Deep-seated Arteriovenous Malformations Research Articles

Effect of cerebral arteriovenous malformation location on outcomes of repeat, single-fraction stereotactic radiosurgery: a matched-cohort analysis.

Patients with deep-seated arteriovenous malformations (AVMs) have a higher rate of unfavorable outcome and lower rate of nidus obliteration after primary stereotactic radiosurgery (SRS). The aim of this study was to evaluate and quantify the effect of AVM location on repeat SRS outcomes. This retrospective, multicenter study involved 505 AVM patients managed with repeat, single-session SRS. The endpoints were nidus obliteration, hemorrhage in the latency period, radiation-induced changes (RICs), and favorable outcome. Patients were split on the basis of AVM location into the deep (brainstem, basal ganglia, thalamus, deep cerebellum, and corpus callosum) and superficial cohorts. The cohorts were matched 1:1 on the basis of the covariate balancing score for volume, eloquence of location, and prescription dose. After matching, 149 patients remained in each cohort. The 5-year cumulative probability rates for favorable outcome (probability difference -18%, 95% CI -30.9 to -5.8%, p = 0.004) and AVM obliteration (probability difference -18%, 95% CI -30.1% to -6.4%, p = 0.007) were significantly lower in the deep AVM cohort. No significant differences were observed in the 5-year cumulative probability rates for hemorrhage (probability difference 3%, 95% CI -2.4% to 8.5%, p = 0.28) or RICs (probability difference 1%, 95% CI -10.6% to 11.7%, p = 0.92). The median time to delayed cyst formation was longer with deep-seated AVMs (deep 62 months vs superficial 12 months, p = 0.047). AVMs located in deep regions had significantly lower favorable outcomes and obliteration rates compared with superficial lesions after repeat SRS. Although the rates of hemorrhage in the latency period and RICs in the two cohorts were comparable, delayed cyst formation occurred later in patients with deep-seated AVMs.

Endovascular embolization for basal ganglia and thalamic arteriovenous malformations.

Basal ganglia and thalamic arteriovenous malformations (AVMs) represent a special subset of malformations. Due to the involvement of vital brain structures and the specifically fine and delicate angioarchitecture of these lesions, it presents unique therapeutic challenges and technical difficulties that require thorough treatment planning, individualized treatment strategies, and advanced techniques for good clinical outcome. In this study, we presented a series of ruptured basal ganglia and thalamic AVMs embolized via a transarterial, transvenous or combined approach. Herein, we summarized our treatment experience and clinical outcomes to further evaluate the effectiveness and safety of endovascular embolization for these AVMs as well as the indications, therapy strategies, and techniques of embolization procedures. Twelve patients with basal ganglia and thalamus AVMs were included in the study. Their average age was 23.83 ± 16.51 years (range, 4-57 years) with a female predominance of 67% at presentation. The AVMs were located in the thalamus in 3 (25%) patients, in the basal ganglia in 3 (25%) patients, and in both sites of the brain in 6 (50%) patients. There were 5 AVMs located on the left side and 7 on the right. The mean nidus diameter was 3.32 ± 1.43 cm (range 1.3-6.1 cm). According to the Spetzler-Martin grading classification, 4 (33.3%) brain AVMs were Grade III, 7 (58.3%) were Grade IV, and 1 (8.3%) was Grade V. All of them presented with bleeding at admission: four of these patients presented with an intracerebral hemorrhage (ICH), 8 ICH in combination with intraventricular hemorrhage (IVH), and no patient with subarachnoid hemorrhage (SAH). Among these patients treated with endovascular embolization, 7 patients were treated by the transarterial approach, 4 patients transvenous approach, and 1 patient underwent the combined approach. A single embolization procedure was performed in 6 patients (50%) and the other 6 cases (50%) were treated in a staged manner with up to three procedures. Procedure-related complications occurred only in two patient (16.7%). Complete AVM obliteration was obtained in 7 patients (58.3%), and partial obliteration was in 4 patients (33.3%). Overall, good or excellent outcomes were obtained in 7 patients (58.3%), and poor functional outcome was observed in 5 patients (41.7%) at the last follow-up. All survived patients achieved anatomic stabilization and there was no postoperative bleeding or recurrence in the follow-up. The management of the basal ganglia and thalamic AVMs is a great challenge, which needs multimodal individualized treatment to improve the chances of radiographic cure and good outcomes. Endovascular therapy is safe and effective in the treatment of cerebral AVMs particularly for deep-seated AVMs such as the basal ganglia and thalamus. Our results demonstrate a high rate of anatomic obliteration with an acceptable rate of complications in the endovascular treatment of these vasculopathies via a transarterial approach or a transvenous approach.

Stereotactic radiosurgery outcome for deep-seated cerebral arteriovenous malformations in the brainstem and thalamus/basal ganglia: systematic review and meta-analysis.

Deep-seated unruptured AVMs located in the thalamus, basal ganglia, or brainstem have a higher risk of hemorrhage compared to superficial AVMs and surgical resection is more challenging. Our systematic review and meta-analysis provide a comprehensive summary of the stereotactic radiosurgery (SRS) outcomes for deep-seated AVMs. This study follows the guidelines set forth by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Statement. We conducted a systematic search in December 2022 for all reports of deep-seated arteriovenous malformations treated with SRS. Thirty-four studies (2508 patients) were included. The mean obliteration rate in brainstem AVM was 67% (95% CI: 0.60-0.73), with significant inter-study heterogeneity (tau2 = 0.0113, I2 = 67%, chi2 = 55.33, df = 16, p-value < 0.01). The mean obliteration rate in basal ganglia/thalamus AVM was 65% (95% CI: 0.58-0.72) with significant inter-study heterogeneity (tau2 = 0.0150, I2 = 78%, chi2 = 81.79, df = 15, p-value < 0.01). The presence of deep draining veins (p-value: 0.02) and marginal radiation dose (p-value: 0.04) were positively correlated with obliteration rate in brainstem AVMs. The mean incidence of hemorrhage after treatment was 7% for the brainstem and 9% for basal ganglia/thalamus AVMs (95% CI: 0.05-0.09 and 95% CI: 0.05-0.12, respectively). The meta-regression analysis demonstrated a significant positive correlation (p-value < 0.001) between post-operative hemorrhagic events and several factors, including ruptured lesion, previous surgery, and Ponce C classification in basal ganglia/thalamus AVMs. The present study found that radiosurgery appears to be a safe and effective modality in treating brainstem, thalamus, and basal ganglia AVMs, as evidenced by satisfactory rates of lesion obliteration and post-surgical hemorrhage.

Surgical Resection of Deep-Seated Arteriovenous Malformations Through Stereotactically Guided Tubular Retractor Systems: A Case Series.

Arteriovenous malformations (AVMs) in the subcortical and/or periventricular regions can cause significant intraventricular and intracranial hemorrhage. These AVMs can pose a unique surgical challenge because traditional, open approaches to the periventricular region require significant cortical/white matter retraction to establish sufficient operative corridors, which may result in risk of neurological injury. Minimally invasive tubular retractor systems represent a novel, feasible surgical option for treating deep-seated AVMs. To explore 5 cases of NICO BrainPath-assisted resection of subcortical/periventricular AVMs. Five patients from a single institution were operated on for deep-seated AVMs using tubular retractor systems. Collected data included demographics, AVM specifications, preoperative neurological status, postoperative neurological status, and postoperative/intraoperative angiogram results. Five patients, ranging from age 10 to 45 years, underwent mini-craniotomy for stereotactically guided tubular retractor-assisted AVM resection using neuronavigation for selecting a safe operative corridor. No preoperative embolization was necessary. Mean maximum AVM nidal diameter was 8.2 mm. All deep-seated AVMs were completely resected without complications. All AVMs demonstrated complete obliteration on intraoperative angiogram and on 6-month follow-up angiogram. Minimally invasive tubular retractors are safe and present a promising surgical option for well-selected deep-seated AVMs. Furthermore, study may elucidate whether tubular retractors improve outcomes after microsurgical AVM resection secondary to mitigation of iatrogenic retraction injury risk.

Susceptibility weighted imaging for qualitative grading of persistent arteriovenous shunting in deep-seated arteriovenous malformations after stereotactic radiation surgery.

To investigate Susceptibility Weighted Imaging (SWI) signal changes in the draining vein of deep-seated arterio-venous malformations (AVMs) following stereotactic radiosurgery (SRS). This is a retrospective study of 32 patients with deep-seated AVMs who were treated with SRS. Pre-SRS treatment and post-SRS treatment MRI were performed at 6, 12, and 24-month intervals. Deep-seated AVMs were classified based on their anatomical location and venous drainage pattern. AVM nidal volume (cm3) was estimated using the ABC/2 method. AV shunting of the AVM draining veins were graded according to its SWI signal intensity: hyperintense (grade III), mixed signal intensity (grade II), hypointense (grade I) and absent (grade 0). Conventional time-of-flight (TOF)-MRA and contrast enhanced (CE)-MRA sequences were performed to document the patency of the vein. Pre-SRS treatment AVM draining veins were either grade III 18/32 (56%) or grade II 14/32 (44%). Using mixed effects analysis, we demonstrate that each month following the SRS treatment nidal volumes decreased at the rate of 0.51cm3/per month (CI -0.61 to (-0.40)) p =.00. Following the treatment, there was a clinically significant relationship between the signal and nidal volume: signal 0 corresponded with average nidal volume of 1.81cm3 (CI 1.40-2.21), signal 1 with nidal volume of 2.06cm3 (CI 1.69-2.44), signal 2 with nidal volume 2.73cm3 (CI 2.35-3.11) and signal 3 with nidal volume 3.13cm3 (CI 2.70-3.56) p = .00. Post-SRS AVM draining veins shows a stepwise regression of the SWI signal grades which can be reliably used as a surrogate to monitor the reduction of AV shunting.

Multimodality Treatment of Deep-seated Cerebral Arteriovenous Malformations: The Experiences of One Center.

Treatment of deep-seated cerebral arteriovenous malformations (AVMs) remains challenging for neurosurgeons or neuroradiologists. This study aims to review the experiences of one center in using multimodality treatment for deep-seated AVMs. The AVM database of Xuanwu Hospital, Capital Medical University was searched, and 96 patients who were diagnosed with a deep-seated cerebral AVM between 2010 and 2020 were identified. The following information was collected and analyzed: patients' clinical features, treatment modality used, posttreatment complications, AVM obliteration rate, rebleeding rate, and functional outcome during follow-up. The patients' posttreatment modified Rankin scale (mRS) scores were split into two groups: good outcome (mRS score ≤ 2) and poor outcome (mRS score ≥ 3). Univariate and multivariate logistic regression analyses were applied to test the predictors of clinical outcomes and AVM obliteration. Eighty-eight out of 96 patients (91.7%) presented with initial hemorrhaging. The pretreatment mRS score was ≤ 2 in 80 patients (88.3%) patients and ≥ 3 in 16 patients (16.7%). Limb weakness was present in 42 patients (43.8%). In this sample, 210 hemorrhages occurred during 2056 person-years before diagnosis, yielding an annual hemorrhage rate of 10.2% per person-year. Angiographic obliteration was achieved in 29 patients (30.2%). At the last follow-up, 80 patients (83.3%) had good clinical outcomes, whereas 16 (16.7%) had a deterioration in their clinical presentation following treatment. Multivariate analyses indicated that pretreatment limb weaknesses and a high Spetzler-Martin grade predicted poor clinical outcomes (P = 0.003 and 0.008, respectively). Fewer feeding arteries were a predictor for AVM obliteration (P = 0.034). Good outcomes can be achieved through multimodal treatment of deep-seated AVMs. A single supplying artery is a predictor of AVM obliteration. Pretreatment limb weaknesses and high Spetzler-Martin grades predict poor clinical outcomes.

Role of Indocyanine Green with FLOW 800 in Removal of Hidden Arteriovenous Malformations

Indocyanine green videoangiography (ICG-VA) with FLOW 800 (Carl Zeiss AG) has been used as a visualization tool to guide arteriovenous malformation (AVM) surgery since 2011. We performed a systematic review and evaluated the quality of evidence available on this topic. In addition, we present a series of our own cases demonstrating the unique use of ICG-VA in the localization and removal of deeper seated AVMs. Using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines for systematic reviews, we identified studies related to ICG-VA with FLOW 800 in AVM surgeries using search terms. The studies were screened and reviewed, and the quality of evidence was analyzed using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) criteria. We performed a retrospective review of our own cases of AVM removal with ICG-VA and FLOW800. Our search revealed 27 relevant studies, 17 of which met our inclusion criteria. The quality of the body of evidence was determined to be "very low" using the GRADE criteria. We used ICG-VA with FLOW 800 analysis for 14 cases of microsurgical AVM removal. This technique provided unique insights into the localization of deep seated AVMs in 8 cases (57%). No residual AVM was found when assessed by the 6-month follow-up angiogram. We present cases highlighting the usefulness of this technique for the localization of certain AVMs. We believe the use of ICG-VA can guide the removal of deeper seated AVMs, because it can reveal surface feeders and draining veins that can be followed to a hidden nidus. Larger, registry-based studies are needed to confirm these findings and improve the overall quality of evidence.

The factors associated with obliteration following stereotactic radiosurgery in patients with brain arteriovenous malformations: a meta-analysis.

Various factors have been reported to affect the obliteration of brain arteriovenous malformations (AVM) following stereotactic radiosurgery (SRS). This meta-analysis was conducted to identify the factors potentially associated with AVM obliteration after SRS. We comprehensively searched databases and included studies that evaluated predictors of AVM obliteration after SRS using Cox proportional hazard regression analysis. Hazard ratios (HRs) with 95% confidence intervals (CIs) were utilized as effect estimates. Twelve studies, involving 4415 AVM cases, were included. According to combined estimates on univariate (UV) and multivariate (MV) analysis, age, gender and prior haemorrhage did not affect the closure probability. The following factors showed a significant and independent association with increased AVM obliteration: smaller AVMs maximal diameter (MV, HR: 1.32), smaller AVM volume (MV, HR: 1.05), AVM volume <10-15 cc (MV, HR: 1.55), higher margin dose (MV, HR: 1.05), margin dose ≥17-18 Gy (MV, HR: 3.71) and early treatment period (MV, HR: 1.78). Previous embolization and deep-seated AVM were independently negative predictors of obliteration whereas deep venous drainage was a positive predictor. Prior surgery, compactness of nidus, lower grading scores and higher SRS maximum dose were associated factors subject to confounding factors. Multiple factors associated with obliteration should be taken into consideration for selection of candidates with AVMs for SRS. AVM volume and radiation dose are the most prominent factor in assessing obliteration after SRS. Age, gender and prior haemorrhage may not affect the consideration of SRS treatment. Cautious use of SRS is needed for previously embolized AVM patients.

Arteriovenous malformations in the basal ganglia and thalamus - A rare case of recurrent stroke

Stroke is rare in children when compare to adults. The aetiology, clinical presentation and outcome of stroke also different from adult. Arterio venous malformations are a rare cause of haemorrhagic stroke in children. Clinical features and secerity depends on site of the lesion. They are prone for recurrence and management of deep seated arterio venous malformations is a difficult one even in an experienced hand. We are presenting a rare case of AVM in basal ganglion region presented with recurrent stoke.

Comparison of management approaches in deep-seated intracranial arteriovenous malformations: Does treatment improve outcome?

Deep-seated intracranial arteriovenous malformations (AVMs) represent a subset of AVMs characterized by variably reported outcomes regarding the risk of hemorrhage, microsurgical complications, and response to stereotactic radiosurgery (SRS). We aimed to compare outcomes of microsurgery, SRS, endovascular therapy, and conservative follow-up in deep-seated AVMs. A prospectively maintained database of AVM patients (1990–2017) was queried to identify patients with ruptured and unruptured deep-seated AVMs (extension into thalamus, basal ganglia, or brainstem). Comparisons of hemorrhage-free survival and poor functional outcome (modified Rankin scale [mRS] > 2) were performed between conservative management, microsurgery (±pre-procedural embolization), SRS (±pre-procedural embolization), and embolization utilizing multivariable Cox and logistic regression analyses controlling for univariable factors with p < 0.05. Of 789 AVM patients, 102 had deep-seated AVMs (conservative: 34; microsurgery: 6; SRS: 54; embolization: 8). Mean follow-up time was 6.1 years and did not differ significantly between management groups (p = 0.393). Complete obliteration was achieved in 49% of SRS patients. Upon multivariable analysis controlling for baseline rupture with conservative management as a reference group, embolization was associated with an increased hazard of hemorrhage (HR = 6.2, 95%CI [1.1–40.0], p = 0.037), while microsurgery (p = 0.118) and SRS (p = 0.167) provided no significant protection from hemorrhage. Controlling for baseline mRS, microsurgery was associated with an increased risk of poor outcome (OR = 9.2[1.2–68.3], p = 0.030), while SRS (p = 0.557) and embolization (p = 0.541) did not differ significantly from conservative management. Deep AVMs harbor a high risk of hemorrhage, but the benefit from intervention Remains uncertain. SRS may be a relatively more effective approach if interventional therapy is indicated.

The Thalamic Arteriovenous Malformations Have Better Prognosis than Basal Ganglia Malformations Regarding Obliteration: Prognostic Factors Analysis

Arteriovenous malformations (AVMs) are rare vascular congenital lesions that affect mainly patients during their productive years of life. In order to obtain a better quality of life for patients with this disease, a multidisciplinary approach is recommended. Radiosurgery is one of the treatment modalities available for AVMs, but many factors may influence the effectiveness of this strategy. Classically, it has been said that deep-seated lesions have a particular behavior compared with AVMs in other regions, but a differentiation between thalamic lesions and those located in the basal ganglia has not been made. Institutional records for central core AVMs treated with radiosurgery between January 2004 and January 2014 were retrospectively analyzed. Brainstem lesions were excluded from the analysis. Forty-nine patients with deep-seated AVMs were included. Forty-three (87.8%) were located in the thalamus and 6 (12.2%) in the area of basal ganglia. The nidus mean volume was 4.1 cm3 (SD:4.1), the maximum diameter mean was of 19.5 mm (SD:8.0). The prescription dose was 18.2 Gy (SD:2.1), and the follow-up time was 75.8 months (SD:32.5). There was a greater obliteration rate in thalamic AVMs compared with those located in the basal ganglia: 81.4% versus 33.3% (P= 0.026), respectively. There was no association between categorical variables and obliteration rate. Stereotactic radiosurgery is a good option for patients with thalamic and basal ganglia AVMs, but a multidisciplinary approach to decision-making is mandatory in order to achieve the best results.

Endoscopic hematoma removal and third ventriculostomy for the management of acute hydrocephalus due to the rupture of a deep-seated arteriovenous malformation: Report of two cases

Endoscopic hematoma removal and third ventriculostomy for the management of acute hydrocephalus due to the rupture of a deep-seated arteriovenous malformation: Report of two cases

Risk of Brain Arteriovenous Malformation Hemorrhage Before and After Stereotactic Radiosurgery.

Background and Purpose- Understanding the hemorrhage risks associated with brain arteriovenous malformations (AVMs) before and after stereotactic radiosurgery (SRS) is important. The aims of this multicenter, retrospective cohort study are to evaluate and compare the rates of pre- and post-SRS AVM hemorrhage and identify risk factors. Methods- We pooled AVM SRS data from 8 institutions participating in the International Radiosurgery Research Foundation. Predictors of post-SRS hemorrhage were determined using a multivariate logistic regression model. Pre- and post-SRS hemorrhage rates were compared using Fisher exact test. Ruptured and unruptured AVMs were matched in a 1:1 ratio using propensity scores, and their outcomes were compared. Results- The study cohort comprised 2320 AVM patients who underwent SRS. Deep AVM location (odds ratio, 1.86; 95% CI, 1.19-2.92; P=0.007), the presence of an AVM-associated arterial aneurysm (odds ratio, 2.44; 95% CI, 1.63-3.66; P<0.001), and lower SRS margin dose (odds ratio, 0.93; 95% CI, 0.88-0.98; P=0.005) were independent predictors of post-SRS hemorrhage. The post-SRS hemorrhage rate was lower for obliterated versus patent AVMs (6.0 versus 22.3 hemorrhages/1000 person-years; P<0.001). The AVM hemorrhage rate decreased from 15.4 hemorrhages/1000 person-years before SRS to 11.9 after SRS ( P=0.001). The outcomes of the matched ruptured versus unruptured AVM cohorts were similar. Conclusions- SRS appears to reduce the risk of AVM hemorrhage, although this effect is predominantly driven by obliteration. Deep-seated AVMs are more likely to rupture during the latency period after SRS. AVM-associated aneurysms should be considered for selective occlusion before SRS of the nidus to ameliorate the post-SRS hemorrhage rate of these lesions.

Blood Flow Assessment of Arteriovenous Malformations Using Intraoperative Indocyanine Green Videoangiography.

Intraoperative indocyanine green (ICG) videoangiography is widely used in patients undergoing neurosurgery. FLOW800 is a recently developed analytical tool for ICG videoangiography to assess semi-quantitative flow dynamics; however, its efficacy is unknown. In this study, we evaluated its functionality in the assessment of flow dynamics of arteriovenous malformation (AVM) through ICG videoangiography under clinical settings. ICG videoangiography was performed in the exposed AVM in eight patients undergoing surgery. FLOW800 analysis was applied directly, and gray-scale and color-coded maps of the surgical field were obtained. After surgery, a region of interest was placed on the individual vessels to obtain time-intensity curves. Parameters of flow dynamics, including the maximum intensity, transit time, and cerebral blood flow index, were calculated using the curves. The color-coded maps provided high-resolution images; however, reconstruction of colored images was restricted by the depth, approach angle, and brain swelling. Semi-quantitative parameters were similar among the feeders, niduses, and drainers. However, a higher cerebral blood flow index was observed in the feeders of large AVM (>3 cm) than in those of small AVM (P < 0.05). Similarly, the cerebral blood flow index values were positively correlated with the nidus volume (P < 0.01). FLOW800 enabled visualization of the AVM structure and safer resection, except in case of deep-seated AVM. Moreover, semi-quantitative values in the individual vessels through using ICG intensity diagram showed different patterns according to size of the AVM. ICG videoangiography showed good performance in evaluating flow dynamics of the AVM in patients undergoing surgery.

Trans-venous embolization of a basal ganglia ruptured arteriovenous malformation with open surgical arterial control: A hybrid technique

Treatment of ruptured deep-seated arteriovenous malformations is challenging and associated with elevated risks. This is due to the proximity or involvement of critical brain structures and the specifically fine and delicate angioarchitecture of these lesions, making both endovascular and surgical access technically complicated. We present the advantages of a true combined, open surgical and endovascular transvenous approach in a hybrid operating room. The technique may overcome in part the difficulties and may improve safety and risk related concerns.

Lenticulostriate Artery Aneurysm Associated with Cerebral Arteriovenous Malformation: Report of Rare Association and Its Endovascular Management

AbstractAneurysms involving the lenticulostriate arteries are rare and are described in the literature in small case series or single-case reports. In this report, we discuss a case of a young woman who presented with acute lateral ventricular bleed and was found to have an arteriovenous malformation within the corona radiata and an aneurysm involving the distal lenticulostriate artery. The aneurysm was treated successfully by endovascular embolization. In deep-seated arteriovenous malformations (AVMs) that are conventionally treated by stereotactic radiosurgery, a targeted approach for treatment of an associated aneurysm could be considered to reduce the risk of rebleed until the AVM is obliterated.

A proposed grading system to evaluate the endovascular curability of deep-seated arteriovenous malformations

BackgroundAggressive treatment of deep-seated AVMs is paramount because of their high tendency to bleed (or to re-bleed). In the literature concerning endovascular therapy, AVMs of the basal ganglia, the semi-ovale center and the midbrain are always considered as a single entity. In this study, the authors address the anatomical classification of these AVMs and propose a classification that considers factors influencing their endovascular curability. MethodsFrom 1995 to 2013, clinical and angiographic data of cerebral AVMs were prospectively collected. We reviewed data from patients treated for a deep-seated AVM with the goal to distinguish factors that influence the curability and the outcome of these AVMs. Results134 patients (mean age: 28years) were consecutively treated by endovascular techniques. We describe an anatomical classification concerning the exact location of the nidus and distinguish 5 different sub-types (anterior, lateral, medial, posterior and midbrain). Then, we propose a grading system based on statistical analysis of our series to evaluate the curability of a deep AVM. This comprehensive score is calculated with the Spetzler-Martin grade, the location of the nidus, its type, arterial feeders and venous drainage. ConclusionsDeep-seated AVMs may be classified according to their exact location; we can distinguish 5 different sub-types (anterior, lateral, medial, posterior and midbrain). Each group presented different arterial supplies and venous drainage that influenced treatment possibilities. The comprehensive grading system that we propose in this study must be tested in another deep-seated AVMs population.

"Dirty coagulation" technique as an alternative to microclips for control of bleeding from deep feeders during brain arteriovenous malformation surgery.

Meticulous haemostasis is one of the most important factors during microneurosurgical resection of brain arteriovenous malformation (AVM). Controlling major arterial feeders and draining veins with clips and bipolar coagulation are well-established techniques, while managing with bleeding from deep tiny vessels still proves to be challenging. This technical note describes a technique used by the senior author in AVM surgery for last 20years in dealing with the issue highlighted. "Dirty coagulation" is a technique of bipolar coagulation of small feeders carried out together with a thin layer of brain tissue that surrounds these fragile vessels. The senior author uses this technique for achieving permanent haemostasis predominantly in large and/or deep-seated AVMs. To illustrate the efficacy of this technique, we retrospectively reviewed the outcome of Spetzler-Martin (SM) grade III-V AVMs resected by the senior author over the last 5years (2010-2015). Thirty-five cases of AVM surgeries (14 SM grade III, 15 SM grade IV and 6 SM grade V) in this 5-year period were analysed. No postoperative intracranial haemorrhage was encountered as a result of bleeding from the deep feeders. Postoperative angiograms showed complete resection of all AVMs, except in two cases (SM grade V and grade III). "Dirty coagulation" provides an effective way to secure haemostasis from deep tiny feeders. This cost-effective method could be successfully used for achieving permanent haemostasis and thereby decreasing postoperative haemorrhage in AVM surgery.

Clinical Experience with Intraoperative Ultrasonographic Image in Microsurgical Resection of Cerebral Arteriovenous Malformations

Intraoperative ultrasonography is widely used in neurosurgery for the management of intracerebral hematoma and brain tumor. However, the clinical value of this method in the surgery of cerebral arteriovenous malformations (AVMs) has not been reported. In this study, the application of intraoperative ultrasonography for AVM surgery was evaluated prospectively. This prospective clinical study comprised 41 patients who underwent microsurgical resection of cerebral AVMs at our institute. After routine craniotomy, ultrasonographic imaging with color Doppler ultrasonography and real-time contrast-enhanced ultrasonographic angiography if necessary were applied as navigated images on the monitor during the operation. Ultrasonographic imaging made it easier to understand the vascular architecture during the operation. Color Doppler flow imaging clearly delineated the shape and margin of the AVMs. Intraoperative real-time contrast-enhanced ultrasonographic angiography enabled the surgeons to categorically identify AVM feeders both on the surface and deep in the tissue. Microneurosurgery with intraoperative ultrasonographic image guidance was a safe, effective, and reliable method for identifying the afferent and efferent vessels and for confirming the complete resection of AVMs. These benefits of image-guided microsurgery were mostly apparent for deep-seated AVMs that were not visible on the surface of the brain.

Strategies on the treatment of intracranial arteriovenous malformations

Surgical treatment of intracranial arteriovenous malformation (AVM) is one of the most difficult tasks for neurosurgeons, especially, for patients with large size AVM or AVM at the eloquent and deep location. Recent advent of endovascular treatment and radiosurgery may replace the role of surgery and decrease the difficulty of treatment of AVM to some extend but not all. Surgical excision with or without preoperative embolization remains the main modality of treatment of intracranial AVMs. However, the procedure of embolization itself also carries certain percentage of risk. Selection of this treatment modality needs to be carefully evluated.For small deep seated AVM and small AVM at the eloquent area, radiosurgery is another therapeutic option. However, the efficacy to achieve obliteration of the AVM by radiosurgery is only 60%-70% in general. Combined embolization and radiosurgery has been advocated as an option for treating large complex AVM. However, current treatment results failed to demonstrate any superiority of the result from this combined treatment.Palliative treatment with partial obliteration of the AVM nidus toreduce arteriovenous shunting is considered to be useful for the decrease of the occurrence of steal phenomenon, however, it may also increase shear stress of the abnormal vascular architecture and resulted in increase rate of hemorrhage.From 1989 to 2011, a total of 367 patients with cerebral AVM were treated at the National Taiwan University Hospital and its’ affiliate hospitals. Of these 367 patients, 143 patients underwent microsurgery as the solo treatment and 214 patients received embolization. In the later group, 25 patients had their AVMs cured after one or multiple sessions of endovascular treatment. The other 189 patients in this group, endovascular treatment can only be applied for the reduction of the flow and the size of the AVM. These patients finally underwent microsurgery as the definite treatment. The treatment morbidity was 11% in microsurgical group and 9% inendovascular group. There were 2 mortalities in surgical group (o.6 %) and 2 in endovascular group (0.9 %).Our current selection criteria for different therapeutic modality and surgical strategy for intracranial AVM will be discussed. Surgical treatment of intracranial arteriovenous malformation (AVM) is one of the most difficult tasks for neurosurgeons, especially, for patients with large size AVM or AVM at the eloquent and deep location. Recent advent of endovascular treatment and radiosurgery may replace the role of surgery and decrease the difficulty of treatment of AVM to some extend but not all. Surgical excision with or without preoperative embolization remains the main modality of treatment of intracranial AVMs. However, the procedure of embolization itself also carries certain percentage of risk. Selection of this treatment modality needs to be carefully evluated. For small deep seated AVM and small AVM at the eloquent area, radiosurgery is another therapeutic option. However, the efficacy to achieve obliteration of the AVM by radiosurgery is only 60%-70% in general. Combined embolization and radiosurgery has been advocated as an option for treating large complex AVM. However, current treatment results failed to demonstrate any superiority of the result from this combined treatment. Palliative treatment with partial obliteration of the AVM nidus toreduce arteriovenous shunting is considered to be useful for the decrease of the occurrence of steal phenomenon, however, it may also increase shear stress of the abnormal vascular architecture and resulted in increase rate of hemorrhage. From 1989 to 2011, a total of 367 patients with cerebral AVM were treated at the National Taiwan University Hospital and its’ affiliate hospitals. Of these 367 patients, 143 patients underwent microsurgery as the solo treatment and 214 patients received embolization. In the later group, 25 patients had their AVMs cured after one or multiple sessions of endovascular treatment. The other 189 patients in this group, endovascular treatment can only be applied for the reduction of the flow and the size of the AVM. These patients finally underwent microsurgery as the definite treatment. The treatment morbidity was 11% in microsurgical group and 9% inendovascular group. There were 2 mortalities in surgical group (o.6 %) and 2 in endovascular group (0.9 %). Our current selection criteria for different therapeutic modality and surgical strategy for intracranial AVM will be discussed.