Learning Curve for Flow Diversion of Posterior Circulation Aneurysms: A Long-Term International Multicenter Cohort Study.

BACKGROUND AND PURPOSE: Flow diversion has gradually become a standard treatment for intracranial aneurysms of the anterior circulation. Recently, the off-label use of the flow diverters to treat posterior circulation aneurysms has also increased despite initial concerns of rupture and the suboptimal results. This study aimed to explore the change in complication rates and treatment outcomes across time for posterior circulation aneurysms treated using flow diversion and to further evaluate the mechanisms and variables that could potentially explain the change and outcomes. MATERIALS AND METHODS: A retrospective review using a standardized data set at multiple international academic institutions was performed to identify patients with ruptured and unruptured posterior circulation aneurysms treated with flow diversion during a decade spanning January 2011 to January 2020. This period was then categorized into 4 intervals. RESULTS: A total of 378 procedures were performed during the study period. Across time, there was an increasing tendency to treat more vertebral artery and fewer large vertebrobasilar aneurysms (P = .05). Moreover, interventionalists have been increasingly using fewer overlapping flow diverters per aneurysm (P = .07). There was a trend toward a decrease in the rate of thromboembolic complications from 15.8% in 2011-13 to 8.9% in 2018-19 (P = .34). CONCLUSIONS: This multicenter experience revealed a trend toward treating fewer basilar aneurysms, smaller aneurysms, and increased usage of a single flow diverter, leading to a decrease in the rate of thromboembolic and hemorrhagic complications.

Risk of Branch Occlusion and Ischemic Complications with the Pipeline Embolization Device in the Treatment of Posterior Circulation Aneurysms.

BACKGROUND AND PURPOSE: Flow diversion with the Pipeline Embolization Device is increasingly used for endovascular treatment of intracranial aneurysms due to high reported obliteration rates and low associated morbidity. While obliteration of covered branches in the anterior circulation is generally asymptomatic, this has not been studied within the posterior circulation. The aim of this study was to evaluate the association between branch coverage and occlusion, as well as associated ischemic events in a cohort of patients with posterior circulation aneurysms treated with the Pipeline Embolization Device. MATERIALS AND METHODS: A retrospective review of prospectively maintained databases at 8 academic institutions from 2009 to 2016 was performed to identify patients with posterior circulation aneurysms treated with the Pipeline Embolization Device. Branch coverage following placement was evaluated, including the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and posterior cerebral artery. If the Pipeline Embolization Device crossed the ostia of the contralateral vertebral artery, its long-term patency was assessed as well. RESULTS: A cohort of 129 consecutive patients underwent treatment of 131 posterior circulation aneurysms with the Pipeline Embolization Device. Adjunctive coiling was used in 40 (31.0%) procedures. One or more branches were covered in 103 (79.8%) procedures. At a median follow-up of 11 months, 11% were occluded, most frequently the vertebral artery (34.8%). Branch obliteration was most common among asymptomatic aneurysms (P < .001). Ischemic complications occurred in 29 (22.5%) procedures. On multivariable analysis, there was no significant difference in ischemic complications in cases in which a branch was covered (P = .24) or occluded (P = .16). CONCLUSIONS: There was a low occlusion incidence in end arteries following branch coverage at last follow-up. The incidence was higher in the posterior cerebral artery and vertebral artery where collateral supply is high. Branch occlusion was not associated with a significant increase in ischemic complications.

Carotid Artery Wall Imaging: Perspective and Guidelines from the ASNR Vessel Wall Imaging Study Group and Expert Consensus Recommendations of the American Society of Neuroradiology.

Identification of carotid artery atherosclerosis is conventionally based on measurements of luminal stenosis and surface irregularities using in vivo imaging techniques including sonography, CT and MR angiography, and digital subtraction angiography. However, histopathologic studies demonstrate considerable differences between plaques with identical degrees of stenosis and indicate that certain plaque features are associated with increased risk for ischemic events. The ability to look beyond the lumen using highly developed vessel wall imaging methods to identify plaque vulnerable to disruption has prompted an active debate as to whether a paradigm shift is needed to move away from relying on measurements of luminal stenosis for gauging the risk of ischemic injury. Further evaluation in randomized clinical trials will help to better define the exact role of plaque imaging in clinical decision-making. However, current carotid vessel wall imaging techniques can be informative. The goal of this article is to present the perspective of the ASNR Vessel Wall Imaging Study Group as it relates to the current status of arterial wall imaging in carotid artery disease.

High-Resolution Vessel Wall Magnetic Resonance Imaging in Angiogram-Negative Non-Perimesencephalic Subarachnoid Hemorrhage.

PURPOSE: Standard magnetic resonance imaging (MRI) rarely identifies the cause of hemorrhage in patients with an angiogram-negative, non-perimesencephalic subarachnoid hemorrhage (SAH). Yet up to 10 % of these patients have recurrent hemorrhage. The aim of the study was to explore the potential role of high-resolution contrast-enhanced 3-Tesla vessel wall-MRI in patients with angiogram-negative SAH. METHODS: We performed intracranial vessel wall-MRI of the circle of Willis using a 3-Tesla scanner in consecutive patients presenting with a spontaneous, angiogram-negative, non-perimesencephalic SAH. Vessel wall-MRI included T1-, T2-, and gadolinium-enhanced T1-weighted two-dimensional black-blood sequences in multiple planes (voxel size 0.4 × 0.4 × 2.0 mm). Two neuroradiologists independently scored abnormalities of the arterial wall. RESULTS: In all, 11 patients (mean age 59 years) underwent vessel wall-MRI. A total of seven patients had vessel wall abnormalities despite normal catheter angiography. Two patients had focal abnormalities contiguous with the outer margin of the basilar artery wall for which we considered a differential of ruptured blood blister aneurysm, thrombosed aneurysm, and loculated extramural blood from elsewhere. Two patients had arterial wall enhancement involving multiple arteries, possibly secondary to SAH. Three patients had arterial wall enhancement at sites of dural penetration, remote from the SAH, likely related to age and atherosclerotic risk factors. Vessel wall-MRI did not alter patient management in this cohort. CONCLUSION: Vessel wall-MRI showed abnormalities in seven patients with angiogram-negative SAH. These findings did not alter patient management, but the findings may be useful for other physicians who choose to perform vessel wall-MRI in this patient population.

Evaluation for Blunt Cerebrovascular Injury: Review of the Literature and a Cost-Effectiveness Analysis.

BACKGROUND AND PURPOSE: Evaluation for blunt cerebrovascular injury has generated immense controversy with wide variations in recommendations regarding the need for evaluation and the optimal imaging technique. We review the literature and determine the most cost-effective strategy for evaluating blunt cerebrovascular injury in trauma patients. MATERIALS AND METHODS: A comprehensive literature review was performed with data extracted to create a decision-tree analysis for 5 different strategies: anticoagulation for high-risk (based on the Denver screening criteria) patients, selective DSA or CTA (only high-risk patients), and DSA or CTA for all trauma patients. The economic evaluation was based on a health care payer perspective during a 1-year horizon. Statistical analyses were performed. The cost-effectiveness was compared through 2 main indicators: the incremental cost-effectiveness ratio and net monetary benefit. RESULTS: Selective anticoagulation in high-risk patients was shown to be the most cost-effective strategy, with the lowest cost and greatest effectiveness (an average cost of $21.08 and average quality-adjusted life year of 0.7231). Selective CTA has comparable utility and only a slightly higher cost (an average cost of $48.84 and average quality-adjusted life year of 0.7229). DSA, whether performed selectively or for all patients, was not optimal from both the cost and utility perspectives. Sensitivity analyses demonstrated these results to be robust for a wide range of parameter values. CONCLUSIONS: Selective CTA in high-risk patients is the optimal and cost-effective imaging strategy. It remains the dominant strategy over DSA, even assuming a low CTA sensitivity and irrespective of the proportion of patients at high-risk and the incidence of blunt cerebrovascular injury in high-risk patients.

Cement embolization of a segmental artery after percutaneous vertebroplasty: a potentially catastrophic vascular complication.

Serious complications related to percutaneous vertebral augmentation procedures, vertebroplasty and kyphoplasty, are rare and most often result from local cement leakage or venous embolization. We describe an adult patient who underwent multi-level, thoracic percutaneous vertebral augmentation procedures for painful osteoporotic compression fractures. The patient's percutaneous vertebroplasty performed at the T9 level was complicated by the asymptomatic, direct embolization of the right T9 segmental artery with penetration of cement into the radicular artery beneath the pedicle. We review the literature regarding the unusual occurrence of direct arterial cement embolization during vertebral augmentation procedures, discuss possible pathomechanisms, and alert clinicians to this potentially catastrophic vascular complication.

Long-term clinical and imaging follow-up of complex intracranial aneurysms treated by endovascular parent vessel occlusion.

BACKGROUND AND PURPOSE: Flow-diverting stents are increasingly being used for the treatment of complex intracranial aneurysms, but the indications for their use in lieu of traditional endovascular PVO have yet to be precisely defined. The purpose of this study was to review the clinical and imaging outcomes of patients with intracranial aneurysms treated by PVO. MATERIALS AND METHODS: A total of 28 patients with intracranial aneurysms, treated by PVO between July 1992 and December 2009, were reviewed. Aneurysms arising from peripheral arteries were excluded. Clinical and imaging data were retrospectively analyzed from a prospectively maintained data base. RESULTS: There were 28 patients with 28 aneurysms treated by PVO. Aneurysms of the anterior circulation presenting with mass effect (n = 11) or discovered incidentally (n = 1), and dissecting-type VB aneurysms presenting with subarachnoid hemorrhage (n = 6) faired the best with high obliteration rates (83.3% and 83.6%, respectively) and no permanent major ischemic complications. In contrast, VB aneurysms presenting with mass effect (n = 7) demonstrated the lowest obliteration rate (57.1%), the highest rate of permanent major ischemic complications (28.6%), and a high mortality rate (28.6%). CONCLUSIONS: PVO is a safe and effective treatment for complex intracranial aneurysms of the carotid artery and dissecting-type VB aneurysms presenting with SAH. In contrast, PVO for aneurysms of the VB circulation presenting with mass effect is less efficacious and associated with significant morbidity and mortality. It is hoped that flow diverters may represent a better treatment technique for these most difficult-to-treat lesions.

Osteogenesis imperfecta, multiple intra-abdominal arterial dissections and a ruptured dissecting-type intracranial aneurysm.

We describe an adult patient with a ruptured dissecting-type superior cerebellar artery aneurysm and known osteogenesis imperfecta. He was successfully treated with coil embolization and intentional parent vessel sacrifice. During his hospital admission, he also suffered from abdominal distension. An incidental note was made of multiple intra-abdominal arterial dissections. These were managed conservatively. We review the rare association of osteogenesis imperfecta and intracranial aneurysms, as well as discuss management implications.

Hydrocephalus secondary to hydrodynamic disequilibrium in an adult patient with a choroidal-type arteriovenous malformation.

We describe an adult patient with an unruptured choroidal-type arteriovenous malformation (AVM) associated with progressive hydrocephalus. There was no evidence of mechanical obstruction of the ventricular system by the AVM nidus itself or a draining vein. However significant reflux into periventricular and transmedullary veins was demonstrated. Following partial targeted embolization of the AVM, no further reflux was observed, the patient's clinical deficits resolved, and the hydrocephalus improved. We suggest a hydrodynamic disorder as a potential pathomechanism of hydrocephalus in this adult patient with an unruptured AVM.

Activation of ETB receptors regulates the abundance of ET-1 mRNA in vascular endothelial cells.

BACKGROUND AND PURPOSE: The factors that influence the cellular levels of endothelin-1 (ET-1) include transcription, mRNA localization, stability and translation, post-translational maturation of preproET-1 and degradation of ET-1. We investigated the regulation of ET-1 mRNA abundance by extracellular ET-1 in porcine aortic endothelial cells (PAECs). EXPERIMENTAL APPROACH: Passsage one cultures of PAECs were incubated in starving medium in the presence or absence of ET-1 and antagonists or pharmacological inhibitors. PreproET-1 mRNA, endothelin-1 promoter activity, Erk and p38 MAPK activation were determined. KEY RESULTS: Exogenous ET-1 reduced cellular ET-1 mRNA content: a reduction of 10 000-fold was observed after 4 h. ET-1 simultaneously reduced the stability of ET-1 mRNA and increased the loading of RNA Polymerase II at the endothelin-1 promoter. In the absence of exogenous ET-1, the ETB-selective antagonist, BQ788, increased ET-1 mRNA. An ETA-selective antagonist had no effect. ET-1 mRNA returned to control levels within 24 h. Whereas activation of p38 MAPK induced by ET-1 peaked at 30 min and returned to control levels within 90 min, Erk1/2 remained active after 4 h of stimulation. Inhibition of p38 MAPK prevented the ET-1-induced decrease in ET-1 mRNA. In contrast, Erk1/2 inhibition increased ET-1 mRNA. Similarly, inhibition of receptor internalization increased ET-1 mRNA in the presence or absence of exogenous ET-1. CONCLUSIONS AND IMPLICATIONS: These results suggest that extracellular ET-1 regulates the abundance of ET-1 mRNA in PAECs, in an ETB receptor-dependent manner, by modulating both mRNA stability and transcription via mechanisms involving receptor endocytosis and both ERK and p38 MAPK pathways.