Pial Artery Supply as an Anatomic Risk Factor for Ischemic Stroke in the Treatment of Intracranial Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE:Although intracranial dural arteriovenous fistulas are principally supplied by dural branches of the external carotid, internal carotid, and vertebral arteries, they can also be fed by pial arteries that supply the brain. We sought to determine the frequency of neurologic deficits following treatment of intracranial dural arteriovenous fistulas with and without pial artery supply.MATERIALS AND METHODS:One hundred twenty-two consecutive patients who underwent treatment for intracranial dural arteriovenous fistulas at our hospital from 2008 to 2015 were retrospectively reviewed. Patient data were examined for posttreatment neurologic deficits; patients with such deficits were evaluated for imaging evidence of cerebral infarction. Data were analyzed with multivariable logistic regression.RESULTS:Of 122 treated patients, 29 (23.8%) had dural arteriovenous fistulas with pial artery supply and 93 (76.2%) had dural arteriovenous fistulas without pial arterial supply. Of patients with pial artery supply, 4 (13.8%) had posttreatment neurologic deficits, compared with 2 patients (2.2%) without pial artery supply (P = .04). Imaging confirmed that 3 patients with pial artery supply (10.3%) had cerebral infarcts, compared with only 1 patient without pial artery supply (1.1%, P = .03). Increasing patient age was also positively associated with pial supply and treatment-related complications.CONCLUSIONS:Patients with dural arteriovenous fistulas supplied by the pial arteries were more likely to experience posttreatment complications, including ischemic strokes, than patients with no pial artery supply. The approach to dural arteriovenous fistula treatment should be made on a case-by-case basis so that the risk of complications can be minimized.

Intracranial dural arteriovenous fistulas (DAVFs) are vascular malformations that connect meningeal arteries to dural venous sinuses or cortical veins. DAVFs account for 10%–15% of all intracranial arteriovenous shunting lesions.^1–14 DAVFs are often thought to be acquired, sometimes in the setting of hypercoagulability.¹⁵ DAVF venous drainage determines the natural history risk of spontaneous intracranial hemorrhage. Thus, venous drainage is incorporated into the most commonly used grading systems of DAVF natural history risk: the Borden-Shucart and Cognard grading scales.^2,3 Drainage to cortical veins is the highest risk category because pressurization of these thin-walled venous structures frequently leads to rupture. Although venous angioarchitecture is a key determinant of natural history risk, the risk of endovascular and/or surgical treatment of DAVFs in the modern era related to underlying lesion angioarchitecture is not well-known.Although DAVFs are most commonly fed by dural branches of the internal carotid, external carotid, and vertebral arteries, they can also have pial artery supply. Pial arteries lie on the surface of the brain. They then branch into penetrating arteries and parenchymal arterioles that lie within and supply the brain parenchyma. The mechanism of pial feeder formation is not well-understood but is believed to be like that of dural feeders, with increased vascular endothelial growth factor secretion from the venous sinus and abnormal angiogenesis.^16–24 Embolization of pial AVFs has been suggested to lead to the development of subsequent DAVFs in up to 25% of cases.^25,26 The inflammatory reaction within the DAVF vessel wall after embolization may also lead to angiogenesis.²⁷Transarterial embolization of DAVFs with pial artery supply with agents that can migrate retrograde (ie, from the dural arteries to the pial arteries) could thus block blood supply to the associated brain parenchyma and cause ischemia. Surgical or endovascular point occlusion of DAVFs with pial artery supply at the fistula site might also result in retrograde thrombosis of feeding pial arteries due to decreased flow. We hypothesized that patients with DAVFs with pial artery supply have a higher risk of postoperative stroke than those who do not have pial supply.     

Progressive versus Nonprogressive Intracranial Dural Arteriovenous Fistulas: Characteristics and Outcomes

BACKGROUND AND PURPOSE:A minority of intracranial dural arteriovenous fistulas progress with time. We sought to determine features that predict progression and define outcomes of patients with progressive dural arteriovenous fistulas.MATERIALS AND METHODS:We performed a retrospective imaging and clinical record review of patients with intracranial dural arteriovenous fistula evaluated at our hospital.RESULTS:Of 579 patients with intracranial dural arteriovenous fistulas, 545 had 1 fistula (mean age, 45 ± 23 years) and 34 (5.9%) had enlarging, de novo, multiple, or recurrent fistulas (mean age, 53 ± 20 years; P = .11). Among these 34 patients, 19 had progressive dural arteriovenous fistulas with de novo fistulas or fistula enlargement with time (mean age, 36 ± 25 years; progressive group) and 15 had multiple or recurrent but nonprogressive fistulas (mean age, 57 ± 13 years; P = .0059, nonprogressive group). Whereas all 6 children had fistula progression, only 13/28 adults (P = .020) progressed. Angioarchitectural correlates to chronically elevated intracranial venous pressures, including venous sinus dilation (41% versus 7%, P = .045) and pseudophlebitic cortical venous pattern (P = .048), were more common in patients with progressive disease than in those without progression. Patients with progressive disease received more treatments than those without progression (median, 5 versus 3; P = .0068), but as a group, they did not demonstrate worse clinical outcomes (median mRS, 1 and 1; P = .39). However, 3 young patients died from intracranial venous hypertension and intracranial hemorrhage related to progression of their fistulas despite extensive endovascular, surgical, and radiosurgical treatments.CONCLUSIONS:Few patients with dural arteriovenous fistulas follow an aggressive, progressive clinical course despite treatment. Younger age at initial presentation and angioarchitectural correlates to venous hypertension may help identify these patients prospectively.

Intracranial dural arteriovenous fistulas (DAVFs) are rare arteriovenous shunts involving the epidural space and adjacent dura mater, which receive arterial supply from meningeal vessels and drain directly to dural venous sinuses or cortical veins.¹ In the early days of cerebral angiography, DAVFs were considered a subset of AVMs: Newton and Cronqvist² classified AVMs by arterial supply as pure dural, mixed pial-dural, or pure pial malformations. Unlike brain AVMs, however, DAVFs are most often thought to be acquired (as opposed to congenital), and DAVFs lack a nidus of vessels in the brain parenchyma. DAVF is also distinguished from nongalenic pial arteriovenous fistula by its fistula location in the dura.Management of a DAVF is based on its expected clinical course: Fistulas demonstrating cortical venous drainage (CVD) generally warrant curative therapy to prevent intracranial hemorrhage, and fistulas without CVD are managed for either symptom palliation or cure.^3–6 Treatment modalities include transarterial or transvenous endovascular embolization to occlude the arteriovenous fistula site, microsurgical interruption of the fistula site, stereotactic radiosurgery, or multimodality therapy. Endovascular procedures are used to treat a most DAVFs and are the treatment of choice for lesions accessible to catheterization.^5,6A small number of patients with DAVFs respond poorly to conventional therapies and demonstrate progressive neurologic and angiographic deterioration with enlargement of existing fistulas, formation of de novo fistulas, and development of features that increase the risk of intracranial hemorrhage.⁷ Reports of such rapidly progressive “runaway” DAVFs are scarce. Only a few cases have been published in the past 15 years; therefore, the pathogenesis, presentation, clinical course, and treatment remain unclear.^4,8–12 The purpose of this single-institution retrospective cohort study was to compare the clinical characteristics, angioarchitecture, and treatment outcomes of patients with progressive (enlarging fistulas or developing de novo fistulas) versus nonprogressive (recurrent original fistula or the presence of multiple unchanging fistulas) intracranial DAVFs.     

Quantifying the Cerebral Hemodynamics of Dural Arteriovenous Fistula in Transverse Sigmoid Sinus Complicated by Sinus Stenosis: A Retrospective Cohort Study

BACKGROUND AND PURPOSE:Sinus stenosis occasionally occurs in dural arteriovenous fistulas. Sinus stenosis impedes venous outflow and aggravates intracranial hypertension by reversing cortical venous drainage. This study aimed to analyze the likelihood of sinus stenosis and its impact on cerebral hemodynamics of various types of dural arteriovenous fistulas.MATERIALS AND METHODS:Forty-three cases of dural arteriovenous fistula in the transverse-sigmoid sinus were reviewed and divided into 3 groups: Cognard type I, type IIa, and types with cortical venous drainage. Sinus stenosis and the double peak sign (occurrence of 2 peaks in the time-density curve of the ipsilateral drainage of the internal jugular vein) in dural arteriovenous fistula were evaluated. “TTP” was defined as the time at which a selected angiographic point reached maximum concentration. TTP of the vein of Labbé, TTP of the ipsilateral normal transverse sinus, trans-fistula time, and trans-stenotic time were compared across the 3 groups.RESULTS:Thirty-six percent of type I, 100% of type IIa, and 84% of types with cortical venous drainage had sinus stenosis. All sinus stenosis cases demonstrated loss of the double peak sign that occurs in dural arteriovenous fistula. Trans-fistula time (2.09 seconds) and trans-stenotic time (0.67 seconds) in types with cortical venous drainage were the most prolonged, followed by those in type IIa and type I. TTP of the vein of Labbé was significantly shorter in types with cortical venous drainage. Six patients with types with cortical venous drainage underwent venoplasty and stent placement, and 4 were downgraded to type IIa.CONCLUSIONS:Sinus stenosis indicated dysfunction of venous drainage and is more often encountered in dural arteriovenous fistula with more aggressive types. Venoplasty ameliorates cortical venous drainage in dural arteriovenous fistulas and serves as a bridge treatment to stereotactic radiosurgery in most cases.

Dural arteriovenous fistulas (DAVFs) account for 10%–15% of intracranial vascular malformations.^1,2 The most common location of an intracranial DAVF is the cavernous sinus, followed by the transverse-sigmoid sinus.^1–3 Major DAVF classification systems, such as the Cognard and Borden systems, grade DAVFs on the basis of venous drainage patterns, in which the presence of retrograde cortical venous drainage (CVD) indicates a higher risk of hemorrhage.^4–7 Cases of venous outlet obstruction playing a role in transforming benign (without CVD) into malignant DAVFs (with CVD) have been reported in the literature.⁸ Sinus stenosis (SS) is frequently associated with idiopathic intracranial hypertension.^9,10 Nevertheless, the incidence of SS and its association with DAVFs have not been thoroughly explored. SS can be found in DAVFs with retrograde or antegrade sinus flow, but its impact on cerebral hemodynamics has rarely been discussed. Theoretically, stenotic and thrombosed sinuses impede the venous outflow, and a DAVF itself increases overall blood volume in the affected sinus; the combination of the 2 hemodynamic disorders adversely affects venous flow and subsequently increases intracranial pressure and the risk of intracranial hemorrhage.Current treatment strategies for DAVFs in the transverse sinus include microsurgery, endovascular treatment, stereotactic radiosurgery (SRS), or their combinations.^11–13 Endovascular treatment has been the treatment of choice for DAVFs with CVD because it provides immediate curative results and minimizes the risk of hemorrhage.^14–16 Nevertheless, the complication rate of endovascular treatment is higher than that of SRS.^14,17,18 By contrast, SRS has hardly any periprocedural risks and achieves DAVF cure rates of between 58% and 73%. Although SRS can reduce the bleeding rate from 20% to 2% after shunting has been totally closed,¹⁹ the latent period for SRS ranges from 1 to 3 years and carries a 4.1% hemorrhagic rate in DAVFs with CVD.^3,20 Therefore, SRS is usually preferred for cases without CVD, and endovascular treatment is more suitable for immediately minimizing the risk of hemorrhage.Several studies have proposed a reconstructive method by using venoplasty and stent placement in combination with transarterial embolization to ameliorate or even cure DAVFs with venous outlet obstruction.^21–23 We wondered whether this approach could downgrade DAVFs with CVD—that is, to restore their normal cortical venous drainage and make them eligible for SRS, thereby minimizing the risk of hemorrhage during the latent period. Therefore, the purpose of the current study was to clarify the following: 1) the incidence of SS in different grades of DAVF in the transverse sigmoid sinus, 2) the impact of SS on DAVF hemodynamics by using quantitative DSA, and 3) the initial treatment results of venoplasty and/or stent placement followed by SRS.     

Transarterial Onyx Embolization of Cranial Dural Arteriovenous Fistulas: Long-Term Follow-Up

BACKGROUND AND PURPOSE:Endovascular therapy with liquid embolic agents is a common treatment strategy for cranial dural arteriovenous fistulas. This study evaluated the long-term effectiveness of transarterial Onyx as the single embolic agent for curative embolization of noncavernous cranial dural arteriovenous fistulas.MATERIALS AND METHODS:We performed a retrospective review of 40 consecutive patients with 41 cranial dural arteriovenous fistulas treated between March 2006 and June 2012 by using transarterial Onyx embolization with intent to cure. The mean age was 57 years; one-third presented with intracranial hemorrhage. Most (85%) had cortical venous drainage. Once angiographic cure was achieved, long-term treatment effectiveness was assessed with DSA and clinical follow-up.RESULTS:Forty-nine embolization sessions were performed; 85% of cranial dural arteriovenous fistulas were treated in a single session. The immediate angiographic cure rate was 95%. The permanent neurologic complication rate was 2% (mild facial palsy). Thirty-five of the 38 patients with initial cure underwent short-term follow-up DSA (median, 4 months). The short-term recurrence rate was only 6% (2/35). All patients with occlusion at short-term DSA undergoing long-term DSA (median, 28 months) had durable occlusion. No patient with long-term clinical follow-up (total, 117 patient-years; median, 45 months) experienced hemorrhage.CONCLUSIONS:Transarterial embolization with Onyx as the single embolic agent results in durable long-term cure of noncavernous cranial dural arteriovenous fistulas. Recurrence rates are low on short-term follow-up, and all patients with angiographic occlusion on short-term DSA follow-up have experienced a durable long-term cure. Thus, angiographic cure should be defined at short-term follow-up angiography instead of at the end of the final embolization session. Finally, long-term DSA follow-up may not be necessary if occlusion is demonstrated on short-term angiographic follow-up.

Endovascular therapy is commonly used for the treatment of noncavernous cranial dural arteriovenous fistulas (cDAVFs). Cyanoacrylates, ethyl alcohol, coils, and particles can be used alone or in combination via transarterial, transvenous, or occasionally direct percutaneous treatment routes. There is no US Food and Drug Administration–approved liquid embolic agent for the treatment of cDAVFs. The ethylene-vinyl alcohol copolymer liquid embolic system (Onyx; Covidien, Irvine, California) is FDA-approved for the presurgical embolization of brain arteriovenous malformations. Since Onyx has become available, transarterial embolization of cDAVFs by using Onyx as the sole endovascular embolic agent has become our preferred treatment strategy. This endovascular treatment approach represents an “off-label” use of the Onyx liquid embolic system.The immediate occlusion rate in large cohort studies of patients treated with transarterial Onyx embolization ranges from 62% to 92%, and short-term durable occlusion has been demonstrated.^1–4 We have previously reported our short-term experience using Onyx in these patients⁵ and have compared the success of this technique with embolization using n-butyl cyanoacrylate.⁶ However, there currently remain no published data on the long-term effectiveness for embolization of cDAVFs by using Onyx, to our knowledge. Here we report our long-term angiographic occlusion rate and clinical follow-up in a cohort of noncavernous cranial DAVFs that were treated by using transarterial Onyx embolization with the intention of complete cure.     

Comparison of 3 Different Types of Spinal Arteriovenous Shunts below the Conus in Clinical Presentation,Radiologic Findings,and Outcomes

BACKGROUND AND PURPOSE:Spinal arteriovenous shunts below the conus constitute 3 types of lesions, which have previously been mainly described in case reports, given their rarity, and are sometimes misdiagnosed. The purpose of this study was to describe the features of each type and compare these types as to epidemiologic features, clinical and radiologic presentations, treatment, and outcomes in a consecutive series of 48 cases.MATERIALS AND METHODS:The prospectively collected data bases of 2 referral centers for spinal vascular lesions were retrospectively reviewed. Spinal arteriovenous shunts below the conus were defined as all dural and intradural shunts below the conus medullaris. Clinical features, radiologic findings, treatment results, and clinical outcomes were assessed.RESULTS:There were filum terminale arteriovenous fistulas in 11 patients (22.9%), radicular arteriovenous shunts in 7 patients (14.6%), and spinal dural arteriovenous fistulas in 30 patients (62.5%). Radicular arteriovenous shunts presented at a younger age (P = .017) and with a higher incidence of back pain symptoms (P = .037). A tethered spinal cord was found in 54.5% of patients with filum terminale arteriovenous fistulas and 23.3% of patients with spinal dural arteriovenous fistulas. After treatment, the angiographic complete obliteration rate was 89.4% and spinal function was improved significantly (P < .001).CONCLUSIONS:Three groups of spinal arteriovenous shunts below the conus can be differentiated according to clinical and radiologic features. Filum terminale arteriovenous fistulas are frequently associated with dysraphic malformations, which may suggest a particular embryologic origin.

Spinal arteriovenous lesions are rare and complex neurovascular diseases that can be categorized according to embryologic considerations,¹ anatomic and imaging features,² or their locations.³ Among the spinal vascular malformations, arteriovenous shunts below the conus medullaris include some particular groups of lesions and are sometimes misdiagnosed due to similar clinical and radiologic presentations, which are worth addressing and differentiating separately.⁴ This group of lesions is distant from the spinal cord,^5,6 presents mainly with progressive myelopathy rather than hemorrhage, and may be associated with dysraphic malformations, which suggest a unique embryologic origin. If diagnosis and angioarchitecture are correctly identified, treatment is relatively simple compared with spinal vascular lesions in other locations.^7,8According to their feeding arteries, we can classify 3 different types of spinal arteriovenous shunts below the conus: shunts fed by the artery of the filum terminale (filum terminale arteriovenous fistulas [FTAVFs]), shunts fed by dural branches (spinal dural arteriovenous fistulas [SDAVFs]), and shunts fed by radicular arteries (radicular arteriovenous shunts [rAVSs]). Previously, these types of vascular malformations have been described mainly in smaller case series or case reports. Since Djindjian et al⁹ reported the first case of FTAVF, several case reports^10–13 and 2 patient series studies^14,15 have been published. rAVSs that are located on a nerve root of the cauda equina have been reported in 2 cases to date.¹⁶ SDAVFs in this region can have lumbar or sacral segmental artery supply and constitute approximately 23% of the dural AVFs in larger series.¹⁷ Clinical and epidemiologic features, their relative proportion to each other, and the associated malformations of these 3 different shunts below the conus have not been described however, and the differential diagnoses of the 3 groups have not been investigated in greater detail, presumably given their rarity.In this study, we review a series of 48 spinal arteriovenous shunts below the conus derived from the combined prospectively maintained data bases of 2 referral centers (Xuanwu Hospital, Beijing, China and Toronto Western Hospital, Toronto, Canada) and thus aim to compare epidemiologic features, clinical presentations, MR imaging and angiographic findings, treatment, and outcomes of 3 types of lesion at this location.     

Liquid Embolic Agents for Endovascular Embolization: Evaluation of an Established (Onyx) and a Novel (PHIL) Embolic Agent in an In Vitro AVM Model

BACKGROUND AND PURPOSE:Embolization plays a key role in the treatment of arteriovenous malformations. The aim of this study was to evaluate an established (Onyx) and a novel (precipitating hydrophobic injectable liquid [PHIL]) liquid embolic agent in an in vitro AVM model.MATERIALS AND METHODS:An AVM model was integrated into a circuit system. The artificial nidus (subdivided into 28 honeycomb-like sections) was embolized with Onyx 18 (group Onyx; n = 8) or PHIL 25 (group PHIL; n = 8) with different pause times between the injections (30 and 60 seconds, n = 4 per study group) by using a 1.3F microcatheter. Procedure times, number of injections, embolization success (defined as the number of filled sections of the artificial nidus), volume of embolic agent, and frequency and extent of reflux and draining vein embolization were assessed.RESULTS:Embolization success was comparable between Onyx and PHIL. Shorter pause times resulted in a significantly higher embolization success for PHIL (median embolization score, 28 versus 18; P = .011). Compared with Onyx, lower volumes of PHIL were required for the same extent of embolization (median volume per section of the artificial nidus, 15.5 versus 3.6 μL; P < .001).CONCLUSIONS:While the embolization success was comparable for Onyx and PHIL, pause time had a considerable effect on the embolization success in an in vitro AVM model. Compared with Onyx, lower volumes of PHIL were required for the same extent of embolization.

Arteriovenous malformations are complex vascular structures composed of feeding arteries, an intervening network of small pathologic blood vessels (the so-called nidus), and draining veins. The lack of an intervening capillary bed allows high-flow arteriovenous shunting of blood. While AVMs can occur throughout the entire body, cerebral AVMs are of particular relevance due to their ability to cause impairing neurologic symptoms and their considerable risk of hemorrhage.¹Alone or in combination with microneurosurgery and stereotactic radiation therapy, embolization plays an important role in the management of cerebral AVMs.² The aim of AVM embolization is complete filling of the nidus, while unwanted reflux into the feeding arteries should be minimized and premature embolization of the draining veins should be avoided.³A wide variety of embolic agents has been and is currently used for embolization of AVMs. At present, the liquid embolic agents (LEAs) ethylene-vinyl alcohol copolymer (EVOH) and n-butyl cyanoacrylate are used most frequently.⁴ Although the embolization results have improved since the introduction of EVOH-based LEAs with rates of complete obliteration ranging from 16% to 100%, the success rate of AVM embolization, especially for complex AVMs, is not yet satisfying.^2,3 Currently, new LEAs are being introduced to improve embolization features, such as embolization efficacy, intraprocedural handling, and control. Furthermore, their use should improve fluoroscopic visibility and reduce artifacts in postinterventional imaging.The aim of this study was to evaluate an established EVOH-based embolic agent and a novel copolymer-based embolic agent in an in vitro AVM model.     

Application of Time-Resolved 3D Digital Subtraction Angiography to Plan Cerebral Arteriovenous Malformation Radiosurgery

BACKGROUND AND PURPOSE:Time-resolved 3D-DSA (4D-DSA) enables viewing vasculature from any desired angle and time frame. We investigated whether these advantages may facilitate treatment planning and the feasibility of using 4D-DSA as a single imaging technique in AVM/dural arteriovenous fistula radiosurgery.MATERIALS AND METHODS:Twenty consecutive patients (8 dural arteriovenous fistulas and 12 AVMs; 13 men and 7 women; mean age, 45 years; range, 18–64 years) who were scheduled for gamma knife radiosurgery were recruited (November 2014 to October 2015). An optimal volume of reconstructed time-resolved 3D volumes that defines the AVM nidus/dural arteriovenous fistula was sliced into 2D-CT-like images. The original radiosurgery treatment plan was overlaid retrospectively. The registration errors of stereotactic 4D-DSA were compared with those of integrated stereotactic imaging. AVM/dural arteriovenous fistula volumes were contoured, and disjoint and conjoint components were identified. The Wilcoxon signed rank test and the Wilcoxon rank sum test were adopted to evaluate registration errors and contoured volumes of stereotactic 4D-DSA and integration of stereotactic MR imaging and stereotactic 2D-DSA.RESULTS:Sixteen of 20 patients were successfully registered in Advanced Leksell GammaPlan Program. The registration error of stereotactic 4D-DSA was smaller than that of integrated stereotactic imaging (P = .0009). The contoured AVM volume of 4D-DSA was smaller than that contoured on the integration of MR imaging and 2D-DSA, while major inconsistencies existed in cases of dural arteriovenous fistula (P = .042 and 0.039, respectively, for measurements conducted by 2 authors).CONCLUSIONS:Implementation of stereotactic 4D-DSA data for gamma knife radiosurgery for brain AVM/dural arteriovenous fistula is feasible. The ability of 4D-DSA to demonstrate vascular morphology and hemodynamics in 4 dimensions potentially reduces the target volumes of irradiation in vascular radiosurgery.

Radiosurgery is an effective treatment alternative for cerebral arteriovenous malformations^1–4 and intracranial dural arteriovenous fistulas (DAVFs).^5–10 In AVM/DAVF radiosurgery, irradiation is delivered in a single fraction stereotactically to only the nidus of an AVM or fistula of a DAVF.Our current clinical practice of AVM/DAVF radiosurgery, integrated stereotactic imaging (MR imaging/MRA and x-ray digital subtraction angiography) is used for nidus/fistula delineation. The integrated multiple-stop stereotactic imaging is considered the reference imaging for AVM/DAVF radiosurgery. MR imaging is superior in delineating radiosurgical target in 3D, and DSA excels in defining the hemodynamics of AVM/AVF and differentiating the nidus/fistula from feeding arteries and draining veins of AVM/DAVF.¹¹ However, the role of DSA as a projective 2D representation of 3D structures in defining the nidus is limited, especially when the AVM is large and the nidus has an oblique long axis relative to the orthogonal DSA projections.¹² Moreover, for AVMs that undergo partial embolization before radiosurgery, the nidus may become intricate, and it may be difficult to define its morphology on 2D-DSA or MR imaging/MRA.¹³ Recently, it was shown that conebeam CT 3D angiography can generate images of a high spatial resolution that depict low-flow nidal compartments better than both DSA and MR imaging, though it lacks temporal information.¹⁴ While our current practice has achieved high tissue conformity in AVM radiosurgery and good therapeutic results,¹⁵ an alternative technique, if chosen, must be able to provide panoramic morphological and hemodynamic evaluation of nidi/fistulas in 1 stop.In contrast to 2D-DSA, fully time-resolved 3D-DSA, also known as 4D-DSA, provides a series of time-resolved 3D volumes that correspond to contrast dynamics with a C-arm-based imaging system.¹⁶ While the reconstruction of a 4D-DSA image from a single rotational image acquisition has some inherited technical difficulties, as mentioned by Royalty,¹⁷ the volumetric vascular morphology and bolus-arrival patterns reconstructed from 4D-DSA algorithms are validated.¹⁷ An animal study based on a canine model also demonstrated that 4D-DSA is capable of delineating vasculature effectively.¹⁸ Small-series studies also suggested that 4D-DSA enhances the ability to visualize the vascular anatomy of an AVM.^19,20 Accordingly, 4D-DSA enables evaluating feeding arteries, nidi, and draining veins in sequential imaging in 3D and eliminates the issue of overlapped vasculatures.In this study, we compare the registration errors of stereotactic 4D-DSA with those of integrated stereotactic imaging and the vascular anatomy of AVMs and DAVFs depicted by 4D-DSA volumes with the planned dose contours for each recruited patient and evaluate whether 4D-DSA may facilitate the planning of AVM/DAVF radiosurgery by minimizing the irradiation volume as 1-stop imaging.     

Dual-Lumen Balloon Catheters May Improve Liquid Embolization of Vascular Malformations: An Experimental Study in Swine

BACKGROUND AND PURPOSE:Liquid embolic agents are increasingly used to treat vascular malformations. We sought to assess embolization with these agents by using a dual-lumen balloon catheter in an experimental setting.MATERIALS AND METHODS:Eighteen injections of liquid embolic agents were performed in the rete mirabile of swine. We used 3 methods to control liquid embolic agent reflux: 1) dual-lumen balloon-catheter (group A, n = 8); 2) injection of liquid embolic agent after proximal n-BCA plug formation through a second microcatheter (group B, n = 4); and 3) standard liquid embolic agent injection (group C, controls, n = 6). The following outcomes were graded by using ordinal scales by angiography, macrophotography, and radiography of retia after euthanasia: 1) angiographic and pathologic extent of liquid embolic agent embolization of the rete, 2) reflux of liquid embolic agents in the parent artery, and 3) density of liquid embolic agents in the proximal rete. Technical complications were also recorded. A successful injection was defined as an embolization that reached the contralateral rete without reflux into proximal external branches. Exact logistic regression analyses were performed to compare groups.RESULTS:There were significant differences among groups for reflux (P = .029) and liquid embolic agent density in the proximal rete (P = .014), while extension to the contralateral rete did not reach statistical significance (P = .07). Injections differed among groups (P = .004), with dual-lumen balloon-catheter injections more frequently successful compared with control injections (P = .019).CONCLUSIONS:Dual-lumen balloon catheters allowed better liquid embolic agent injections than standard injections.

Ethylene-vinyl alcohol copolymer liquid embolic agents (LEAs) have changed the management of vascular malformations such as arteriovenous malformations and dural arteriovenous fistulas.^1–4 LEAs such as Onyx (Covidien, Irvine, California) can be injected through small microcatheters, and on injection, they precipitate out of the dimethyl-sulfoxide solvent and slowly harden after coming in contact with blood. These agents are cohesive rather than adhesive and perhaps better controlled than other agents such as n-BCA. In many cases, these features (of LEAs such as Onyx/Phil) may permit longer injections and possibly more complete embolizations than other LEAs.¹The standard method used to control injections is to slowly inject the LEA, allowing some reflux for a short plug proximal to the catheter tip to form and harden, and to wait for the LEA to preferentially move in an antegrade direction deep into the nidus of the malformation. One factor potentially limiting the efficacy of the injection is excessive reflux of LEA back along the catheter, which can enter and occlude unwanted vessels.⁵ Additionally, if a segment of microcatheter that is too long is left in contact with the LEA for too long, the proximal plug may entrap the catheter tip in place. Removal of entrapped catheters has led to intracranial hemorrhages, leading to an FDA warning regarding this aspect of treatment with Onyx.⁶Several potential solutions to these problems have been proposed. One option is to use 2 microcatheters together: One microcatheter with a detachable tip is used for the injection of the LEA, while the other microcatheter is used to deliver n-BCA quickly, intentionally gluing the detachable portion of the first catheter, forming the proximal plug that will prevent reflux of LEA, and ensuring antegrade embolization of the nidus.^7–9 Another option is to use a dimethyl-sulfoxide–compatible dual-lumen balloon catheter, in which 1 lumen is used to inflate a balloon and prevent reflux, while the second lumen delivers the embolic agent (Scepter; MicroVention, Tustin, California).^5,10Animal models may be useful to inform clinical applications of embolic agents.^11–14 We sought to explore whether using a dual-lumen balloon catheter could improve embolization of the swine rete (a model often used for experimental AVM embolization)^12,15,16 and prevent excessive reflux compared with more traditional techniques. We hypothesized that the use of the balloon would promote more complete nidus filling with less reflux and fewer complications than other methods.     

Intracranial Arteriovenous Shunting: Detection with Arterial Spin-Labeling and Susceptibility-Weighted Imaging Combined

BACKGROUND AND PURPOSE:Arterial spin-labeling and susceptibility-weighted imaging are 2 MR imaging techniques that do not require gadolinium. The study aimed to assess the accuracy of arterial spin-labeling and SWI combined for detecting intracranial arteriovenous shunting in comparison with conventional MR imaging.MATERIALS AND METHODS:Ninety-two consecutive patients with a known (n = 24) or suspected arteriovenous shunting (n = 68) underwent digital subtraction angiography and brain MR imaging, including arterial spin-labeling/SWI and conventional angiographic MR imaging (3D TOF, 4D time-resolved, and 3D contrast-enhanced MRA). Arterial spin-labeling/SWI and conventional MR imaging were reviewed separately in a randomized order by 2 blinded radiologists who judged the presence or absence of arteriovenous shunting. The accuracy of arterial spin-labeling/SWI for the detection of arteriovenous shunting was calculated by using the area under receiver operating curve with DSA as reference standard. κ coefficients were computed to determine interobserver and intermodality agreement.RESULTS:Of the 92 patients, DSA showed arteriovenous shunting in 63 (arteriovenous malformation in 53 and dural arteriovenous fistula in 10). Interobserver agreement was excellent (κ =0.83–0.95). In 5 patients, arterial spin-labeling/SWI correctly detected arteriovenous shunting, while the conventional angiographic MR imaging did not. Compared with conventional MR imaging, arterial spin-labeling/SWI was significantly more sensitive (0.98 versus 0.90, P = .04) and equally specific (0.97) and showed significantly higher agreement with DSA (κ = 0.95 versus 0.84, P = .01) and higher area under the receiver operating curve (0.97 versus 0.93, P = .02).CONCLUSIONS:Our study showed that the combined use of arterial spin-labeling and SWI may be an alternative to contrast-enhanced MRA for the detection of intracranial arteriovenous shunting.

Intracranial arteriovenous shunting (AVS) related to dural arteriovenous fistulas (DAVFs) or AVMs may lead to several neurologic complications, including acute intracranial hemorrhage (ICH).^1–3 DSA remains the reference standard to confirm AVS and assess its angioarchitecture. However, conventional brain MR imaging, including time-of-flight and contrast-enhanced MR angiography, is commonly performed in patients with suspected AVS, particularly in the setting of acute ICH. Time-resolved (4D) contrast-enhanced MRA is routinely performed in patients suspected of having AVS or for characterizing a known AVM or DAVF.^4–6 Limitations of this approach include low spatial resolution, incomplete brain coverage, and technical difficulties.^4–7Recently, 2 noncontrast MR imaging techniques, namely SWI and arterial spin-labeling (ASL), were also reported useful for the detection of intracranial AVS. SWI can demonstrate the venous drainage as high signal intensity because of increased blood flow and the presence of a large amount of oxyhemoglobin,^8–11 while ASL can improve the detection of AVS by showing venous ASL signal.^12–16 To our knowledge, no previous study has yet compared the accuracy for detecting AVS of these noncontrast techniques with the conventional MR imaging protocol, including contrast-enhanced MRA. During a 4-year period, we have systematically performed 3T MR imaging, including SWI, ASL, and conventional angiographic MR imaging (ie, TOF-MRA, 3D and 4D contrast-enhanced MRA), in all consecutive patients referred for DSA (considered the reference standard in the present study) for known or suspected AVS. This study sought to determine the accuracy of the combined use of ASL and SWI (ASL/SWI) for the detection of AVS in comparison with conventional MR imaging, including contrast-enhanced MRA.     

Changing Clinical and Therapeutic Trends in Tentorial Dural Arteriovenous Fistulas: A Systematic Review

BACKGROUND AND PURPOSE:Tentorial dural arteriovenous fistulas are characterized by a high hemorrhagic risk. We evaluated trends in outcomes and management of tentorial dural arteriovenous fistulas and performed a meta-analysis evaluating clinical and angiographic outcomes by treatment technique.MATERIALS AND METHODS:We performed a comprehensive literature search for studies on surgical and endovascular treatment of tentorial dural arteriovenous fistulas. We compared the proportion of patients undergoing endovascular, surgical, and combined endovascular/surgical management; the proportion of patients presenting with ruptured tentorial dural arteriovenous fistulas; and proportion of patients with good neurologic outcome across 3 time periods: 1980–1995, 1996–2005, and 2006–2014. We performed a random-effects meta-analysis, evaluating the rates of occlusion, long-term good neurologic outcome, perioperative morbidity, and resolution of symptoms for the 3 treatment modalities.RESULTS:Twenty-nine studies with 274 patients were included. The proportion of patients treated with surgical treatment alone decreased from 38.7% to 20.4% between 1980–1995 and 2006–2014. The proportion of patients treated with endovascular therapy alone increased from 16.1% to 48.0%. The proportion of patients presenting with ruptured tentorial dural arteriovenous fistulas decreased from 64.4% to 43.6%. The rate of good neurologic outcome increased from 80.7% to 92.9%. Complete occlusion rates were highest for patients receiving multimodality treatment (84.0%; 95% CI, 72.0%–91.0%) and lowest for endovascular treatment (71.0%; 95% CI, 56.0%–83.0%; P < .01). Long-term good neurologic outcome was highest in the endovascular group (89.0%; 95% CI, 80.0%–95.0%) and lowest for the surgical group (73.0%; 95% CI, 51.0%–87.0%; P = .03).CONCLUSIONS:Patients with tentorial dural arteriovenous fistulas are increasingly presenting with unruptured lesions, being treated endovascularly, and experiencing higher rates of good neurologic outcomes. Endovascular treatment was associated with superior neurologic outcomes but lower occlusion rates.

Intracranial dural arteriovenous fistulas (DAVFs) are abnormal direct shunts between the dural arteries and dural veins.¹ The shunt is located in the intracranial dura mater with venous drainage directed to the dural venous sinuses or cortical veins. Dural arteriovenous fistulas account for 10%–15% of all intracranial vascular shunts.^1,2 Tentorial dural arteriovenous fistulas (TDAVFs) constitute only 4% of DAVFs and are characterized by a high hemorrhagic risk. Because of this, these lesions are treated aggressively on diagnosis.^3–5Traditionally, surgical resection was the only treatment available for these lesions. However, endovascular embolization, either alone or in combination with surgery, is increasingly used.⁶ Stereotactic radiosurgery is also increasingly used as an adjunct to surgical and endovascular treatment.⁷ We performed a systematic review of the literature on surgical and endovascular treatment of TDAVFs from 1980 to 2014. The purpose of our study was the following: 1) to determine whether there was a shift from primarily surgical treatments to endovascular and multimodality treatment during this time period, 2) to determine whether the proportion of patients presenting with ruptured TDAVFs during this time period has changed, 3) to determine whether the rate of good neurologic outcome has changed, and 4) to evaluate clinical and angiographic outcomes in endovascular, surgical, and combined treatments by performing a random-effects meta-analysis.     

Endovascular Treatment of Dural Arteriovenous Fistulas of the Transverse and Sigmoid Sinuses Using Transarterial Balloon-Assisted Embolization Combined with Transvenous Balloon Protection of the Venous Sinus

BACKGROUND AND PURPOSE:Combined transarterial balloon-assisted endovascular embolization with double-lumen balloon microcatheters and concomitant transvenous balloon protection was described as a promising treatment technique for dural arteriovenous fistulae of the transverse and sigmoid sinus. The purpose of this study was to evaluate the technical efficacy and safety of this combined treatment technique.MATERIALS AND METHODS:Nine consecutive patients presenting with dural arteriovenous fistulas of the transverse and sigmoid sinuses underwent combined transarterial and transvenous balloon-assisted endovascular embolization. Prospectively collected data were reviewed to assess the technical success rate, complication rate, and clinical outcome.RESULTS:Six patients presented with clinically symptomatic Borden type I, and 3 patients, with Borden type II dural arteriovenous fistulas of the transverse and sigmoid sinuses (3 men, 6 women; mean age, 50.4 years). Transarterial embolization was performed with a double-lumen balloon with Onyx and concomitant transvenous sinus protection with a dedicated venous remodeling balloon. Complete angiographic occlusion at the latest follow-up (mean, 4.8 months) was achieved in 6 patients, and near-complete occlusion, in 2 patients. Clinical cure or remission of symptoms was obtained in 6 and 2 patients, respectively. One patient with a residual fistula underwent further treatment in which the dural arteriovenous fistula was cured by sinus occlusion. Complete occlusion of the dural arteriovenous fistula was visible on the follow-up angiography after final treatment in 8 patients. One patient refused follow-up angiography but was free of symptoms. There were no immediate or delayed postinterventional complications.CONCLUSIONS:Transarterial balloon-assisted embolization of dural arteriovenous fistulas of the transverse and sigmoid sinuses with combined transvenous balloon protection is safe and offers a high rate of complete dural arteriovenous fistula occlusion and remission of clinical symptoms.

During the past few decades, endovascular embolization has become the first-line treatment for a wide range of dural arteriovenous fistulas (dAVFs). Several transarterial and transvenous endovascular approaches have been advocated. Preliminary studies on the use of double-lumen balloon microcatheters for transarterial embolization of dAVFs with Onyx (Covidien, Irvine, California) have shown encouraging results. These studies have reported high occlusion rates, reduction of reflux into the feeding artery, a reduced quantity of injected Onyx and peri-interventional time, and low complication rates.^1–9 In addition, transvenous balloon-assisted sinus protection during transarterial embolization has been reported to be another useful adjunct to the endovascular treatment of dAVFs.^10–12 Transvenous balloon protection of the recipient sinus has mainly been associated with a reduction in inadvertent occlusion of the lumen of a functioning sinus, preservation of venous patency, facilitation of occlusion of abnormal arteriovenous connections within the sinus wall and separate venous channels, and increased penetration of embolic material by retrograde reflux into other dural feeders of the fistula network. Techniques aiming to preserve the underlying sinus may have lower complication rates than sinus-occluding embolization techniques, in which the recipient venous sinus has to be sacrificed.¹³ Therefore, transarterial balloon-assisted embolization with a concomitant transvenous balloon protection technique theoretically has the advantages of both techniques combined; this combination leads to increased occlusion and reduced complication rates.The purpose of this study was to report the angiographic and clinical outcomes of patients with dAVFs of the transverse and sigmoid sinuses treated with a combined approach of transarterial balloon-assisted endovascular embolization and double-lumen balloon microcatheters with concomitant transvenous balloon protection.     

Comparison of Dynamic Contrast-Enhanced 3T MR and 64-Row Multidetector CT Angiography for the Localization of Spinal Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE:For the localization of spinal dural arteriovenous fistulas, it is not determined whether dynamic contrast-enhanced MRA is more reliable than multidetector CTA. The aim of this study was to compare the agreement between intra-arterial DSA, dynamic contrast-enhanced MRA at 3T, and 64-row multidetector CTA for the localization of spinal dural arteriovenous fistulas.MATERIALS AND METHODS:We enrolled 12 consecutive patients (11 men, 1 woman; age range, 46–83 years; mean, 65 years) who underwent preoperative dynamic contrast-enhanced MRA at 3T and 64-row multidetector CTA. The spinal dural arteriovenous fistula location was confirmed by intra-arterial DSA as the reference standard. Two reviewers independently evaluated the level of the artery feeding the spinal dural arteriovenous fistula on the basis of continuity between the feeder and abnormal spinal vessels on 3T dynamic contrast-enhanced MRA and 64-row multidetector CTA images. Interobserver and intermodality agreement was determined by calculation of the κ coefficient.RESULTS:On DSA, the vessel feeding the spinal dural arteriovenous fistula was the intercostal artery (7 cases), the lumbar artery (3 cases), and the internal iliac artery or the ascending pharyngeal artery (1 case each). For the fistula level, interobserver agreement was excellent for 3T dynamic contrast-enhanced MRA (κ = 0.97; 95% CI, 0.92–1.00) and very good for 64-row multidetector CTA (κ = 0.84; 95% CI, 0.72–0.96). Intermodality agreement with DSA was good for 3T dynamic contrast-enhanced MRA (κ = 0.78; 95% CI, 0.49–1.00) and moderate for 64-row multidetector CTA (κ = 0.41; 95% CI, 0.020–0.84).CONCLUSIONS:For the localization of spinal dural arteriovenous fistulas, 3T dynamic contrast-enhanced MRA may be more reliable than 64-row multidetector CTA.

Spinal dural arteriovenous fistulas (SDAVF) are the most commonly encountered spinal vascular shunt lesions and a treatable cause of myelopathy.¹ The arteriovenous shunt is located inside the dura mater close to the spinal nerve root, where the arterial blood from a radiculomeningeal artery enters a radicular vein. Shunt interruption by either neurosurgery or superselective embolization is the basic treatment strategy,^1–3 and pretreatment localization of SDAVF is important for their adequate treatment. Catheter spinal DSA is the standard technique that accurately detects the location of SDAVF and their feeders. However, an exhaustive search for the lesion by selective catheterization is time-consuming and increases the amount of radiation exposure and contrast material and is accompanied by risks for neurologic complications.^4,5Noninvasive imaging modalities such as multidetector CTA and dynamic contrast-enhanced (DCE)-MRA reliably detect SDAVF and may predict the level of their location.^5–11 However, the noninvasive technique more reliable for the localization of SDAVF remains to be identified, and interobserver and intermodality agreement for the location of SDAVF on CTA and DCE-MRA studies has not been fully investigated.In multidetector CTA, scanner performance can be improved by adding detector rows,¹² and, in DCE-MRA, higher magnetic fields improve the image quality while reducing the acquisition time.¹³ In the present study, we compared the agreement between DSA, DCE-MRA at 3T, and 64-row multidetector CTA (64-CTA) for the localization of SDAVF.     

Endovascular treatment of intracranial dural arteriovenous fistulas with cortical venous drainage: new management using Onyx

BACKGROUND AND PURPOSE: DAVFs (dural arteriovenous fistulas) represent one of the most dangerous types of intracranial AV shunts. Most of them are cured by arterial or venous embolization, but surgery/radiosurgery can be required in case of failure. Our goal was to reconsider the endovascular treatment strategy according to the new possibilities of arterial embolization using non polymerizing liquid embolic agent.MATERIALS AND METHODS: Thirty patients were included in a prospective study during the interval between July 2003 and November 2006. Ten of these had type II, 8 had type III, and 12 had type IV fistulas. Sixteen presented with hemorrhage. Five had been treated previously with other embolic materials.RESULTS: Complete angiographic cure was obtained in 24 cases. Of these 24 cures, 20 were achieved after a single procedure. Cures were achieved in 23 of 25 patients who had not been embolized previously and in only 1 of 5 previously embolized patients. Among these 24 patients, 23 underwent a follow-up angiography, which has confirmed the complete cure. Partial occlusion was obtained in 6 patients, 2 were cured after additional surgery, and 2 underwent radiosurgery. Onyx volume injected per procedure ranged from 0.5 to 12.2 mL (mean, 2.45 mL). Rebleeding occurred in 1 completely cured patient at day 2 due to draining vein thrombosis. One patient had cranial nerve palsy that resolved. Two ethmoidal dural arteriovenous fistulas were occluded. All 10 of the patients with sinus and then CVR drainage were cured.CONCLUSION: Based on this experience, we believe that Onyx may be the treatment of choice for many patients with intracranial dural arteriovenous fistula (ICDAVF) with direct cortical venous reflux (CVR). The applicability of this new embolic agent indicates the need for reconsideration of the global treatment strategy for such fistulas.

Several studies have shown an association between intracranial (IC) dural arteriovenous fistula (DAVF) venous drainage patterns and clinical presentation.^1,2 DAVFs draining retrogradely into cortical veins exhibit a much higher incidence of hemorrhage or venous infarction.^3,4 The annual mortality rate for cortical venous reflux (CVR) may be as high as 10.4%, whereas the annual risk for hemorrhage or nonhemorrhagic neurologic deficits during follow-up are 8.1% and 6.9%, respectively, resulting in an annual event rate of 15%.⁴ In subjects presenting with hemorrhage, the risk of rebleeding has been evaluated at 35% in the 2 weeks after the initial hemorrhage.³ Consequently, DAVFs with CVR require treatment aimed at a complete and definitive fistula closure. In general, treatment of such fistulas primarily involves an endovascular approach, and if this fails, surgical or radiosurgical approaches are used. The present prospective study investigated the use of a new nonadhesive liquid embolic agent, Onyx (ev3, Irvine, Calif), in the treatment of DAVF with CVR.     

Calcified Cerebral Emboli,A “Do Not Miss” Imaging Diagnosis: 22 New Cases and Review of the Literature

BACKGROUND AND PURPOSE:Calcified cerebral emboli are a rarely reported but devastating cause of stroke and may be the first manifestation of vascular or cardiac disease. Our aim was to evaluate the diagnosis, prevalence, imaging appearance, presumed embolic source, treatment, and outcome of patients with calcified cerebral emboli.MATERIALS AND METHODS:Our radiology information system was searched for all CT scans by using keywords “calcified,” “emboli,” and their permutations. The radiology information system was also searched to identify all “stroke” CT reports to calculate the prevalence of calcified cerebral emboli. We also performed a MEDLINE search to identify all published case reports.RESULTS:Twenty-two cases were identified from our database, and 48 were cases reported from the literature. The middle cerebral artery was the site of 83% of calcified emboli. Presumed sources were calcific aortic stenosis (36%), carotid atherosclerotic plaque (30%), and mitral annular calcification (11%). Spontaneous embolism occurred in 86%. Surgical treatment was performed in 34% of patients. Sixty-four percent of the patients with calcified aortic stenosis underwent aortic valve replacement. Among those with identifiable arterial disease, 53% underwent endarterectomy. Forty-one percent of patients experienced at least 1 recurrent stroke. The prevalence of calcified cerebral emboli identified on stroke CT scans at our institution was 2.7%. Seventy-three percent of cases were correctly identified. Twenty-seven percent were misdiagnosed on initial interpretation, while 9% were overlooked on preliminary interpretation.CONCLUSIONS:Calcified cerebral emboli are more common than previously assumed, are frequently overlooked or misinterpreted, affect clinical course when diagnosed, and carry substantial risk for recurrent stroke.

Calcified cerebral emboli are a rarely reported but potentially devastating cause of stroke and may be the first manifestation of vascular or cardiac disease. Proper identification can guide treatment toward preventing future embolic events, neurologic impairment, and death. Noncontrast CT of the head is the most common imaging procedure used as the initial assessment of suspected stroke. The first imaging report of calcified cerebral emboli was published in 1981.¹ Since then, there have been only 48 cases reported in the literature.^1–38The purpose of this study was to evaluate the diagnosis, prevalence, imaging appearance, presumed embolic source, treatment, and outcome of patients with calcified cerebral emboli. We report the first comprehensive review of the literature and present the largest imaging series to date, to our knowledge. We demonstrate that these emboli are more common than previously assumed, are frequently overlooked, and carry substantial risk for recurrent stroke.     

Decreased Superior Sagittal Sinus Diameter and Jugular Bulb Narrowing Are Associated with Poor Clinical Outcome in Vein of Galen Arteriovenous Malformation

BACKGROUND AND PURPOSE:Few clinical and imaging findings are known to be associated with poor outcome in neonates and infants with vein of Galen arteriovenous malformations. In the present consecutive series of 35 patients, we evaluated both the diameter of the superior sagittal sinus at onset and the diameter of the jugular bulb on follow-up as potential factors related to poor outcome.MATERIALS AND METHODS:Thirty-five consecutive neonates and infants who were prospectively collected in a single-center data base were included in this review. Outcome was assessed by using the Bicêtre Outcome Score. Both the absolute diameter of the superior sagittal sinus and its ratio to the biparietal diameter were measured at onset, compared with age-matched controls, and correlated to patient outcome.RESULTS:The diameter of the superior sagittal sinus at onset and its ratio to the biparietal diameter were significantly smaller in the vein of Galen arteriovenous malformation population compared with the matched population (P = .0001) and were correlated significantly with a risk of poor clinical outcome (P = .008). Development of jugular bulb narrowing was also related to poor clinical outcome (P < .0001).CONCLUSIONS:Decreased superior sagittal sinus diameter may reflect a decrease of cerebral blood flow due to cerebral arterial steal and intracranial hydrovenous disorders. This finding may be considered cerebral blood flow deterioration and thus taken into consideration in the management decisions for patients with vein of Galen arteriovenous malformations. Likewise, our data suggest that progressive jugular bulb narrowing may indicate earlier intervention to prevent severe narrowing.

Vein of Galen aneurysmal malformations are rare congenital choroidal arteriovenous malformations.¹ In true Vein of Galen arteriovenous malformations (VGAMs), arteriovenous fistulas drain into an aberrantly persistent fetal median prosencephalic vein, coined the “vein of Markowski,”² which constitutes an embryonic precursor of the vein of Galen, thus forcing the deep venous system to drain through persistent alternative embryonic routes, mainly the lateromesencephalic and lateropontine veins and the superior petrosal sinus.³ VGAMs are supposed to be associated with high morbidity and mortality.^4–8 Lasjaunias et al^9,10 proposed a neonatal scoring system for these malformations, a multiorgan evaluation, to decide the indication and timing of treatment. Certain clinical and imaging findings, such as a low neonatal score,^9,10,11 encephalomalacia,^10–12 intraparenchymal calcifications,¹⁰ and the angioarchitecture of the VGAM (choroidal type nidus and jugular stenosis without cavernous drainage), have been associated with a poorer prognosis.In the present series, we tried to determine additional signs identifiable on cross-sectional imaging that may be associated with poor clinical outcome. Anecdotally, we have observed that the diameter of the superior sagittal sinus (SSS) in babies with VGAM appeared smaller compared with children without cerebral arteriovenous malformations and that on angiography, a delayed and decreased cortical venous drainage through the SSS was present. We presumed that these findings were related to the downstream venous hypertension induced by the arteriovenous shunt; therefore, it could be an indirect marker for high-flow angiopathy, venous congestion, and arterial steal, which, in turn, may be associated with poor clinical outcome. Therefore, in the present series, we wanted to evaluate, in a consecutive series, whether a smaller diameter of the superior sagittal sinus, which can already be present at birth in babies with VGAM, can predict outcome. In addition, we evaluated whether jugular bulb stenosis or occlusion, which are more likely to appear during the first year of life, can predict outcome.     

Symptom Differences and Pretreatment Asymptomatic Interval Affect Outcomes of Stenting for Intracranial Atherosclerotic Disease

BACKGROUND AND PURPOSE:Different types of symptomatic intracranial stenosis may respond differently to interventional therapy. We investigated symptomatic and pathophysiologic factors that may influence clinical outcomes of patients with intracranial atherosclerotic disease who were treated with stents.MATERIALS AND METHODS:A retrospective analysis was performed of patients treated with stents for intracranial atherosclerosis at 4 centers. Patient demographics and comorbidities, lesion features, treatment features, and preprocedural and postprocedural functional status were noted. χ² univariate and multivariate logistic regression analysis was performed to assess technical results and clinical outcomes.RESULTS:One hundred forty-two lesions in 131 patients were analyzed. Lesions causing hypoperfusion ischemic symptoms were associated with fewer strokes by last contact [χ² (1, n = 63) = 5.41, P = .019]. Nonhypoperfusion lesions causing symptoms during the 14 days before treatment had more strokes by last contact [χ² (1, n = 136), 4.21, P = .047]. Patients treated with stents designed for intracranial deployment were more likely to have had a stroke by last contact (OR, 4.63; P = .032), and patients treated with percutaneous balloon angioplasty in addition to deployment of a self-expanding stent were less likely to be stroke free at point of last contact (OR, 0.60; P = .034).CONCLUSIONS:More favorable outcomes may occur after stent placement for lesions causing hypoperfusion symptoms and when delaying stent placement 7–14 days after most recent symptoms for lesions suspected to cause embolic disease or perforator ischemia. Angioplasty performed in addition to self-expanding stent deployment may lead to worse outcomes, as may use of self-expanding stents rather than balloon-mounted stents.

Intracranial atherosclerotic disease (ICAD) causes considerable morbidity and mortality, accounting for up to one-third of ischemic strokes in some series, particularly in certain populations.^1–3 Some lesions prove recalcitrant to first-line medical management, and, in recent decades, endovascular treatments have emerged and evolved as complementary therapies.^4,5 Early series demonstrated technical feasibility and acceptable safety for percutaneous transluminal angioplasty (PTA) and then stent placement of lesions in ICAD.^5–17 Initially, intracranial procedures were performed with devices designed and approved for coronary interventions, with subsequent release of angioplasty balloons specifically engineered for intracranial use.^5,12,17–33 In 2005, the Wingspan stent system with Gateway PTA balloon catheter (Stryker, Kalamazoo, Michigan) became the first stent approved for treatment of ICAD in the United States.^{5,12,18–22,25,34} Numerous studies reported progressively improved outcomes and low complication rates, but randomized data proving efficacy were lacking.^{5,12,18,20,24,25,35,36} In 2011, enrollment in the first randomized, controlled trial to evaluate stent placement versus medical management of ICAD, the Stent placement and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial, was halted early due to high complication rates in the stent placement group as compared with the medical management group.⁴The results of SAMMPRIS have elicited strong responses from both proponents and detractors of stent placement, with clinical decisions now changing.⁵ This current study retrospectively analyzes results of stent placement procedures performed for ICAD at 4 centers, with attention given to factors not specifically assessed in SAMMPRIS that may help guide further investigations of endovascular ICAD management.     

Cerebral Angiography for Evaluation of Patients with CT Angiogram-Negative Subarachnoid Hemorrhage: An 11-Year Experience

BACKGROUND AND PURPOSE:CT angiography is increasingly used to evaluate patients with nontraumatic subarachnoid hemorrhage given its high sensitivity for aneurysms. We investigated the yield of digital subtraction angiography among patients with SAH or intraventricular hemorrhage and a negative CTA.MATERIALS AND METHODS:An 11-year, single-center retrospective review of all consecutive patients with CTA-negative SAH was performed. Noncontrast head CT, CTA, DSA, and MR imaging studies were reviewed by 2 experienced interventional neuroradiologists and 1 neuroradiologist.RESULTS:Two hundred thirty patients (mean age, 54 years; 51% male) with CTA-negative SAH were identified. The pattern of SAH was diffuse (40%), perimesencephalic (31%), sulcal (31%), isolated IVH (6%), or identified by xanthochromia (7%). Initial DSA yield was 13%, including vasculitis/vasculopathy (7%), aneurysm (5%), arteriovenous malformation (0.5%), and dural arteriovenous fistula (0.5%). An additional 6 aneurysms/pseudoaneurysms (4%) were identified by follow-up DSA, and a single cavernous malformation (0.4%) was identified by MRI. No cause of hemorrhage was identified in any patient presenting with isolated intraventricular hemorrhage or xanthochromia. Diffuse SAH was due to aneurysm rupture (17%); perimesencephalic SAH was due to aneurysm rupture (3%) or vasculitis/vasculopathy (1.5%); and sulcal SAH was due to vasculitis/vasculopathy (32%), arteriovenous malformation (3%), or dural arteriovenous fistula (3%).CONCLUSIONS:DSA identifies vascular pathology in 13% of patients with CTA-negative SAH. Aneurysms or pseudoaneurysms are identified in an additional 4% of patients by repeat DSA following an initially negative DSA. All patients with CT-negative SAH should be considered for DSA. The pattern of SAH may suggest the cause of hemorrhage, and aneurysms should specifically be sought with diffuse or perimesencephalic SAH.

Nontraumatic subarachnoid hemorrhage occurs in 30,000 patients per year in the United States, which accounts for 5% of strokes.¹ Patient mortality approximates 45% within a month after SAH,¹ and the identification of a treatable cause of SAH is imperative.Cerebral aneurysm rupture accounts for most SAHs,² but a cause of hemorrhage is not identified in 15%–20% of patients.^2–4 Prior studies have demonstrated that the pattern of SAH on a noncontrast head CT may predict the probability of identifying a causative vascular lesion, though CT angiography or digital subtraction angiography is needed to identify these lesions.^5–9The evaluation of SAH varies, and no consensus exists as to the best algorithm. Increasingly, CTA is performed in the evaluation of SAH, given its noninvasive nature and wide availability. CTA has a reported a sensitivity of 97%–100% for the detection of intracranial aneurysms.^10–13 However, it fails to identify a cause for SAH in 5%–30% of patients.^14,15 DSA remains the criterion standard in the diagnosis of vascular lesions resulting in SAH with a reported sensitivity of 99%.^16,17 Given the superior sensitivity of DSA and the importance of identifying a treatable cause of SAH, DSA is frequently performed in patients presenting with SAH and negative CTA findings.Prior studies demonstrated that DSA identifies a cause of SAH in 4%–14% of patients with negative CTA findings.^{3,4,14,18–20} Moreover, the diagnostic yield of repeat DSA after initially negative DSA findings is reported to be between 4% and 16%.^14,15,21 We describe our experience with initial and repeat DSA in patients with CTA negative for SAH during an 11-year period at a large neurovascular referral center.     

CT Angiography Findings in Carotid Blowout Syndrome and Its Role as a Predictor of 1-Year Survival

BACKGROUND AND PURPOSE:Carotid blowout is a serious late complication of prior treatment of advanced head and neck cancer. We evaluate the efficacy of CTA in the diagnosis of impending carotid blowout syndrome in patients with head and neck cancer, and its capability to predict clinical outcome.MATERIALS AND METHODS:The clinical data of 29 patients with impending carotid blowout who underwent CTA were collected and analyzed. Imaging signs included tissue necrosis, exposed artery, viable perivascular tumor, pseudoaneurysm, and contrast extravasation. DSA was obtained in 20 patients. One-year outcomes were compared based on management.RESULTS:The most common CTA finding was necrosis (94%), followed by exposed artery (73%), viable tumor (67%), pseudoaneurysm (58%), and contrast extravasation (30%). Exposed artery, pseudoaneurysm, and contrast extravasation were the 3 CTA findings related to outcomes. All of the pseudoaneurysm and contrast extravasation cases were associated with an exposed artery. An exposed artery was the most important prognostic predictor and could not be diagnosed on DSA. Patients without the 3 findings on CTA (group 1) had the best survival rate at 1-year follow-up, followed by patients with the 3 findings treated immediately by permanent artery occlusion (group 2). Patients with the 3 findings who had no immediate treatment (group 3) had the worst outcomes (P < .001 in group 1 vs group 3 and group 2 vs group 3; P = .056 group 1 vs group 2).CONCLUSIONS:CTA, with its ability to diagnose an exposed artery compared with DSA, may offer important management and prognostic information in patients with impending carotid blowout.

Carotid blowout syndrome (CBS) is defined as rupture of the carotid artery and its branches and is a serious complication after treatment of advanced head and neck cancer. Potential causes of CBS include radical resection, radiation therapy and radiation necrosis, carotid exposure, wound infection, pharyngocutaneous fistula, and recurrent or persistent carcinoma.¹ The overall incidence of carotid blowout after neck dissection has been reported to be as high as 4.3%, and the risk is increased another 7.6-fold with further radiation therapy.² CBS typically occurs 2–20 years after surgery or radiation therapy,^3,4 and average estimates of cumulative neurologic morbidity and mortality are above 60% and 40%, respectively, in patients with CBS.⁵ CBS can be categorized into 1 of 3 categories: threatened, impending, and acute carotid blowout.¹ Threatened carotid blowout is defined as physical examination or imaging results that suggest inevitable hemorrhage from 1 of the carotid arteries or its branches if no action is taken. Impending carotid blowout (also called sentinel hemorrhage) is defined as transient hemorrhage that resolves spontaneously or with packing or pressure. Acute carotid blowout represents hemorrhage that cannot be controlled by packing or pressure.¹ Surgical management of carotid blowout is usually technically difficult and is associated with high morbidity and mortality rates.^1,2,6,7 After surgical ligation or permanent arterial occlusion (PAO) of the carotid artery, the incidence of immediate or delayed cerebral ischemic complications can be as high as 15%–20%.^7,8–12 The complication rate of a balloon occlusion test before PAO of the carotid artery is reported to be as high as 3.2%, and it may be even higher in fragile postirradiation vessels.¹³ Delayed ischemia after passing the balloon occlusion test is yet another concern.^10,14,15 Stent-graft deployment, with or without coiling, is another endovascular treatment of CBS. Stent-grafting can preserve the affected carotid flow but has a high rate of early and delayed complications.^16–19 No significant difference in short-term outcome between stent-graft deployment and PAO has been reported,²⁰ and long-term results have not been reported.¹⁷CTA has become widely available and is sensitive and specific in the detection of hemorrhagic vascular disorders such as aneurysms, arteriovenous malformations, dural arteriovenous fistulas, and intracranial dissections. Contrast extravasation on CTA predicts hematoma expansion, mortality, and clinical outcome in primary intracerebral hemorrhage.^21–26 To our knowledge, there have been no past reports about the use of CTA in the diagnosis of CBS or as an outcome predictor. The aim of our study was to evaluate the efficacy of CTA in the diagnosis of impending CBS, and its capability to predict clinical outcome after management.     

Pressure Cooker Technique for Endovascular Treatment of Spinal Arteriovenous Fistulas: Experience in 15 Cases

BACKGROUND AND PURPOSE:Spinal arteriovenous fistulas are challenging to cure by endovascular means, with a risk of incomplete occlusion or delayed recurrence. The authors report herein their preliminary experience using the pressure cooker technique for the embolization of spinal arteriovenous fistulas.MATERIALS AND METHODS:Fifteen patients (8 men; mean age, 60.3 years) underwent an endovascular treatment of a spinal arteriovenous fistula (12 dural spinal arteriovenous fistulas and 3 epidural spinal arteriovenous fistulas) in 2 different institutions using the pressure cooker technique. Two microcatheters could be navigated in the segmental artery in all patients using 2 guiding catheters. A proximal plug was achieved with highly concentrated cyanoacrylate ± coils. The liquid embolic agent injected to cure the fistula was diluted cyanoacrylate (n = 11) or ethylene-vinyl alcohol (n = 4). Technical and clinical complications were systematically recorded. Clinical and angiographic outcomes were systematically evaluated at follow-up.RESULTS:One (6.7%) procedure-related complication was recorded, which consisted of a transient radicular deficit, related to nerve root ischemia. Clinical improvement was observed in 10/14 (71%) patients for whom clinical follow-up was available. Complete spinal arteriovenous fistula occlusion on a follow-up angiography was observed in 11/12 patients (91.7%) for whom angiographic follow-up was available. One patient (8.3%) presented with a delayed recurrence at 29 months.CONCLUSIONS:The pressure cooker technique is feasible, with either glue or ethylene-vinyl alcohol, for the embolization of spinal arteriovenous fistulas. Our results suggest the safety and effectiveness of this technique.

Spinal arteriovenous fistulas (SAVFs) are rare vascular malformations involving the spinal cord and corresponding to an abnormal arteriovenous shunt between spinal dural arteries and a radicular vein or the epidural venous plexus, which “contaminates” secondarily the spinal venous drainage.^1,2 Most of these SAVFs are clinically revealed by a venous congestion, responsible for progressive sensory and/or motor deficits of the inferior limbs, often associated with sphincter disturbance (ie, urinary/fecal incontinence, sexual impotence).³The best treatment option for SAVFs is still a matter of debate because no randomized controlled trial has compared endovascular treatment and surgery. Even if it is minimally invasive, the main drawback of the endovascular treatment is the risk of incomplete occlusion of the shunt point, which may lead to treatment failure or recurrence.⁴The pressure cooker technique (PCT) has been developed to improve the penetration of liquid embolic agents in the embolization of brain AVMs, increasing the occlusion rate in the endovascular treatment of brain AVMs.⁵The purpose of our study was to report our experience with the PCT for the endovascular treatment of SAVFs.     

Autosomal Dominant Polycystic Kidney Disease and Intracranial Aneurysms: Is There an Increased Risk of Treatment?

BACKGROUND AND PURPOSE:Autosomal dominant polycystic kidney disease is associated with an increased risk of intracranial aneurysms. Our purpose was to assess whether there is an increased risk during aneurysm coiling and clipping.MATERIALS AND METHODS:Data were obtained from the National Inpatient Sample (2000–2011). All subjects had an unruptured aneurysm clipped or coiled and were divided into polycystic kidney (n = 189) and control (n = 3555) groups. Primary end points included in-hospital mortality, length of stay, and total hospital charges. Secondary end points included the International Classification of Diseases, Ninth Revision codes for iatrogenic hemorrhage or infarction; intracranial hemorrhage; embolic infarction; and carotid and vertebral artery dissections.RESULTS:There was a significantly greater incidence of iatrogenic hemorrhage or infarction, embolic infarction, and carotid artery dissection in the patients with polycystic kidney disease compared with the control group after endovascular coiling. There was also a significantly greater incidence of iatrogenic hemorrhage or infarction in the polycystic kidney group after surgical clipping. However, the hospital stay was not longer in the polycystic kidney group, and the total hospital charges were not higher. Additional analysis within the polycystic kidney group revealed a significantly shorter length of stay but similar in-hospital costs when subjects underwent coiling versus clipping.CONCLUSIONS:Patients with polycystic kidney disease face an increased risk during intracranial aneurysm treatment, whether by coiling or clipping. This risk, however, does not translate into longer hospital stays or increased hospital costs. Despite the additional catheterization-related risks of dissection and embolization, coiling results in shorter hospital stays and similar mortality compared with clipping.

Autosomal dominant polycystic kidney disease (ADPCKD) is a genetic disorder affecting 1 in 1000 individuals worldwide and is associated with an increased risk of intracranial aneurysms, ranging from 4% to 23%^1–6 compared with the general population risk of 2%–3%.^7–10 Patients with ADPCKD are also at increased risk for aneurysm rupture earlier in life (mean age, 35–45 years),^1,11–13 compared with the general population (mean age, 50–54 years).^14,15There is evidence that the associated vascular defects in ADPCKD may be due to mutations in the PKD1 and PKD2 genes, located on the short arm of chromosomes 16 and 4.^16,17 Abnormalities of these genes in mouse models correspond with increased rates of arterial dissection, arterial rupture, and intracranial vascular abnormalities.¹⁸ To our knowledge, only 1 study to date has investigated whether these issues engender an increased risk when treating intracranial aneurysms (whether by endovascular coiling or surgical clipping).² The purpose of this investigation was to assess whether ADPCKD confers an increased peri- and immediate postprocedural risk of aneurysm coiling and clipping.