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.     

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.     

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.     

Assessment of dural arteriovenous fistulas of the cavernous sinuses on 3D dynamic MR angiography

BACKGROUND AND PURPOSE: Flow voids within the cavernous sinuses and/or certain venous drainage on spin-echo MR imaging and time-of-flight (TOF) flow enhancement on MR angiography (MRA) have indicated high-velocity shunt flow and have been used for screening patients with dural arteriovenous fistulas (DAVFs) of the cavernous sinuses. In this investigation, the capabilities of 3D dynamic MRA as a flow-independent approach and those of conventional MR imaging techniques were compared with selective angiography for the diagnosis of DAVFs of the cavernous sinuses.MATERIALS AND METHODS: This retrospective study involved 18 patients with angiographically proved DAVFs of the cavernous sinuses and 12 control subjects. Sixteen partially overlapping sequential MR images were acquired on contrast-enhanced 3D dynamic MRA between the petrosal bone and the orbital roof. Two experienced observers blinded to the clinical data and results of angiography independently graded 3D dynamic MRA, fast spin-echo T2-weighted imaging (FSE T2WI), and TOF MRA.RESULTS: The average area under the receiver operating characteristic curve values and interobserver κ scores for the diagnosis of DAVFs on 3D dynamic MRA, FSE T2WI, and TOF MRA were 0.99, 0.89, and 0.95; and 0.92, 0.71, and 0.73, respectively. Those for the diagnosis of anterior, posterior, and retrograde cortical venous drainage on 3D dynamic MRA were 0.72, 0.95, and 0.81; and 0.56, 0.50, and 0.49, respectively.CONCLUSION: In this small series, screening 3D dynamic MRA directly demonstrates DAVFs of the cavernous sinuses and has improved diagnostic capability.

In patients with the classic triad of pulsating exophthalmos, orbital bruit, and conjunctival chemosis, the clinical diagnosis of arteriovenous fistulas (AVFs) of the cavernous sinuses is not difficult, and cerebral angiography is performed for definitive diagnosis. However, dural AVFs (DAVFs) without anterior drainage may not cause typical congestive orbito-ocular features, and thrombosis of the draining veins may lead to spontaneous resolution of the disorder.^1–6 Therefore, it is desirable to perform less invasive diagnostic examinations before conventional angiography. So far, flow voids within the cavernous sinuses and/or inferior petrosal sinuses on spin-echo MR images followed by time of flight (TOF) flow enhancement on source images of MR angiography (MRA) have been indicative of AVF.^7–10 Although these are safe and practical methods, dependence on flow velocity sometimes makes it impossible to distinguish fast normal flow from abnormal shunt flow or slow abnormal shunt flow from normal flow.^9–13The recent advancement of MR imaging technology has allowed first-pass contrast-enhanced dynamic MRA and 2D MR digital subtraction angiography to be applied to cerebral arteriovenous malformations (AVMs) or DAVFs.^14–18 In addition, although the conventional use of 3D dynamic MRA for their diagnosis has been difficult due to the limitation of low temporal resolution, its application has been described in recently published articles.^19,20 However, until now, there has not been a comparative study of dynamic MRA and conventional MR imaging for the diagnosis of DAVFs of the cavernous sinuses.According to a study of dynamic CT of the cavernous sinuses²¹ and physiologic studies on the cerebral circulation time,^22,23 it was hypothesized that imaging temporal resolution under several seconds would demonstrate DAVFs of the cavernous sinuses on dynamic MRA. Therefore, we used the 3D data-acquisition technique, a standard pulse sequence, and postulated that early enhancement of the cavernous sinuses was a main direct feature of the shunts. This methodology will improve the diagnostic capability for screening of DAVFs of the cavernous sinuses.     

Embolization of Intracranial Dural Arteriovenous Fistulas Using PHIL Liquid Embolic Agent in 26 Patients: A Multicenter Study

BACKGROUND AND PURPOSE:The introduction of liquid embolic agents has revolutionized endovascular approach to cranial vascular malformations. The aim of the study was to retrospectively assess the efficacy and safety of Precipitating Hydrophobic Injectable Liquid (PHIL), a new nonadhesive liquid embolic agent, in the treatment of patients with cranial dural arteriovenous fistulas. The primary end point was the rate of complete occlusion of dural arteriovenous fistulas. Secondary end points included the incidence of adverse events and clinical status at 3-month follow-up.MATERIALS AND METHODS:This was a retrospective multicenter study. Twenty-six consecutive patients with dural arteriovenous fistulas (de novo or previously treated) treated by injection of PHIL only or with PHIL in combination with other embolization products (such as Onyx or detachable coils) were included in the study. Recruitment started in August 2014 and ended in September 2015.RESULTS:Twenty-two (85%) patients were treated with PHIL only, with 3 patients treated with both PHIL and Onyx, and 1, with both PHIL and coils. Immediate complete angiographic occlusion was achieved in 20 (77%) patients. Of the 6 patients with residual fistulas, 3 were retreated with PHIL and 1 achieved angiographic cure. An adverse event was seen in 1 patient who developed worsening of preexisting ataxia due to acute thrombosis of the draining vein.CONCLUSIONS:PHIL appears to be safe and effective for endovascular treatment of cranial dural arteriovenous fistulas. Short-term angiographic and clinical results are comparable with those of Onyx, with the added advantage of easier preparation and improved homogeneous cast visualization. The use of iodine as a radio-opacifier also produces considerably less artifacts on CT compared with tantalum-based embolic materials.

Dural arteriovenous fistulas (DAVFs) are a rare type of acquired intracranial vascular malformation consisting of a pathologic shunt located within the dura mater of the brain.^1–3 These lesions have been categorized by Awad et al,⁴ Borden et al,⁵ and Cognard et al⁶ according to their locations and patterns of venous drainage. Acute presentation with intracranial hemorrhage occurs in up to 65% of patients,⁶ and patients with a previous intracranial hemorrhage may have up to a 35% risk of another neurologic event within 2 weeks.⁷Endovascular embolization has become the primary treatment approach for DAVFs.^1,8,9 The goal of endovascular therapy is to achieve complete obliteration of the fistulous point between the feeding arteries and the draining veins. This can be safely accomplished by occluding the draining veins, which often results in complete closure of the lesion, unlike in cerebral arteriovenous malformations.The introduction of liquid embolic agents has a significant impact on the endovascular approach to DAVFs. Precipitating Hydrophobic Injectable Liquid (PHIL; MicroVention, Tustin, California) is a new nonadhesive liquid embolic agent comprising a copolymer dissolved in dimethyl-sulfoxide (DMSO). It is delivered by slow and controlled injection through a DMSO-compatible microcatheter under fluoroscopic control. An iodine component is chemically bonded to the copolymer to provide homogeneous radio-opacity during fluoroscopic visualization. When it comes in contact with human blood, the DMSO solvent dissipates, causing the copolymer to precipitate in situ into a coherent embolus. The PHIL liquid embolic system is available in 3 formulations: 25%, 30%, and 35%. PHIL 25% will travel more distally and penetrate deeper into the fistula due to its lower viscosity compared with PHIL 30% or 35%. The latter 2 are more appropriate for use in high-flow arteriovenous shunts with ≥1 direct fistula. Higher strength formulations are also preferred when increased fluoroscopic visibility is desirable.The aim of our study was to assess the efficacy and safety of PHIL in the treatment of patients with cranial DAVFs.     

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.     

Onyx 18 embolisation of dural arteriovenous fistula via arterial and venous pathways: preliminary experience and evaluation of the short-term outcomes

Objective

This paper mainly focuses on our preliminary experience and short-term outcome evaluation of embolisation of non-cavernous dural arteriovenous fistulas (ncsDAVFs) and cavernous sinus dural arteriovenous fistulas (csDAVFs) using Onyx 18 (ev3, Plymouth, MN), and in combination with coils, via arterial and venous approaches, respectively.

Methods

Between August 2008 and March 2010, 21 DAVFs (11 ncsDAVFs and 10 csDAVFs; age range: 28–68 years; 12 females and 9 males) were undertaken. Borden classification showed Type III in 1 and Type II in 10 ncsDAVFs, and Type II in 4 and Type I in 6 csDAVFs. Onyx 18 was used in 11 ncsDAVFs (10 via single feeder and 1 via 2 feeders). Onyx 18 or in combination with coils was used in 10 csDAVFs (9 via the inferior petrosal sinus and 1 via the superior ophthalmic vein).

Results

Total occlusion in immediate angiography was achieved in 18 cases (85.7%; 10 ncsDAVFs and 8 csDAVFs), and near-total occlusion in 1 ncsDAVF and 2 csDAVFs. Onyx 18 was migrated into normal vasculature in two ncsDAVFs without any sequelae. One csDAVF had VI cranial nerve palsy post-operatively, which completely recovered 2 weeks post-embolisation. Follow-up angiography at 3–12 months showed complete occlusion in 20 cases (95.2%; 10 ncsDAVFs and 10 csDAVFs). One ncsDAVF (4.8%) recurred after 3 months and was successfully re-embolised.

Conclusion

Preliminary results achieved after embolising 11 ncsDAVFs and 10 csDAVFs using Onyx 18 and in combination with coils via arterial and venous pathways, respectively, appeared to be safe, feasible and effective, as 95.2% of cases were totally occluded without any clinical sequelae.Dural arteriovenous fistulas (DAVFs) are the abnormal vascular shunts of dura mater that are usually found within or near the wall of dural venous sinuses [1]. Nevertheless, the location of DAVF lesions is not constant; it can occur in any part of dura and its subsidiaries. With the development of newer techniques and embolic materials in the world of interventional neuroradiology, endovascular therapy has now been developing as the primary treatment strategy to cure DAVFs, with successful results [2]. However, depending upon the location of fistula, its venous drainage pattern and it feeding vessels, approaching vascular pathways has to be considered carefully. Patients may present with intracranial haemorrhage, intracranial hypertension or brain herniation and other serious consequences depending upon the cortical venous reflux (CVR) pattern [3,4].For satisfactory embolisation of either type of DAVF, embolic material that can adequately disperse into whole fistulous channels is required. Onyx 18, which is made up of 6% ethylene vinyl alcohol (ensuring that it can travel distally and penetrate deep into a target area, owing to its low viscosity) (ev3, Plymouth, MN) is a similar kind of non-adhesive liquid embolic agent having better penetration quality and has been widely used for the treatment of cerebral arteriovenous malformations [5]. However, literature about the use of Onyx 18 via either pathway to embolise DAVF is still limited.Here we presente our preliminary experience about the use of Onyx 18 together with coils via arterial and venous pathways to embolise non-cavernous (ncsDAVF) and cavernous sinus dural arteriovenous fistulas (csDAVF), and their short-term outcome evaluation. We have detailed the embolisation techniques, their effectiveness and related complications.     

Assessment of craniospinal arteriovenous malformations at 3T with highly temporally and highly spatially resolved contrast-enhanced MR angiography

BACKGROUND AND PURPOSE: Patients with arteriovenous malformation (AVM) are known to have an elevated risk of complications with conventional catheter angiography (CCA) but nonetheless require monitoring of hemodynamics. Thus, we aimed to evaluate both anatomy and hemodynamics in patients with AVM noninvasively by using contrast-enhanced MR angiography (CE-MRA) at 3T and to compare the results with CCA.MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained for this Health Insurance Portability and Accountability Act–compliant study. Twenty control subjects without vascular malformation (6 men, 18–70 years of age) and 10 patients with AVMs (6 men, 20–74 years of age) underwent supra-aortic time-resolved and high-spatial-resolution CE-MRA at 3T. Large-field-of-view coronal acquisitions extending from the root of the aorta to the cranial vertex were obtained for both MRA techniques. Image quality was assessed by 2 specialized radiologists by using a 4-point scale. AVM characteristics and nidus size were evaluated by using both CE-MRA and CCA in all patients.RESULTS: In patients, 96.6% (319/330) of arterial segments on high-spatial-resolution MRA and 87.7% (272/310) of arterial segments on time-resolved MRA were graded excellent/good. MRA showed 100% specificity for detecting feeding arteries and venous drainage (n = 8) and complete obliteration of the AVM in 2 cases (concordance with CCA). Nidus diameters measured by both MRA and CCA resulted in a very strong correlation (r = 0.99) with a mild overestimation by MRA (0.10 cm by using the Bland-Altman plot).CONCLUSION: By combining highly temporally resolved and highly spatially resolved MRA at 3T as complementary studies, one can assess vascular anatomy and hemodynamics noninvasively in patients with AVM.

Craniospinal arteriovenous malformation (AVM) typically presents in a young adult with intracranial hemorrhage (30%–82%), headache, seizures, or focal neurologic deficits that are either related to mass effect or to vascular steal phenomena.¹ Hemorrhage occurs with an annual incidence of 2%–4%^2,3 and remains the prime vector for mortality and morbidity (10% and 16%–50%, respectively).^4–6 Several investigators have identified features predictive of hemorrhage, including small nidus size, deep nidus location, single deep venous drainage, associated arterial aneurysm, impaired venous drainage, and high intranidal pressure.^7–10 Safe and accurate diagnostic work-up is essential to provide an architectural map and to define hemodynamic indices and risk predictors. Moreover, follow-up studies may be required for monitoring posttherapy. The current gold standard for assessment of AVM is conventional catheter angiography (CCA), which is associated with ≤1.3% of major complications and death (<0.1%).^11–13 In this context, multiple catheter examinations in patients with AVM are expected to elevate the risk of complications and hemorrhage.Recent advances in the performance of contrast-enhanced MR angiography (CE-MRA) at 3T have underscored its growing potential for detailed evaluation of the supra-aortic arteries and veins.^14–16 Techniques have been established for both highly temporally resolved and highly spatially resolved CE-MRA, by using only modest contrast doses.^17,18 Whereas high-spatial-resolution MRA can quickly provide detailed images of intracranial and extracranial vessels, time-resolved MRA adds hemodynamic information and can capture transient processes, such as early venous filling, which is the hallmark of an arteriovenous fistula (AVF).^17,19 Moreover, cortical venous reflux has a high yearly risk of hemorrhage^20–24 and influences treatment.^24–28 Micro-AVMs as a potential source of fatal intracranial hematoma represent approximately 8%–10% of surgically treated brain AVMs.^29,30 Time-resolved MRA may potentially identify an early filling vein in a micro-AVF because the anatomy of a very small nidus may not be assessable. Furthermore, an early filling vein may be the only evidence of a residual shunt after radiosurgery or endovascular therapy.These 2 approaches can, therefore, provide complementary diagnostic information to each other for evaluation of high-flow AVMs. The purpose of our study was to evaluate the potential of these complementary modes in defining the relevant vascular anatomy and hemodynamics noninvasively in patients with AVM and to compare the findings with those on digital subtraction angiography (DSA).     

Diffuse pachymeningeal hyperintensity and subdural effusion/hematoma detected by fluid-attenuated inversion recovery MR imaging in patients with spontaneous intracranial hypotension

BACKGROUND AND PURPOSE: Fluid-attenuated inversion recovery (FLAIR) MR imaging has advantages to detect meningeal lesions. FLAIR MR imaging was used to detect pachymeningeal thickening and thin bilateral subdural effusion/hematomas in patients with spontaneous intracranial hypotension (SIH).MATERIALS AND METHODS: Eight patients were treated under clinical diagnoses of SIH. Chronologic MR imaging studies, including the FLAIR sequence, were retrospectively reviewed.RESULTS: Initial MR imaging showed diffuse pachymeningeal thickening as isointense in 6 cases, hypoisointense in 1 case, and isohyperintense in 1 case on the T1-weighted MR images, and hyperintense in all cases on both T2-weighted and FLAIR MR images. Dural (pachymeningeal) hyperintensity on FLAIR MR imaging had the highest contrast to CSF, and was observed as linear in all patients, usually located in the supratentorial convexity and also parallel to the falx, the dura of the posterior fossa convexity, and the tentorium, and improved after treatment. These characteristics of diffuse pachymeningeal hyperintensity on FLAIR MR imaging were similar to diffuse pachymeningeal enhancement (DPME) on T1-weighted imaging with gadolinium. Initial FLAIR imaging clearly showed subdural effusion/hematomas in 6 of 8 patients. The thickness of subdural effusion/hematomas sometimes increased transiently after successful treatment and resolution of clinical symptoms.CONCLUSION: Diffuse pachymeningeal hyperintensity on FLAIR MR imaging is a similar sign to DPME for the diagnosis of SIH but does not require injection of contrast medium. FLAIR is useful sequence for the detection of subdural effusion/hematomas in patients with SIH.

Spontaneous intracranial hypotension (SIH) syndrome is characterized by low CSF pressure and positional headache caused by leakage of spinal CSF.^1,2 MR imaging has revolutionized the identification, diagnosis, management, and understanding of SIH. The characteristic MR signs of SIH include diffuse pachymeningeal (dura mater) enhancement (DPME), bilateral subdural effusion/hematomas, downward displacement of the brain, enlargement of the pituitary gland, prominence of the spinal epidural venous plexus, engorgement of cerebral venous sinuses (“venous distension sign,” etc),³ venous sinus thrombosis,⁴ and isolated cortical vein thrombosis.⁵ DPME after gadolinium administration may be the most common and indicative sign^1,2 and forms the basis of the proposed “syndrome of orthostatic headache and diffuse pachymeningeal gadolinium enhancement.”⁶The cause of DPME remains unclear. Histologic examination of meningeal biopsy specimens consistently demonstrates a thin layer of fibroblasts as well as small, thin-walled, dilated blood vessels without evidence of inflammation on the subdural surface, the so-called dural border cell layer.⁷ These findings strongly suggest that dural venous dilation following the Monro-Kellie rule is the most likely explanation of DPME associated with SIH, which states that decreased CSF volume caused by CSF leakage requires volume compensation resulting in meningeal venous hyperemia and subsequent pachymeningeal enhancement.⁸ However, previous studies did not include detailed neuroradiologic evaluations of the pachymeninges in patients with SIH without artificial contrast materials to evaluate the transient and functional changes of the dura mater.⁹Bilateral subdural effusion/hematomas are also classic intracranial signs in the diagnosis of SIH, which again may be explained by the Monro-Kellie rule.^1,6,8 The incidence of subdural effusion/hematomas associated with SIH is 10% to 50% with use of conventional neuroradiologic techniques.^10,11 Subdural effusion/hematomas associated with SIH tend to be thin (typically 2–7 mm), do not cause appreciable mass effect, occur typically over the convexities of the brain, and appear as variable MR signal intensities depending on the fluid protein concentration or presence of blood.¹The fluid-attenuated inversion recovery (FLAIR) pulse sequence cancels the signal intensity from CSF and causes heavy T2 weighting because of the very long TE, resulting in excellent definition of anatomic detail, such as brain surface sulci, and high lesion contrast in areas close to the CSF.¹² This method is commonly used to detect meningeal lesions such as subarachnoid hemorrhage and meningitis.^13–15 Therefore, FLAIR MR imaging may be the optimum sequence to evaluate the thickened dura associated with SIH and to detect the very thin subdural effusion/hematomas located close to the subarachnoid CSF space.Our study used FLAIR MR imaging to examine the thickened dura and subdural effusion/hematomas in patients with SIH.     

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.     

Diagnostic accuracy of CT angiography with matched mask bone elimination for detection of intracranial aneurysms: comparison with digital subtraction angiography and 3D rotational angiography

BACKGROUND AND PURPOSE: Our aim was to determine the diagnostic accuracy of multisection CT angiography combined with matched mask bone elimination (CTA-MMBE) for detection of intracranial aneurysms compared with digital subtraction angiography (DSA) and 3D rotational angiography (3DRA).MATERIALS AND METHODS: Between January 2004 and February 2006, 108 patients who presented with clinically suspected subarachnoid hemorrhage underwent both CTA-MMBE and DSA for diagnosis of an intracranial aneurysm. Two neuroradiologists, independently, evaluated 27 predefined vessel locations in the CTA-MMBE images for the presence of an aneurysm. After consensus, diagnostic accuracy of CTA was calculated per predefined location and per patient. Interobserver agreement was calculated with κ statistics.RESULTS: In 88 patients (81%), 117 aneurysms (82 ruptured, 35 unruptured) were present on DSA. CTA-MMBE detected all ruptured aneurysms except 1. Overall specificity, sensitivity, positive predictive value, and negative predictive value of CTA-MMBE were 0.99, 0.90, 0.98, and 0.95 per patient and 0.91, 1.00, 0.97, and 0.99 per location, respectively. Sensitivity was 0.99 for aneurysms ≥3 mm and 0.38 for aneurysms <3 mm. Interobserver agreement for aneurysm detection was excellent (κ value of 0.92 per location and 0.80 per patient).CONCLUSION: CTA-MMBE is accurate in detecting intracranial aneurysms in any projection without overprojecting bone. CTA-MMBE has limited sensitivity in detecting very small aneurysms. Our data suggest that DSA and 3DRA can be limited to the vessel harboring the ruptured aneurysm before endovascular treatment, after detection of a ruptured aneurysm with CTA.

In current clinical practice, CT angiography (CTA) is the most frequently used noninvasive diagnostic tool for detection of intracranial aneurysms in the acute setting.^1–8 However, detection of intracranial aneurysms by CTA is limited because axial source section evaluation is tedious and 3D visualization is hampered by overprojecting bone, especially in the region of the skull base.^2,9–13 Several methods to remove bone, such as subtraction and manual or automated bone editing, have been developed.^7,8,14–19 Drawbacks of these methods are the complexity of use, dependence on the user, or high dose of radiation.Matched mask bone elimination (MMBE) is a relatively new technique to remove bone from CTA source images (CTA-MMBE) in an automatic and user-independent way with little additional radiation dose.^20–22 In CTA-MMBE, a second nonenhanced low-dose scan (about a quarter of the radiation dose of a regular CTA) is used to identify bony structures that can subsequently be masked in the CTA scan.Digital subtraction angiography (DSA) is the gold standard for detection of intracranial aneurysms. Extension of DSA with 3D rotational angiography (3DRA) can further improve detection of intracranial aneurysms that may be obscured by overprojecting vessels.^23–25 The advantages of DSA over CTA are superior spatial and contrast resolution, no interference of bony structures, and the possibility to perform direct endovascular interventions.^26,27 However, DSA is an invasive technique with a small but significant risk of neurologic complications, estimated to occur in 0.3%–1.8% of patients.^28,29The purpose of this study was to determine the diagnostic accuracy of CTA-MMBE for detection of intracranial aneurysms in a large patient population with clinically suspected subarachnoid hemorrhage (SAH) with DSA and 3DRA as reference standards.     

Transcranial color-coded duplex sonography for detection of distal internal carotid artery stenosis

BACKGROUND AND PURPOSE: Gradation of high-grade intracranial internal carotid artery (ICA) stenosis poses a challenge to noninvasive neurovascular imaging, which seems critical for angioplasty in the ICA segments C1 and C5. We investigated cutoff values of intracranial ICA stenosis for transcranial color-coded sonography (TCCS) and compared this method with the “gold standard,” digital subtraction angiography (DSA).Materials and METHODS: Forty patients (mean age, 58.9 ± 13.8 years) with intracranial ICA lesions were prospectively examined by using TCCS and DSA. Two standard TCCS coronal imaging planes were used to evaluate the intracranial ICA. In addition, a control group of 128 volunteers without cerebrovascular disease (mean age, 48.8 ± 15.9 years) was investigated to establish standard velocity values.RESULTS: DSA confirmed 96 stenoses and 8 occlusions of the intracranial ICA in the study population. In 9% and 7% of cases, stenosis confined to the C1 or C5 segment was >50% and 70%, respectively. Receiver-operating curves demonstrated cutoff values for >70% stenosis in C1 when the peak systolic velocity (PSV) was >200 cm/s (specificity, 100%; sensitivity, 71%) or the C1/submandibular ICA index was >3 (specificity, 93%; sensitivity, 86%).CONCLUSIONS: TCCS is a reliable adjunctive method to detect and quantify significant stenosis of the intracranial ICA. The assessment of the C1/ICA index and peak systolic velocities maximizes the diagnostic accuracy of C1 stenosis to >70% when extracranial ICA stenosis coexists. Further studies need to be performed to compare the diagnostic accuracies of MR angiography and TCCS with that of DSA.

Detection of atherosclerotic narrowing of intracranial cerebral arteries is important in stroke management and aids in the identification of patients with high risk for vascular events.^1–3 Ischemic stroke due to atherosclerosis of intracranial large arteries has been reported in approximately 8%–29% of adults in general, with a higher prevalence in African and Asian populations.^4–6 The intracranial internal carotid artery (ICA) is the most common location for intracranial stenosis of >50%; such cases compose up to 49% of all intracranial artery stenoses.^1,7 Patients with severe (≥70%) intracranial stenosis have a higher risk of stroke than patients with moderate (50%–69%) intracranial stenosis.⁸ Treatment of significant stenosis relies on antiplatelet and antithrombotic agents as well as on aggressive lipid-lowering therapies.^9,10 Endovascular treatments involving angioplasty for 50%–99% ICA stenosis have also been applied but are considered experimental approaches in need of validation by controlled studies.^11–13Because the course of intracranial ICA is complicated due to its tortuosity and variability, classification of this portion of the vessel may differ between authors,^14–16 in turn complicating interpretation of the data. The “gold standard” used to assess the intracranial ICA remains digital subtraction angiography (DSA). DSA is usually performed only after noninvasive imaging procedures, such as MR angiography (MRA) and, to a lesser degree, conventional transcranial Doppler (TCD) sonography, have suggested intracranial stenosis. With TCD sonography, intracranial ICA stenosis is considered when flow velocities exceed normal values and/or exhibit abnormal flow patterns. Unlike cases of extracranial ICA disease, stenosis gradation of the intracranial ICA has not been calculated.^17,18 With MRA, intracranial ICA stenosis in the C5 as well as the C3 and C1 segments is frequently indicated by flow-void artifacts, especially when using time-of-flight sequences, because of the inherent signal-intensity loss of parallel imaging, which can only be compensated in part by the use of MR imaging contrast agents.¹⁹ Due to these MRA artifacts, calculation of ICA stenosis gradation is difficult, and semiquantitative scales, rather than percentages of stenosis, are frequently used to describe the lesion.²⁰Although the criteria for detecting significant (>50%) stenosis of basal cerebral arteries has been defined for transcranial color-coded sonography (TCCS),^21–24 little data can be found on grading intracranial ICA stenosis. The aim of this study was to elaborate the TCCS criteria for detection and quantification of significant intracranial ICA stenosis and to correlate them with conventional DSA criteria as the standard of reference.     

Nontraumatic skull base defects with spontaneous CSF rhinorrhea and arachnoid herniation: imaging findings and correlation with endoscopic sinus surgery in 27 patients

BACKGROUND AND PURPOSE: Defects at the skull base leading to spontaneous CSF rhinorrhea are rare lesions. The purpose of our study was to correlate CT and MR findings regarding the location and content of CSF leaks in 27 patients with endoscopic sinus surgery observations.MATERIALS AND METHODS: Imaging studies in 27 patients with intermittent CSF rhinorrhea (CT in every patient including 10 examinations with intrathecal contrast, plain CT in 2 patients, and MR in 15 patients) were analyzed and were retrospectively blinded to intraoperative findings.RESULTS: CT depicted a small endoscopy-confirmed osseous defect in 3 different locations: 1) within the ethmoid in 15 instances (53.6% of defects) most commonly at the level of the anterior ethmoid artery (8/15); 2) adjacent to the inferolateral recess of the sphenoid sinus in 7 patients including one patient with bilateral lesions (8/28 defects, 28.6%); 3) within the midline sphenoid sinus in 5 of 28 instances (17.9%). Lateral sphenoid defects (3.5 ± 0.80 mm) were larger than those in ethmoid (2.7 ± 0.77 mm, P ≤ 0.029) or midsphenoid location (2.4 ± 0.65 mm, P ≤ 0.026). With endoscopy proven arachnoid herniation in 24 instances as reference, MR was correct in 14 of 15 instances (93.3%), CT cisternography in 5 of 8 instances (62.5%). Plain CT in 1 patient was negative.CONCLUSION: In patients with a history of spontaneous CSF rhinorrhea, CT was required to detect osseous defects at specific sites of predilection. MR enabled differentiating the contents of herniated tissue and allowed identification of arachnoid tissue as a previously hardly recognized imaging finding.

The term “spontaneous” CSF rhinorrhea has been applied to describe nasal discharge of CSF unrelated to trauma, surgery, malformation, tumor, or previous radiation therapy.^1–4 Spontaneous CSF rhinorrhea is uncommon. Estimates of the spontaneous cause among all causes of CSF rhinorrhea are subject to variation ranging from only 6%,⁵ 11.4%,⁶ 14%,³ 21%,⁷ to 23%.⁸ Periodic release of CSF from the nose was first described by Galen in 200 B.C. and was considered a physiologic phenomenon until Thomson, in 1899, assembled 21 patients in a monograph reporting spontaneous CSF rhinorrhea as a pathologic clinical entity.^9,10Spontaneous CSF rhinorrhea has been recognized as a distinct entity with respect to clinical presentation,^2,11,12 treatment,^13–15 and propensity for recurrence.^8,16,17 As early as 1968, Ommaya et al⁹ postulated the existence of “high-pressure leaks” related to intracranial tumors and of “normal pressure leaks” occasionally associated with empty sella. The role of empty sella as an indicator of raised intracranial pressure as well was supported by the observation of elevated CSF pressure in individual patients¹¹ and in a series of 10 patients who underwent lumbar puncture after sealing of the defect.¹⁸ In addition to the presence of an empty sella as a radiologic sign,¹⁹ a common clinical constellation in patients with spontaneous CSF rhinorrhea is female sex, middle age, and obesity.^{8,14,15,18–22}Spontaneous CSF leaks have been postulated to represent a manifestation of benign intracranial hypertension²² or pseudotumor cerebri.²³ Pulsatile-increased hydrostatic pressure is capable of bone erosion during the course of many years.^2,24 To become effective as a CSF leak, bone erosion and creation of an osteodural defect is required to occur at pneumatized parts of the skull base leading to communication of the subarachnoid space with the sinonasal spaces or temporal bone cavity. Related to CSF rhinorrhea, a review of the literature up to 1972¹⁰ identified the cribriform plate, craniopharyngeal canal, sella, and spheno-occipital synchondrosis as possible sites of predilection. Arachnoid granulations in proximity to the ethmoid and sphenoid sinus have been implicated as precursors of osteodural leaks.² Accordingly, arachnoid granulations causing erosion of the temporal bone may present with CSF otorrhea.^2,25,26Among the imaging techniques used to localize the site of the fistula, radionuclide isotope cisternography and CT cisternography were of limited sensitivity in 66% of patients only.³ When active leaks were present, CT cisternography provided positive results in 85% of patients.²⁷ However, in cases of inactive fistulas, CT cisternography failed to recognize the site of leakage in 27.7%²⁸ and in 19% of patients.²⁹ Advances in CT and MR imaging techniques have improved sensitivity, which amounted to 88.25%³⁰ and 93%³¹ for high-resolution CT and for MR cisternography to 89%,^6,31 93.6%,²⁸ and 100%^32,33 even in patients with inactive leaks. Therefore, high-resolution CT, MR cisternography, or a combination of both techniques have replaced the previously used invasive procedures.A confounding nomenclature exists regarding the contents of osteodural defects such as meningocele,^10,14 meningoencephalocele,⁴ encephalocele,^11,34 meningeal or arachnoid hernia,^24,35 arachnoid diverticulum,³⁶ or arachnoid cyst.³⁷ These differing designations reflect variable contents of herniation and occasional inaccuracy because of the limited ability to visualize the lesions by imaging^24,29 and during transcranial surgery.^1,10 Knowledge of the contents of herniation may modify the grafting technique and therefore facilitates preoperative planning.¹⁶ The endoscopic skull base approach has rendered direct visualization of the defect and its contents feasible.^38–40 Therefore, endoscopy was chosen as a standard of reference in this study. CT and MR findings in this series of patients with spontaneous CSF rhinorrhea were particularly assessed regarding the contents of herniation and location and correlated with endoscopy. Predisposing factors (arachnoid granulation, empty sella) and the size of the osseous defect were assessed on CT images.     

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 traumatic injuries of the vertebral artery

BACKGROUND AND PURPOSE: There are a few reports regarding the treatment of traumatic vertebral arteriovenous fistulas and pseudoaneurysms. Our aim was to describe the clinical and angiographic results of endovascular therapy for traumatic injuries of the vertebral artery.MATERIALS AND METHODS: The clinical and angiographic features of 18 traumatic injuries of the vertebral artery during an 8-year period were reviewed. There were 14 male (78%) and 4 female patients (22%). The average age was 28 years (range, 11–49 years). Of the 18 lesions of the vertebral artery, 17 (95%) were the result of penetrating trauma (gunshot or stab wound injury) and 1 (5%) was iatrogenic (jugular vein catheter). In 16 (89%) instances, the injury resulted in an arteriovenous fistula, and in the other 2 (11%), in a pseudoaneurysm. All patients were treated with an endovascular approach by using different techniques (balloon occlusion, coil embolization, and/or stent deployment).RESULTS: Endovascular therapy resulted in immediate lesion total occlusion in 16 (89%) patients. Delayed total occlusion was demonstrated angiographically during follow-up in the 2 remaining patients. Clinical improvement was documented in all patients, and there were no clinically symptomatic complications.CONCLUSION: In this small series, endovascular techniques were a safe and effective method of treatment and were not associated with significant morbidity or mortality.

Vertebral artery traumatic lesions can be classified either as dissecting, thrombotic, pseudoaneurysm, or arteriovenous fistula (AVF). AVFs compromising the vertebral artery are rare lesions, defined by the presence of an abnormal shunt between the extracranial vertebral artery or 1 of its muscular or radicular branches and an adjacent vein.^1-3 These lesions can be of traumatic or spontaneous origin.^1-6 Traumatic fistulas are frequently associated with penetrating neck injuries.^7-8 Less frequent causes include puncture of the vertebral artery after gaining jugular vein access for central line placement, neck surgery, dislocations, and fractures of the cervical spine.^9-11Approximately 30% of AVFs can be asymptomatic,¹² discovered incidentally after auscultation of a neck bruit. However, these lesions can have ischemic symptoms of vertigo, diplopia, and cephalgia secondary to arterial steal. The presence of myelopathy or cervical neuralgia is rare but can result after arterial blood reflux into spinal pial veins or after root compression by engorged epidural veins.²Closure of the AVF or pseudoaneurysm with preservation of the parent artery is the main goal of treatment, rarely achieved with surgery but frequently attained with an endovascular approach.¹² In this article, our purpose was to review our experience in the management of traumatic injuries of the vertebral artery, to evaluate the morphologic characteristics of this uncommon condition, and to determine the benefits of endovascular treatment on the basis of clinical and angiographic results.     

Endovascular treatment of peripheral aneurysms of the posterior inferior cerebellar artery

BACKGROUND AND PURPOSE: Peripheral aneurysms of the posterior inferior cerebellar artery (PICA) are rare, and pre-existing literature concerning their endovascular treatment is limited. The purpose of this study was to assess the etiology and clinical characteristics of peripheral PICA aneurysms and to evaluate the angiographic and clinical results of the patients who underwent endovascular treatment for a peripheral PICA aneurysm in a single center.MATERIALS AND METHODS: Twelve consecutive patients with 12 peripheral PICA aneurysms (10 ruptured) included in an internal data base were retrospectively reviewed. Posttreatment and follow-up angiograms were analyzed, and the clinical outcome was recorded.RESULTS: The etiology was dissection in 7 (58%) and unknown in 5 cases (42%). Three dissecting aneurysms reruptured before endovascular treatment, and another 3 demonstrated angiographic progress. Four aneurysms were treated by endosaccular coiling, 6 (all dissecting) by parent artery occlusion, and in 2 cases endovascular treatment failed. Angiographic outcome was complete aneurysm and/or parent artery occlusion in 9 cases and neck remnant in 1 case. One aneurysm needed retreatment at follow-up. One lethal procedural complication occurred, and transient ischemic symptoms appeared in 2 patients. The clinical outcome was good in 7 patients, whereas 3 patients, all poor clinical grade, died (1 for unrelated reasons). No rebleedings have occurred during the follow-up.CONCLUSION: In this series, most peripheral PICA aneurysms were secondary to arterial dissection. They were unstable with a high risk of rebleeding and a high mortality if not treated without delay. Endovascular treatment was effective in preventing rehemorrhage.

Posterior inferior cerebellar artery (PICA) aneurysms account for approximately 0.5% to 3.0% of all intracranial aneurysms,^1,2 and most are located right at the origin or in the first anteromedullary segment of the vessel.^2-4 Roughly, only a fifth of the PICA aneurysms are thought to arise from more distal segments of the PICA.^2-4 Approximately 28% of all aneurysms located in the vertebrobasilar arteries, including PICA, have been estimated to be of dissecting origin.⁵ Among peripheral PICA aneurysms, dissecting etiology has been found in 0%-80% of the cases.^6-9Due to anatomic location of the PICAs (proximity to brain stem and lower cranial nerves), their surgical treatment is associated with significant risk of neurologic complications.¹⁰ Endovascular technique enables treating these lesions without craniotomy and the risks related to surgical manipulation. Despite the recently increased number of publications, the pre-existing literature concerning endovascular treatment of peripheral PICA aneurysms is limited and controversial.^6-9,11-21 In the present study, a consecutive series of 12 patients harboring a peripheral PICA aneurysm allocated for endovascular treatment in a single center was retrospectively analyzed.     

The Pathophysiology of Idiopathic Normal Pressure Hydrocephalus: Cerebral Ischemia or Altered Venous Hemodynamics?

BACKGROUND AND PURPOSE: Many theories of normal pressure hydrocephalus (NPH) stress the importance of ischemia in the deep white matter. Alternate theories stress a reduction in superficial venous compliance and changes in pulse-wave propagation. An overlap in the cerebral blood flow volumes measured between NPH and controls suggests that ischemia may not be a prerequisite for this condition. This study sought to compare blood flow and compliance measures in a cohort of patients with NPH selected for having arterial inflows above the normal range to see if deep brain ischemia or superficial hemodynamic changes contribute to the pathophysiology of NPH.MATERIALS AND METHODS: Twenty patients with NPH and arterial inflows above the normal range were selected. They underwent MR imaging with flow quantification measuring the total blood inflow, sagittal/straight sinus outflow, aqueduct stroke volume, and arteriovenous delay (AVD). Patients were compared with 12 age-matched controls.RESULTS: The deep outflow volumes were normal. The superficial venous outflow was reduced as a percentage of the inflow by 9% (P = .04). The sagittal sinus compliance as measured by the AVD was reduced by 50% (P = .0001), and the aqueduct stroke volume was elevated by 192% (P = .02).CONCLUSION: Ischemia in the deep venous territory is not a prerequisite for NPH. Patients with high-inflow NPH show alterations in superficial venous compliance and a reduction in the blood flow returning via the sagittal sinus. These changes together suggest that an elevation in superficial venous pressure may occur in NPH.

Normal pressure hydrocephalus (NPH) was first described 40 years ago by Adams et al¹ in patients with a clinical triad of ataxia, incontinence, and dementia who also had dilated ventricles but normal CSF pressures. A rational basis for the diagnosis and treatment of this disease should rest on an adequate understanding of its underlying pathophysiology. Many physiologic changes have been noted to occur in this disease process, with ventricular dilation being the most obvious. Other changes noted are an increase in the resistance to the reabsorption of CSF,² an alteration in the site of CSF reabsorption (ie, through the deep brain rather than through the arachnoid granulations),^3,4 hyperdynamic aqueduct CSF flow,⁵ reduced compliance of the subarachnoid space,^6,7 a normal CSF pressure but increased CSF pulse pressure (6–8 times normal),⁸ and an overall reduction in cerebral blood flow (CBF).⁹ Any theory of causation should be able to link all of these disparate findings.Many of the current theories of NPH take the finding of a global reduction in CBF as a starting point in trying to account for the pathophysiology of this condition. Studies of many groups have shown an overall reduction in CBF in NPH.⁹ Most popular theories interpret the CBF reduction found in NPH to be secondary to the degree of ventricular dilation.⁹ The literature, however, indicates that whereas a direct correlation between reduced CBF and ventricular size has been suggested in some studies,^10,11 others have refuted this finding.^12,13 Mathew et al¹⁴ suggested that dilation of the ventricular system stretches the anterior cerebral arteries over the corpus callosum, thereby reducing flow. Ventricular dilation has also been suggested to increase intraparenchymal pressure and directly compress the capillary bed or venous drainage.¹⁵ Switching cause and effect, others have highlighted the finding that the vascular disease associated with ischemia actually causes the ventricular dilation by damaging the deep white matter. It is reported that watershed ischemia may exist in the deep white matter in NPH, between the boundary from the middle cerebral artery perforators and the deep medullary pial branches,¹⁴ and this leads to tissue loss. Another recent theory suggests: “With aging, the arterioles in the deep white matter close down, leading to deep white matter ischemia, which is noted with greater frequency in patients with NPH. If there is decreased arterial blood flow in, there will be less venous blood flow out, and consequently less CSF resorption via the transparenchymal/transvenous route.”¹⁵ Finally, it has also been suggested that ischemia is an epiphenomenon, occurring secondary to the stagnation of vasoactive peptides (stagnation occurs in the CSF/interstitial fluid, and the peptides are reabsorbed through the deep white matter) and that these may interfere with cerebrovascular reactivity.¹⁶The problem with placing ischemia at the center of the causation of NPH is that not all patients have ischemia. Owler et al,¹⁷ using coregistered MR imaging and positron-emission tomography imaging data, found the CBF of the cerebrum in patients with NPH to be 24.8 ± 4.3 mL/100 g/min, with controls having a global flow of 30.5 ± 5.2 mL/100 g/min. Despite the 19% reduction in the mean CBF noted in NPH, it is apparent that the SD of the NPH data is wide enough to theoretically place 16% of patients with NPH within the normal range. This finding brings mandatory ischemia in NPH into doubt. Ischemia also fails to provide an explanation for the dynamic findings of NPH. The hydrodynamics of NPH have been shown to involve a reduction in the compliance of the subarachnoid space, brain, and the arterial tree.¹⁸ The reduced compliance directs a larger proportion of what would otherwise be a reduced total arterial pulsation toward the ventricles, increasing the aqueduct stroke volume.¹⁸ With this in mind, I compared blood flow and compliance measures in a cohort of patients with NPH, selected to have arterial inflows above the normal range, to see if deep brain ischemia or superficial venous hemodynamic changes contribute to the pathophysiology of NPH in these patients.     

Additional Value of 3D Rotational Angiography in Angiographically Negative Aneurysmal Subarachnoid Hemorrhage: How Negative Is Negative?

BACKGROUND AND PURPOSE: In some patients with nonperimesencephalic nontraumatic subarachnoid hemorrhage (aneurysmal SAH), no aneurysm can be found on digital subtraction angiography (DSA), and repeat DSA is advocated. 3D rotational angiography (3DRA) is considered superior to DSA in the detection of small intracranial aneurysms. In this study, we assessed the additional diagnostic value of 3DRA in detecting DSA-occult aneurysms in 23 patients with aneurysmal SAH.MATERIALS AND METHODS: Between January 2006 and September 2007, 298 patients with suggested ruptured intracranial aneurysm were referred for DSA, and in 98 patients, DSA was negative. Of these 98 patients, 28 had aneurysmal SAH, and in 23 of these additional 3DRA was performed in the same or in a repeat angiographic procedure.RESULTS: In 18 of 23 patients (78%), a ruptured small aneurysm was diagnosed on additional 3DRA. The location of 18 aneurysms was the anterior communicating artery (n = 11), the middle cerebral artery (n = 3), the posterior communicating artery (n = 2), the ophthalmic artery (n = 1), and the posterior inferior cerebellar artery (n = 1). Aneurysm size was 3 mm in 4, 2 mm in 9, and 1 mm in 5. Of 18 aneurysms, 9 were treated with coil placement; 7 with surgical clipping; and 2 were not treated.CONCLUSION: In this study, 18 of 23 (78%) patients with negative findings on DSA had a small ruptured aneurysm when studied with 3DRA. These were most commonly located on the anterior communicating artery.

In 15%–20% of patients with a spontaneous subarachnoid hemorrhage (SAH), no aneurysm is found on the first digital subtraction angiography (DSA).¹ In two thirds of these patients, CT shows a perimesencephalic pattern of hemorrhage (blood confined to the cisterns around the midbrain); these patients invariably have a good prognosis, which obviates additional angiography.^2-4 Patients with a nonperimesencephalic pattern of hemorrhage on CT (aneurysmal SAH) are at risk of rebleeding. In most of these patients, the source of the hemorrhage is an occult aneurysm, but intracranial artery dissections, dural arteriovenous malformations, trauma, bleeding disorders, substance abuse, or other causes should also be considered.³ Repeat DSA^5-7 or even exploratory surgery^8,9 is generally advocated to detect an angiographically occult ruptured aneurysm, and in approximately one third of patients, an aneurysm is eventually detected during surgery or on the second or third DSA. In other studies,^10,11 repeat angiography is considered justified only when the initial examination is technically inadequate, when vasospasm is present, or if further bleeding occurs. In an estimated 4%–5% of patients with aneurysmal SAH, no source of hemorrhage can be identified. These patients are at risk of vascular complications and poor outcome.⁴Since its introduction more than a decade ago, 3D rotational angiography (3DRA) is considered superior to DSA both in the detection of intracranial aneurysms and in pretreatment evaluation.^12-14 3DRA has several advantages over DSA: the possibility of free rotation of images, the lack of overprojecting bony structures, and extensive postprocessing capabilities that allow better detection of small aneurysms and better evaluation of local anatomy. To date, no studies are available using 3DRA in the detection of small ruptured aneurysms in patients with DSA-negative aneurysmal SAH. In this study, we assessed the additional diagnostic value of 3DRA performed in 23 patients with angiographically negative aneurysmal SAH.