Radiosurgery for intracranial dural arteriovenous fistulas (DAVFs): a review

The management of intracranial dural arteriovenous fistulas (DAVFs) is complex and may require a combination of various treatment techniques. Endovascular embolization has recently emerged as the primary definitive treatment modality. However, an increasing body of literature has supported the use of stereotactic radiosurgery as the sole therapeutic modality or in combination with embolization and/or surgery. We review the rationale, results, and complications of stereotactic radiosurgery for intracranial DAVFs.     

Results of combined stereotactic radiosurgery and transarterial embolization for dural arteriovenous fistulas of the transverse and sigmoid sinuses.

OBJECT: Most dural arteriovenous fistulas (DAVFs) of the transverse and sigmoid sinuses do not have angiographically demonstrated features associated with intracranial hemorrhage and, therefore, may be treated nonsurgically. The authors report their experience using a staged combination of radiosurgery and transarterial embolization for treating DAVFs involving the transverse and sigmoid sinuses. METHODS: Between 1991 and 1998, 25 patients with DAVFs of the transverse and/or sigmoid sinuses were treated using stereotactic radiosurgery; 22 of these patients also underwent transarterial embolization. Two patients were lost to follow-up review. Clinical data, angiographic findings, and follow-up records for the remaining 23 patients were collected prospectively. The mean duration of clinical follow up after radiosurgery was 50 months (range 20-99 months). The 18 women and five men included in this series had a mean age of 57 years (range 33-79 years). Twenty-two (96%) of 23 patients presented with pulsatile tinnitus as the primary symptom; two patients had experienced an earlier intracerebral hemorrhage (ICH). Cognard classifications of the DAVFs included the following: I in 12 patients (52%), IIa in seven patients (30%), and III in four patients (17%). After treatment, symptoms resolved (20 patients) or improved significantly (two patients) in 96% of patients. One patient was clinically unchanged. No patient sustained an ICH or irradiation-related complication during the follow-up period. Seventeen patients underwent follow-up angiographic studies at a mean of 21 months after radiosurgery (range 11-38 months). Total or near-total obliteration (> 90%) was seen in 11 patients (65%), and more than a 50% reduction in six patients (35%). Two patients experienced recurrent tinnitus and underwent repeated radiosurgery and embolization at 21 and 38 months, respectively, after the first procedure. CONCLUSIONS: A staged combination of radiosurgery and transarterial embolization provides excellent symptom relief and a good angiographically verified cure rate for patients harboring low-risk DAVFs of the transverse and sigmoid sinuses. This combined approach is a safe and effective treatment strategy for patients without angiographically determined risk factors for hemorrhage and for elderly patients with significant comorbidities.     

Complex dural arteriovenous fistulas. Results of combined endovascular and neurosurgical treatment in 16 patients

Of the 88 patients evaluated for symptomatic dural arteriovenous (AV) fistula over the past 8 years, 16 had large or complicated lesions that could not be treated with standard transvascular approaches or in which such treatment had been unsuccessful. Eleven fistulas were located in the transverse sinus, two in the cavernous sinus, two in the straight sinus, and one in the falx-tentorial region near the vein of Galen. The patients were treated with a combination of endovascular and neurosurgical techniques. Fourteen patients underwent preoperative transarterial embolization; this procedure closed the fistula in one patient. In the remaining 15 patients, surgery was performed to provide access to the fistula for embolization from either the venous or the arterial side, or for excision of the fistula. Transvenous embolization completely obliterated the fistula in seven of nine patients; the fistulas were embolized incompletely through the feeding arteries in two patients; and complete surgical resection of the lesion was accomplished in four patients. Complications related to venous occlusion occurred in two patients and one patient suffered communicating hydrocephalus that was effectively treated by shunting. There were no deaths. The results suggest that combined endovascular and neurosurgical techniques are a safe and effective means for the treatment of selected complex dural AV fistulas.     

Spinal arteriovenous malformations: a comparison of dural arteriovenous fistulas and intradural AVM's in 81 patients

The medical records and arteriograms of 81 patients with spinal arteriovenous malformations (AVM's) were reviewed, and the vascular lesions were classified as dural arteriovenous (AV) fistulas or intradural AVM's. Intradural AVM's were further classified as intramedullary AVM's (juvenile and glomus types) and direct AV fistulas, which were extramedullary or intramedullary in location. Dural AV fistulas were defined as being supplied by a dural artery and draining into spinal veins via an AV shunt in the intervertebral foramen. Intramedullary AVM's were defined as having the AV shunt contained at least partially within the cord or pia and receiving arterial supply by medullary arteries. Of the 81 patients, 27 (33%) had dural AV fistulas and 54 (67%) had intradural AVM's. Several dissimilarities in clinical and radiographic findings of the two subgroups were evident. The patients with intramedullary AVM's were younger; the age at onset of symptoms averaged 27 years compared to 49 years for dural AV fistulas. The most common initial symptom associated with dural AV fistulas was steadily progressive paresis, whereas hemorrhage was the most common presenting symptom in cases of intramedullary lesions. No patients with dural AV fistulas had subarachnoid hemorrhage. Activity exacerbated symptoms more frequently in patients with dural lesions. Associated vascular anomalies occurred only in cases of intradural AVM's. In 96% of the dural lesions the AV nidus was in the low thoracic or lumbar region; in only 15% did the intercostal or lumbar arteries supplying the AVM also provide a medullary artery which supplied the spinal cord. In contrast, most intradural AVM's (84%) were in the cervical or thoracic segments of the spinal cord and all of them were supplied by medullary arteries. Transit of contrast medium through the intradural AVM's was rapid in 80% of cases, suggesting high-flow lesions. Forty-four percent of the patients with AVM's of the spinal cord had associated saccular arterial or venous spinal aneurysms. No dural AV fistulas displayed these characteristics. A good outcome occurred in 88% of patients with dural AV fistulas after nidus obliteration, while 49% of patients with intramedullary AVM's did well after surgery or embolization. These findings suggest that dural and intradural AVM's differ in etiology (acquired vs. congenital) and that they have different pathophysiology, radiographic findings, clinical presentation, and response to treatment.     

Benefits and limitations of image guidance in the surgical treatment of intracranial dural arteriovenous fistulas

Summary Background. Despite major advances in endovascular embolization techniques, microsurgical resection remains a reliable and effective treatment modality for dural arteriovenous fistulas (DAVF). However, intraoperative detection of these lesions and identification of feeding arteries and draining veins can be challenging. In a series of 6 patients who were not candidates for definitive treatment by endovascular embolization we evaluated the benefits and limitations of computer-assisted image guidance for surgical ablation of DAVF. Methods. Of the 6 patients, 5 presented with haemorrhage and one with seizures. Diagnosis of DAVF was made by conventional angiography and dynamic contrast enhanced MR angiography (CE-MRA). All patients were surgically treated with the assistance of a 3D high resolution T1-weighted MR data set and time-of-flight MR angiography (MRA) obtained for neuronavigation. Registration was based on cranial fiducials and image-guided surgery was performed with the navigation system. Findings. Four of the 6 patients suffered from DAVF draining into the superior sagittal sinus, one fistula drained into paracavernous veins adjacent to the superior petrosal sinus and one patient had a pial fistula draining in the straight sinus. DAVF diagnosed with conventional angiography could be located on CE-MRA and MRA prior to surgery. MRI and MRA images were combined on the neuronavigation workstation and DAVF were located intraoperatively by using a tracking device. In 4 out of 6 cases neuronavigation was used for direct intraoperative identification of DAVF. Brain shift prevented direct tracking of pathological vessels in the other 2 cases, where navigation could only be used to assist craniotomy. Microsurgical dissection and coagulation of the fistulas led to complete cure in all patients as confirmed by angiography. Conclusions. Neuronavigation may be used as an additional tool for microsurgical treatment of DAVF. However, in this small series of 6 cases, surgical procedures have not been substantially altered by the use of the neuronavigation system. Image guidance has been beneficial for the location of small, superficially located DAVF, whereas a navigated approach to deep-seated lesions was less accurate due to the familiar problem of brain shift and brain retraction during surgery. Both authors equally contributed to this work.     

Single stage transcranial exposure of large dural venous sinuses for surgically-assisted direct transvenous embolization of high-grade dural arteriovenous fistulas: technical note

Background  

High-grade dural arteriovenous fistulas (DAVFs) with retrograde cortical leptomeningeal drainage are formidable lesions because of their risk for intracranial hemorrhage. Treatment is aimed at occluding venous outflow to achieve obliteration of the fistula. In DAVFs that involve a large dural venous sinus (transverse sigmoid sinus or superior sagittal sinus), occluding venous outflow can be accomplished endovascularly with transvenous embolization. However, in some cases of DAVFs with reflux into cortical leptomeningeal veins, there may be venous restrictive disease downstream, such as occlusive thrombosis, which can prohibit endovascular access via the transfemoral or transjugular routes. In these instances, a transcranial approach can be performed to expose the large dural venous sinus distal to the site of occlusion for direct catheterization of the venous outflow for transvenous embolization. This combined surgical and endovascular strategy provides direct access to the venous outflow and bypasses the site of thrombotic obstruction.     

Arterial aneurysms associated with intracranial dural arteriovenous fistulas: epidemiology,natural history,and management. A systematic review

Neurosurgical Review - Arterial aneurysms are uncommon among patients with dural arteriovenous fistulae (DAVFs), and there is limited information available to guide treatment decisions in such...     

Late deterioration of neurologic function in patients surgically treated for spinal dural arteriovenous fistulas

BackgroundA limited number of reports on the long-term neurologic outcome of patients with SDAVFs treated by surgery and/or embolization are available in the literature. The aim of our study is to neurologically evaluate these patients at 2 different follow-up stages, after surgery, to demonstrate a possible late neurologic deterioration after an initial improvement.MethodsBetween January 1987 and May 2002, 29 patients with SDAVFs were operated on at the Verona Department of Neurosurgery. In this group we retrospectively identified 16 patients who had 2 different clinical follow-ups, at a mean of 4.5 and 9.2 years, respectively. We compared their neurologic status using the ALS. All these data were obtained from clinical charts and phone interviews.ResultsThe epidemiologic, clinical, and radiologic features of our group of patients are very similar to those previously described in the literature. Comparing the global clinical status between the 2 different follow-up stages, we observed a late deterioration in 8 cases (50%). A worsening of the mean G and M values of the ALS was also noted. Spinal angiography and contrast-enhanced MRI did not show any signs of recurrence of the fistula.ConclusionsOur study confirms the possible occurrence of a late clinical deterioration in as many as 50% of patients surgically treated for a SDAVF. We deem that the main pathophsyologic mechanism underlining this phenomenon is a gradual and irreversible decline in spinal function related to those hemodynamic modifications induced by the fistula and to the persistence of a state of anatomofunctional deficiency of the spinal venous drainage.     

Early rebleeding from intracranial dural arteriovenous fistulas: report of 20 cases and review of the literature.

OBJECT: In this study the authors sought to estimate the frequency, seriousness, and delay of rebleeding in a homogeneous series of 20 patients whom they treated between May 1987 and May 1997 for arteriovenous fistulas (AVFs) that were revealed by intracranial hemorrhage (ICH). The natural history of intracranial dural AVFs remains obscure. In many studies attempts have been made to evaluate the risk of spontaneous hemorrhage, especially as a function of the pattern of venous drainage: a higher occurrence of bleeding was reported in AVFs with retrograde cortical venous drainage, with an overall estimated rate of 1.8% per year in the largest series in the literature. However, very few studies have been designed to establish the risk of rebleeding, an omission that the authors seek to remedy. METHODS: Presenting symptoms in the 20 patients (17 men and three women, mean age 54 years) were acute headache in 12 patients (60%), acute neurological deficit in eight (40%), loss of consciousness in five (25%), and generalized seizures in one (5%). Results of the clinical examination were normal in five patients and demonstrated a neurological deficit in 12 and coma in three. Computerized tomography scanning revealed intracranial bleeding in all cases (15 intraparenchymal hematomas, three subarachnoid hemorrhages, and two subdural hematomas). A diagnosis of AVF was made with the aid of angiographic studies in 19 patients, whereas it was a perioperative discovery in the remaining patient. There were 12 Type III and eight Type IV AVFs according to the revised classification of Djindjian and Merland, which meant that all AVFs in this study had retrograde cortical venous drainage. The mean duration between the first hemorrhage and treatment was 20 days. Seven patients (35%) presented with acute worsening during this delay due to radiologically proven early rebleeding. Treatment consisted of surgery alone in 10 patients, combined embolization and surgery in eight, embolization only in one, and stereotactic radiosurgery in one. Three patients died, one worsened, and in 16 (80%) neurological status improved, with 15 of 16 AVFs totally occluded on repeated angiographic studies (median follow up 10 months). CONCLUSIONS: The authors found that AVFs with retrograde cortical venous drainage present a high risk of early rebleeding (35% within 2 weeks after the first hemorrhage), with graver consequences than the first hemorrhage. They therefore advocate complete and early treatment in all cases of AVF with cortical venous drainage revealed by an ICH.     

Use of a self-expanding stent with balloon angioplasty in the treatment of dural arteriovenous fistulas involving the transverse and/or sigmoid sinus: functional and neuroimaging-based outcome in 10 patients

OBJECT: The goal of this study was to evaluate the clinical and angiography results in 10 patients with transverse-sigmoid dural arteriovenous fistulas (DAVFs) treated using sinus angioplasty and dural sinus stent insertion. METHODS: Between 2001 and 2003, 10 consecutive patients (six men and four women, age range 54-79 years) who had presented with transverse and/or sigmoid sinus DAVFs with or without sinus thrombosis underwent self-expanding stent placement and balloon angioplasty. Eight fistulas involved the transverse sinus, three the sigmoid sinus, and one the torcular and occipital sinuses. According to the Djindjian-Merland grading system, there were two Type I, five Type Ila, one Type Ilb, and two Type IV DAVFs. The mean clinical follow-up period was 21.1 months. At the last follow-up examination, seven patients were asymptomatic and three were dramatically improved. The mean angiography follow-up period was 7.5 months for the available population: four patients had complete DAVF occlusion, four had significant flow reduction, and two who experienced clinical improvement refused conventional angiography control studies. Delayed computerized tomography angiography scans were obtained to evaluate stent permeability in nine of the 10 patients. Stent permeability was demonstrated in eight of the nine patients with available control studies at a mean follow up of 20.8 months. There were two transient neurological deficits but no severe and permanent complications. CONCLUSIONS: In this series, sinus stent insertion resulted in a cure or significant clinical improvement in all patients harboring a DAVF, with no severe or permanent complication. Stent placement for transverse and/or sigmoid sinus DAVFs is a promising technique whose viability should be confirmed in larger series with longer follow-up periods.     

Usefulness of intravascular ultrasound in embolization of dural arteriovenous fistula: a case report

A 66-year-old male was admitted with right homonymous hemianopsia. Angiograms revealed a dural arteriovenous fistula (DAVF) involving the left transverse-sigmiod sinus. The DAVF was fed by the left occipital, middle meningeal, and posterior auricular arteries and drained into the left transverse sinus with occlusion of the left internal jugular vein and reversed flow of the left occipital cortical veins. Positron emission tomography (PET) study showed decreased regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rOEF) and regional cerebral metabolic rate of oxygen (rCMRO2) and increased regional cerebral blood volume (rCBV). The patient was treated by transarterial and transvenous embolization. Before transvenous embolization, we attempted to observe the perisinus structure used by intravascular ultrasound (IVUS). IVUS was able to demonstrate multiple channels formed by DAVF and transvenous embolization was performed accurately at the exact fistulous site. After treatment, the DAVF had completely disappeared but clinical symptom had hardly any changed. A PET study showed that the rCBF and rCBV were normalized but rOEF and rCMRO2 had not changed. Eight months after treatment, PET study showed some normalization of rOEF and rCMRO2 of the left occipital lobe with the clinical symptom. IVUS is useful in determining the exact sites of transvenous embolization of DAVF.     

Management,risk factors and outcome of cranial dural arteriovenous fistulae: a single-center experience

Background  

The role of endovascular interventions in managing dural arteriovenous fistulas (DAVFs) is increasing. Furthermore, in patients with aggressive DAVFs, different surgical interventions are required for complete obliteration or disconnection. Our objective was to evaluate the management of patients with intracranial DAVFs treated in our institution to identify the parameters that may help guide the long-term management of these lesions.     

Combined transvenous and transarterial embolization of a tentorial-incisural dural arteriovenous malformation followed by primary stent placement in the associated stenotic straight sinus. Case report

Dural arteriovenous malformations (AVMs) involving the tentoria-incisura are associated with an aggressive clinical course characterized by subarachnoid and intracranial hemorrhage (ICH). In these lesions, venous outflow obstruction precipitates leptomeningeal venous drainage, resulting in the arterialization of pial veins and the formation of venous aneurysms, both of which are prone to hemorrhage. Stenotic lesions of the dural sinuses also contribute to the development of retrograde leptomeningeal drainage, which is responsible for the aggressive clinical course of the dural AVM. Endovascular approaches are successful in the treatment of these lesions and of any potential venous outflow obstruction caused by stenosis of a dural sinus. The authors report on a patient with a tentorial-incisural dural AVM and an accompanying stenotic venous sinus. A combined transvenous and transarterial embolization procedure was performed, resulting in complete obliteration of the dural AVM, followed by primary stent placement across a stenotic segment of the straight sinus and normalization of venous outflow. The authors conclude that dural AVMs can be treated safely by using a combined transarterial and transvenous approach and that an extensive search for venous outflow obstruction often reveals stenosis of a draining sinus. Consideration should be given to primary stent placement in the stenotic sinus to protect against ICH.