Comparative Outcomes of Mechanical Thrombectomy in Acute Ischemic Stroke Patients with ASPECTS 2-3 vs. 4-5.

BACKGROUND: The influence of Alberta Stroke Program Early CT Score (ASPECTS) on outcomes following mechanical thrombectomy (MT) for acute ischemic stroke (AIS) patients with low ASPECTS remains unknown. In this study, we compared the outcomes of AIS patients treated with MT for large vessel occlusion (LVO) categorized by ASPECTS value. METHODS: We conducted a retrospective analysis involving 305 patients with AIS caused by LVO, defined as the occlusion of the internal carotid artery and/or the M1 segments of the middle cerebral artery, stratified into two groups: ASPECTS 2-3 and 4-5. The primary outcome was favorable outcome defined as a 90-day modified Rankin Scale (mRS) score of 0-3. Secondary outcomes were 90-day mRS 0-2, 90-day mortality, any intracerebral hemorrhage (ICH), and symptomatic ICH (sICH). We performed multivariable logistic regression analysis to evaluate the impact of ASPECTS 2-3 vs. 4-5 on outcomes. RESULTS: Fifty-nine patients (19.3%) had ASPECTS 2-3 and 246 (80.7%) had ASPECTS 4-5. Favorable outcomes showed no significant difference between the two groups (adjusted odds ratio [aOR]= 1.13, 95% confidence interval [CI]: 0.52-2.41, p=0.80). There were also no significant differences in 90-day mRS 0-2 (aOR= 1.65, 95% CI: 0.66-3.99, p=0.30), 90-day mortality (aOR= 1.14, 95% CI: 0.58-2.20, p=0.70), any ICH (aOR= 0.54, 95% CI: 0.28-1.00, p=0.06), and sICH (aOR= 0.70, 95% CI: 0.27-1.63, p = 0.40) between the groups. CONCLUSIONS: AIS patients with LVO undergoing MT with ASPECTS 2-3 had similar outcomes compared to ASPECTS 4-5.

Modeling the Mechanical Microenvironment of Coiled Cerebral Aneurysms.

Successful occlusion of cerebral aneurysms using coil embolization is contingent upon stable thrombus formation, and the quality of the thrombus depends upon the biomechanical environment. The goal of this study was to investigate how coil embolization alters the mechanical micro-environment within the aneurysm dome. Inertialess particles were injected in three-dimensional, computational simulations of flow inside patient aneurysms using patient-specific boundary conditions. Coil embolization was simulated as a homogenous porous medium of known permeability and inertial constant. Lagrangian particle tracking was used to calculate the residence time and shear stress history for particles in the flow before and after treatment. The percentage of particles entering the aneurysm dome correlated with the neck surface area before and after treatment (pretreatment: R2 = 0.831, P < 0.001; post-treatment: R2 = 0.638, P < 0.001). There was an inverse relationship between the change in particles entering the dome and coil packing density (R2 = 0.600, P < 0.001). Following treatment, the particles with the longest residence times tended to remain within the dome even longer while accumulating lower shear stress. A significant correlation was observed between the treatment effect on residence time and the ratio of the neck surface area to porosity (R2 = 0.390, P = 0.007). The results of this study suggest that coil embolization triggers clot formation within the aneurysm dome via a low shear stress-mediated pathway. This hypothesis links independently observed findings from several benchtop and clinical studies, furthering our understanding of this treatment strategy.

A Novel Patient-Specific Computational Fluid Dynamics Study of the Activation of Primary Collateral Pathways in the Circle of Willis During Vasospasm.

The Circle of Willis (CoW) is a redundant network of blood vessels that perfuses the brain. The ringlike anatomy mitigates the negative effects of stroke by activating collateral pathways that help maintain physiological perfusion. Previous studies have investigated the activation of these pathways during embolic stroke and internal carotid artery occlusion. However, the role of collateral pathways during cerebral vasospasm-an involuntary constriction of blood vessels after subarachnoid hemorrhage-is not well-documented. This study presents a novel technique to create patient-specific computational fluid dynamics (CFD) simulations of the Circle of Willis before and during vasospasm. Computed tomographic angiography (CTA) scans are segmented to model the vasculature, and transcranial Doppler ultrasound (TCD) measurements of blood flow velocity are applied as boundary conditions. Bayesian analysis leverages information about the uncertainty in the measurements of vessel diameters and velocities to find an optimized parameter set that satisfies mass conservation and that is applied in the final simulation. With this optimized parameter set, the diameters, velocities, and flow rates fall within typical literature values. Virtual angiograms modeled using passive scalar transport agree closely with clinical angiography. A sensitivity analysis quantifies the changes in collateral flow rates with respect to changes in the inlet and outlet flow rates. This analysis can be applied in the future to a cohort of patients to investigate the relationship between the locations and severities of vasospasm, the patient-to-patient anatomical variability in the Circle of Willis, and the activation of collateral pathways.

Endothelial Responses to Curvature-Induced Flow Patterns in Engineered Cerebral Aneurysms.

Hemodynamic factors have long been associated with clinical outcomes in the treatment of cerebral aneurysms. Computational studies of cerebral aneurysm hemodynamics have provided valuable estimates of the mechanical environment experienced by the endothelium in both the parent vessel and aneurysmal dome walls and have correlated them with disease state. These computational-clinical studies have recently been correlated with the response of endothelial cells (EC) using either idealized or patient-specific models. Here, we present a robust workflow for generating anatomic-scale aneurysm models, establishing luminal cultures of ECs at physiological relevant flow profiles, and comparing EC responses to curvature mediated flow. We show that flow patterns induced by parent vessel curvature produce changes in wall shear stress (WSS) and wall shear stress gradients (WSSG) that are correlated with differences in cell morphology and cellular protein localization. Cells in higher WSS regions align better with the flow and display strong Notch1-extracellular domain (ECD) polarization, while, under low WSS, differences in WSSG due to curvature change were associated with less alignment and attenuation of Notch1-ECD polarization in ECs of the corresponding regions. These proof-of-concept results highlight the use of engineered cellularized aneurysm models for connecting computational fluid dynamics to the underlying endothelial biology that mediates disease.

Safety and efficacy of the Pipeline Flex embolization device with Shield Technology for the acute treatment of ruptured internal carotid artery pseudoaneurysms: a multi-institution case series.

OBJECTIVE: Ruptured blister, dissecting, and iatrogenic pseudoaneurysms are rare pathologies that pose significant challenges from a treatment standpoint. Endovascular treatment via flow diversion represents an increasingly popular option; however, drawbacks include the requirement for dual antiplatelet therapy and the potential for thromboembolic complications, particularly acute complications in the ruptured setting. The Pipeline Flex embolization device with Shield Technology (PED-Shield) offers reduced material thrombogenicity, which may aid in the treatment of ruptured internal carotid artery pseudoaneurysms. METHODS: The authors conducted a multi-institution, retrospective case series to determine the safety and efficacy of PED-Shield for the treatment of ruptured blister, dissecting, and iatrogenic pseudoaneurysms of the internal carotid artery. Clinical, radiographic, treatment, and outcomes data were collected. RESULTS: Thirty-three patients were included in the final analysis. Seventeen underwent placement of a single device, and 16 underwent placement of two devices. No thromboembolic complications occurred. Four patients were maintained on aspirin alone, and all others were treated with long-term dual antiplatelet therapy. Among patients with 3-month follow-up, 93.8% had a modified Rankin Scale score of 0-2. Complete occlusion at follow-up was observed in 82.6% of patients. CONCLUSIONS: PED-Shield represents a new option for the treatment of ruptured blister, dissecting, and iatrogenic pseudoaneurysms of the internal carotid artery. The reduced material thrombogenicity appeared to improve the safety of the PED-Shield device, as this series demonstrated no thromboembolic complications even among patients treated with only single antiplatelet therapy. The efficacy of PED-Shield reported in this series, particularly with placement of two devices, demonstrates its potential as a first-line treatment option for these pathologies.

A smartphone pupillometry tool for detection of acute large vessel occlusion.

OBJECTIVES: Pupillary light reflex (PLR) parameters can be used as quantitative biomarkers of neurological function. Since digital infrared pupillometry is expensive, we sought to examine alterations in PLR parameters using a smartphone quantitative pupillometry platform in subjects with acute ischemic stroke (AIS). MATERIALS AND METHODS: Patients were enrolled if they presented to the emergency department as a stroke code activation and had evidence of a large vessel occlusion (LVO) on computed tomography angiography. Controls were enrolled from hospital staff. A smartphone pupillometer was used in AIS patients with LVO pre-mechanical thrombectomy, immediately post-thrombectomy, and at 24 h post-thrombectomy. Clinical and demographic data were collected, along with the proprietary Neurological Pupil index (NPi) score from the NPi-200 digital infrared pupillometer. PLR parameters were compared using mean differences. The absolute and non-absolute inter-eye difference in each parameter for each subject were also analyzed by measuring 1 - (R:L) to determine alteration in the equilibrium between subject pupils. The NPi was analyzed for mean differences between cohorts. RESULTS: Healthy controls (n = 132) and AIS patients (n = 31) were enrolled. Significant differences were observed in PLR parameters for healthy subjects when compared to pre-thrombectomy subjects in both mean and absolute inter-eye differences after post hoc Bonferroni correction. The proprietary NPi score was not significantly different for all groups and comparisons. CONCLUSIONS: Significant alterations in the PLR were observed in AIS patients with LVO before thrombectomy, indicating the potential use of smartphone pupillometry for detection of LVO.

International controlled study of revascularization and outcomes following COVID-positive mechanical thrombectomy.

BACKGROUND AND PURPOSE: Previous studies suggest that mechanisms and outcomes in patients with COVID-19-associated stroke differ from those in patients with non-COVID-19-associated strokes, but there is limited comparative evidence focusing on these populations. The aim of this study, therefore, was to determine if a significant association exists between COVID-19 status with revascularization and functional outcomes following thrombectomy for large vessel occlusion (LVO), after adjustment for potential confounding factors. METHODS: A cross-sectional, international multicenter retrospective study was conducted in consecutively admitted COVID-19 patients with concomitant acute LVO, compared to a control group without COVID-19. Data collected included age, gender, comorbidities, clinical characteristics, details of the involved vessels, procedural technique, and various outcomes. A multivariable-adjusted analysis was conducted. RESULTS: In this cohort of 697 patients with acute LVO, 302 had COVID-19 while 395 patients did not. There was a significant difference (p < 0.001) in the mean age (in years) and gender of patients, with younger patients and more males in the COVID-19 group. In terms of favorable revascularization (modified Thrombolysis in Cerebral Infarction [mTICI] grade 3), COVID-19 was associated with lower odds of complete revascularization (odds ratio 0.33, 95% confidence interval [CI] 0.23-0.48; p < 0.001), which persisted on multivariable modeling with adjustment for other predictors (adjusted odds ratio 0.30, 95% CI 0.12-0.77; p = 0.012). Moreover, endovascular complications, in-hospital mortality, and length of hospital stay were significantly higher among COVID-19 patients (p < 0.001). CONCLUSION: COVID-19 was an independent predictor of incomplete revascularization and poor functional outcome in patients with stroke due to LVO. Furthermore, COVID-19 patients with LVO were more often younger and had higher morbidity/mortality rates.

De novo epilepsy after microsurgical resection of brain arteriovenous malformations.

OBJECTIVE: Seizures are the second most common presenting symptom of brain arteriovenous malformations (bAVMs) after hemorrhage. Risk factors for preoperative seizures and subsequent seizure control outcomes have been well studied. There is a paucity of literature on postoperative, de novo seizures in initially seizure-naïve patients who undergo resection. Whereas this entity has been documented after craniotomy for a wide variety of neurosurgically treated pathologies including tumors, trauma, and aneurysms, de novo seizures after bAVM resection are poorly studied. Given the debilitating nature of epilepsy, the purpose of this study was to elucidate the incidence and risk factors associated with de novo epilepsy after bAVM resection. METHODS: A retrospective review of patients who underwent resection of a bAVM over a 15-year period was performed. Patients who did not present with seizure were included, and the primary outcome was de novo epilepsy (i.e., a seizure disorder that only manifested after surgery). Demographic, clinical, and radiographic characteristics were compared between patients with and without postoperative epilepsy. Subgroup analysis was conducted on the ruptured bAVMs. RESULTS: From a cohort of 198 patients who underwent resection of a bAVM during the study period, 111 supratentorial ruptured and unruptured bAVMs that did not present with seizure were included. Twenty-one patients (19%) developed de novo epilepsy. One-year cumulative rates of developing de novo epilepsy were 9% for the overall cohort and 8.5% for the cohort with ruptured bAVMs. There were no significant differences between the epilepsy and no-epilepsy groups overall; however, the de novo epilepsy group was younger in the cohort with ruptured bAVMs (28.7 ± 11.7 vs 35.1 ± 19.9 years; p = 0.04). The mean time between resection and first seizure was 26.0 ± 40.4 months, with the longest time being 14 years. Subgroup analysis of the ruptured and endovascular embolization cohorts did not reveal any significant differences. Of the patients who developed poorly controlled epilepsy (defined as Engel class III-IV), all had a history of hemorrhage and half had bAVMs located in the temporal lobe. CONCLUSIONS: De novo epilepsy after bAVM resection occurs at an annual cumulative risk of 9%, with potentially long-term onset. Younger age may be a risk factor in patients who present with rupture. The development of poorly controlled epilepsy may be associated with temporal lobe location and a delay between hemorrhage and resection.

Qualitative and Quantitative Wall Enhancement on Magnetic Resonance Imaging Is Associated With Symptoms of Unruptured Intracranial Aneurysms.

BACKGROUND AND PURPOSE: Aneurysmal wall enhancement (AWE) on vessel wall magnetic resonance imaging (VW-MRI) has been described as a new imaging biomarker of unstable unruptured intracranial aneurysms (UIAs). Previous studies of symptomatic UIAs are limited due to small sample sizes and lack of AWE quantification. Our study aims to investigate whether qualitative and quantitative assessment of AWE can differentiate symptomatic and asymptomatic UIAs. METHODS: Consecutive patients with UIAs were prospectively recruited for vessel wall magnetic resonance imaging at 3T from October 2014 to October 2019. UIAs were categorized as symptomatic if presenting with sentinel headache or oculomotor nerve palsy directly related to the aneurysm. Evaluation of wall enhancement included enhancement pattern (0=none, 1=focal, and 2=circumferential) and quantitative wall enhancement index (WEI). Univariate and multivariate analyses were used to identify the parameters associated with symptoms. RESULTS: Two hundred sixty-seven patients with 341 UIAs (93 symptomatic and 248 asymptomatic) were included in this study. Symptomatic UIAs more frequently showed circumferential AWE than asymptomatic UIAs (66.7% versus 17.3%, P<0.001), as well as higher WEI (median [interquartile range], 1.3 [1.0-1.9] versus 0.3 [0.1-0.9], P<0.001). In multivariate analysis, both AWE pattern and WEI were independent factors associated with symptoms (odds ratio=2.03 across AWE patterns [95% CI, 1.21-3.39], P=0.01; odds ratio=3.32 for WEI [95% CI, 1.51-7.26], P=0.003). The combination of AWE pattern and WEI had an area under the curve of 0.91 to identify symptomatic UIAs, with a sensitivity of 95.7% and a specificity of 73.4%. CONCLUSIONS: In a large cohort of UIAs with vessel wall magnetic resonance imaging, both AWE pattern and WEI were independently associated with aneurysm-related symptoms. The qualitative and quantitative features of AWE can potentially be used to identify unstable intracranial aneurysms.

Effect of Hispanic Status in Mechanical Thrombectomy Outcomes After Ischemic Stroke: Insights From STAR.

Background and Purpose: Epidemiological studies have shown racial and ethnic minorities to have higher stroke risk and worse outcomes than non-Hispanic Whites. In this cohort study, we analyzed the STAR (Stroke Thrombectomy and Aneurysm Registry) database, a multi-institutional database of patients who underwent mechanical thrombectomy for acute large vessel occlusion stroke to determine the relationship between mechanical thrombectomy outcomes and race. Methods: Patients who underwent mechanical thrombectomy between January 2017 and May 2020 were analyzed. Data included baseline characteristics, vascular risk factors, complications, and long-term outcomes. Functional outcomes were assessed with respect to Hispanic status delineated as non-Hispanic White (NHW), non-Hispanic Black (NHB), or Hispanic patients. Multivariate analysis was performed to identify variables associated with unfavorable outcome or modified Rankin Scale ≥3 at 90 days. Results: Records of 2115 patients from the registry were analyzed. Median age of Hispanic patients undergoing mechanical thrombectomy was 60 years (72­84), compared with 63 years (54­74) for NHB, and 71 years (60­80) for NHW patients (P<0.001). Hispanic patients had a higher incidence of diabetes (41%; P<0.001) and hypertension (82%; P<0.001) compared with NHW and NHB patients. Median procedure time was shorter in Hispanics (36 minutes) compared to NHB (39 minutes) and NHW (44 minutes) patients (P<0.001). In multivariate analysis, Hispanic patients were less likely to have favorable outcome (odds ratio, 0.502 [95% CI, 0.263­0.959]), controlling for other significant predictors (age, admission National Institutes Health Stroke Scale, onset to groin time, number of attempts, procedure time). Conclusions: Hispanic patients are less likely to have favorable outcome at 90 days following mechanical thrombectomy compared to NHW or NHB patients. Further prospective studies are required to validate our findings.

Management of Moderate Blunt Thoracic Aortic Injuries in Patients with Intracranial Hemorrhage.

BACKGROUND: Blunt thoracic aortic injuries (BTAIs) are the second most common cause of death due to blunt-force trauma in the United States. Patients with minimal injuries do not typically require surgical repair, whereas patients with severe injuries are treated emergently. Moderate aortic injuries are repaired in a semielective fashion, but the optimal management of patients with moderate BTAI with associated intracranial hemorrhage (ICH) is unknown. We sought to analyze the management and outcomes of patients presenting with concomitant moderate BTAI and ICH. METHODS: Consecutive patients who received a thoracic endovascular aortic repair (TEVAR) at our institution for treatment of moderate BTAI between January 2014 and December 2017 were retrospectively reviewed as part of an institutional review board-approved protocol. Patients were classified by our BTAI classification into "minimal", "moderate", or "severe". ICH was identified on computed tomography scan and its severity determined by the neurosurgical team. Outcome measures included surgical timing and surgical outcomes. RESULTS: Fifty-two patients had a moderate BTAI and underwent TEVAR, 20 (38 %) of whom presented with ICH. Median time from admission to surgery was 58.5 hr for patients with ICH and 26.5 hr for non-ICH patients. Intraoperative heparin was administered in all patients without ICH and in 19 of 20 (95%) patients with ICH after the ICH met criteria for stability. Protamine reversal was utilized in 80% of patients with ICH and 75% of non-ICH patients. No patient developed ischemic stroke or spinal cord ischemia. Worsening ICH was seen in only one patient, who also received heparin infusion for pulmonary embolus 24 hr before TEVAR. There were no aortic-related mortalities in either group. Thirty-day all-cause mortality was 5% for patients with ICH and 3% for non-ICH patients. CONCLUSIONS: Patients with moderate BTAI and stable ICH are not at increased risk of TEVAR-related complications. Administration of intraoperative heparin during TEVAR appears to be safe and does not worsen ICH.

Lagrangian Trajectory Simulation of Platelets and Synchrotron Microtomography Augment Hemodynamic Analysis of Intracranial Aneurysms Treated With Embolic Coils.

As frequency of endovascular treatments for intracranial aneurysms increases, there is a growing need to understand the mechanisms for coil embolization failure. Computational fluid dynamics (CFD) modeling often simplifies modeling the endovascular coils as a homogeneous porous medium (PM), and focuses on the vascular wall endothelium, not considering the biomechanical environment of platelets. These assumptions limit the accuracy of computations for treatment predictions. We present a rigorous analysis using X-ray microtomographic imaging of the coils and a combination of Lagrangian (platelet) and Eulerian (endothelium) metrics. Four patient-specific, anatomically accurate in vitro flow phantoms of aneurysms are treated with the same patient-specific endovascular coils. Synchrotron tomography scans of the coil mass morphology are obtained. Aneurysmal hemodynamics are computationally simulated before and after coiling, using patient-specific velocity/pressure measurements. For each patient, we analyze the trajectories of thousands of platelets during several cardiac cycles, and calculate residence times (RTs) and shear exposure, relevant to thrombus formation. We quantify the inconsistencies of the PM approach, comparing them with coil-resolved (CR) simulations, showing the under- or overestimation of key hemodynamic metrics used to predict treatment outcomes. We fully characterize aneurysmal hemodynamics with converged statistics of platelet RT and shear stress history (SH), to augment the traditional wall shear stress (WSS) on the vascular endothelium. Incorporating microtomographic scans of coil morphology into hemodynamic analysis of coiled intracranial aneurysms, and augmenting traditional analysis with Lagrangian platelet metrics improves CFD predictions, and raises the potential for understanding and clinical translation of computational hemodynamics for intracranial aneurysm treatment outcomes.

Middle meningeal artery embolization treatment of nonacute subdural hematomas in the elderly: a multiinstitutional experience of 151 cases.

OBJECTIVE: The incidence of already common chronic subdural hematomas (CSDHs) and other nonacute subdural hematomas (NASHs) in the elderly is expected to rise as the population ages over the coming decades. Surgical management is associated with recurrence and exposes elderly patients to perioperative and operative risks. Middle meningeal artery (MMA) embolization offers the potential for a minimally invasive, less morbid treatment in this age group. The clinical and radiographic outcomes after MMA embolization treatment for NASHs have not been adequately described in elderly patients. In this paper, the authors describe the clinical and radiographic outcomes after 151 cases of MMA embolization for NASHs among 121 elderly patients. METHODS: In a retrospective review of a prospectively maintained database across 15 US academic centers, the authors identified patients aged ≥ 65 years who underwent MMA embolization for the treatment of NASHs between November 2017 and February 2020. Patient demographics, comorbidities, clinical and radiographic factors, treatment factors, and clinical outcomes were abstracted. Subgroup analysis was performed comparing elderly (age 65-79 years) and advanced elderly (age > 80 years) patients. RESULTS: MMA embolization was successfully performed in 98% of NASHs (in 148 of 151 cases) in 121 patients. Seventy elderly patients underwent 87 embolization procedures, and 51 advanced elderly patients underwent 64 embolization procedures. Elderly and advanced elderly patients had similar rates of embolization for upfront (46% vs 61%), recurrent (39% vs 33%), and prophylactic (i.e., with concomitant surgical intervention; 15% vs 6%) NASH treatment. Transfemoral access was used in most patients, and the procedure time was approximately 1 hour in both groups. Particle embolization with supplemental coils was most common, used in 51% (44/87) and 44% (28/64) of attempts for the elderly and advanced elderly groups, respectively. NASH thickness decreased significantly from initial thickness to 6 weeks, with additional decrease in thickness observed in both groups at 90 days. At longest follow-up, the treated NASHs had stabilized or improved in 91% and 98% of the elderly and advanced elderly groups, respectively, with > 50% improvement seen in > 60% of patients for each group. Surgical rescue was necessary in 4.6% and 7.8% of cases, and the overall mortality was 8.6% and 3.9% for elderly and advanced elderly patients, respectively. CONCLUSIONS: MMA embolization can be used safely and effectively as an alternative or adjunctive minimally invasive treatment for NASHs in elderly and advanced elderly patients.

The ability of magnetic resonance black blood vessel wall imaging to evaluate blunt cerebrovascular injury following acute trauma.

BACKGROUND AND PURPOSE: Blunt cerebrovascular injury (BCVI) is associated with a significant risk of ischemic stroke when left untreated. Cross-sectional imaging is vital to early BCVI diagnosis and treatment; however, conventional luminal vessel imaging is limited in its ability to evaluate for vessel wall pathology. The purpose of this study is to evaluate the ability of vessel wall magnetic resonance imaging (VWI) to detect and evaluate BCVI in acutely injured trauma patients relative to neck computed tomographic angiography (CTA). MATERIALS AND METHODS: Trauma patients with suspected BCVI on initial neck CTA were prospectively recruited for VWI evaluation. Two neuroradiologists blinded to patient clinical history and CTA findings evaluated each artery independently on VWI and noted the presence and grade of BCVI. These results were subsequently compared to neck CTA findings relative to expert clinical consensus review. Interrater reliability of VWI for detecting BCVI was evaluated using a weighted Cohen κ-statistic. RESULTS: Ten trauma patients (40 cervical arteries) were prospectively evaluated using both CTA and VWI. Out of 18 vascular lesions identified as suspicious for BCVI on CTA, six lesions were determined to represent true BCVI by expert consensus review. There was almost perfect agreement between VWI and expert consensus regarding the presence and grade of BCVI (κ=0.82). This agreement increased when considering only low grade BCVI. There was only fair agreement between CTA and expert clinical consensus (κ=0.36). This agreement decreased when considering only low grade BCVI. CONCLUSIONS: VWI can potentially accurately identify and evaluate BCVI in acutely injured trauma patients with excellent inter-rater reliability.

Transcranial Doppler ultrasonography in neurological surgery and neurocritical care.

Transcranial Doppler (TCD) ultrasonography is an inexpensive, noninvasive means of measuring blood flow within the arteries of the brain. In this review, the authors outline the technology underlying TCD ultrasonography and describe its uses in patients with neurosurgical diseases. One of the most common uses of TCD ultrasonography is monitoring for vasospasm following subarachnoid hemorrhage. In this setting, elevated blood flow velocities serve as a proxy for vasospasm and can herald the onset of ischemia. TCD ultrasonography is also useful in the evaluation and management of occlusive cerebrovascular disease. Monitoring for microembolic signals enables stratification of stroke risk due to carotid stenosis and can also be used to clarify stroke etiology. TCD ultrasonography can identify patients with exhausted cerebrovascular reserve, and after extracranial-intracranial bypass procedures it can be used to assess adequacy of flow through the graft. Finally, assessment of cerebral autoregulation can be performed using TCD ultrasonography, providing data important to the management of patients with severe traumatic brain injury. As the clinical applications of TCD ultrasonography have expanded over time, so has their importance in the management of neurosurgical patients. Familiarity with this diagnostic tool is crucial for the modern neurological surgeon.

Magnetic resonance vessel wall imaging in cerebrovascular diseases

Cerebrovascular diseases manifest as abnormalities of and disruption to the intracranial vasculature and its capacity to carry blood to the brain. However, the pathogenesis of many cerebrovascular diseases begins in the vessel wall. Traditional luminal and perfusion imaging techniques do not provide adequate information regarding the differentiation, onset, or progression of disease. Intracranial high-resolution MR vessel wall imaging (VWI) has emerged as an invaluable technique for understanding and evaluating cerebrovascular diseases. The location and pattern of contrast enhancement in intracranial VWI provides new insight into the inflammatory etiology of cerebrovascular diseases and has potential to permit earlier diagnosis and treatment. In this report, technical considerations of VWI are discussed and current applications of VWI in vascular malformations, blunt cerebrovascular injury/dissection, and steno-occlusive cerebrovascular vasculopathies are reviewed.

Added Value of Vessel Wall Magnetic Resonance Imaging in the Differentiation of Moyamoya Vasculopathies in a Non-Asian Cohort.

BACKGROUND AND PURPOSE: Although studies have evaluated the differential imaging of moyamoya disease and atherosclerosis, none have investigated the added value of vessel wall magnetic resonance imaging (MRI). This study evaluates the added diagnostic value of vessel wall MRI in differentiating moyamoya disease, atherosclerotic-moyamoya syndrome (A-MMS), and vasculitic-MMS (V-MMS) with a multicontrast protocol. METHODS: We retrospectively reviewed the carotid artery territories of patients with clinically defined vasculopathies (moyamoya disease, atherosclerosis, and vasculitis) and steno-occlusive intracranial carotid disease. Two neuroradiologists, blinded to clinical data reviewed the luminal imaging of each carotid, evaluating collateral extent and making a presumed diagnosis with diagnostic confidence. After 3 weeks, the 2 readers reviewed the luminal imaging+vessel wall MRI for the presence, pattern and intensity of postcontrast enhancement, T2 signal characteristics, pattern of involvement, and presumed diagnosis and confidence. RESULTS: Ten A-MMS, 3 V-MMS, and 8 moyamoya disease cases with 38 affected carotid segments were included. There was significant improvement in diagnostic accuracy with luminal imaging+vessel wall MRI when compared with luminal imaging (87% versus 32%, P<0.001). The most common vessel wall MRI findings for moyamoya disease were nonenhancing, nonremodeling lesions without T2 heterogeneity; for A-MMS eccentric, remodeling, and T2 heterogeneous lesions with mild/moderate and homogeneous/heterogeneous enhancement; and for V-MMS concentric lesions with homogeneous, moderate enhancement. Inter-reader agreement was moderate to substantial for all vessel wall MRI characteristics (κ=0.46-0.86) and fair for collateral grading (κ=0.35). There was 11% inter-reader agreement for diagnosis on luminal imaging when compared with 82% for luminal imaging+vessel wall MRI (P<0.001). CONCLUSIONS: Vessel wall MRI can significantly improve the differentiation of moyamoya vasculopathies when combined with traditional imaging techniques.

Natural History and Management of Blunt Traumatic Pseudoaneurysms of the Internal Carotid Artery: The Harborview Algorithm Based Off a 10-Year Experience.

OBJECTIVE: To define the natural history of, and treatment strategy for, blunt traumatic internal carotid artery (ICA) pseudoaneurysms. BACKGROUND: The natural history and management of traumatic ICA pseudoaneurysms is controversial. METHODS: We retrospectively identified all traumatic ICA pseudoaneurysms diagnosed on head/neck computed tomographic angiography at a high-volume trauma center over a 10-year period. Radiographic and clinical data were recorded, and a treatment algorithm was derived. RESULTS: Forty-three pseudoaneurysms were diagnosed in 39 patients. All patients were treated with daily aspirin unless contraindicated, and 82% underwent daily transcranial Doppler ultrasonography with embolic monitoring. A rate of 8 or more emboli per hour was predictive of embolic stroke (P = 0.0076). Acute ischemic or embolic stroke was seen in 7 patients (16%) with an overall mortality in this subpopulation of 42% (n = 3). Four patients (9%) underwent acute surgical treatment (parent vessel sacrifice and/or arterial bypass) for ongoing ischemia. Long-term radiographic and clinical follow-up was obtained for 36 surviving patients (mean = 8 months; range: 1 week-5 years), all of whom were maintained on daily aspirin. No delayed ischemic or embolic events were reported. For ICA pseudoaneurysms treated with aspirin and observation alone, 9 (28%) increased in size, 17 (53%) decreased or stabilized, and 6 (19%) resolved. Enlargement of 5 mm or more in maximal diameter underwent delayed endovascular treatment with a 100% obliteration rate and no complications. CONCLUSIONS: Traumatic ICA pseudoaneurysms are safely treated with daily aspirin, embolic monitoring, and radiographic surveillance. Acute stroke or hemorrhage, or delayed radiographic progression, are indications for endovascular or surgical treatment.