12-item version (WHODAS-12) in patients scheduled for neurosurgical procedures for brain tumours, cerebrovascular or spinal diseases. Disability was assessed with the WHODAS-12, quality of life with the eight-item European Health Interview Survey-Quality of Life, well-being with the Psychological General Well-Being Index-Short and general health with the Karnofsky Performance Status (KPS) scales. Factor analysis was used to confirm WHODAS-12 one-factor structure; root mean square error of approximation (RMSEA) and χ2/d.f. ratio were used to test the model fit. Internal consistency was assessed with Cronbach's α coefficient, item-total correlation and interitem correlation; convergent validity was assessed with Pearson's coefficient and discriminative validity was assessed with the t-test, dividing patients between those with KPS greater than 90 and KPS of 90 or less. The one-factor structure was confirmed (RMSEA=0.079; χ2/d.f.=2.16) and internal consistency was adequate. Correlations between the three outcome measures were significant, negative and moderate; the t-test showed disability scores to be statistically significantly higher in patients with KPS of 90 or less. Our results confirm factor structure and validity of WHODAS-12 in Italian neurosurgical inpatients; we therefore support its use in neurosurgery departments.

Racial and socioeconomic disparities in incidence of hospital-acquired complications following cerebrovascular procedures.

BACKGROUND: Patients with cerebrovascular disease undergo complex surgical procedures, often requiring prolonged inpatient hospitalization. Previous studies have demonstrated associations between racial/demographic factors and clinical outcomes in patients undergoing cerebrovascular procedures (CVPs). The Centers for Medicare and Medicaid Services have published a series of 11 hospital-acquired conditions (HACs) deemed "reasonably preventable" for which related costs of treatment are not reimbursed. We hypothesize that race and payer status disparities impact HAC frequency in patients undergoing CVPs and that HAC incidence is associated with length of stay and hospital costs. OBJECTIVE: To assess health disparities in HACs among the cerebrovascular neurosurgical patient population. METHODS: Data were collected from the Nationwide Inpatient Sample (NIS) database from 2002 to 2010. CVPs and HACs were identified by International Classification of Diseases, Ninth Revision, Clinical Modification diagnostic and procedure codes. HAC incidence was evaluated according to demographics including race, payer status, and median zip code income via multivariable analysis. Secondary outcomes of interest included length of stay and resulting inpatient charges. RESULTS: From 2002 to 2010, there were 1 290 883 CVP discharges with an HAC rate of 0.5%. Significant disparities in HAC frequency existed according to ethnicity and insurance provider. Minorities and Medicaid patients had increased frequency of HACs (P < .05), as well as prolonged length of stay and higher inpatient costs (P < .05). CONCLUSION: HAC incidence is associated with racial and socioeconomic factors in patients who undergo CVPs. Awareness of these disparities may lead to improved processes and protocol implementation, which might help to decrease the frequency of these potentially avoidable events.

Two-year vascular hospitalisation rates and associated costs in patients at risk of atherothrombosis in France and Germany: highest burden for peripheral arterial disease.

OBJECTIVES: To obtain Western European perspectives on the economic burden of atherothrombosis in patients with multiple risk factors only (MRF), cerebrovascular disease (CVD), coronary artery disease (CAD), and in the under-evaluated group of patients with peripheral arterial disease (PAD), we examined vascular-related hospitalisation rates and associated costs in France and Germany. DESIGN: The prospective REACH Registry enrolled 4693 patients in France, and 5594 patients in Germany (from December 2003 until June 2004). METHODS: For each country, 2-year rates and costs associated with cardiovascular events and vascular-related hospitalisations were examined for patients with MRF, CVD, CAD, and PAD. RESULTS: Two-year hospitalisation costs were highest for patients with PAD (3182.1€ for France; 2724.4€ for Germany) and lowest for the MRF group (749.1€ for France; 503.3€ for Germany). Peripheral revascularizations and amputations were the greatest contributors to costs for all risk groups. Across all PAD subgroups, peripheral procedures constituted approximately half of the 2-year costs. CONCLUSION: Hospitalisation rates and costs associated with atherothrombotic disease in France and Germany are high, especially so for patients with PAD.

Endovascular neurosurgery in the United States: a survey of 59 vascular neurosurgeons with endovascular training.

OBJECTIVE: We sought to assess general aspects of endovascular neurosurgery training, practice, and management for the treatment of intracranial aneurysms, arteriovenous malformations, acute ischemic stroke, and extracranial or intracranial occlusive disease within neurosurgery training and practice in the United States. METHODS: A questionnaire was sent electronically to 80 U.S. neurosurgeons with endovascular training. RESULTS: Fifty-nine surveys (74%) were returned. Survey responses illustrated different practice patterns and varying management of cerebrovascular disorders by neurosurgeons with endovascular training. CONCLUSION: Our findings provide a snapshot of current neurosurgical endovascular practices in the United States.

Reporting standards for angioplasty and stent-assisted angioplasty for intracranial atherosclerosis.

BACKGROUND AND PURPOSE: Intracranial cerebral atherosclerosis causes ischemic stroke in a significant number of patients. Technological advances over the past 10 years have enabled endovascular treatment of intracranial atherosclerotic stenosis. The number of patients treated with angioplasty or stent-assisted angioplasty for this condition is increasing. Given the lack of universally accepted definitions, the goal of this document is to provide consensus recommendations for reporting standards, terminology, and written definitions when reporting clinical and radiological evaluation, technique, and outcome of endovascular treatment using angioplasty or stent-assisted angioplasty for stenotic and occlusive intracranial atherosclerosis. SUMMARY OF REPORT: This article was written under the auspices of Joint Writing Group of the Technology Assessment Committee, Society of NeuroInterventional Surgery, Society of Interventional Radiology; Joint Section on Cerebrovascular Neurosurgery of the American Association of Neurological Surgeons and Congress of Neurological Surgeons; and the Section of Stroke and Interventional Neurology of the American Academy of Neurology. A computerized search of the National Library of Medicine database of literature (PubMed) from January 1997 to December 2007 was conducted with the goal to identify published endovascular cerebrovascular interventional data in stenotic intracranial atherosclerosis that could be used as benchmarks for quality assessment. We sought to identify those risk adjustment variables that affect the likelihood of success and complications. This document offers the rationale for different clinical and technical considerations that may be important during the design of clinical trials for endovascular treatment of intracranial stenotic and occlusive atherosclerosis. Included in this guidance document are suggestions for uniform reporting standards for such trials. These definitions and standards are primarily intended for research purposes; however, they should also be helpful in clinical practice and applicable to all publications. CONCLUSIONS: In summary, the definitions proposed represent recommendations for constructing useful research data sets. The intent is to facilitate production of scientifically rigorous results capable of reliable comparisons between and among similar studies. In some cases, the definitions contained here are recommended by consensus of a panel of experts in this writing group for consistency in reporting and publication. These definitions should allow different groups to publish results that are directly comparable.

Simulation of cerebral hemodynamics for preoperative risk assessment.

BACKGROUND: An important part of the medical treatment of many cerebrovascular diseases is the occlusion of brain supplying arteries. Until now, the risk of this intervention can only be estimated by invasive diagnostics including the risk of cerebrovascular accidents. METHODS AND RESULTS: As a supporting tool, a computer model of the circle of Willis was designed. The model is based upon linear differential equations describing electrotechnical circuits extended non-linearly. By these means, time continuous simulations of different states and the online observation of all calculated state variables such as blood pressure and blood flow in every modeled vessel became feasible. For individual simulations, model parameters were determined by MR-angiography and boundary values by simultaneous Duplex-measurements in both carotid and vertebral arteries. State variables generated by the model behaved physiologically and the reaction of individual cerebrovascular systems in critical situations could be investigated by special scenarios. Inaccuracies concerning the determination of model parameters and boundary values of the used differential equations are likely to be resolved in the near future through a more careful and technically improved determination of these values. CONCLUSIONS: Computer models of subjects were created taking in account the individual anatomical and non-linear physical properties of real vascular systems supplying the brain. Thereby information could be obtained concerning the hemodynamic effects of an iatrogenic vascular occlusion.