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.     

The importance of venous hypertension in the formation of dural arteriovenous fistulas: a case report of multiple fistulas remote from sinus thrombosis

Various hypotheses have been reported concerning the pathogenesis of dural arteriovenous fistulas (DAVFs). However, it is still controversial whether sinus thrombosis or venous hypertension has a greater influence on the formation of DAVFs. We present a rare case of multiple DAVFs that developed after sinus thrombosis. Chronic venous hypertension secondary to sinus thrombosis in the left transverse-sigmoid sinus induced the multiple DAVFs, including one in the right cavernous sinus, which was remote from the occluded sinus. This case indicates the importance of venous hypertension in the formation of DAVFs. Received: 27 November 2000/Accepted: 13 March 2001     

重症硬脑膜静脉窦血栓的局部溶栓治疗

目的 研究重症硬脑膜静脉窦血栓的局部溶栓治疗的方法及疗效。方法 总结我院自2000年以来6例重症硬脑膜静脉窦血栓的局部溶栓治疗经验，男4例，女2例，其中4例采用一侧股动脉及对侧股静脉Seldinger穿刺，2例采用股动脉Seldinger穿刺及上矢状窦前1／3穿刺。导管置入一侧颈内动脉及静脉窦血栓处后，于颈内动脉及静脉窦血栓处先后各用尿激酶50万U，以每分钟1万U泵入，再于静脉窦血栓处泵入尿激酶持续溶栓，维持外周血中纤维蛋白原含量1．0～1．5g／L，同时予全身肝素化，维持外周血活化部分凝血活酶时间正常值的2～3倍。结果 本组6例，5例痊愈，颅内压转正常，头痛消失，无神经功能障碍，其中4例数字减影血管造影(DSA)见浅表静脉扩张消失，静脉窦显影正常，1例浅表静脉扩张明显改善，静脉窦显影较前好转；1例好转，颅内压较前降低，头痛好转，DSA见浅表静脉扩张消失，静脉窦显影正常，抗凝治疗1个月后颅内压正常，头痛消失，神经功能恢复正常。结论 重症硬脑膜静脉窦血栓采用动静脉系统联合应用尿激酶局部溶栓治疗是快速、安全、有效的方法，经股静脉途径不易到达静脉窦血栓处者，可以行上矢状窦入路。     

Endovascular treatment of anterior cranial fossa dural arteriovenous fistula

We describe the technique and results of the endovascular treatment of anterior cranial fossa dural arteriovenous fistulas (DAVF) in four symptomatic patients. Catheterization was via the superior sagittal sinus in two patients and via the ophthalmic artery in two patients. Embolization was performed using detachable platinum coils in the former two patients and a liquid embolic system (Onyx-18, MTI) in the latter. We were able to reach the fistula site and to embolize the arteriovenous shunting zone in all of the patients. The final angiogram showed complete occlusion of the DAVFs, and all patients recovered completely. No complications related to either approach were observed. Endovascular treatment of anterior cranial fossa DAVFs is feasible by either transvenous or transarterial access.     

Percutaneous transvenous packing of cavernous sinus with Onyx for cavernous dural arteriovenous fistula

Objective

The aim of this study is to describe the technique and results of the transvenous approach for occlusion of cavernous dural arteriovenous fistulas (DAVFs) with Onyx.

Methods

Eleven patients presenting with clinically symptomatic DAVFs, were treated between August 2005 and February 2007 at Beijing Tiantan Hospital. We were able to navigate small hydrophilic catheters and microguidwires through the facial vein or inferior petrosal sinus (IPS) into the ipsilateral cavernous sinus. After reaching the fistula site the cavernous sinus was packed with Onyx or combining with detachable platinum coils.

Results

We were able to reach the fistula site and to achieve a good packing of Onyx or combining with coils within the arteriovenous shunting zone in 10 patients. The final angiogram showed complete occlusion of the arteriovenous fistula. Two (18.2%) patients developed a bradycardia during DMSO injection. No complications related to the approach were observed.

Conclusions

Transvenous occlusion of cavernous DAVFs is a feasible approach, even via facial vein or via IPS. Onyx may be another option for cavernous packing other than detachable platinum coils.     

Transorbital puncture for the treatment of cavernous sinus dural arteriovenous fistulas

This report describes a series of patients for whom dural arteriovenous fistulae (DAVFs) of the cavernous sinus were successfully embolized using a percutaneous, transorbital technique to directly cannulate the cavernous sinus. A vascular access needle and catheter are percutaneously advanced along the inferolateral aspect of the orbit to access the cavernous sinus via the superior orbital fissure. Safe and effective embolization is achieved without the need for a surgical cut-down.     

Embolization of dural cavernous fistulas via superior ophthalmic vein approach.

PURPOSETo present the results of our treatment of dural cavernous sinus fistulas with surgical exposure of the superior ophthalmic vein (SOV), retrograde venous catheterization, and coil embolization of the cavernous sinus.METHODSTwelve patients with dural cavernous sinus fistulas were treated via a retrograde transvenous SOV approach in our hospital during a 3-year period. All patients had been referred by ophthalmologists because of secondary glaucoma and decreased visual acuity. Angiography showed preferential venous drainage of the dural cavernous sinus fistulas to an enlarged ipsilateral SOV. A total of 13 SOV exposures were performed, one patient with bilateral fistulas required bilateral treatment. The vein was surgically exposed by an ophthalmologist and then catheterized. Platinum coils were delivered through a microcatheter at the fistula site and into the root of the SOV, until there was complete angiographic closure.RESULTSCatheterization and embolization were successful in 12 of the 13 patients, with complete angiographic occlusion of the fistula. Two patients with bilateral fistulas had transient worsening of symptoms on the contralateral side. Three patients required follow-up angiography. No early complications occurred, and late complications were minor in two cases. All patients except one with long-standing symptoms recovered premorbid visual acuity. At follow-up, 11 (92%) of the 12 embolized fistulas remained occluded.CONCLUSIONSRetrograde catheterization of the SOV and embolization of the cavernous sinus with coils is a direct, safe, and efficient way to occlude dural cavernous sinus fistulas.     

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.     

经眼上静脉途径栓塞治疗自发性海绵窦硬膜动静脉瘘

目的 观察填塞海绵窦（ＣＳ）,治疗海绵窦硬膜动静脉瘘的疗效。方法 经眼上静脉（ＳＯＶ）途径栓塞治疗复发性海绵窦硬膜动静脉瘘,因ＳＯＶ显著扩张、动脉化,使导管可直接插入ＣＳ,推入栓塞材料,填塞ＣＳ,治愈海绵窦硬膜动脉静脉瘘,同时又不影响同侧颈内动脉的供血。结果 ９例病人通过脑血管造影,确证为Ｂａｒｒｏｗ分类的Ｂ,Ｃ和Ｄ型瘘,经栓塞ＣＳ治疗,２个月后９例病人的症状全部消失。结论该法是自发性海绵窦硬膜动     

Transvenous embolization of dural fistulas involving the transverse and sigmoid sinuses

Eleven patients with dural fistulas involving the transverse and sigmoid sinuses were treated by transvenous embolization with coils or liquid adhesives. Seven patients underwent preoperative embolization of the external supply followed by direct surgical exposure of the sinus: liquid adhesives were used in four patients and coils in the remaining three. Four of these patients had complete obliteration of their fistulas and there was 95% reduction in the remaining three. Four patients had transvenous placement of coils from a transfemoral approach. In three, the ipsilateral sigmoid sinus was thrombosed and a contralateral approach across the torcular herophili was used. Coils were used in all four patients; one patient also had liquid adhesives placed within the sinus. Complete cure was achieved in one patient, 95% reduction in another, and 50% and 40%, reductions in the remaining two. Two transient complications occurred, one related to venous occlusion secondary to liquid adhesives and another related to transient occlusion of the vestibular aqueduct. Obliteration of dural fistulas involving the transverse and sigmoid sinuses can be achieved by placement of embolic material within the involved sinus from a transvenous approach; both coils and liquid adhesives can achieve this goal.     

Transvenous embolization of dural caroticocavernous fistulae: technical considerations

Sixteen patients with symptomatic dural caroticocavernous fistulae were treated by transvenous embolization, via the jugular vein and inferior petrosal sinus. The fistula was occuladed by thrombogenic coils. Complete resolution of symptoms and signs was achieved in 14 patients, and complete angiographic resolution was also obtained in 14 patients. Failures to achieve angiographic cure were attributed to failure to reach the fistula within the cavernous sinus precisely. Factors which make placement of the catheter at the fistula difficult are trabeculae within the cavernous sinus, a specific configuration of the superior ophthalmic vein and venous thrombosis. To improve the efficacy of tranvenous embolization, every possible venous route to the cavernous sinus therefore should be tried, to facilitate reaching the fistula and the possibility of transvenous embolization should not be thwarted by venous thrombosis.     

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.     

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.     

硬脑膜动静脉瘘的治疗

目的 探讨不同方法治疗的不同类型的硬脑膜动静脉瘘(DAVF)的疗效。方法 采用经动脉入路在供血动脉内采用低浓度NBCA胶、弹簧圈、游离纤毛钢圈、PVA等栓塞治疗；经静脉入路在瘘口静脉端用弹簧圈栓塞，或直接开颅手术夹闭瘘口、静脉窦表面颅骨钻孔后直接穿刺作静脉窦内栓塞及静脉内支架植入等方法治疗不同部位和不同类型的DAVF32例。结果 8例前颅凹底DAVF，5例经动脉入路栓塞治疗，2例治愈，3例临床好转；3例(1例经静脉入路治疗失败后)前颅凹底入路行开颅瘘口直接夹闭治愈。14例海绵窦区DAVF，7例经眼上静脉入路海绵窦内栓塞治愈，4例经动脉入路，治愈1例，好转3例。5例横窦区DAVF，2例经静脉入路窦内栓塞治愈，2例动脉入路栓塞后好转，1例行窦孤立手术治愈。4例多处瘘口的上矢状窦DAVF，联合多种治疗方法经多次治疗，临床好转。1例左侧颈静脉孔区DAVF联合多种治疗方法经多次治疗治愈。结论 前颅凹底DAVF以直接手术行瘘口夹闭疗效好，经动脉入路低浓度胶栓塞可治愈但需注意危险吻合；海绵窦区DAVF经静脉入路栓塞多可治愈。横窦区DAVF静脉入路栓塞瘘口静脉端效果好；复杂性DAVF治疗困难，目前联合多种治疗方法可以达到临床改善。将治疗策略定在针对瘘口的静脉端，可望达到临床治愈。     

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.     

经静脉入路海绵窦内液体胶联合弹簧圈栓塞海绵窦区硬脑膜动静脉瘘

目的探讨应用经静脉入路联合液体胶和弹簧圈介入栓塞海绵窦区硬脑膜动静脉瘘的方法和策略。方法回顾性分析应用经静脉入路联合液体胶和弹簧圈栓塞治疗的8例海绵窦区硬脑膜动静脉瘘患者,包括瘘口的血管构筑学、治疗方法和疗效。结果所有患者均采用经静脉入路液体胶联合弹簧圈栓塞,其中经面静脉-眼上静脉入路1例,经岩下窦入路7例。8例均临床治愈,患者术后即刻造影提示瘘口完全消失。除术后早期头痛外无其他介入相关并发症。临床随访3个月～3年,患者无临床症状复发。结论经静脉入路应用液体胶联合弹簧圈介入栓塞对于海绵窦区硬脑膜动静脉瘘是安全、有效且经济的治疗方法 。     

Suspected dural arteriovenous fistula: results with screening MR angiography in seven patients.

Previous studies have shown that spin-echo (SE) magnetic resonance (MR) imaging has been helpful in the assessment of dural arteriovenous fistula (DAVF); however, direct visualization of the fistula site is limited. Thus, conventional plain angiography is required to establish the diagnosis. Because of this limitation, the additional use of MR angiography may improve noninvasive screening for this disorder. Seven patients with DAVFs proved at plain angiography were evaluated with SE MR imaging and with three-dimensional (3D) time-of-flight (TOF) MR angiography. In six of seven cases, 3D TOF MR angiography demonstrated the fistula site. Correlation was good when compared with findings at plain angiography. Occlusion of the dural sinus was found at plain angiography in three of seven patients but was missed at SE imaging in all three. MR angiography also failed to demonstrate sinus occlusion in two of three patients. Arterial feeders could not be seen on SE MR images, but MR angiography improved their depiction. Plain angiography demonstrated abnormal venous drainage into distended cortical veins in three patients, but dilated cortical veins were noted in only two of the patients on both SE MR images and MR angiograms.     

硬脑膜动静脉瘘的治疗

目的　探讨不同方法治疗不同类型的硬脑膜动静脉瘘 (DAVF)的疗效。方法　采用经动脉入路在供血动脉内采用低浓度NBCA胶、弹簧圈、游离纤毛钢圈、PVA等栓塞治疗 ;经静脉入路在瘘口静脉端用弹簧圈栓塞 ,或直接开颅手术夹闭瘘口、静脉窦表面颅骨钻孔后直接穿刺作静脉窦内栓塞及静脉内支架植入等方法治疗不同部位和不同类型的DAVF 32例。结果　 8例前颅凹底DAVF ,5例经动脉入路栓塞治疗 ,2例治愈 ,3例临床好转 ;3例 (1例经静脉入路治疗失败后 )前颅凹底入路行开颅瘘口直接夹闭治愈。 14例海绵窦区DAVF ,7例经眼上静脉入路海绵窦内栓塞治愈 ,4例经动脉入路 ,治愈 1例 ,好转 3例。 5例横窦区DAVF ,2例经静脉入路窦内栓塞治愈 ,2例动脉入路栓塞后好转 ,1例行窦孤立手术治愈。 4例多处瘘口的上矢状窦DAVF ,联合多种治疗方法经多次治疗 ,临床好转。 1例左侧颈静脉孔区DAVF联合多种治疗方法经多次治疗治愈。结论　前颅凹底DAVF以直接手术行瘘口夹闭疗效好 ,经动脉入路低浓度胶栓塞可治愈但需注意危险吻合 ;海绵窦区DAVF经静脉入路栓塞多可治愈。横窦区DAVF静脉入路栓塞瘘口静脉端效果好 ;复杂性DAVF治疗困难 ,目前联合多种治疗方法可以达到临床改善。将治疗策略定在针对瘘口的静脉端 ,可望达到临床治愈。     

Transvenous embolization of dural fistulas involving the cavernous sinus

Because of the risks associated with arterial embolization of cavernous dural fistulas, we have sought an alternative method to promote fistula closure. Thirteen patients underwent transvenous embolization as a treatment for symptomatic cavernous dural fistulas. All procedures were performed from a femoral vein access through the inferior petrosal sinus or basilar plexus. In five patients the inferior petrosal sinus was not angiographically demonstrable; however, embolization was still possible through this route in two patients. The embolic agents used were detachable balloons in one patient, coils alone in five, coils and liquid adhesives in four, coils plus silk sutures in one, silk sutures alone in one, and liquid adhesives alone in one. Nine patients had follow-up angiograms, which showed complete obliteration of the fistulas and complete resolution of related symptoms. One patient had complete resolution of clinical symptoms but refused follow-up angiography. Another patient had 50% decrease in fistula flow on the follow-up angiogram and improvement in clinical symptoms. Two patients had complete fistula obliteration after embolization and progressive improvement in symptoms but follow-up angiograms had not been obtained. Follow-ups ranged from 1 to 97 months (mean, 15 months). Two complications were related to this treatment. An embolic stroke followed transient placement of a balloon in the internal carotid in one patient, and a second patient developed transient visual loss when the venous outflow pathways were occluded before fistula closure. The fistula was immediately closed with complete recovery of vision. With recent advances in microcatheter and embolic agent technology, transvenous closure of cavernous dural fistulas is now possible.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.