MR imaging findings of intracranial dural arteriovenous fistulas: relations with venous drainage patterns

BACKGROUND AND PURPOSE: Venous drainage patterns are a major determinant of clinical outcome in intracranial dural arteriovenous fistula (DAVF) patients. In this study, we sought to identify MR imaging finding differences between DAVF types classified on the basis of venous drainage patterns. METHODS: Twenty-seven patients diagnosed as having DAVFs by conventional angiography were included. Medical records (n = 27), and MR imaging (n = 27) and MR angiography (MRA; n = 11) findings were retrospectively reviewed. MR imaging findings included flow void cluster, engorged ophthalmic vein/proptosis, white matter hyperintensity, intracranial hemorrhage, dilated leptomeningeal or medullary vessels, venous pouch, and leptomeningeal or medullary vascular enhancements. MRA findings included identifiable fistula, venous flow-related enhancement, and prominent extracranial vessels. Patients' presentations and MR imaging findings were compared among angiographic type I, II, and III cases (according to Borden's classification), and MRA findings were compared between cases with and without retrograde leptomeningeal venous drainage (RLVD). RESULTS: Patient presentations were aggressive in one (13%) of the type I cases, 5 (50%) of the type II cases, and 8 (100%) of the type III cases (P = .002). Aggressive presentations included hemorrhage, focal neurologic deficits, seizures, intracranial hypertension, and an altered mental status. MR images showed significantly higher frequencies of dilated leptomeningeal or medullary vessels in a higher type [0 in type I, 5 (42%) in type II, and 7 (100%) in type III], and of leptomeningeal or medullary vascular enhancements [0 in type I, 4 (33%) in type II, and 7 (100%) in type III]. By using MRA, fistulas were identified only in cases with RLVD (5 [83%]). Venous flow-related enhancement was present in 10 cases (91%). A sole false-negative case on MRA, as compared with conventional angiography, resulted from nonvisualization of the slow venous flow (8%). No false-positive fistula was found at the other intracranial sites in all cases. Overall, MRA assessment for DAVF was adequate for both fistula and venous flow-related enhancement in 10 cases (91%) and inadequate in a remaining case because of the fistular location out of field. CONCLUSION: MR imaging demonstration of leptomeningeal or medullary vascular dilation and enhancements may be associated with features that are considered predictors of a poor outcome and indicates a need for urgent therapy in intracranial dural AVF patients. MRA is a complementary tool for the identification of dural AVF with venous flow-related enhancement.     

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.     

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.     

MR imaging of dural arteriovenous fistulas draining into cerebellar cortical veins

BACKGROUND AND PURPOSE: Retrograde leptomeningeal venous drainage (RLVD) in a dural arteriovenous fistula (DAVF) is associated with intracerebral hemorrhage, nonhemorrhagic neurologic deficit, or death, and recognizing the presence of this drainage is important. We investigated the MR findings of DAVFs draining into cerebellar cortical veins and compared these findings with those of conventional angiography. METHODS: The MR and angiographic findings of six patients (five men, one woman; mean age, 73.4 years) with DAVF with RLVD into cerebellar cortical veins were reviewed retrospectively. Signal intensity characteristics, contrast material enhancement, topography of the lesion, and presence of signal voids were evaluated on MR images. Site of the shunt, feeding arteries, and draining veins were evaluated on angiograms. RESULTS: In all patients, MR images showed high signal intensity on T2-weighted images and peripheral enhancement on gadolinium-enhanced T1-weighted images at the inferior aspect of the cerebellar hemisphere. A combination of posterior meningeal and occipital arteries was the most frequent blood supply (83%) for these DAVFs. In all six patients, the inferior hemispheric vein was the primary draining vein. CONCLUSION: The characteristic MR findings of DAVF draining into cerebellar cortical veins represent venous congestive encephalopathy in the territory of the involved cortical vein.     

Pre- and post-treatment MR imaging and single photon emission CT in patients with dural arteriovenous fistulas and retrograde leptomeningeal venous drainage

BACKGROUND AND PURPOSE: Dural arteriovenous fistulas (DAVFs) with disturbed regional cerebral blood flow (rCBF) include retrograde leptomeningeal venous drainage (RLVD). We examined rCBF disturbances in patients with DAVFs by studying MR imaging and single photon emission CT (SPECT) changes before and after treatment. METHODS: In 22 patients with DAVFs and RLVD, we studied their symptoms, pre- and post-treatment MR imaging and SPECT findings, and treatment results. Patients were assigned to two groups: Type 1 included those with RLVD into more than one venous sinus, and type 2, those with RLVD into a single venous sinus. RESULTS: Eleven patients had type 1 RLVD. In these patients, preoperative T2-weighted MR images showed no hyperintense areas, and angiographic evidence showed flow into more than one venous sinus. The other 11 patients had type 2 RLVD. In these patients, preoperative SPECT demonstrated hypoperfused areas that coincided with hyperintense areas on T2-weighted MR images. After treatment, the hyperintense areas disappeared, and symptoms improved in seven of these patients (type 2a). Their preoperative SPECT studies demonstrated preservation of vasoreactivity after an acetazolamide challenge. In the other four patients (Type 2b), the hyperintense areas and symptoms persisted after treatment. Their preoperative SPECT studies revealed a marked disturbance of vasoreactivity. CONCLUSION: In patients with drainage into a single venous sinus, we consistently observed areas of hyperintensity on MR images. These results and findings of hypoperfusion on SPECT scans apparently reflect venous congestion, whereas unpreserved vasoreactivity after an acetazolamide challenge on SPECT scans reflects venous infarction. The preservation of vasoreactivity after the challenge appears to be a good prognostic indicator.     

Venous congestion: an MR finding in dural arteriovenous malformations with cortical venous drainage.

PURPOSETo present the MR findings of intracranial dural arteriovenous malformations with cortical venous drainage, emphasizing the parenchymal changes.METHODSConventional MR and x-ray angiograms in 13 patients with dural arteriovenous malformations and cortical venous reflux were reviewed. The site of the shunt, location of the venous reflux, and presence of venous stenosis were assessed on the angiograms. Parenchymal changes, dilated vessels, and venous occlusive disease were assessed on MR.RESULTSOn MR, 10 of the 13 patients (77%) had dilated pial vessels. Two patients had hydrocephalus. Two patients presented with parenchymal bleeds, one with a subdural component, both remote from the nidus. Two patients presented with subarachnoid hemorrhage. One patient had a parenchymal bleed 9 months after presentation. Venous occlusion was evident on MR in 2 patients. Diffuse white matter edema in the cerebellar or cerebral hemispheres was present on MR in 4 patients and correlated with neurologic deficits. In 2 of these 4 patients, gadolinium enhancement was seen in the periphery of the involved hemisphere.CONCLUSIONSOn MR a surplus of pial vessels suggests a dural arteriovenous malformation with cortical venous drainage. The MR finding of white matter edema deep in the cerebral or cerebellar hemispheres is direct evidence of a venous congestion.     

Intracranial dural arteriovenous fistulas with retrograde cortical venous drainage: assessment with cerebral blood volume by dynamic susceptibility contrast magnetic resonance imaging

BACKGROUND AND PURPOSE: Retrograde cortical venous drainage (RCVD) is the most major risk factor for aggressive behavior of intracranial dural arteriovenous fistulas (DAVF). The purpose of this study was to assess the efficacy of relative cerebral blood volume (rCBV) map for RCVD in patients with DAVF. METHODS: Ten patients with angiographically proven DAVF with RCVD, 2 reference patients with DAVF without RCVD, and 10 control subjects underwent examinations with dynamic susceptibility contrast (DSC)-MR imaging. Four patients with DAVF with unilateral RCVD were evaluated, before and after treatment. The calculation of mean rCBV ratio was performed on a hemispheric basis. The mean rCBV ratio was defined as the value on one side (higher value side) divided by that on the other side (lower value side). RESULTS: In all patients with DAVF with RCVD, the rCBV map showed an increase in rCBV of the angiographically proved affected hemisphere. In 2 reference patients with DAVF without RCVD and all control subjects, the rCBV map showed no increase of rCBV. The mean rCBV ratio in patients with DAVF with RCVD was significantly higher than that of control subjects (P = .0002). Treatment response for RCVD was indicated by a decrease of CBV on the rCBV map and by a decrease of 22% in the mean rCBV ratio. CONCLUSIONS: Increased rCBV by DSC-MR correlated with RCVD in patients with DVAF. The assessment with rCBV for RCVD may be more quantitative than that with angiogram.     

Gadolinium-DTPA enhanced MR imaging of spinal dural arteriovenous fistulas

To evaluate the role of magnetic resonance (MR) in the diagnosis of dural arteriovenous (AV) fistulas and the resulting myelopathy, the MR examinations of 11 patients with symptoms and signs of slowly progressive myelopathy of the lower spinal cord have been reviewed. Patients with intradural or extradural AV malformations were excluded. Six patients have been examined without the use of a contrast agent. The other five patients were studied prior and after intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (DTPA). Serpentine linear areas of low signal due to flow void effects within the subdural space have been detected in seven patients. The T1-weighted sagittal images and T2-weighted sagittal and axial images demonstrated signal intensity changes within the center of the cord due to prolongation of T1 and T2 relaxation times. In addition, a relatively abrupt increase of the sagittal and transverse diameters of the lower thoracic cord was found in all cases. In nine patients T1-weighted, proton-density and T2-weighted sagittal images presented "blurred" margins of the lower thoracic cord. After intravenous administration of Gd-DTPA (0.1 mmol/kg), contrast enhancement was present not only within these vessels but also within the lower spinal cord. There was only slight enhancement of the cord immediately after injection of the contrast agent, but significant enhancement was observed 40-45 min later.     

Flow-sensitive alternating inversion recovery (fair) imaging for retrograde cortical venous drainage related to intracranial dural arteriovenous fistula

Introduction  

To evaluate the hypothesis that flow-sensitive alternating inversion recovery (FAIR) magnetic resonance (MR) imaging can detect retrograde cortical venous drainage (RCVD) in patients with intracranial dural arteriovenous fistula (DAVF).     

Clinical and angiographic characteristics of cavernous sinus dural arteriovenous fistulas manifesting as venous infarction and/or intracranial hemorrhage

Introduction  Cavernous sinus (CS) dural arteriovenous fistulas (DAVFs) rarely cause venous infarction (VI) and/or intracranial hemorrhage (ICH) despite the presence of cortical venous drainage (CVD). The present study investigated the characteristics of CS DAVFs manifesting as VI/ICH. Materials and methods  Fifty-four patients treated for CS DAVFs were retrospectively studied. Results  Six patients presented with VI/ICH. Two of the three patients presenting with ICH had CVD only to the superficial sylvian vein (SSV) or the deep sylvian vein (DSV). Three patients presenting with VI had multiple drainages, and angiography of these patients showed a varix on the SSV, drainage into the DSV with agenesis of the second and third segment of basal vein of Rosenthal, and thrombosis of the distal petrosal vein. CS DAVF with CVD only carries higher risk of VI/ICH than multiple drainages. Many CS DAVFs presenting with VI, especially those with drainage into the petrosal vein, have multiple drainages in the early stage. Thrombosis of the inferior and superior petrosal sinuses and superior orbital vein gradually increases pressure of the CVD, and then, VI may occur. In contrast, CS DAVFs with CVD only from the beginning, common in the patients with drainage into the SSVs and DSVs, are likely to cause ICH. Conclusion  Angiographic risk factors causing VI/ICH are CVD only, varix formation, agenesis of the second and third segment of basal vein of Rosenthal, and thrombosis of the superior orbital vein, lateral half of the superior petrosal sinus, and distal CVD.     

Intracranial dural arteriovenous fistulas: classification, imaging findings, and treatment

Intracranial DAVFs are pathologic dural-based shunts and account for 10%-15% of all intracranial arteriovenous malformations. These malformations derive their arterial supply primarily from meningeal vessels, and the venous drainage is either via dural venous sinuses or through the cortical veins. DAVFs have a reported association with dural sinus thrombosis, venous hypertension, previous craniotomy, and trauma, though many lesions are idiopathic. The diagnosis is dependent on a high level of clinical suspicion and high-resolution imaging. Cross-sectional imaging techniques by using CT and MR imaging aid in the diagnosis, but conventional angiography remains the most accurate method for complete characterization and classification of DAVFs. The pattern of venous drainage observed on dynamic vascular imaging determines the type of DAVF and correlates with the severity of symptoms and the risk of hemorrhage.     

Tortuous, engorged pial veins in intracranial dural arteriovenous fistulas: correlations with presentation, location, and MR findings in 122 patients.

BACKGROUND AND PURPOSE: Tortuous, engorged veins can be identified on the venous phase of the brain circulation in patients with venous congestion related to an intracranial dural arteriovenous fistula (DAVF). The term pseudophlebitic pattern (PPP) has been used to describe this finding. The purpose of this study was to determine the prevalence of PPP in patients with intracranial DAVF and to analyze the relationship of this sign to presentation, location of the fistula, presence of retrograde leptomeningeal venous drainage, and MR findings. METHODS: We retrospectively reviewed the charts and imaging findings of 130 patients with intracranial DAVF. In 122 patients the venous phase of the brain circulation was adequately assessed. The PPP was graded as mild, moderate, or severe. RESULTS: PPP was found in 51 patients (42%). Thirty-two (73%) of the 44 patients who had a hemorrhage, neurologic deficit, or seizure had PPP as compared with 16 (21%) of the 75 who had a bruit or orbital signs. The three patients with either congestive heart failure or increasing head circumference had PPP. Fourteen (88%) of the 16 who had fistula of the superior sagittal sinus, straight sinus, or superior petrosal sinus had PPP. PPP was seen in 46 (81%) of 57 patients who had retrograde leptomeningeal venous drainage and in five (8%) of the 65 who had only sinosal drainage. Fourteen (88%) of the 16 who had white matter T2 hyperintensity on MR images had severe PPP. CONCLUSION: The PPP reflects venous congestion and is associated with an aggressive presentation with or without retrograde leptomeningeal venous drainage. PPP may be a useful prognostic indicator and should be considered in treatment decisions.     

Embolization of intracranial dural arteriovenous fistulas with Onyx-18

Background and purpose

The use of Onyx in the treatment of AVMs has been reported in the literature, but experience in the treatment of DAVF is lacking. We report the clinical outcome obtained in the treatment of dural arteriovenous fistulas (DAVFs) using a new liquid embolic agent, Onyx-18.

Methods

The present series included 21 patients; 9 had DAVFs draining directly into the cortical veins, 6 had DAVFs draining directly into the dural sinus, 4 had DAVFs draining through the ophthalmic veins and 2 had DAVFs involving the dural sinus with leptomeningeal retrograde venous drainage Clinical data were extracted from hospital files and all patients were followed.

Results

In 14 patients (70%) there was complete angiographic elimination of the shunts and resolution of the symptoms. The remaining 7(30%) patients was not cured with residual shunts. Adverse events occurred in 6(30%) of 21 patients with 1 DAVF located at the transverse sigmoid sinus, 2 at tentorium, and 3 at the cavernous sinus. Cranial deficits occurred in 3(15%) patients, brain infarction in 1(5%) patient and microcatheter gluing in 1(3.2%) patient. At final follow up, 20 patients were asymptomatic with 1 showed clinical improvement.

Conclusion

Definitive cure may be attained effectively with Onyx in dural arteriovenous fistulas and adjunctive to surgery and radiotherapy. Location of the DAVFs affected the outcome of transarterial embolization.     

Dural arteriovenous fistulas with cortical venous drainage: incidence, clinical presentation, and treatment

BACKGROUND AND PURPOSE: Our purpose was to report our experience with intracranial dural arteriovenous fistulas (DAVFs) with cortical venous drainage during a 12-year period. PATIENTS AND METHODS: Between January 1994 and January 2006, 91 patients with intracranial DAVFs presented at our institution, and 29 (32%) had cortical venous drainage. There were 5 women and 24 men (mean age, 53.9 years; range, 24-77). Clinical presentation was intraparenchymal or subarachnoid hemorrhage in 18 patients (62%), seizures in 4 patients (14%), visual symptoms in 2 patients (7%), pulsatile bruit in 1 patient (3%), and the DAVF (14%) was incidentally discovered in 4 patients. RESULTS: In 2 patients, the DAVF had been obliterated spontaneously at the time of scheduled embolization 10 and 2 months after hemorrhage, respectively. Five patients with an anterior fossa DAVF underwent successful surgery. In 14 patients, the DAVF was completely occluded with embolization alone, and in 7 patients, embolization was followed by surgery. Altogether, complete occlusion was angiographically confirmed in 28 of 29 DAVFs; the result of radiosurgery of 1 DAVF is pending. There were no complications of surgery; embolization was complicated by postembolization hemorrhage in 1 patient (3%). CONCLUSION: Most DAVFs with cortical venous drainage have an aggressive clinical course. Treatment by a neurovascular team by using surgery, embolization, or a combination resulted in cure in all cases, with a very low complication rate.     

Enhanced cervical MRI in identifying intracranial dural arteriovenous fistulae with spinal perimedullary venous drainage

Diagnosis of an intracranial dural arteriovenous fistula (DAVF) with spinal perimedullary venous drainage is challenging because the presenting symptoms are usually related to dysfunction of the spine, not of the brain. Repeated spinal angiograms are usually performed before the diagnosis is finally made by cerebral angiography. We report two cases of intracranial DAVFs with spinal perimedullary venous drainage. In both cases contrast-enhanced cervical MRI demonstrated dilated lower brainstem and upper spinal veins, which, we believe, is a good indicator of the existence of such drainage. We suggest that, in cases with perimedullary serpentine enhancement on thoracic or lumbar MR images, additional Gd-enhanced cervical spinal MR imaging should be performed. The simple process of tracing the veins upwards may avoid a lot of unnecessary examinations and delay in the diagnosis. Received: 3 July 1997 Accepted: 6 August 1997     

Simultaneous arteriovenous shunting and venous congestion identification in dural arteriovenous fistulas using susceptibility-weighted imaging: initial experience

In this short report, we describe the potential contribution of SWI in the noninvasive evaluation of DAVFs. SWI images were compared with DSA for the identification of the location of the fistulous point, the presence of CVR, and the presence of the PPP. In 5 of 6 patients, it was possible to identify the fistulous locations depicted as hyperintensity within venous structures. Cortical venous reflux was underestimated on SWI in 3 cases of robust CVR and not identified in 2 cases of less severe CVR. The PPP seen on angiograms correlated anatomically with increased number, caliber, and tortuosity of hypointense veins seen on SWI. Furthermore, SWI was superior to conventional MR imaging in the detection of these dilated veins. These preliminary results suggest an important role for SWI in the detection and assessment of the complex hemodynamics associated with DAVFs.     

Dural arteriovenous fistulas: evaluation with MR imaging

The preangiographic diagnosis of cerebral dural arteriovenous fistula (DAVF) can be difficult. The magnetic resonance (MR) images of 12 patients with angiographically proved DAVF were evaluated to characterize the appearance of these lesions and to identify those patients at increased risk for complications. Patients with DAVF demonstrating venous occlusive disease are at higher risk for complications from the arterialized collateral venous system. This venous occlusive disease is demonstrated best at arteriography. The MR imaging appearance of dilated cortical veins without a parenchymal nidus is suggestive of a DAVF with veno-occlusive disease. Eight of the 12 patients in our series demonstrated this finding at angiography. Complications, including infarction and hemorrhage, were identified at MR imaging in eight patients with MR imaging evidence of veno-occlusive disease. At angiography 42% of these complications were not apparent. In one patient with a DAVF draining into an unobstructed right sigmoid sinus, results of MR study were normal. Although patients with DAVF without veno-occlusive disease may have normal findings at MR imaging, DAVF associated with veno-occlusive disease and dilated pial venous drainage can be documented on MR images. This subset of DAVF patients, many of whom were identified only at MR imaging, is at higher risk for complications due to veno-occlusive disease. These patients are believed to require more urgent therapy. MR imaging is useful in the pretherapeutic planning for patients with DAVF.