Intracranial dural arteriovenous fistulas with spinal venous drainage: relation between clinical presentation and angiographic findings.

PURPOSETo investigate why some patients with an intracranial dural arteriovenous fistula (DAVF) with spinal venous drainage have myelopathy and others do not.METHODSWe reviewed the clinical and radiologic data for 12 patients who had a DAVF with spinal venous drainage diagnosed at our institutions from 1982 to 1995.RESULTSSix patients had progressive spinal cord indications of disease (patients with myelopathy) and six others (patients without myelopathy) had cerebral indications (five had intracranial hemorrhage and one had a seizure). Cerebral angiography showed a posterior fossa DAVF with spinal venous drainage in all cases. The clinical presentation of DAVFs with spinal venous drainage was compared with the extent of the drainage. In patients without myelopathy, the spinal venous drainage exited the intradural canal via the cervical medullary-radicular veins and was therefore limited to the cervical perimedullary veins. In patients with myelopathy, no medullary-radicular vein was seen, and the venous drainage descended along the perimedullary veins of the entire spinal cord toward the conus medullaris.CONCLUSIONWe found an exact relation between clinical presentation and venous drainage of DAVFs with spinal venous drainage. Patients had no myelopathy when the venous drainage was limited to the cervical cord; myelopathy was present when the venous drainage descended toward the conus medullaris.     

Intracranial dural arteriovenous fistulae with perimedullary venous drainage. Anatomical, clinical and therapeutic considerations

We report five cases of intracranial dural arteriovenous fistula (DAVF) with perimedullary venous drainage. All the patients presented with rapidly progressive myelopathy and three had autonomic disorders. The DAVF were on the tentorium cerebelli (two cases), sigmoid (one), superior petrosal (one), and cavernous sinus (one). Slow venous drainage was directed through dilated perimedullary cervical veins. The transverse sinus was occluded in two cases. MRI, performed in four cases, demonstrated high signal on T2-weighted spin-echo sequences in the medulla oblongata and upper cervical spinal cord consistent with oedema, which signal resolved after complete cure of the DAVF in three cases. Embolisation was performed in all cases. It was followed by clinical deterioration in two cases and in the dramatic improvement in the other three, with complete clinical cure in two. Extensive venous thrombosis may explain the deterioration observed in one case. Received: 22 April 1998 Accepted: 15 September 1998     

Arteriovenous fistulas at the cervicomedullary junction presenting with subarachnoid hemorrhage: six case reports with special reference to the angiographic pattern of venous drainage

BACKGROUND AND PURPOSE: Cases with spinal perimedullary arteriovenous fistulas (SPAVFs) or spinal dural arteriovenous fistulas (SDAVFs) at the cervicomedullary junction are rare. We performed a retrospective, angiographic study of 6 such patients to assess whether available angiographic data were predictive of the risk for hemorrhage. METHODS: We report 6 patients with arteriovenous fistulas at the cervicomedullary junction. All presented with subarachnoid hemorrhage (SAH). Angiography demonstrated that 4 of the 6 fistulas were SDAVFs fed by the meningeal branch of the vertebral artery; the other 2 were SPAVFs fed by the anterior spinal artery. Drainage was via the perimedullary vein of the cervicomedullary junction. RESULTS: An ascending venous route into the intracranial sinus was recognized in all 6 cases; in 3 the draining system contained varices. In 2 cases, the venous route was on the ventral side of the brain stem with drainage into the cavernous sinus. In 4 cases, the venous route was lateral at the brain stem with drainage into the inferior petrosal sinus. CONCLUSION: SPAVFs and SDAVFs at the cervicomedullary junction that manifest an ascending venous route into the intracranial sinus present an increased risk for SAH.     

Intracranial dural fistulas with exclusive perimedullary drainage: the need for complete cerebral angiography for diagnosis and treatment planning

Three patients are presented with slowly progressive tetraparesis caused by an intracranial dural arteriovenous fistula with exclusive perimedullary venous drainage. MR imaging showed a swollen cervicothoracic cord with central myelopathy and dilated perimedullary veins. Bilateral vertebral angiography initially failed to demonstrate the fistulas, and diagnosis was established with external carotid angiography. All 3 patients were successfully treated with glue embolization, 1 after failed surgical exploration. Angiographic cure of the fistula resulted in clinical cure in 1 patient and stabilization in 2 patients.     

Spinal Dural Arteriovenous Fistula: Imaging Features and Its Mimics

Spinal dural arteriovenous fistula (SDAVF) is the most common spinal vascular malformation, however it is still rare and underdiagnosed. Magnetic resonance imaging findings such as spinal cord edema and dilated and tortuous perimedullary veins play a pivotal role in the confirmation of the diagnosis. However, spinal angiography remains the gold standard in the diagnosis of SDAVF. Classic angiographic findings of SDAVF are early filling of radicular veins, delayed venous return, and an extensive network of dilated perimedullary venous plexus. A series of angiograms of SDAVF at different locations along the spinal column, and mimics of serpentine perimedullary venous plexus on MR images, are demonstrated. Thorough knowledge of SDAVF aids correct diagnosis and prevents irreversible complications.     

Retrograde cortical and deep venous drainage in patients with intracranial dural arteriovenous fistulas: comparison of MR imaging and angiographic findings

BACKGROUND AND PURPOSE: We assessed MR imaging, specifically contrast-enhanced three-dimensional (3D) magnetization-prepared rapid gradient-echo (MP-RAGE), in evaluating retrograde venous drainage in patients with intracranial dural arteriovenous fistulas (dAVFs) that may result in catastrophic venous infarction or hemorrhage. METHODS: Twenty-one patients with angiographically proved dAVFs underwent nonenhanced spin-echo (SE) and fast SE imaging, 3D fast imaging with steady-state precession, and enhanced SE and 3D MP-RAGE imaging. Retrograde venous drainage was categorized as cerebral cortical, deep cerebral, posterior fossa medullary, ophthalmic, or spinal venous. We assessed retrograde venous drainage and graded its severity. MR imaging and angiographic severities were correlated. Sensitivity, specificity, and accuracy were calculated to evaluate the diagnostic utility of each technique compared with conventional angiography. We retrospectively correlated angiograms and MR images. RESULTS: Enhanced 3D MP-RAGE and T1-weighted SE images had higher diagnostic accuracy higher than nonenhanced images, especially when retrograde drainage involved cerebral cortical, posterior fossa, and spinal veins. Correlation of severity for enhanced MP-RAGE images and enhanced T1-weighted images with angiograms was good to excellent and better than that with nonenhanced images. All sequences had low diagnostic accuracy when drainage was via deep cerebral veins. On retrospective review, 3D MP-RAGE images showed two thrombotic inferior petrosal sinuses. CONCLUSION: Enhanced MR images were superior to nonenhanced images in assessing retrograde venous drainage in intracranial dAVFs. Enhanced 3D MP-RAGE is superior to enhanced T1-weighted SE imaging for determining the route and severity of venous reflux because of its increased spatial resolution and ability to contiguously delineate the venous system.     

Craniocervical dural fistula associated with cervical myelopathy: angiographic demonstration of normal venous drainage of the thoracolumbar cord does not rule out diagnosis.

We report a case of craniocervical dural arteriovenous fistula with perimedullary venous drainage associated with cervical myelopathy in which spinal angiography showed a normal venous phase after injection of the artery of Adamkiewicz. We conclude that because of the complex venous drainage of the spinal cord, a dural arteriovenous fistula with spinal drainage cannot be ruled out solely because a normal venous phase is seen in the lower part of the cord, as has previously been suggested.     

Paravertebral arteriovenous malformations with epidural drainage: clinical spectrum, imaging features, and results of treatment.

BACKGROUND AND PURPOSE: Arteriovenous malformations (AVMs) of the spine or spinal cord can be characterized as spinal cord AVMs, spinal cord and dural arteriovenous fistulas, and AVMs occurring outside the dura but draining into the epidural veins. The purpose of this study was to review the clinical spectrum, imaging features, and results of treatment of paravertebral arteriovenous malformations (PVAVMs) with epidural drainage. METHODS: The clinical records and images of 10 patients with PVAVMs were analyzed retrospectively for clinical presentation, MR findings, angioarchitecture, pathophysiology, treatment efficacy, and clinical follow-up. RESULTS: Seven patients had myelopathy. The MR findings for three of these patients showed spinal cord hyperintensity on T2-weighted sequences and prominent perimedullary vessels. Angiography, performed in two of the three patients, showed evidence of reflux into the perimedullary veins from the PVAVMs. Each of these two patients underwent surgical clipping of the radicular vein leading to the perimedullary veins. In three of the seven patients, there were large epidural veins compressing the cord. Angiography performed in these patients showed large PVAVMs with multiple feeders, which were treated by a combination of transarterial and transvenous embolization. One of the seven patients had an associated spinal cord arteriovenous malformation. In three patients with incidental PVAVMs, cure was achieved by using a combination of coils and liquid adhesives by the endovascular route. CONCLUSION: The clinical presentation of PVAVMs is variable, and symptomatic lesions are the result of compression by epidural veins or of congestive myelopathy. A clear understanding of the anatomy and pathophysiology is necessary to plan treatment. Endovascular techniques are capable of curing the malformation, alleviating the symptoms, or both in a significant proportion of these lesions.     

The anterior medullary–anterior pontomesencephalic venous system and its bridging veins communicating to the dural sinuses: normal anatomy and drainage routes from dural arteriovenous fistulas

Introduction  We evaluated the normal venous anatomy of the anterior medullary/anterior pontomesencephalic venous (AMV/APMV) system and bridging veins connected to the dural sinuses using magnetic resonance (MR) imaging and demonstrated cases of dural arteriovenous fistulas (DAVFs) with bridging venous drainage. Materials and methods  MR images obtained using a 3D gradient echo sequence in 70 patients without lesions affecting the deep or posterior venous channels were reviewed to evaluate the normal anatomy of the AMV/APMV system and bridging veins. MR images and digital subtraction angiography in 80 cases with intracranial or craniocervical junction DAVFs were reviewed to evaluate the bridging venous drainage from DAVFs. Results  MR images clearly revealed AMV/APMV in 35 cases. Fifteen cases showed a direct connection between AMV and APMV, while 15 cases showed an indirect communication via the transverse pontine vein or the bridging vein. In the five remaining cases, the AMV and APMV end separately to the bridging vein or the transverse pontine vein. Bridging veins were identified in 34 cases, connecting to the cavernous sinus in 33, to the suboccipital cavernous sinus in 11, and the inferior petrosal sinus in five cases. In 80 DAVF cases, seven of 40 cavernous sinus DAVFs, two craniocervical junction DAVFs, and one inferior petrosal sinus DAVF drained via bridging veins to the brain stem. Conclusion  The AMV/APMV and bridging veins showed various anatomies and frequently showed a connection to the cavernous sinus. Knowledge of the venous anatomy is helpful for the diagnosis and intravascular treatment of DAVFs.     

三维增强磁共振静脉成像评价颅内静脉系统

目的:比较三维增强FLASH序列和2D TOF序列MR静脉成像(MRV)对颅内静脉系统的诊断价值.方法:本组11例中健康志愿者6例(正常组),脑静脉窦血栓形成患者5例(病变组),均同时行3D增强FLASH和2D TOF序列MRV扫描,病变组5例患者同时行DSA检查.将脑内主要静脉(14支)的显示情况分为3级:满意显示,一般显示和未显示.比较两种扫描方法对脑内静脉和静脉血栓的显示情况.结果:正常组中三维增强FLASH和2D TOF序列对所观察的14支脑静脉的满意显示率、一般显示率和未显示率分别为88.10%,5.95%,5.95%和30.95%,53.57%,15.48%.三维增强FLASH未显示结构主要为下矢状窦.病变组5例中DSA共发现12处血管病变,三维增强FLASH显示优于2D TOF 10处,两者相仿2处.结论:三维增强FLASH对脑静脉系统的显示优于2D TOF序列,可以提供高质量的脑内静脉结构的图像,对诊断脑静脉内血栓形成有重要临床价值.     

Peripheral spinal cord hypointensity on T2-weighted MR images: a reliable imaging sign of venous hypertensive myelopathy

BACKGROUND AND PURPOSE: MR findings reported in conjunction with spinal dural arteriovenous fistula (SDAVF) include cord swelling, increased T2 signal within the spinal cord, and parenchymal enhancement, each of which is nonspecific. Enlarged vessels on the cord surface, the most specific MR finding, is noted in only half of SDAVF patients. Nevertheless, we have frequently observed MR peripheral hypointensity of the spinal cord in SDAVF on T2-weighted images, which is not characteristic of nonvascular or nonhemorrhagic causes of myelopathy and which has not been described in association with SDAVF. We hypothesized that peripheral cord hypointensity might reliably suggest the diagnosis of SDAVF or other causes of venous hypertensive myelopathy. METHODS: We reviewed the MR findings in 11 consecutive cases of angiographically confirmed symptomatic SDAVF and in four cases of intracranial dural arteriovenous fistula with spinal drainage, a lesion that also causes spinal cord deficits mediated by venous hypertensive myelopathy. RESULTS: In each case, T2 hypointensity involving the cord periphery was present. This sign has not been previously described in association with either SDAVF or other causes of venous hypertensive myelopathy. It appears, however, to be a relatively constant imaging feature of SDAVF. CONCLUSION: In the absence of spinal hemorrhage, T2 hypointensity involving the periphery of the spinal cord suggests venous hypertensive myelopathy as a cause of spinal cord dysfunction.     

First-Pass Contrast-Enhanced MR Angiography in Evaluation of Treated Spinal Arteriovenous Fistulas: Is Catheter Angiography Necessary?

BACKGROUND AND PURPOSE:Catheter angiography is typically used for follow-up of treated spinal AVFs. The purpose of this study was to determine the diagnostic performance and utility of first-pass contrast-enhanced MRA in the posttreatment evaluation of spinal AVFs compared with DSA.MATERIALS AND METHODS:A retrospective review was performed of all patients at our tertiary referral hospital (from January 2000 to April 2015) who underwent spine MR imaging, first-pass contrast-enhanced MRA, and DSA after surgical and/or endovascular treatment of a spinal AVF. Presence of recurrent or residual fistula on MRA, including vertebral level of the recurrent/residual fistula, was evaluated by 2 experienced neuroradiologists blinded to DSA findings. Posttreatment conventional MR imaging findings were also evaluated, including presence of intramedullary T2 hyperintensity, perimedullary serpentine flow voids, and cord enhancement. The performance of MRA and MR imaging findings for diagnosis of recurrent/residual fistula was determined by using DSA as the criterion standard.RESULTS:In total, 28 posttreatment paired MR imaging/MRA and DSA studies were evaluated in 22 patients with prior spinal AVF and 1 patient with intracranial AVF with prior cervical perimedullary venous drainage. Six image sets of 5 patients demonstrated recurrent/residual disease at DSA. MRA correctly identified all cases with recurrent/residual disease with 1 false-positive (sensitivity, 100%; specificity 95%; P < .001), with correct localization in all cases without interobserver disagreement. Conventional MR imaging parameters were not significantly associated with recurrent/residual spinal AVF.CONCLUSIONS:First-pass MRA demonstrates high sensitivity and specificity for identifying recurrent/residual spinal AVFs and may potentially substitute for DSA in the posttreatment follow-up of patients with spinal AVFs.

Spinal AVFs (SAVFs) can cause radicular/perimedullary venous reflux and present with progressive myelopathy due to cord congestion. The goal of treatment is to disconnect the refluxing vein to protect the cord from further damage. The most common vascular lesion to present in this fashion is the spinal dural AVF. However, similar clinical and radiologic appearances can occur with intracranial dural fistulas draining into the spinal venous system, epidural fistulas with intrathecal venous reflux as well as perimedullary and filum terminale fistulas. Prevalence of recurrent or residual fistulas after treatment of SAVFs ranges from 3.4% to 27.8% and is associated with progressive myelopathy and morbidity.¹ Fistula recurrence may occur early within 1 month after treatment or present in delayed fashion years after successful treatment.¹ Conventional spine MR imaging findings of SAVF, including perimedullary flow voids, intramedullary T2 hyperintensity, and cord enhancement, are not reliable markers of residual/recurrent fistula.^2,3 Using clinical symptoms alone to assess for residual or recurrent disease may result in delayed diagnosis and irreversible progression of symptoms.⁴ Therefore, posttherapy evaluation of patients with previously treated SAVF is commonly performed to ensure complete fistula occlusion. DSA remains the criterion standard test; however, it is an invasive test associated with some procedural risks.⁵ Spine MRA may be a useful noninvasive tool for initial posttreatment evaluation of SAVFs and may have the potential to be a substitute for DSA for this indication.^3,4,6 In this study, we evaluated the performance of MRA for identifying recurrent/residual SAVF posttreatment, compared with DSA and conventional MR imaging findings.     

Phase-contrast MR angiography of vascular malformations of the spinal cord at 0.5 T.

Preliminary experience with phase-contrast magnetic resonance (MR) angiography at 0.5 T applied in 12 cases of vascular malformations of the spinal cord is reported. There were six intramedullary arteriovenous malformations (AVMs), four perimedullary fistulas, and two dural arteriovenous fistulas with perimedullary drainage, all proved with x-ray angiography. The small size of the vessels and their location within a bony structure presented a technical challenge. Serpentine vascular signal patterns were identified within the spinal canal in all cases, showing good correlation with the x-ray angiographic pattern. Relative to spin-echo images, MR angiograms allowed better visualization of the venous drainage. The nidus of intramedullary AVMs was more difficult to recognize. The ability to manipulate the velocity-encoding value allows better characterization of flow speed. The results underline the two dimensions of the phase-contrast technique, which provides both anatomic images and dynamic information about vascular malformations. MR angiography does not replace selective x-ray angiography, which is indispensable for therapeutic strategy (endovascular procedure or surgery), but it can be considered a valuable alternative to x-ray angiography during follow-up.     

低颅压综合征的MRI诊断

目的 分析低颅压综合征的MRI表现,以提高对本病的认识. 资料与方法 搜集经临床证实的低颅压综合征10例,治疗前均行MRI检查,其中3例仅行平扫,7例同时平扫和增强,3例加MRA,1例加MRV. 结果 10例均有硬脑膜增厚、静脉窦和脑静脉扩张;6例可见脑下垂和脑室缩小表现;4例可见侧枝静脉窦显影(基底丛和岩下窦);5例可见垂体增大;4例出现硬膜下积液;增强7例均见硬脑膜均匀性增厚强化,软脑膜无强化,2例见脊膜强化. 结论 低颅压综合征具有特征性的MRI表现,结合脑脊液压力检测,可以明确诊断.     

46例脑动静脉畸形的MRI和MRA分析

目的：探讨MRI和MRA检查在脑AVM临床诊断中的价值。方法：46例脑动静脉畸形作了常规MRI和MR血管造影,MRI采用SET1、T2加权成像,MRA采用三维时飞跃法。结果：MRI准确显示了46例AVM的瘤巢,11例可见亚急性出血灶,5例可见含铁血黄素沉积,23例病灶区组织软化或萎缩,4例有占位效应。3D-TOF RMA显示41例AVM供血动脉、23例引流静脉。5例加做增强3D-TOF及6例加做2D-TOF后,引流静脉显示明显改善。结论：MRI和MRA结合应用能对脑血管畸形作出较准确的诊断,为临床治疗提供所需的基本信息并对治疗效果作出客观的评价。     

Angiography-induced closure of perimedullary spinal arteriovenous fistula

Type 4 spinal vascular malformations are called perimedullary arteriovenous fistulae, in which there is a shunt between a radicular artery and intradural veins. We report the spinal MR imaging and angiography findings of the angiography-induced closure of a type 4 spinal vascular malformation.     

Three-dimensional MR vascular imaging of the spine using gadolinium-DTPA.

To investigate the fine vascular structures in the spinal and paraspinal region, the authors performed three-dimensional GRASS scanning after the administration of contrast material. The scan sequence was sagittal volume scan, TR/TE 100/16, with a flip angle of 45 degrees. First-order gradient moment nulling was employed. Four normal volunteers and 31 patients were studied. Using this technique, longitudinal anterior epidural veins and vertebral arteries were clearly identified. Paraspinal fine vessels of slow to moderate flow, including dilated anterior spinal artery, radiculo-medullary vein, and perimedullary coronal venous plexus, were demonstrated in pathological cases. In addition, with processing of the volume data set, phlebographic projection images of the ladder-shaped anterior epidural venous system could be generated. This method provided more detailed information on epidural and intradural vessels than conventional MR imaging.     

Double spinal dural arteriovenous fistulas

We present a patient with double spinal dural arteriovenous fistulas revealed by progressive myelopathy. Numerous dilated veins extending along the entire length of the spinal cord were found on MR imaging. Angiography showed a first spinal dural fistula at the level of T7 with descending venous drainage and a second spinal dural fistula at the level of T5 with ascending venous drainage. Both fistulas were cured by therapeutic embolization.     

Cerebral MR venography: normal anatomy and potential diagnostic pitfalls

BACKGROUND AND PURPOSE: MR venography is often used to examine the intracranial venous system, particularly in the evaluation of dural sinus thrombosis. The purpose of this study was to evaluate the use of MR venography in the depiction of the normal intracranial venous anatomy and its variants, to assess its potential pitfalls in the diagnosis of dural venous sinus thrombosis, and to compare the findings with those of conventional catheter angiography. METHODS: Cerebral MR venograms obtained in 100 persons with normal MR imaging studies were reviewed to determine the presence or absence of the dural sinuses and major intracranial veins. RESULTS: Systematic review of the 100 cases revealed transverse sinus flow gaps in 31% of the cases, with 90% of these occurring in the nondominant transverse sinus and 10% in the codominant transverse sinuses. No flow gaps occurred in the dominant transverse sinuses. The superior sagittal and straight sinuses were seen in every venogram; the occipital sinus was seen in only 10%. The vein of Galen and internal cerebral veins were also seen in every case; the basal veins of Rosenthal were present in 91%. CONCLUSIONS: Transverse sinus flow gaps can be observed in as many as 31% of patients with normal MR imaging findings; these gaps should not be mistaken for dural sinus thrombosis.     

The craniocervical venous system in relation to cerebral venous drainage

BACKGROUND AND PURPOSE: Passing from the supine to the upright position favors cerebral venous outflow into vertebral venous systems rather than into the internal jugular veins. We sought to determine venous connections between dural venous sinuses of the posterior cranial fossa and craniocervical vertebral venous systems. METHODS: Corrosion casts of the cranial and cervical venous system were obtained from 12 fresh human cadavers, and anatomic confirmation was made by dissection of three previously injected fresh human specimens. MR venography was performed to provide radiologic correlation. RESULTS: The lateral, posterior, and anterior condylar veins and the mastoid and occipital emissary veins were found to represent the venous connections between the dural venous sinuses of the posterior cranial fossa and the vertebral venous systems. This study revealed the nearly constant presence of the anterior condylar confluent (ACC) located on the external orifice of the canal of the hypoglossal nerve. The ACC offered multiple connections with the dural venous sinuses of the posterior cranial fossa, the internal jugular vein, and the vertebral venous system. All these structures were shown by MR venography. CONCLUSION: The lateral, posterior, and anterior condylar veins and the mastoid and occipital emissary veins connect the dural venous sinuses of the posterior cranial fossa with the vertebral venous systems. These connections are clinically relevant, because encephalic drainage occurs preferentially through the vertebral venous system in the upright position. The ACC is a constant anatomic structure that may play an important role in the redirection of cerebral blood in the craniocervical region.