Treatment Of Cerebral Arteriovenous Malformations Research Articles

Role of Gamma Knife Radiosurgery in Neurosurgery: Past and Future Perspectives

The gamma knife was the first radiosurgical device developed at the Karolinska Institute in 1967. Stereotactic radiosurgery using the gamma knife has been widely accepted in clinical practice and has contributed to the development of neurosurgery. More than 500,000 patients have been treated by gamma knife stereotactic radiosurgery so far, and the method is now an indispensable neurosurgical tool. Here we review long-term outcomes and development of stereotactic radiosurgery using the gamma knife and discuss its future perspectives. The primary role of stereotactic radiosurgery is to control small well-demarcated lesions such as metastatic brain tumors, meningiomas, schwannomas, and pituitary adenomas while preserving the function of surrounding brain tissue. The gamma knife has been used as a primary treatment or in combination with surgery, and some applications have been accepted as standard treatment in the field of neurosurgery. Treatment of cerebral arteriovenous malformations has also been drastically changed after emergence of this technology. Controlling functional disorders is another role of stereotactic radiosurgery. There is a risk of radiation-induced adverse events, which are usually mild and less frequent. However, especially in large or invasive lesions, those risks are not negligible and pose limitations. Advancement of irradiation technology and dose planning software have enabled more sophisticated and safer treatment, and further progress will contribute to better treatment outcomes not only for brain lesions but also for cervical lesions with less invasive treatment.

Early results of CyberKnife radiosurgery for arteriovenous malformations

The authors describe a method that utilizes an image-guided robotic radiosurgical apparatus (the CyberKnife) for treatment of cerebral arteriovenous malformations (AVMs). This procedure required the development of an original technique that allows a high degree of automation. Angiographic images were imported into the treatment planning software by coregistering CT and 3D rotational angiography. The nidus contour was delineated using the contouring tools of the treatment planning system. Functional MR imaging was employed for contouring critical cortical regions, such as the motor cortex and language areas. Once the radiation dose to be delivered to the target volume and dose constraints to critical structures were prescribed, the inverse treatment planning function determined the optimal treatment plan. A series of 279 patients with cerebral AVMs underwent CyberKnife radiosurgery. One transitory adverse effect of the radiation procedure was observed. Eight bleeding occurrences were noted before complete AVM obliteration. Of the 102 patients with follow-up > 36 months, 80 underwent angiographic evaluation. In this group, 65 patients (81.2%) showed complete angiographic obliteration of their AVM. In 8 more patients, complete angiographic obliteration was demonstrated by MR angiography only. This is the first report describing a technique developed for CyberKnife radiosurgery of cerebral AVMs. The use of different imaging modalities for automatic delineation of the target and critical structures combined with the employment of the inverse treatment planning capability is the crucial point of the procedure. The procedure proved to be safe and efficient.

Revascularization of Onyx Induced Intra-Operative Occlusion of Vertebro-Basilar Artery Using the Merci Device

Endovascular embolization is an important modality in the treatment of cerebral arteriovenous malformations (AVMs). Onyx is an ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide that is approved for use as an embolic agent for brain AVMs. We describe a case of revascularization of an occluded vertebro-basilar artery during embolization of an AVM with Onyx, by using the Merci device. Reflux embolization of patent vessels is a rare complication of using Onyx to treat AVMs. It can be successfully managed by retrieving the Onyx substance using mechanical retrieval devices like the Merci device.

Long-term results of embolization arteriovenous malformations with hystoacryl

N-butyl cyanoacrylate (Hystoacryl) is one of the most frequently used glues for the treatment of cerebral arteriovenous malformation. However, long-term results of its treatment with Hystoacryl are insufficiently studied. 136 patients were examined. Catamnesis was (4 ± 1) year. The quality of life is reduced due to cognitive and motor disorders.

Surgical planning for microsurgical excision of cerebral arterio-venous malformations using virtual reality technology

To evaluate the feasibility of surgical planning using a virtual reality platform workstation in the treatment of cerebral arterio-venous malformations (AVMs) Patient-specific data of multiple imaging modalities were co-registered, fused and displayed as a 3D stereoscopic object on the Dextroscope, a virtual reality surgical planning platform. This system allows for manipulation of 3D data and for the user to evaluate and appreciate the angio-architecture of the nidus with regards to position and spatial relationships of critical feeders and draining veins. We evaluated the ability of the Dextroscope to influence surgical planning by providing a better understanding of the angio-architecture as well as its impact on the surgeon's pre- and intra-operative confidence and ability to tackle these lesions. Twenty four patients were studied. The mean age was 29.65 years. Following pre-surgical planning on the Dextroscope, 23 patients underwent microsurgical resection after pre-surgical virtual reality planning, during which all had documented complete resection of the AVM. Planning on the virtual reality platform allowed for identification of critical feeders and draining vessels in all patients. The appreciation of the complex patient specific angio-architecture to establish a surgical plan was found to be invaluable in the conduct of the procedure and was found to enhance the surgeon's confidence significantly. Surgical planning of resection of an AVM with a virtual reality system allowed detailed and comprehensive analysis of 3D multi-modality imaging data and, in our experience, proved very helpful in establishing a good surgical strategy, enhancing intra-operative spatial orientation and increasing surgeon's confidence.

経験未熟な術者がＡＶＭを安全・確実に摘出するために―脳溝開放の重要性と意図的段階手術―

経験未熟な術者がＡＶＭを安全・確実に摘出するために―脳溝開放の重要性と意図的段階手術―

New thermoreversible liquid embolic agent for embolotherapy: technical report

To evaluate potential feasibility of new liquid embolic agent, thermoreversible gelation polymer (TGP), for embolotherapy. TGP is a liquid polymer that was originally developed as a cell culture medium for tissue engineering. TGP becomes liquid at temperatures lower than the sol-gel transition temperature (TT) and becomes a gel at temperatures higher than the TT. The TT can be adjusted from 10 degrees C to 40 degrees C, allowing gelation at body temperature without solvent. The renal arteries in six swine were embolized with TGP. Angiographic evaluations were obtained 0, 3 h, and 14 days after embolization. The animals were sacrificed at day 14 after angiogram. All renal arteries were successfully embolized with TGP using cooling catheter. No acute and chronic clinical complication was observed. Follow-up angiogram demonstrated complete or near complete occlusion of renal arteries. No untoward inflammatory response was observed in acute and chronic specimen. This embolic material has potential feasibility to be used in the treatment of cerebral arteriovenous malformations, aneurysms, or hyper vascular tumors.

Embolization as an Adjuvant in the Treatment of Cerebral Arteriovenous Malformations

Embolization as an Adjuvant in the Treatment of Cerebral Arteriovenous Malformations

Hemodynamic aspects of the endovascular treatment of cerebral arterio-venous malformations and their perioperative care (preliminary study)

Hemodynamic aspects of the endovascular treatment of cerebral arterio-venous malformations and their perioperative care (preliminary study)

Fluid embolization in neurointerventions

Liquid embolization materials have been playing a major role in the endovascular treatment of cerebrovascular pathologies.There are now two different liquid embolics being used for his purpose.Cyanoacrilic glue is the one which has been used extensively in the last two decades especially in the endovascular treatment of cerebral arteriovenous malformations (AVM) Until 1999, it had been the the only embolizing agent for this treatment offering the limited advantage of penetrating the nidus of the malformations. After implication of new liquid embolic Onyx (Onyx low density), we have been developing a revolutionary intranidal Onyx injection technique. It allows us to penetrate the AVM nidus much better with prolonged intranidal injections. It is possible to obtain either a cure in much higher rate or create significant reduction in the size of the AVM with a single microcatheter injection in a single embolization session. The other form of Onyx that is called Onyx high density also opened a fairly different avenue in endovascular cerebral aneurysm management.The technique applied by this material let us achieve very satisfactory results in the treatment of large and giant aneurysms.The technique started to be used in the treatment of aneurysms which otherwise have no effective treatment alternatives.

Angiographic Exclusion of Intracranial Arteriovenous Malformations Using Onyx®

Historically, endovascular treatment for cerebral arteriovenous malformations (AVMs) has been reserved as an adjunct to other modalities, namely radiosurgery and microsurgery, as the cure rate for cerebral AVMs treated solely with endovascular technique and older embolic agents is low. We report a series of five consecutive patients treated successfully with Onyx®, the newest available embolic agent, with resultant angiographic cure. Five patients aged three, nine, 33, 49, and 63 years were treated endovascularly for cerebral AVMs with a total of 19 embolizations with Onyx(®). All procedures were performed under general anesthesia with biplanar fluoroscopy. Complete angiographic obliteration of the AVM nidus was obtained in all cases with no residual filling. No immediate hemorrhagic or thromboembolic complications were observed. This early experience suggests that Onyx® has excellent embolization potential, and endovascular cure of AVMs may now be achieved with single modality therapy. Long terms data needs to be collected to further validate this observation.

Treatment of multiple arteriovenous malformations in pediatric patients with hereditary hemorrhagic telangiectasia and spontaneous hemorrhage

Due to inheritance of an autosomal dominant genetic mutation, patients with hereditary hemorrhagic telangiectasia (HTT) have an increased risk of harboring a cerebral arteriovenous malformation (AVM). They are also significantly more likely to have multiple AVMs. The natural history of AVMs in patients with HHT as well as their rate of hemorrhage is not clearly defined. Furthermore, spontaneous regression of such lesions has been reported. Treatment of cerebral AVMs in patients with HHT presents a particular challenge, especially with detection of incidental lesions following screening of asymptomatic patients. The management of HHT in two pediatric patients in whom hemorrhaging from a cerebral AVM occurred but who also had other lesions is presented here. Both patients were treated with stereotactic radiosurgery.

What future for vascular neurosurgery?

What future for vascular neurosurgery?

Onyx®: a unique neuroembolic agent

Rupture of a cerebral arteriovenous malformation can result in devastating hemorrhage with a possibility of serious neurological injury or death. Endovascular embolization is an important adjunct in the treatment of cerebral arteriovenous malformations, and in a small number of cases may provide definitive treatment. Currently available embolic agents have several shortcomings, including the possibility of recanalization, adhesiveness to the endovascular microcatheter and suboptimal handling at the time of surgical resection. Onyx® is an ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide that was approved by the US FDA in July 2005 as an embolic agent for brain arteriovenous malformations. Although long-term follow-up is limited, this agent appears to offer several advantages over the other available embolic agents for the endovascular management of arteriovenous malformations and other vascular lesions.

2-Hexyl Cyanoacrylate (Neuracryl M) Embolization of Cerebral Arteriovenous Malformations

Neuracryl M is a newly designed liquid embolic agent. In an attempt to verify the safety and efficacy of neuracryl M, we participated in the PROVASIS Trial, a pilot study using this agent in the preoperative treatment of cerebral arteriovenous malformations (AVMs). Because the trial was prematurely terminated by the sponsoring company because of financial considerations, we now present our data as a single center series. Between November 2002 and December 2003, six patients were enrolled in the PROVASIS trial at our institution, and four of these patients were randomized to treatment with neuracryl M. The patients were a 30-year-old man with a right frontal lobe AVM, a 20-year-old man with a right cerebellar AVM, a 26-year-old woman with a midline cerebellar AVM, and a 47-year-old man with a left parietotemporal lobe AVM. All patients underwent AVM embolization with neuracryl M, followed by definitive treatment, either open surgery or radiosurgery. In each case, there were no permanent complications, and blood loss was minimal. Follow-up imaging demonstrated either complete AVM obliteration (open surgery) or substantial diminution in AVM size (radiosurgery). Our data provide preliminary evidence supporting the thesis that neuracryl M is a safe and effective liquid embolic agent for the preoperative embolization of cerebral AVMs. Larger trials and continued experience using this novel liquid embolic agent are warranted.

Postembolization Neurological Deficitsin Cerebral Arteriovenous Malformations: Stratification By Arteriovenous Malformation Grade

To stratify the risk of embolization during the treatment of cerebral arteriovenous malformations (AVMs) by grade and to assess its impact on the overall treatment risk. Patients with cerebral AVMs treated with embolization between 1995 and 2004 were retrospectively reviewed. Age, sex, AVM grade, location of lesion, number and location of embolized arteries, and number of embolization sessions were analyzed with respect to neurological or vascular complications after embolization. Embolization was performed in 153 patients: 508 vessels were embolized during 203 sessions (mean, 3.3 vessels per patient). The mean angiographic and clinical follow-up periods were 1.7 and 2.1 years, respectively (range, 3-60 mo). The periprocedural morbidity and mortality rate was 11.8%, but at the last follow-up examination, only 2% of survivors were significantly disabled (modified Rankin score > 2). One (0.7%) patient died, and 17 patients experienced unexpected neurological deficits immediately after embolization. Five of these patients demonstrated near or total recovery during follow-up. The number of branches embolized was the only variable significantly related to neurological deficit (P < 0.017). The long-term rates of neurological deficits after embolization were 0, 5, 7, 10, and 18%, respectively, for AVM Grades I through V. Among 114 patients who underwent preoperative embolization, follow-up deficit rates of Grades I through V were 0, 5, 6, 6, and 25%, respectively. Long-term permanent deficits from embolization occurred in 8.6% of patients. Endovascular treatment carries a procedural risk related to AVM grade and number of branches treated. This risk should be weighed carefully in the context of overall treatment morbidity and mortality.

Copolymer of 2-hydroxyethyl methacrylate for cerebral arteriovenous malformation: an experimental study

To investigate the feasibility of using methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) to embolize cerebral arteriovenous malformations (AVM). Methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) in the ratio of 9:1 were solved in 16% alcohol so as to make a kind of copolymer (CoHEMA). 12 g glass beads 2 mm in diameter were put into a container so as to construct an in vitro model of AVM. The container was connected with a normal saline bottle via microcatheter. CoHEMA, as embolized, was injected through the microcatheter and the diffusion of CoHEMA was observed till the water flow was stopped. CoHEMA was injected through microcatheter into the pharyngeal ascending arteries near the rete mirabile (RMB) tissue, similar to the human AVM, under digital subtraction angiography until satisfactory embolization was obtained, totally 9 RMB tissues in 7 pigs. Five pigs were injected with normal saline as controls. The pigs were killed 2 days, 2 weeks, and 6 months after embolization respectively and the bilateral RMB tissues were taken out to undergo pathological examination. Nine AVM models in vitro were constructed with the copolymer dispersed symmetrically among the glass beads and stopped the fluid across the model effectively. No copolymer adhered to the wall of microcatheter. Nine RMB tissues of 6 pigs were embolized by using CoHEMA. Six of the seven pigs survived the procedure except one died of too fast injection of copolymer in the primary stage. Follow-up angiography was performed in four pigs and found that no recanalization occurred and the copolymer was diffused in the vessels 80-150 microm in diameter. In the specimens obtained 2 days after embolization, neutrophilic granulocytes scattered surrounding the copolymer, suggesting minor inflammatory reaction. In the specimens obtained 2 weeks after embolization no vessel wall damage and morphological change were found except minor inflammatory reaction inside the vessels and surrounding tissues. In the specimens obtained 2 to 6 months after embolization hyperplasia of connective tissue, minor or mediate chronic inflammatory reaction, and giant cell reaction inside the vessels and surrounding tissues. With low viscosity, better biocompatibility, and embolic instability, and easy to be injected through delivery microcatheter, CoHEMA is an excellent non-adhesive embolic material and can be used in embolic treatment of cerebral AVM.

Endovascular treatment of cerebral arteriovenous malformations with emphasis on the curative role of embolisation

Valavanis A, Pangalu A, Tanaka M. Endovascular treatment of cerebral arteriovenous malformations with emphasis on the curative role of embolisation. Schweiz Arch Neurol Psychiatr 2004;155:341-7. Cerebral arteriovenous malformations are complex and only partially understood vascular lesions of the central nervous system with a natural history characterised by significant morbidity and mortality mainly due to an increased hemorrhagic risk, Microneurosurgical removal, radiosurgical obliteration and neuroendovascular embolisation are the principal therapeutic modalities applied individually or in various combinations according to varying selection criteria for the treatment of cerebral arteriovenous malformations. In this context embolisation plays a central role cither as a complementary or as the sole treatment technique. This report summarises the evolutive 18 years of continuous experience of the senior author with the neuroradiological evaluation and endovascular treatment of 644 patients with a cerebral arteriovenous malformation. Special emphasis is given to the underlying concepts and specific endovascular techniques developed for the complete, i.e. curative embolisation of cerebral arteriovenous malformations. Precise angiographic analysis of the vascular composition and intrinsic angioarchitecture of the nidus of the arteriovenous malformation by super-selective microcatheterisation is required to identify the types of feeding arteries and patterns of their supply, the number and vascular connections of nidal compartments, the types of arteriovenous shunts, the morphology of the vascular spaces composing the nidus and the number and exit patterns of draining veins. Complete angiographic investigation for recognition of secondarily induced phenomena of the cerebral vasculature, such as arterial and venous high-flow angiopathy and so-called perinidal angiogenesis is essential for a comprehensive evaluation and assessment of the associated haemorrhagic risk. Based on a precise topographic classification, detailed angioarchitectural analysis, application of superselective multimicrocatheterisation techniques along with a controlled intranidal injection of non-absorbable liquid embolic materials, nearly 40% of cerebral arteriovenous malformations can be completely and stably obliterated and therefore curatively treated by single session or multistaged embolisation with a morbidity of 1.3% and a mortality of 13%. which arc lower than the known natural history of this disease.

Basics and Principles in the Application of Onyx LD Liquid Embolic System in the Endovascular Treatment of Cerebral Arteriovenous Malformations

Onyx is a new liquid embolic system (Micro Therapeutics, Inc., Irvine, CA) consisting of ethylene-vinyl alcohol copolymer (EVOH), formed of 48 mol/L ethylene and 52 mol/L vinyl alcohol, dissolved in dimethyl-sulfoxide (DMSO) and mixed with micronized tantalum powder (35% weight per volume) for radiopaque visualization. In its low density form it is predominantly used worldwide in the treatment of cerebral 1-6 or spinal7,8 arteriovenous malformations (AVMs), other more rare indications are hypervascularized tumors9, peripheral AVMs or arteriovenous fistulas (AVFs)10, and there is also an extensive use in experimental work 11-12. Onyx LD means low density of EVOH in the range of 6 to 8 % (Onyx 18 to 34) compared to high density Onyx 500+ (containing 20 % of EVOH) used for aneurysm occlusions. The basics of Onyx LD liquid system and the main principles of its application in endovascular AVM therapy are described and discussed in this chapter.

Application of intraoperative real-time ultrasound in the surgical treatment of cerebral arteriovenous malformation

To investigate the value of intraoperative real-time ultrasound during surgery of cerebral arteriovenous malformations (AVMs). Thirteen patients with cerebral AVMs, 12 supratentorial and 1 infratentorial, underwent microsurgical treatment. Intraoperative ultrasound (IOUS) with multimodality was performed before the starting of resection in order to: (1) localize and delineate the AVM, (2) differentiate the embolized and perfused parts of AVM, and (3) identify the feeding arteries and draining veins. After removal of the lesion, sonographic examination was repeated to detect the residual AVM tissue and the findings were compared with the intra- and/or post-operative angiographic finding. Total resection was achieved in all 13 patients with AVM under real-time ultrasonographic navigation. The niduses of AVM were localized and defined precisely by IOUS due to their dichromatic flow pattern. The embolized parts of AVM exhibited hyperechogenicity without blood signals. The feeding and draining vessels were distinguished from normal ones morphologically and hemodynamically. Complete removal of the AVM determined sonographically was then confirmed by angiography. Intraoperative real-time ultrasound allows accurate localization and navigation of the cerebral AVMs, provides valuable information during surgery, and helps determine the degree of removal of the cerebral AVM.