Retinal and intracranial arteriovenous malformations: Wyburn-Mason syndrome.

A 7-year-old girl who failed a vision screening examination was found to have a retinal arteriovenous malformation (AVM) in her right eye along with a small angioma of her right lower lip. Magnetic resonance imaging and cerebral angiography revealed a large AVM involving the thalamus and basal ganglia as well as a small AVM involving the right ophthalmic artery. The combination of retinal and intracranial AVMs is known as Wyburn-Mason syndrome. The retinal AVMs of this syndrome do not grow or bleed. Visual loss is usually the result of optic neuropathy from associated orbitocranial AVMs. The natural course of the intracranial AVMs of this syndrome is poorly documented. However, they tend to be extensive and inaccessible and therefore difficult to treat.     

脑动静脉畸形Ⅳ型胶原酶信使核糖核酸的原位杂交研究

目的　应用原位杂交技术检测脑动静脉畸形 (AVM)及正常对照组大脑皮质动脉标本中相对分子质量为 92 0 0 0的IV型胶原酶 (MMP 9)、72 0 0 0的IV型胶原酶 (MMP 2 )及其它们的组织抑制因子 1和 2 (TIMP 1和TIMP 2 )的信使核糖核酸 (mRNA) ,并定位产生它们的细胞 ;用透射电镜观察AVM的超微结构 ,以探讨大脑AVM的发病机制。方法　用地高辛标记的MMP 2、MMP 9、TIMP 1和TIMP 2反义RNA(antisenseRNA)探针与AVM和对照组 (各 5例 )皮质动脉组织进行原位杂交 ,定位产生它们的细胞 ,并用正义RNA (senseRNA)探针作阴性对照 ;对杂交组织的相邻切片 ,进行HE染色和Weigert弹力和胶原纤维染色 ,透射电镜观察。结果　 5例大脑AVM标本中均见MMP 9mRNA阳性杂交信号。杂交阳性信号位于血管内膜、中膜和外膜 ,且以外膜最为密集。外膜部分断裂、厚薄不一 ,甚至分层。可见平滑肌细胞退变 ,甚至分解成细胞碎片。阳性杂交信号定位于单核细胞、成纤维细胞和平滑肌细胞。对照组动脉标本中未发现MMP 9mRNA阳性杂交信号。在AVM和供血动脉组织中未发现MMP 2、TIMP 1和TIMP 2mRNA的阳性杂交信号。结论　血管内膜的破坏与大脑AVM形成有关 ;外膜也参与了脑AVM的形成过程 ;外膜胶原纤维的破坏与外膜中MMP 9mRNA高含量呈正相关。     

术中B超辅助切除脑动静脉畸形

目的:探讨术中实时超声在脑动静脉畸形(AVM)外科治疗中的应用价值。方法:15例脑AVM患者接受显微外科治疗,术中病变切除前行超声检查,以定位AVM边界与周围脑组织结构关系;辨别供血动脉和引流静脉;确定血肿与AVM的关系。病变切除后重复超声检查AVM残留与否,并与术后血管造影结果对比。结果:15例患者病变均在实时超声导航下获得全切除。畸形血管团可被准确定位和界定范围,血肿区为高回声无血流信号,供血动脉血流动力学有别于正常血管,术中超声影像上病变的全切除为血管造影所证实。结论:术中实时超声能对脑AVM进行准确定位,并可判定脑AVM的全切除;AVM术中定位可为术前MRI、DSA起到有价值的补充。     

Progressive spontaneous occlusion of a cerebellar AVM: pathogenetic hypothesis and review of literature

Cerebral arteriovenous malformation (AVM) is a complex network of vascular channels consisting of arterial feeders, a nidus and enlarged venous drainage. AVMs usually increase in size with time, but may rarely obliterate; spontaneous angiographic regression occurs in less than 1.5% of cerebral AVMs. Several causes of spontaneous regression have been postulated such us hemodynamic alterations due to hemorrhage, hypercoagulability, atherosclerosis, and tromboembolism from associated aneurysms. In this report we describe a case of spontaneous, complete and asymptomatic occlusion of a left cerebellar hemispheric AVM; angiograms clearly demonstrate a progressive decrease in size of the AVM at follow-up. Thrombosis of the dominant-draining vein caused by turbulent blood flow seemed to be the main driver. Possible mechanisms leading to the occlusion are discussed and a review of the literature is reported.     

Growing Organized Hematomas Following Gamma Knife Radiosurgery for Cerebral Arteriovenous Malformation : Five Cases of Surgical Excision

Organized hematoma is a rare complication that can develop following gamma knife radiosurgery (GKS) for cerebral arteriovenous malformation (AVM). Here, we describe 5 patients with growing organized hematomas that developed from completely obliterated AVMs several years after GKS. The patients were 15, 16, 30, 36, and 38 years old at the time of GKS, respectively, and 3 patients were female. Four AVMs were located in the lobe of the brain, and the remaining AVM were in the thalamus. Between 2-12 years after GKS, patients developed progressive symptoms such intractable headache or hemiparesis and enhancing mass lesions were identified. Follow-up visits revealed the slow expansion of the hematomas and surrounding edema. Steroids were ineffective, and thus surgery was performed. Histology revealed organized hematomas with a capsule, but there was no evidence of residual AVMs or vascular malformation. After surgery, the neurological symptoms of all patients improved and the surrounding edema resolved. However, the hematoma continued to expand and intraventricular hemorrhage developed in 1 patient whose hematoma was only partially removed. GKS for cerebral AVM can be complicated by growing, organized hematomas that develop after complete obliteration. Growing hematomas should be surgically evacuated if they are symptomatic. Radical resection of the hematoma capsule is also strongly recommended.     

术中超声导航辅助切除脑动静脉畸形

目的探讨术中实时超声导航在脑动静脉畸形(AVM)外科治疗中的应用价值。方法26例脑AVM显微手术切除术中,使用Aloka SSD 4000型超声检查仪扫描,进行AVM定位、辨别供血动脉和引流静脉;确定血肿与AVM的关系以及血流动力学监测。病变切除后重复超声检查AVM残留与否,并与术后脑血管造影结果对比。结果26例畸形血管团均住实时超声下清晰显示并获得全切除。血肿区为高同声无血流信号;供血动脉与正常血管在血流动力学上有差别;术中超声影像所示的病变全切除为术后血管造影所证实。结论术中实时超声能够对脑AVM进行准确定位,指导皮质切口的设计,并可判定病灶是否全切除.对于术前的MRI、DSA检查起到很有价值的补充作用。     

Vascular structure of arteriovenous malformations.

Cerebral arteriovenous malformations (AVMs) are classified angiographically into two types: the arteriovenous fistula (AVF) type and the plexiform type. However, the differences in vascular structure of these two types have not been clarified. The purpose of the present study is to elucidate the vascular structure of plexiform AVMs and to discuss the clinical significance of this classification of AVMs. Specimens of AVMs resected in 8 cases and identified by cerebral angiography as plexiform AVMs were examined. Immediately after their removal, microdissection of the terminal arterial feeder, the nidus, and the venous drainer was performed under a microscope. A histological examination of each element was then conducted. Microdissection of a portion of the vascular mass that formed the nidus made it possible to separate individual vessels of the mass from each other. Many of these individual vessels connected with the feeder on one side, while the other side anastomosed with the drainer, thus exhibiting the morphology of an AVF. From our examination of the AVMs in the present study, we inferred that the plexiform type is fundamentally a conglomeration of AVFs. It is therefore suggested that the vascular structure of this type of AVM is not fundamentally different from that of the AVF type.     

三维CT血管造影在脑动静脉畸形诊治中的初步应用经验

目的 评估三维CT血管造影（3D－CTA）在脑动静脉畸形诊断及术前评估中的应用。方法 对我科收治的25例脑动静脉畸形患者采用3D－CTA检查，并同期行脑数字减影血管造影（DSA），比较两种检查的结果。结果 3D－CAT显示了24例动静脉畸形，3D－CTA在显示畸形血管闭、供血动脉和引流静脉的三维构造以及空间关系上优于DSA，并能显示三者与颅骨的关系。3D－CTA虽未能发现1例小型小脑动静脉畸形，但其显示了一个位于小脑后下动脉（PICA）远端的供血动脉动脉瘤，并确定了出血系动脉瘤而非动静脉畸形。3D－CTA可以模拟手术入路时可观察到的血管构造，有助于正确判断动静脉畸形的各种成分，提高手术的安全性。结论 3D－CTA对脑动静脉畸形的诊断及其术前评估有其独特的价值。尤其适合于大型脑动静脉畸形、动静脉畸形合并动脉瘤以及颅内巨大血肿怀疑系动静脉畸形破裂者。它与DSA可互补，但尚无法取代DSA。     

脑动静脉畸形的血管结构学研究

目的:探讨脑动静脉畸形血管结构学与临床之间的联系,以及硬脑膜供血和软脑膜循环的发生机制和作用。方法:回顾性的分析195例的临床资料,根据其DSA表现进行研究分析。结果:195例分属于不同的结构类型。并与不同的临床表现相对应。113例伴随硬脑膜供血或软脑膜循环。结论:血管结构学与AVMs临床症状直接相关。     

Quantification of intracerebral steal in patients with arteriovenous malformation

Eleven patients with angiographically and/or pathologically proved arteriovenous malformations (AVMs) were studied using dynamic, single-photon-emission computed tomography (DSPECT). Quantification of regional cerebral blood flow in structurally normal areas remote from the AVM disclosed areas of decreased flow compared with normal controls in eight of 11 patients examined. Areas of hypoperfusion correlated with altered function as manifested by epileptogenic foci and impaired cognitive function. Dynamic, single-photon-emission computed tomography provides a noninvasive technique to monitor quantitatively hemodynamic changes associated with AVMs. Our findings suggest that such changes are present in the majority of patients with AVMs and that they may be clinically significant. The potential application of regional cerebral blood flow imaging by DSPECT in the management of patients with AVMs is discussed.     

Cerebral Arteriovenous Malformation Associated with Moyamoya Disease

The coexistence of moyamoya disease (MMD) with an arteriovenous malformation (AVM) is exceedingly rare. We report two cases of AVM associated with MMD. The first case was an incidental AVM diagnosed simultaneously with MMD. This AVM was managed expectantly after encephalo-duro-arterio-synangiosis (EDAS) as the main feeders stemmed from the internal carotid artery, which we believed would be obliterated with the progression of MMD. However, the AVM persisted with replacement of the internal carotid artery feeders by new external carotid artery feeders from the EDAS site. The AVM was eventually treated with gamma knife radiosurgery considering an increasing steal effect. The second case was a de novo AVM case. The patient was initially diagnosed with MMD, and acquired an AVM eight years later that was slowly fed by the reconstituted anterior cerebral artery. Because the patient remained asymptomatic, the AVM is currently being closely followed for more than 2 years without further surgical intervention. Possible differences in the pathogenesis and the radiologic presentation of these AVMs are discussed with a literature review. No solid consensus exists on the optimal treatment of MMD-associated AVMs. Gamma knife radiosurgery appears to be an effective treatment option for an incidental AVM. However, a de novo AVM may be managed expectantly considering the possible risks of damaging established collaterals, low flow characteristics, and probably low risks of rupture.     

Expression of myosin heavy chain isoforms by smooth muscle cells in cerebral arteriovenous malformations

We have characterised the blood vessels found in normal cerebral vasculature and in arteriovenous malformations (AVMs), based on the expression of smooth muscle cell (SMC)-specific proteins. The marker proteins used were smooth muscle alpha-actin and four myosin heavy chain isoforms (SM1, SM2, SMemb and NMHC-A). Specimens of AVM obtained during surgery, and normal cerebral vessels from autopsy cases were studied immunohistochemically and compared. The arterial components of AVM contained an abundance of SMCs of the contractile phenotype, which were positive for alpha-actin, SM1 and SM2, but not for SMemb and NMHC-A. These components showed the same staining pattern as mature normal arteries. Two different types of abnormal veins were found in the AVM specimens: large veins with a thick and fibrous wall (so-called 'arterialised' veins) and intraparenchymal thin-walled sinusoidal veins. The former expressed alpha-actin, SM1, SM2, and SMemb, the latter expressed alpha-actin, SM1, and SM2. These marker expression patterns resembled those of normal cerebral arteries, and the results were compatible with arterialisation of the cerebral veins caused by arteriovenous shunting. However, the expression of SMemb was found only in the arterialised type of veins, not in the sinusoidal type or the arteries that had sustained abnormal blood flow in the AVMs. The thick-walled veins in the AVMs showed the same staining pattern as normal veins of dural plexus origin (large subarachnoid veins and dural sinuses). It is therefore possible to assume that they originated from the dural plexus, and extended into the brain during the formation of AVMs.     

The endovascular treatment of arteriovenous malformations

Embolization of cerebral arteriovenous malformations (AVMs) is a useful therapeutic modality. The primary purpose of treatment is to obliterate the AVM to prevent future hemorrhage. A small proportion of cerebral AVMs might be obliterated angiographically, but angiographic obliteration does not necessarily equate with cure, and follow-up evaluation of these cases is mandatory. The primary role of embolization is as an adjunct to surgical excision or radiosurgery. Palliative embolization of cerebral AVMs that are disabling on the basis of medically intractable seizures and/or progressive neurological deficits might be indicated, but considerable clinical judgment is required to select cases that can benefit from this palliative intervention. The history, indications, techniques, embolic agents, risks and complications are reviewed. Several illustrative cases are presented.     

Cerebral Arteriovenous Malformations as Acquired Lesions: Case Reports and Review of the Literature

Cerebral arteriovenous malformations (AVMs) are generally attributed to congenital lesions that arise from aberrant vasculogenesis between the fourth and eighth weeks of embryonic life. However, this dogma has been challenged by several recent observations, one of which is de novo formation of AVMs. Forty cases of de novo AVMs were published between 2000 and 2019, all of which involved a history of intracranial insult, such as vascular abnormalities or nonvascular conditions, prior to AVM diagnosis. We hereby present two unique operative cases of ruptured de novo AVMs in older adult patients. Case 1 is novel in the sense that the patient did not experience any kind of environmental trigger (“second hit”) such as a previous intracranial insult, while Case 2 serves as the second report of a de novo AVM patient with a medical history of Bell's palsy.Although the exact mechanisms of AVM formation remain to be elucidated, it is likely to be a multifactorial process related to environmental and hemodynamic factors.     

Epidermal nevus syndrome with azygos anterior cerebral artery

Epidermal nevus syndrome is a neurocutaneous disorder characterized by the association of epidermal nevi with central nervous system or skeletal abnormalities. Central nervous system abnormalities include hemimegalencephaly, hydrocephalus, various migration disorders, intraspinal lipomas, and enlarged spinal roots. Rarely, vascular anomalies cause neurologic signs. We report on a 30-month-old girl with epidermal nevus syndrome who also exhibited vascular malformations of the azygos anterior cerebral artery, a cortical aneurysm, and right internal carotid artery hypoplasia. This rare vascular abnormality was not previously reported in patients with epidermal nevus syndrome.     

Impact of cerebral arteriovenous malformations on systemic and cerebral hemodynamics

Shunt through cerebral arteriovenous malformations (AVMs) causes not only cerebral hemodynamic changes, but also affects the cardiovascular system as a whole. Forty-two patients aged 15 to 62 years were examined. Group 1 included 19 patients with AVM < 20 cm3; Group 2 comprised 23 patients with AVMs > 21 cm3. Cerebral angiography revealed AVMs afferents and stroma. Before and after surgery, total cerebral blood flow was estimated by color duplex scanning of cephalic large arteries; and the heart and systemic hemodynamics were evaluated by ECG, echoECG, and 24-hour blood pressure monitoring. Thus, small AVMs with insignificant arteriovenous shunt do not considerably affect cerebral and systemic hemodynamics (eukinetic hemodynamics). Large AVMs enhance functional load on the cardiovascular system whose hyperfunction as the basic mechanism of cerebral blood flow compensation in arteriovenous shunt through cerebral AVMs is effected by increasing cardiac and stroke, circulating blood volume, blood pressure, and tachycardia. These changes are functional.     

Frequency of spinal arteriovenous malformations in patients with unexplained myelopathy

The authors reviewed charts of 78 myelopathy patients who underwent spinal angiography for possible arteriovenous malformations (AVMs). Twenty-two patients had an AVM. No neurologic complications from angiography were observed. MRI findings of increased T2 signal or flow voids were strongly associated with AVMs. Spinal angiography should be performed in all patients with unexplained myelopathy after neurologic evaluation and an MRI demonstrating increased T2 signal or flow voids.     

Cerebral arteriovenous malformations and movement disorders.

A series of six patients with movement disorders associated with cerebral arteriovenous malformations (AVM) is reported. The AVMs were classified according to the Spetzler-Martin classification as grade V (one patient), grade IV (four patients), and as grade III (one patient). One patient had action-induced hemidystonia caused by a contralateral frontoparietal AVM which compressed the putamen and was supplied partially by enlarged lenticulostriate arteries. Two patients presented with unilateral cortical tremor associated with contralateral high-frontal cortical/subcortical AVMs sparing the basal ganglia. Another patient developed hemidystonia and hemichorea-hemiballism after bleeding of a contralateral temporooccipital AVM and subsequent ischemia. Two patients had focal dystonia after thalamic and basal ganglia hemorrhage from AVMs. Five patients were operated on. The movement disorder was abolished in one patient postoperatively. Different mechanisms were identified that are relevant for the development of AVM-related movement disorders: mass effect, diaschisis, local parenchymal altered cerebral blood flow, and hemorrhagic or ischemic structural lesions.     

The microsurgical treatment of the supratentorial arteriovenous malformations. Part II--complications

BACKGROUND AND PURPOSE: The aim of this study was an analysis of complications after surgical treatment of the cerebral supratentorial arteriovenous malformations (AVM), assessment of their clinical sequelae, and attempt to find factors influencing their occurrence. MATERIAL AND METHODS: 88 consecutive patients operated on for AVM in the years 1983-2000 were included in a retrospective study. In all patients microsurgical, selective removal of AVM was performed, without prior embolization. The statistical analysis was carried out by means of exact Fisher test and c2 test. RESULTS: Complications in the postoperative period were observed in 45.5%, including short-term deterioration (27.3%) and symptoms present till the day of discharge (18.2%). Mechanisms of deterioration were as follows: significant intraoperative hemorrhage (5.7%), hemodynamic disturbances after AVM removal (20.5%) and resection of AVM in the eloquent area (19.3%). Many variables that may contribute to the complications were studied. Factors increasing the risk of significant intraoperative hemorrhage are: steal effect visible in angiography (32% vs. 10%, p<0.05), intraventricular penetration of AVM (38% vs. 11%, p<0.05). Factors increasing the risk of hemodynamic disturbances are: feeding from the medial cerebral artery (MCA) (31% vs. 8%, p=0.02) and complex venous drainage (32% vs. 14%, p=0.05). CONCLUSIONS: The most common causes of postoperative deterioration are hemodynamic disturbances after AVM removal and manipulation in the eloquent area. Hemodynamic disturbances worsened the prognosis significantly, and were the only cause of mortality (3.4%). However, massive intraoperative hemorrhage and operation in the eloquent area did not influence the outcome significantly. Risk factors for intraoperative hemorrhage are steal effect and intraventricular penetration of AVM. Risk factors for hemodynamic disturbances are feeding AVM from MCA and complex venous drainage.