Spontaneous obliteration of pial arteriovenous malformations: a review of 27 cases

BACKGROUND AND PURPOSE: Brain arteriovenous malformations (AVMs) occur in approximately 0.14% of the population. The most common presentations are hemorrhage (50%) and seizures (25%). Although they are congenital abnormalities, their angioarchitecture may vary over time. A rare but well-recognized phenomenon of AVMs is that of spontaneous obliteration. It is not known what factors predispose to spontaneous obliteration. The purpose of our study was to determine whether spontaneous thrombosis of AVMs can be predicted by their angioarchitecture and whether there is any risk of recurrence once obliteration has occurred. METHODS: We retrospectively reviewed the angiographic and cross-sectional imaging data amassed over an 18-year period, including follow-up imaging studies and mail surveys of referring and family physicians. A control group was obtained from contemporaneous AVMs of a similar size. RESULTS: We identified 28 cases of spontaneous obliteration in a series of 2162 patients. The mean time between initial diagnostic angiography and angiographic obliteration was 10 months, during which time there was no intervention and no history of repeat hemorrhage; nor had hemorrhage recurred during the follow-up period (mean, 53 months). Most of the AVMs were deep (22/27) with only one draining vein (21/27) and few feeding arteries. In more than half the cases (15/27) drainage was exclusively into the superficial venous system. CONCLUSION: Spontaneous obliteration is rare (1.3%). Common features include hemorrhagic presentation and few arterial feeding vessels. Although we found no instance of repeat hemorrhage during the follow-up period, AVMs can recanalize, and follow-up is therefore recommended.     

DSA对脑动静脉畸形出血的预测分析

目的:探讨脑动静脉畸形(AVM)血管造影形态与出血关系,预测脑动静脉畸形(AVM)出血的危险性。方法:回顾性分析104例数字减影脑血管畸形资料。结果:穿支动脉供血、单支引流和深部引流、小病灶及位于基底节和后颅窝者易出血。结论:通过观察脑动静脉畸形(AVM)供血动脉(类型)、大小、位置、引流静脉数目及通畅情况,可以对脑动静脉畸形(AVM)的出血情况进行预测。     

Intranidal aneurysms in cerebral arteriovenous malformations: evaluation and endovascular treatment.

Patients with cerebral arteriovenous malformations (AVMs) have an increased risk of hemorrhage if an intranidal aneurysm is present. Angiograms from 125 patients with cerebral AVMs were evaluated, and 15 (12%) had intranidal aneurysms. All 15 patients had a history of bleeding. Five patients underwent particulate or liquid embolization before surgical excision of or radiation therapy for the AVM. All aneurysms were thrombosed at the time of embolization. Ten patients underwent radio-surgery alone. Eight of the 10 underwent angiographic follow-up (mean, 33 months); seven patients showed complete obliteration of the AVM without residual aneurysm. Histologic evaluation showed intranidal aneurysms to be thin-walled vascular structures, and they are the likely site for AVM hemorrhage. Embolization is an effective method for achieving thrombosis of the intranidal aneurysm and may be beneficial in patients undergoing radiation therapy because of a long latency period between treatment and thrombosis of the AVM.     

Angiographic and clinical characteristics of patients with cerebral arteriovenous malformations associated with hereditary hemorrhagic telangiectasia

BACKGROUND AND PURPOSE: Cerebral arteriovenous malformations (AVMs) are occasionally associated with hereditary hemorrhagic telangiectasia (HHT), which is characterized by the presence of multiple mucocutaneous telangiectasia, epistaxis, and familial inheritance. We analyzed the angiographic and clinical characteristics of patients with cerebral AVMs related to HHT. METHODS: Among 638 patients with cerebral AVMs, we identified 14 patients with HHT. The AVMs were classified as those with nidi of 1 cm or less (micro AVMs), those with nidi between 1 and 3 cm (small AVMs), and those of the fistulous type (arteriovenous fistulas [AVFs]). RESULTS: A total of 28 AVMs were found; seven of 14 patients had multiple AVMs. The 28 AVMs were categorized as 12 micro AVMs, eight small AVMs, and eight AVFs. All except one micro AVM were asymptomatic, whereas all small AVMs were symptomatic. Three of eight AVFs were asymptomatic. All 28 AVMs were located on the cortex. All micro AVMs and AVFs had single feeders and single draining veins, whereas the small AVMs had multiple feeders in all lesions and single draining veins in six of eight lesions. CONCLUSION: Multiple, cortical, micro AVMs or AVFs harboring single feeding arteries and single draining veins should raise clinical suspicion of HHT-related AVMs.     

Angiographic follow-up of large cerebral AVMs incompletely embolized with isobutyl-2-cyanoacrylate

This study evaluated the long-term angiographic results in large cerebral arteriovenous malformations (AVMs) partially embolized with isobutyl-2-cyanoacrylate. Preembolization, immediate postembolization, and long-term follow-up angiograms were performed in 30 large, partially embolized brain AVMs. Particular attention was paid to the relative size of the residual AVM nidus and the embolized arterial feeders, to recruitment of new feeders, to the size of residual draining veins, and to the speed of arteriovenous shunt. Nine cases with less than 50% AVM nidus obliteration showed no significant morphologic changes. In 18 cases with 50-75% obliteration of the AVM nidus, 11 (61.1%) showed no significant changes, six (33.3%) showed enlargement of the AVM nidus, and one (5.5%) evolved to complete angiographic obliteration. In three cases with 75-99% AVM nidus obliteration, one remained unchanged, one showed an increase in the size of the AVM nidus, and one evolved to complete obliteration. Evaluation by plain film, CT, and cerebral angiography of the isobutyl-2-cyanoacrylate deposits showed that when the polymer was positioned predominantly in arterial feeders there was invariably reconstitution of the AVM nidus through leptomeningeal, deep medullary, and/or dural collaterals. This phenomenon did not occur when the isobutyl-2-cyanoacrylate was deposited mainly in the AVM nidus.     

Spontaneous regression of cerebral arteriovenous malformation in hereditary hemorrhagic telangiectasia

Cerebral arteriovenous malformations (AVMs) are associated with hereditary hemorrhagic telangiectasia (HHT). I report a case of a patient with HHT with four cerebral AVMs in whom one AVM spontaneously regressed during a 5-year period. The spontaneous regression of this AVM in this patient with HHT supports the theory that AVMs associated with this syndrome have a different natural history than that of typical sporadic AVMs.     

Cerebral MR venography

This paper illustrates the technique and clinical use of cerebral MR venography (MRV). Dural sinus thrombosis is detected by both two-dimensional time-of-flight (TOF) and three-dimensional phase-contrast (PC) techniques. Venous angiomas are demonstrated by the three-dimensional PC method. The arterial feeders, nidus and draining veins of cerebral arteriovenous malformation (AVM) can be visualized on contrast-enhanced TOF three-dimensional MR angiogram. The high-flow draining veins of cerebral and dural AVMs, vein of Galen malformation and carotid cavernous fistula are better seen on contrast-enhanced three-dimensional gradient-echo MRV.     

Pseudoaneurysm formation secondary to spontaneous thrombosis of a massive cerebral arteriovenous malformation

Summary A case of a large cerebral arteriovenous malformation (AVM) with spontaneous partial thrombosis and intracerebral hematoma is reported. The unusual and unique features of the radionuclide brain scan and cerebral angiogram are described. The characteristic angiographic features of residual tortuosity and dilatation or pseudoaneurysm formation at the bifurcations of the feeding arteries in a partially thrombosed cerebral AVM have not been described previously in the literature.     

Brain edema associated with unruptured brain arteriovenous malformations

Introduction  Brain edema in unruptured brain arteriovenous malformations (AVMs) is rare; this study examines (1) its frequency and clinical presentation, (2) imaging findings with emphasis on venous drainage abnormalities, and (3) implications of these findings on natural history and management. Methods  Presentation and imaging features of all unruptured brain AVMs were prospectively collected in our brain AVM database. Neurological findings, size, location, venous drainage pattern, presence of venous thrombosis, ectasia, or stenosis, and brain edema were specifically recorded. Treatment details of all patients with brain edema and their clinical and imaging follow-up were reviewed. Finally, a comparison was made between patients with and without edema. Results  Brain edema was found in 13/329 unruptured brain AVMs (3.9%). Neurological deficit (46.2%), venous thrombosis (38.5%), venous ectasia (84.6%), stenosis (38.5%), and contrast stagnation in the draining veins (84.6%) were more frequent in patients with brain edema than without edema. Eight patients with brain edema received specific treatment (embolization = 5, surgery = 2, radiosurgery = 1). Clinical features correlated well with change in degree of edema in six. Three of five embolized patients were stable or showed improvement after the procedure. On follow-up, however, intracranial hemorrhage developed in three. Conclusion  Brain edema in unruptured brain AVMs is rare, 3.9% in this series. Venous outflow abnormalities are frequently associated and appear to contribute to the development of edema. Progressive nonhemorrhagic symptoms are also associated, with a possible increased risk of hemorrhage. Palliative embolization arrests the nonhemorrhagic symptoms in selected patients, although it may not have an effect on hemorrhagic risk.     

Intravascular pressure measurements in feeding pedicles of brain arteriovenous malformations

Pressure measurements in arterial feeders of arteriovenous malformations (AVMs) can be easily acquired during endovascular treatment procedures. In this study, mean arterial pressure values in arterial feeders (Pfed) of brain AVMs were determined using a pressure measuring system connected to a standard microcatheter. A total of 148 measurements were performed in 139 patients. Mean systemic arterial pressure values were subtracted for correction. The levels of correlation between the pressure values and various clinical parameters (i.e., AVM location, size, previous hemorrhage) and pathoanatomical features of the AVM (e.g., nidus structure, number of draining veins) were determined. Pfed values were 54.5 mmHg on average. Pfed was lower in more distally located AVMs, in larger lesions and in AVMs with multiple drainage veins. Pressure values were significantly higher in patients with previous hemorrhage and in smaller AVMs. Our results support the importance of hemodynamic parameters in determining the presentation of AVMs. More extensive studies using this simple technique may further elucidate these mechanisms and may result in improved criteria for patient selection and reduction of complications.     

Embolization of cerebral arteriovenous malformations with silk: histopathologic changes and hemorrhagic complications.

PURPOSETo evaluate the safety of silk as an embolic agent for preoperative embolization of cerebral arteriovenous malformations (AVMs) by assessing the histopathologic changes and hemorrhagic complications associated with its use.METHODSHistopathologic specimens, medical records, and radiologic records of 73 patients with AVMs embolized with silk (alone or in combination with other agents) were reviewed retrospectively. Forty-eight histologic specimens obtained at surgery were analyzed for inflammatory responses and compared with the time interval between embolization and surgery. Postembolization angiograms were assessed for vasculitis and CT scans were reviewed for evidence of hemorrhage after embolization.RESULTSThere was no angiographic evidence of vasculitis. Histologic evidence of vasculitis was absent or mild in 92% of cases and histologic evidence of perivascular inflammation was absent or mild in 73% of cases. The frequency of histologic changes associated with vasculitis, perivascular inflammation, and vessel necrosis varied with the time interval between embolization and AVM resection. Intracranial hemorrhage, as a direct complication of silk use, occurred in one patient. Another patient had subarachnoid hemorrhage 24 hours after embolization, caused by rupture of a posteroinferior cerebellar artery aneurysm. Intraventricular high-density material appeared on routine postembolization CT scans in two other patients who had intraventricular AVM extension. This high-density material was thought to be contrast extravasation from intrinsically leaky AVM nidus vessels and not frank hemorrhage.CONCLUSIONEmbolization of AVMs with silk does not result in marked inflammation or increased hemorrhagic complications as compared with other agents.     

脑血管畸形的MRI诊断：与CT,脑血管造影对比分析

报道了６４例脑动静脉畸型和８例脑海绵状血管瘤的ＭＲＩ表现，并对ＭＲＩ、ＣＴ及脑血管造影在脑血管畸形诊断中的应用价值进行了对比分析。６４例脑动静脉畸形的ＭＲＩ均见到典型征象──流空信号簇。２９例见到粗大的供应动脉或／和引流静脉，１４例见到扩大的静脉窦。结果表明，ＭＲＩ对于脑动静脉畸形及其并发症的诊断优于ＣＴ，并可弥补脑血管造影的不足。ＭＲＩ与ＣＴ的联合应用对脑海绵状血管瘤的定性诊断很有意义。     

出血性脑动静脉畸形的影像特点与血管内治疗

目的：探讨以出血发病的脑动静脉畸形的影像学特点与血管内治疗的技术操作。方法：经脑CT或MRI确认为脑实质内出血的56例病例，经DSA全脑血管造影证实为脑动静脉畸形(AVM)，根据AVM病灶的特点，行经血管内超选择应用α-氰基丙烯酸正丁酯栓塞或结合放射外科治疗。结果：56例在1-3次栓塞后，36例病灶完全消除；1例因AVM中有新生的动脉瘤及1例术后1年发生出血而行第2次栓塞治愈，1例在接受X-刀治疗后3个月再次出血，经手术后痊愈。结论：AVM病灶内或病灶旁存在动脉瘤和动脉囊样扩张、引流静脉细小和脑室内生长的AVM是引起脑出血的主要原因，而在栓塞中优先处理动脉瘤样病变对防止脑出血有重要意义。     

Exceptional multiplicity of cerebral arteriovenous malformations associated with hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome).

PURPOSETo describe the clinical and imaging features of seven patients with hereditary hemorrhagic telangiectasia and an exceptional number of cerebral arteriovenous malformations (AVMs).METHODSOne hundred thirty-six patients from a dedicated hereditary hemorrhagic telangiectasia clinic were screened systematically for cerebral AVMs by means of MR imaging. Thirty-one were found to have abnormalities suggestive of a vascular malformation. Eighteen of these 31 patients subsequently underwent diagnostic cerebral angiography.RESULTSOf the 18 patients who had cerebral angiography, all were found to have at least one AVM and seven were found to have three or more AVMs. The number of cerebral AVMs detected ranged from three to nine. At angiography, the AVMs varied in size from 3 to 25 mm in maximal dimension and consisted of a poorly defined plexiform nidus that typically had a single arterial feeding pedicle and a single draining vein. The two largest AVMs (20- and 25-mm nidus, respectively) contained intranidal aneurysms. Treatment included embolization, surgical excision, or follow-up management.CONCLUSIONSMultiple cerebral AVMs are associated with hereditary hemorrhagic telangiectasia and further highlight the uniqueness of central nervous system involvement by this systemic angiodysplasia. MR imaging can underestimate the number and size of cerebral AVMs; therefore, catheter angiography is necessary to establish the extent of central nervous system involvement in this disorder.     

Subclassification and Treatment Results of Ethanol Embolotherapy of Type II Arteriovenous Malformations of the Extremity and Body

PurposeTo evaluate the safety and efficacy of ethanol and coil embolization of type II arteriovenous malformation (AVM) according to a new subtype classification.Materials and MethodsEighty-four type II AVMs in the body or extremity of 79 patients who underwent AVM treatment from 1996 to 2017 were retrospectively subclassified according to the angiographic morphology of the draining vein as type IIa (arterioles shunt to focal segment of single draining vein), type IIb (arterioles shunt to venous sac with multiple draining veins), and type IIc (arterioles shunt along long segment of draining vein). Coil and ethanol embolization of the focal or long segment of the draining vein or the venous sac was performed with direct puncture or transvenous approach according to subtype. Treatment outcomes, number of treatment sessions, and complications were analyzed.ResultsAVM cure (ie, complete embolization) rates were 95%, 76%, and 65% in types IIa, IIb, and IIc AVMs, respectively. The cure rate of type IIa AVMs was significantly better than that of type IIc AVMs (P = .015). Median numbers of treatment sessions were 1 in types IIa and IIb AVMs and 2.5 in type IIc AVMs, with a significant difference between type IIc and the other 2 types (P < .05). Minor complications occurred in 20% of patents and major complications occurred in 7%.ConclusionsThe cure rate of type IIa AVMs was significantly better than that of type IIc AVMs, which also required significantly more treatment sessions than the other 2 types.     

Size determination of supratentorial arteriovenous malformations by MR,CT and angio

Summary Twenty patients with high-flow supratentorial arteriovenous malformations (AVMs) were studied by magnetic resonance imaging (MR), computed tomography (CT), and selective cerebral angiography. The size of the malformation measured on MR was found, in general, to be smaller than the size determined from angiographic films. This discrepancy increased as the size of the AVM increased. AVM size on CT and angiography was found to be essentially equivalent. The reason for these differences between MR and CT or angiography was the ability to separate out the draining veins by MR, whereas this was difficult on projection films and contrast enhanced CT. Calcification was more easily detected by CT than by MR. MR better detected hemorrhage, which could be mistaken for old infarction on CT. Foci of cystic change within the nidus of the AVM were equally evident on MR and CT. Due to its sensitivity in discriminating between AVM nidus and adjacent draining veins and MR's ability to show the AVM in three planes, MR appeared to be more accurate in defining the AVM nidus than either CT or cerebral angiography. Such accurate delineation is crucial in patients prior to stereotactic radiosurgery.     

MRI — a noninvasive tool for evaluating therapeutic embolisation of cerebral arteriovenous malformations

Of 86 patients with whose cerebral arteriovenous malformations (AVMs) were embolised in the period 1985–1990 29 were examined by high-field spin-echo (SE) magnetic resonance imaging (MRI) after endovascular therapy with gistoacryl-lipiodol. Embolisation-related changes in the nidus of the AVM and in the surrounding brain parenchyma were assessed. Results were compared with pretreatment MR and CT, and with follow-up angiograms in all patients. In accordance with angiographic findings, complete obliteration of pathological vessels was noted in 7 patients (24.1%) and partial occlusion in 22 (75.9%); small ischaemic infarcts were observed in 8 patients (27.6%) and extravascular deposits of blood breakdown products were seen in 3 (10.3%). MRI is a valuable noninvasive technique for assessing morphology and haemodynamics of cerebral AVMs before and after treatment. However, following embolotherapy, variable effects on signal intensity in vascular lumina caused by flowing blood, thrombosis and the embolisation agent have to be carefully analysed. To assess the exact site of histoacryl-lipiodol in embolised nidus territories or small areas of possible intracerebral hemorrhage, the time interval between endovascular therapy and MR examinations may have to be modified. Offprint requests to: L. Prayer     

脑动静脉畸形的CT诊断（附100例分析）

报告并分析了１００例经脑血管造影及手术证实的脑动静脉畸形的ＣＴ表现。ＣＴ阳性率为９７％，诊断准确度为６６％。将ＣＴ阳性者分为未破裂ＡＶＭ和破裂ＡＶＭ二组，描述了各的ＣＴ特征，并与血管造影结果对照。未破裂ＡＶＭ组中２２例有占位效应，破裂ＡＶＭ多为血 管造影微小ＡＶＭ。１３例血管造影隐性ＡＶＭ，ＣＴ均为阳性。比较了ＣＴ和血管造影对脑ＡＶＭ的诊断价值。     

Two-dimensional thick-slice MR digital subtraction angiography in the assessment of small to medium-size intracranial arteriovenous malformations

Assessment of intracranial arteriovenous malformations (AVMs) by conventional catheter angiography carries risks; moreover, this invasive procedure is often repeated for follow-up. We investigated the clinical applicability of two-dimensional thick-slice, contrast-enhanced magnetic resonance digital subtraction angiography (2D MRDSA) with high temporal resolution in the assessment of AVMs. We performed 78 2D MRDSA studies of treated or untreated small to medium-size AVMs on a 1.5 tesla imager. Two observers independently evaluated demonstration of nidus flow void on T2-weighted images and each component of the AVM on 2D MRDSA employing a three-point grading scale. In 55 patients with AVMs, the mean ratings of nidus flow voids, feeding vessels, nidi, draining vessels and early venous filling on MRI were 2.8, 2.4, 2.6, 2.8 and 2.8, respectively. sensitivity, specificity, positive and negative predictive values for an AVM using 2D MRDSA were 87, 100, 100 and 78%, respectively and for nidus flow voids on T2-weighted images 80, 91, 96 and 66%, respectively. 2D MRDSA can thus demonstrate haemodynamic features of AVMs. It can be employed as a less invasive, dynamic angiographic tool for follow-up of AVMs previously delineated by catheter angiography.     

Bleeding complications after basilar artery fibrinolysis with tissue plasminogen activator

BACKGROUND AND PURPOSE: Fibrinolysis with local intraarterial urokinase infusion for basilar artery thrombosis has been associated with a low rate of spontaneous symptomatic cerebral hemorrhage, even when patients have been treated late in the course of symptoms. Because urokinase is presently unavailable in the United States, this study was undertaken to determine the frequency of spontaneous cerebral hemorrhage in basilar artery fibrinolysis performed with tissue plasminogen activator (tPA). METHODS: In a retrospective review of our initial experience with cerebral fibrinolysis for acute stroke using intraarterial tPA, four cases of basilar thrombosis were identified. Doses of the fibrinolytic agent and heparin, angiographic findings, clinical courses, and bleeding complications for these patients were determined. These results were compared with those from a prior study of 20 similar consecutive patients treated with urokinase. RESULTS: Symptom duration before treatment was unlimited. Intraarterial doses of tPA were 20 to 50 mg. Patients received full systemic anticoagulation with heparin. Complete basilar artery recanalization was achieved in 75% of patients. Two patients treated with tPA had angioplasty and stent placement for related high-grade stenosis. Spontaneous symptomatic cerebral hemorrhage occurred in three (75%) of the four tPA-treated patients and in three (15%) of the 20 urokinase-treated patients. CONCLUSION: The cerebral hemorrhage complication rate for intraarterial fibrinolysis with tPA was very high in cases of basilar artery thrombosis at the doses we used. Protocol adjustments should be considered.