On the basis of our experience, we established the current protocol in which dural arteriovenousfistulas of the lateral and sigmoid sinuses are treated, when possi- ble, solely by transvenous embolization. This practice is used in any patient with cortical venous drainage or whose life is impaired by associated symptoms. Surgical excision or surgical access for transvenous packing is reserved for those unusual lesions that we are unable to treat completely by transvenous embolization or for instances in which anatomic peculiarities preclude en- dovascular venous access to the fistula. Transarterial embolization is reserved as an adjunct to transvenous embolization. The shortcomings of our study include a relatively small patient population, the continuing evo- lution of technology and techniques, a somewhat limited patient follow-up, and absence of cohort control sub- jects. Nonetheless, we believe that transfemoral, trans- venous embolization is a safe and efficacious method for treating dural arteriovenous malformations of the lat- eral and sigmoid sinuses when the involved sinus is endovascularly accessible.
Dural arteriovenousfistulas (DAVFs) are a subtype of vascular malformations related to the dura mater that show a shunt between the extracranial arteries (eg, branches of the external carotid artery) and the intracranial venous sinus (transverse or sigmoid si- nus). Cerebral digital subtraction angiography (DSA) is a well-established method for establishing diagnosis and treating patients with DAVF and also for evalu- ating vascular morphology, the hemodynamic charac- teristics of a fistula, and results of endovascular treat- ment (1, 2). Other diagnostic imaging procedures, such as cerebral CT or MR imaging, depict only a
Dural arteriovenousfistulas (AVFs) usually occur in the cavernous sinus or in the posterior fossa, accounting for 10% to 15% of intracranial arteriovenous malformations (1). They are con- sidered to be acquired and may develop spon- taneously or after trauma (2, 3). The treatment of dural AVFs may include open surgery and/or endovascular surgery (4 – 8). Interlocking de- tachable coils (IDCs) (Target Therapeutics, Fremont, Calif) have been developed; we report their successful use in the treatment of dural AVFs.
PURPOSE: To examine the clinical and radiographic findings in a large group of patients having or suspected of having a spinal dural arteriovenous fistula. METHODS: An analysis of 240 spinal angiograms in 132 patients revealed 97 vascular malformations that included 66 spinal dural arteriovenousfistulas. Sixteen patients had 1 or more normal spinal angiograms that were per- formed for suspected spinal dural arteriovenousfistulas on other imaging studies. The imaging and clinical data were reviewed in all patients who had or were suspected of having a spinal dural arteriovenous fistula and who had a spinal MR (n 5 44) and a myelogram (n 5 37). RESULTS: Spinal dural arteriovenousfistulas were more common in males (3.4:1) with an average age of 62 years (range, 37 to 81 years). The average time from onset of symptoms to diagnosis was 27 months. Clinical findings included weakness (55%), a progressive clinical course (100%), and a myelopathy on exam (84%). The nidus of the fistula was located between T-6 and T-12 in 61%, in the sacrum in 9%, and intracranially in 8%. In the spinal dural arteriovenous fistula group, vessels were seen on supine myelography in all patients. MR findings in this group included increased T2 signal in the cord (100%), gadolinium enhancement (88%), mass effect (45%), and flow voids (T1, 35%; T2, 45%). The patients in the negative spinal angiogram group were younger (average age, 51 years), had symptoms longer (average time from symptom onset to spinal angiogram, 59 months), and presented with numbness or pain (76%). When compared with the patients with spinal dural arteriovenous fistula, acute or stable deficits were more common (31%), and myelop- athy on exam was less common (56%). Although the angiogram-negative patients commonly had vessels on the myelogram (92%), abnormal T2 signal in the cord was unusual (17%). CONCLUSIONS: In the appropriate clinical setting, high T2 signal of the spinal cord is the most sensitive imaging finding in spinal dural arteriovenous fistula. The presence of mass effect and enhancement should not discourage this diagnosis. The likelihood of finding a spinal dural arte- riovenous fistula in a patient without T2 signal on MR is low.
PURPOSE: To determine the efficacy of porous metallic stents in the treatment of experimentally created carotid-jugular fistulas. METHODS: Carotid-jugular fistulas were constructed surgically in five mongrel dogs. Porous metallic stents were placed endovascularly across the fistula holes within the carotid artery; carotid angiography was performed before, immediately after, and 1 and 2 months after stent placement. The fistula specimens were resected 2 months after stent placement; gross and light microscopic analyses were performed. RESULTS: Angiography revealed complete closure of three of the five fistulas 1 month after stent placement; two of the five fistulas remained patent but demonstrated diminished flow rate. All carotid arteries were widely patent throughout the study. Gross pathology of the carotid-jugular specimens revealed fibrous connective tissue and collagen within the fistula hole. A thin layer of endothelium covered the stent wires and the fibrous connective tissue overlying the fistula hole. CONCLUSIONS: The stents were effective in closing three of the five fistulas and reducing flow through the fistulas in the remaining animals. With further refinements and variations in technique, porous metallic stents may prove a viable alternative to current endovascular devices for treatment of certain arteriovenousfistulas.
studying ingrowth of fibrous tissue following im- plantation of a vascular graft (3). Previous re- searchers have had some success using porous metallic stents to close experimentally created arteriovenousfistulas in the carotid arteries of mongrel dogs (1). These porous metallic stents (Wallstents) did not produce immediate closure of the fistulas but rather eventual closure in 60% (3 of 5), which was due to fibrocellular tissue filling the pores between stent wires with even- tual plugging of the fistula holes. Our study was modeled after this experiment. The only differ- ence was in the construction of the stent. We added a silicone coating to the same type of porous metallic stent (Wallstent), but all other conditions of the two experiments were con- stant and unchanged. It was our intention to examine the effectiveness of coated stents in the hope that the fistulas would occlude imme- diately.
D espite being the most commonly encountered spinal vas- cular malformation, spinal dural arteriovenousfistulas (SDAVFs) are rare and still underdiagnosed entities, which, if not treated properly, can lead to considerable morbidity with progressive spinal cord symptoms. Because presenting clinical symptoms are unspecific, the neuroradiologist is often the first clinician to raise the possibility of this diagnosis, which ini- tially rests mainly on MR imaging. For a thorough under- standing of the disease and for planning the therapeutic strat- egy, however, selective spinal digital subtraction angiography (DSA) still is necessary. The aim of the following article is to review the epidemiology, etiology, clinical and imaging fea- tures, and therapeutic approaches of this type of spinal vascu- lar malformation. Because an understanding of spinal vascular malformations both from an etiologic and pathophysiologic standpoint is based on the spinal vascular anatomy, we will start by briefly describing the salient features of the spine and spinal cord arterial supply and venous drainage followed by a classification of spinal vascular malformations in general and a classification of dural arteriovenous (AV) shunts in particular.
PURPOSE: To investigate the clinical presentation, angiographic findings, endovascular management, and clinical outcome in dural arteriovenousfistulas (DAVFs) of the marginal sinus. METHODS: Fourteen patients with DAVFs of the marginal sinus were identified from angiographic studies and medical records of all patients treated for DAVFs at our institution between July 1990 and August 1995. The endovascular treatment and clinical outcomes of these patients are reported. RESULTS: Eleven patients had pulse-synchronous bruit, two had intracranial hemorrhage, and one had ataxia. Thirteen patients were cured with endovascular techniques alone and one was cured by a combination of preoperative embolization followed by surgical obliteration of the fistula. The sole complication of treatment was a partial left hypoglossal nerve palsy, which resolved spontaneously. CONCLUSION: DAVFs of the marginal sinuses are potentially life-threatening lesions that can be treated with endo- vascular techniques for a high rate of cure and a low rate of morbidity.
Traditional way of diagnosis of CAVF is invasive investiga- tions such as cardiac catheterization and coronary angiog- raphy. Most of the fistulas are small and found incidentally during coronary angiography. Coronary ang- iography still remains the gold standard for imaging the coronary arteries, but sometimes origin and relation of CAVF to adjacent cardiac structures may be ambiguous. It is difficult to measure and observe abnormal tortuous blood vessels with coronary angiography in one section, under such conditions non-invasive methods such as transthoracic echocardiography combined with Doppler and color flow imaging, transoesophageal echocardiogra- phy, magnetic resonance imaging and contrast enhanced multislice tomography can be used as adjunct to coronary angiography [5,6,16-18].
In cases 1 and 2, neither sinus thrombosis nor intracranial hemorrhage can thus account for spon- taneous dural AVF closure. We believe that this spontaneous closure could be explained by the in- trinsic compression of the arteriovenous shunts within the sinus wall. To our knowledge, no expla- nation has yet been issued concerning this phenom- enon. Neither of case 1 and 2 showed coagulation disorders during hospital follow-up. Changes af- fecting the structure or conformation of the sinus wall could, however, be involved. A focal increase in sinus size could lead to focal compression of the arteriovenous shunts within the wall itself, thus leading to the final occlusion of the dural AVF. The initial cause of the structural or conformational changes affecting the sinus remains uncertain. Sim- ilarly, because cases are rare, we are unable to iden- tify patients’ characteristics predisposing them to spontaneous dural AVF closure.
the previous irradiation field. The treatment result was classified as almost complete obliteration (Fig 4). The other two DAVFs had relatively high-flow arte- riovenous shunts before radiosurgery. The follow-up MR images and color Doppler sonograms showed small shunts remaining at 19 and 27 months, respec- tively. These results were classified as partial obliter- ation (see Table). The partially obliterated DAVFs had relatively high-flow arteriovenous shunts ob- served on X-ray angiograms as compared with the others. None of the patients had symptom worsening or complications during the follow-up period.
Nonetheless, once an AV shunt in the deep lumbosacral region is suspected, the most probable differential diagnosis for an SDAVF is an arteriovenous malformation of the filum terminale. In both cases, namely SDAVF and filum terminale–AVM, symp- toms are caused by medullary venous congestion resulting in comparable myelopathic disorders and a progressive clinical course. In contrast to lsSDAVFs, the filum terminale artery arising from the anterior spinal artery predominantly feeds a filum terminale–AVM.
TVE is performed by retrograde catheterization of the in- volved dural sinus or cortical vein followed by deposition of coils and/or liquid embolic agents adjacent to the shunt. The aim of this treatment is occlusion of the arteriovenous fistula and/or disconnection of leptomeningeal or cortical reflux with preservation of normal venous drainage. TVE is more safely used when the diseased sinus segment has minimal contribu- tions to normal venous outflow and can be completely oc- cluded. More caution is required when the dural venous sinus maintains drainage of normal veins—in these circumstances,
RESULTS: DSA revealed SDAVF in 20 abnormalities of which 19 were spinal and 1 was tentorial with spinal drainage, as well as SAVM in 11 patients. In 3 patients, MRA and DSA were both normal. For detection of spinal arteriovenous abnormalities, neither false-positive nor false-negative MRA results were obtained. The MRA-derived level of the feeding artery in SDAVF agreed with DSA in 14 of 19 cases. In 5 cases, a mismatch of 1 vertebral level (not side) was noted for the feeding artery. For the tentorial AVF, only the spinal drainage was depicted; the feeding artery was outside the MRA field of view. In intradural SAVM, the main feeding artery was identified by MRA in 10 of 11 patients. MRA could differentiate between glomerular and fistulous SAVM in 4 of 6 cases and between sacral SDAVF and filum terminale SAVM in 2 of 5 cases.