The influence of hemodynamic and anatomic factors on hemorrhage from cerebral arteriovenous malformations

Treatment of Brain Arteriovenous Malformations

Brain arteriovenous malformations (AVMs) are a rare entity of vascular anomalies, characteristic of anatomical shunting where arterial blood directly flows into the venous circulation. The main aim of the active treatment policy of brain AVMs is the prevention of haemorrhage. There are well-established treatment strategies that continually improve in their safety and efficacy, primarily due to the advances in imaging modalities, targeted and novel techniques, the development of alternative treatment approaches, and even better experience with the disease itself. There are interesting imaging novelties that may be prospectively applicable in the decision-making and planning of the most effective treatment approach for individual patients with intracranial AVM. Surgery is often considered the first-line treatment; however, each patient should be evaluated individually, and the risks of the active treatment policy should not overcome the benefits of the spontaneous natural history of the disease. All treatment modalities, i.e., surgery, radiosurgery, endovascular embolization, and observation, are justified but need to be meticulously selected for each individual patient in order to deliver the best treatment outcome. This chapter deals with historical and currently applied dogmas, followed by introductions of advances in each available treatment modality of AVM management.

Re-rupture in ruptured brain arteriovenous malformations: a retrospective cohort study based on a nationwide multicenter prospective registry

BACKGROUND

This study aimed to investigate the natural history of re-rupture in ruptured brain arteriovenous malformations (AVMs) and to provide comprehensive insights into its associated factors and prevention.

METHODS

This study included 1712 eligible ruptured AVMs from a nationwide multicenter prospective collaboration registry between August 2011 and September 2021. The natural rupture risk before intervention and the annual rupture risk after intervention were both assessed. Cox proportional hazard regression models and Kaplan-Meier survival curves were used to explore independent factors associated with AVM re-rupture. The correlation between these factors and AVM re-rupture was verified in multiple independent cohorts, and the prevention effect of intervention timing and intervention strategies on AVM re-rupture was further analyzed.

RESULTS

The annual re-rupture risk in ruptured AVMs was 7.6%, and the cumulative re-rupture risk in the first 1, 3, 5, and 10 years following the initial rupture were 10%, 25%, 37.5%, and 50%, respectively. Cox proportional hazard regression analysis confirmed adult patients, ventricular system involvement, and any deep venous drainage as independent factors associated with AVM re-rupture. The intervention was found to significantly reduce the risk of AVM re-rupture (annual rupture risk 11.34% vs 1.70%, p<0.001), especially in those who underwent surgical resection (annual rupture risk 0.13%).

CONCLUSIONS

The risk of re-rupture in ruptured AVMs is high. Adult patients, ventricular system involvement, and any deep venous drainage are independent risk factors for re-rupture. Applying the results universally to all ruptured AVM cases may be biased. Intervention could effectively reduce the risk of re-rupture.

Neuromonitoring in Children with Cerebrovascular Disorders

BACKGROUND

Cerebrovascular disorders are an important cause of morbidity and mortality in children. The acute care of a child with an ischemic or hemorrhagic stroke or cerebral sinus venous thrombosis focuses on stabilizing the patient, determining the cause of the insult, and preventing secondary injury. Here, we review the use of both invasive and noninvasive neuromonitoring modalities in the care of pediatric patients with arterial ischemic stroke, nontraumatic intracranial hemorrhage, and cerebral sinus venous thrombosis.

METHODS

Narrative review of the literature on neuromonitoring in children with cerebrovascular disorders.

RESULTS

Neuroimaging, near-infrared spectroscopy, transcranial Doppler ultrasonography, continuous and quantitative electroencephalography, invasive intracranial pressure monitoring, and multimodal neuromonitoring may augment the acute care of children with cerebrovascular disorders. Neuromonitoring can play an essential role in the early identification of evolving injury in the aftermath of arterial ischemic stroke, intracranial hemorrhage, or sinus venous thrombosis, including recurrent infarction or infarct expansion, new or recurrent hemorrhage, vasospasm and delayed cerebral ischemia, status epilepticus, and intracranial hypertension, among others, and this, is turn, can facilitate real-time adjustments to treatment plans.

CONCLUSIONS

Our understanding of pediatric cerebrovascular disorders has increased dramatically over the past several years, in part due to advances in the neuromonitoring modalities that allow us to better understand these conditions. We are now poised, as a field, to take advantage of advances in neuromonitoring capabilities to determine how best to manage and treat acute cerebrovascular disorders in children.

Management of Brain Arteriovenous Malformations: A Review

Brain arteriovenous malformations (bAVM) are vascular malformations of the brain affecting all ages. The optimum management strategy is essentially devoid of high-quality evidence and is highly nuanced and embedded in local customs. This study summarizes the frequently employed management strategies, drawing conclusions on the utility of each method of treatment and delving into controversies surrounding them. A literature search on PubMed and Medline was done on January 3^rd, 2022. 11,767 articles were found, and abstracts were reviewed. Full-text review of 153 articles led to chapters from three books and 71 articles incorporated into a summative discussion. Spetzler-Ponce (S-P) Class A patients may be offered surgery if they are good surgical candidates and have a good number of high-quality years of life left. The exception is diffuse Spetzler-Martin (S-M) grade 2 in a patient older than 40 years: radiosurgery for unruptured and embolization for ruptured. S-P Class B may be offered surgery if a compact nidus or if younger than 40 years. If diffuse or age greater than 40, radiosurgery may be preferred if the Pollock-Flickinger score is less than 2.5. For the remainder of S-P Class B, conservative management may be preferred. S-P Class C is generally not treated unless young or those patients with poorly controlled seizures affecting their quality of life are willing to risk permanent neurological deficits. While the quality of studies is generally high, the level of evidence is concerning with only one randomized controlled trial (RCT). Most research output hails from high-income countries, i.e., perhaps not universally applicable to all settings owing to possible genetic, environmental, and resource differences. More research is needed: large volume studies in the pregnant population, validation of scoring systems in pediatric age groups, clinical trials focused on combination multi-staged treatment modalities, and studies originating from the developing world.

Cerebral Digital Subtraction Angiography in Acute Intracranial Hemorrhage: Considerations in Critically Ill Children

Cerebrovascular disorders are an important cause of morbidity and mortality in children. Although minimally invasive, cerebral digital subtraction angiography (DSA) has been shown to be safe in children and is a valuable, and perhaps underutilized, technique for the diagnosis and management of pediatric cerebrovascular disorders in the critical care setting. Through a case-based approach, we explore the utility of DSA in critically ill children with acute intracranial hemorrhage (ICH). We discuss the use of DSA in the acute management of aneurysm and arteriovenous malformation rupture as well as cerebral vasospasm. Those caring for critically ill children with acute ICH should consider cerebral DSA as part of a comprehensive approach to the diagnosis and management of these conditions.

Optimal control problem arising in mathematical modeling of cerebral vascular pathology embolization

Arteriovenous malformation (AVM) of the brain is a congenital vascular abnormality, in which the arterial and venous blood pools are intertwined and directly connected. This dangerous disease causes a high risk of intracranial hemorrhage and disrupts brain functioning. The preferred method of AVM treating is embolization, which is the endovascular filling of abnormal AVM vessels with a special embolic agent. Despite the fact that this method is widely used in neurosurgery, in some cases its use is accompanied by perioperative AVM vessels rupture. In this regard, the aim of this work is to study the optimal scenarios for multi-stage AVM embolization from the effectiveness and safety of the procedure point of view. Mathematically, the joint movement of blood and embolic agent in the AVM body is described on the basis of a one-dimensional two-phase filtration model, which takes into account the redistribution of blood to surrounding healthy vessels. For the numerical solution of the resulting integro-differential system of equations, a monotonic modification of the CABARET scheme is used. To find optimal embolization scenarios, the optimal control problem with phase constraints arising from medicine is formulated. A modified particle swarm optimization method is used to solve this problem numerically. This technique is used to obtain optimal embolization scenarios on the basis of real patients clinical data collected during neurosurgical operations.

Endovascular Management of Hemorrhagic Stroke

Significant advances in endovascular neurosurgery tools, devices, and techniques are changing the approach to the management of acute hemorrhagic stroke. The endovascular treatment of intracranial aneurysms emerged in the early 1990s with Guglielmi detachable coils, and since then, it gained rapid popularity that surpassed open surgery. Stent-assisted coiling and balloon remodeling techniques have made the treatment of wide-necked aneurysms more durable. With the introduction of flow diverters and flow disrupters, many aneurysms with complex geometrics can now be reliably managed. Arteriovenous malformations and fistulae can also benefit from endovascular therapy by embolization using n-butyl cyanoacrylate (NBCA), Onyx, polyvinyl alcohol (PVA), and coils. In this article, we describe the role of endovascular treatment for the most common causes of intracerebral and subarachnoid hemorrhages, particularly ruptured aneurysms and vascular malformations.

Hemodynamic Analysis of Cerebral AVMs with 3D Phase-Contrast MR Imaging

BACKGROUND AND PURPOSE

The hemodynamics associated with cerebral AVMs have a significant impact on their clinical presentation. This study aimed to evaluate the hemodynamic features of AVMs using 3D phase-contrast MR imaging with dual velocity-encodings.

MATERIALS AND METHODS

Thirty-two patients with supratentorial AVMs who had not received any previous treatment and had undergone 3D phase-contrast MR imaging were included in this study. The nidus diameter and volume were measured for classification of AVMs (small, medium, or large). Flow parameters measured included apparent AVM inflow, AVM inflow index, apparent AVM outflow, AVM outflow index, and the apparent AVM inflow-to-outflow ratio. Correlation coefficients between the nidus volume and each flow were calculated. The flow parameters between small and other AVMs as well as between nonhemorrhagic and hemorrhagic AVMs were compared.

RESULTS

Patients were divided into hemorrhagic (n = 8) and nonhemorrhagic (n = 24) groups. The correlation coefficient between the nidus volume and the apparent AVM inflow and outflow was .83. The apparent AVM inflow and outflow in small AVMs were significantly smaller than in medium AVMs (P < .001 for both groups). The apparent AVM inflow-to-outflow ratio was significantly larger in the hemorrhagic AVMs than in the nonhemorrhagic AVMs (P = .02).

CONCLUSIONS

The apparent AVM inflow-to-outflow ratio was the only significant parameter that differed between nonhemorrhagic and hemorrhagic AVMs, suggesting that a poor drainage system may increase AVM pressure, potentially causing cerebral hemorrhage.

Interrater Reliability in the Measurement of Flow Characteristics on Color-Coded Quantitative DSA of Brain AVMs

BACKGROUND AND PURPOSE

Hemodynamic features of brain AVMs may portend increased hemorrhage risk. Previous studies have suggested that MTT is shorter in ruptured AVMs as assessed on quantitative color-coded parametric DSA. This study assesses the interrater reliability of MTT measurements obtained using quantitative color-coded DSA.

MATERIALS AND METHODS

Thirty-five color-coded parametric DSA images of 34 brain AVMs were analyzed by 4 neuroradiologists with experience in interventional neuroradiology. Hemodynamic features assessed included MTT of the AVM and TTP of the dominant feeding artery and draining vein. Agreement among the 4 raters was assessed using the intraclass correlation coefficient.

RESULTS

The interrater reliability among the 4 raters was poor (intraclass correlation coefficient = 0.218; 95% CI, 0.062-0.414; P value = .002) as it related to MTT assessment. When the analysis was limited to cases in which the raters selected the same image to analyze and selected the same primary feeding artery and the same primary draining vein, interrater reliability improved to fair (intraclass correlation coefficient  = 0.564; 95% CI, 0.367-0.717; P < .001).

CONCLUSIONS

Interrater reliability in deriving color-coded parametric DSA measurements such as MTT is poor so minor differences among raters may result in a large variance in MTT and TTP results, partly due to the sensitivity and 2D nature of the technique. Reliability can be improved by defining a standard projection, feeding artery, and draining vein for analysis.

Neuroprotective effect of indomethacin in normal perfusion pressure breakthrough phenomenon

Loss of cerebral autoregulation in normal perfusion pressure breakthrough (NPPB) phenomenon has been reported in other Central Nervous System diseases such as neonatal intraventricular haemorrhage. Several studies have demonstrated that low-dose indomethacin prevents this latter condition. A previous rat model was used to resemble NPPB phenomenon. Study animals were distributed in 4 groups that received 3 doses of indomethacin at different concentrations prior to fistula occlusion 60 days after its creation. Control animals received saline solution. Intracranial pressure (ICP) increased in all groups following fistula creation, whereas mean arterial pressure (MAP) and cerebral perfusion pressure (CPP) decreased as a manifestation of cerebral hypoperfusion and intracranial hypertension. The administration of indomethacin was associated with raised MAP and CPP, as well as decreased ICP. Sodium fluorescein extravasation was slight in study animals when comparing with control ones. Histological analysis evidenced diffuse ischaemic changes with signs of neuronal apoptosis in all brain layers in control animals. These findings were only focal and slight in study animals. The results suggest the usefulness of indomethacin to revert, at least partially, the haemodynamic effects of NPPB phenomenon in this experimental model, as well as to reduce BBB disruption and histological ischemia observed in absence of indomethacin.

Treatment Outcomes of Endovascular Embolization Only in Patients with Unruptured Brain Arteriovenous Malformations: A Subgroup Analysis of ARUBA (A Randomized Trial of Unruptured Brain Arteriovenous Malformations)

BACKGROUND AND PURPOSE

Endovascular embolization only has been advocated for treatment of brain arteriovenous malformations in recent trials. Our aim was to evaluate the results of embolization only in a cohort of patients who were enrolled in the A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) study at 39 clinical sites in 9 countries.

MATERIALS AND METHODS

We analyzed the rates and severity of stroke and death in patients who underwent embolization only. Events were identified through in-person neurologic follow-up visits performed at 6-month intervals during the first 2 years and annually, with telephone contact every 6 months thereafter. All event-related data were reviewed by independent adjudicators.

RESULTS

Among 30 patients who had embolization planned, 26 underwent embolization only. A total of 13 stroke events were reported in the follow-up period among 26 subjects (ischemic, hemorrhagic, or both in 4, 7, and 2 subjects, respectively). The adverse event occurred after the first embolization in 11 of 13 patients. One patient had a major motor deficit, and 2 patients developed major visual field deficits. One event was fatal. The modified Rankin Scale score was 0-2 at last follow-up in 11 of the 12 stroke survivors. Estimated stroke-free survival was 46% at 12 months.

CONCLUSIONS

Although the rates of stroke and/or death were high in patients treated with embolization only in ARUBA, the rates of favorable outcomes following stroke were high during follow-up.

Brain arteriovenous malformation with transdural blood supply: Current status

Arterial blood supply to a brain arteriovenous malformation (BAVM) is mainly derived from the internal carotid artery (ICA) and vertebral basilar artery (VBA) system. However, in certain cases, arteries supplying the meninges may also contribute to the blood supply of the BAVM, resulting in the formation of a BAVM with transdural blood supply (TBS). To review the current status of BAVM with TBS, a literature search was performed in the PubMed database. Articles were screened for relevance and suitability of data. According to recent studies, the mechanisms by which TBS to a BAVM forms are mainly classified into the congenital and acquired type. BAVM with TBS is common in elderly patients and is characterized by intracranial hemorrhage, epilepsy, chronic headache and increased intracranial pressure. Digital subtraction angiography is the gold standard for diagnosing BAVM with TBS. Superselective angiography is also important. Treatments for BAVM with TBS include surgical resection, endovascular treatment (EVT), stereotactic radiosurgery and combined treatment. Surgical resection is difficult to perform. EVT has become the major therapy for treating BAVM with TBS due to its low procedural invasiveness. Combination of surgical resection and EVT may be a good option. In addition, stereotactic radiosurgery is frequently used as a complementary treatment to surgical and endovascular interventions. The prognosis of BAVM with TBS is not favorable, as the defect involves a complex arterial supply system.

Risk factors for hemorrhage of brain arteriovenous malformation

Patients with brain arteriovenous malformation (bAVM) are at risk of intracranial hemorrhage (ICH). Overall, bAVM accounts for 25% of hemorrhagic strokes in adults <50 years of age. The treatment of unruptured bAVMs has become controversial, because the natural history of these patients may be less morbid than invasive therapies. Available treatments include observation, surgical resection, endovascular embolization, stereotactic radiosurgery, or combination thereof. Knowing the risk factors for bAVM hemorrhage is crucial for selecting appropriate therapeutic strategies. In this review, we discussed several biological risk factors, which may contribute to bAVM hemorrhage.

Differences in bleeding patterns and outcome after intracerebral hemorrhage due to vascular malformations

BACKGROUND

Atypical intracerebral hemorrhage is a common form of primary manifestation of vascular malformations.

OBJECTIVE

The aim of the present study is to determine clues to the cause of bleeding according to hemorrhage pattern (lobar, basal ganglia, infratentorial).

METHODS

We retrospectively evaluated 343 consecutive neurosurgical patients with intracerebral hemorrhage (ICH), who were admitted to our neurosurgical department between 2006 and 2016. The study cohort includes only neurosurgical patients. Patients who underwent treatment by neurologists are not represented in this study. We assessed location of hemorrhage, hematoma volumes to rule out differences and predicitve variables for final outcome.

RESULTS

In 171 cases (49.9%) vascular malformations, such as arteriovenous malformations (AVMs), cavernomas, dural fistulas and aneurysms were the cause of bleeding. 172 (50.1%) patients suffered from an intracerebral hemorrhage due to amyloid angiopathy or long standing hypertension. In patients with infratentorial hemorrhage a malformation was more frequently detected as in patients with supratentorial hemorrhage (36% vs. 16%, OR 2.9 [1.8;4.9], p<0.001). Among the malformations AVMs were most common (81%). Hematoma expansion was smaller in vascular malformation than non-malformation caused bleeding (24.1 cm3 vs. 64.8 cm3, OR 0.5 [0.4;0.7], p < 0.001,). In 6 (2.1%) cases diagnosis remained unclear. Final outcome was more favorable in patients with vascular malformations (63% vs. 12%, OR 12.8 [4.5;36.2], p<0.001).

CONCLUSION

Localization and bleeding patterns are predictive factors for origin of the hemorrhage. These predictive factors should quickly lead to appropriate vascular diagnostic measures. However, due to the inclusion criteria the validity of the study is limited and multicentre studies with further testing in general ICH patients are required.

Grades of brain arteriovenous malformations and risk of hemorrhage and death

Objective

To assess the relationship of the grade of unruptured and untreated Brain Arteriovenous Malformations (AVMs), with the risk of subsequent stroke and death during follow‐up.

Methods

This prospective study was drawn from a cohort of adult patients with unruptured AVMs, who participated in the conservative treatment arm (medical management only for headache or seizures) of the randomized clinical trial of unruptured brain AVMs (ARUBA study). The grade of AVMs (Spetzler–Martin scale) was dichotomized into categories: AVMs of grades I and II were considered low grade; AVMs of grades III and IV were considered high grade. There were no grade V AVM patients in ARUBA. The primary outcome was symptomatic stroke (hemorrhagic or ischemic – documented by imaging) or death.

Results

The conservative treatment group had 123 patients (“as treated” analysis). 71 (57.7%) had lesions characterized for this analysis as low‐grade lesions and 52 (42.2%) as high grade. From the total of 10 (8.13%) primary outcomes, three occurred (4.22%) in low‐grade AVMs and seven (13.46%) in high‐grade AVMs (P = 0.0942).

Interpretation

Statistical analysis of the cohort of patients with unruptured and untreated AVMs from ARUBA study showed that the graduation categories (Spetzler–Martin grades) were not associated with the outcome of subsequent stroke or death.

Analysis of the Expression of Angioarchitecture-related Factors in Patients with Cerebral Arteriovenous Malformation

Background:

Cerebral arteriovenous malformation (cAVM) is a type of vascular malformation associated with vascular remodeling, hemodynamic imbalance, and inflammation. We detected four angioarchitecture-related cytokines to make a better understanding of the potential aberrant signaling in the pathogenesis of cAVM and found useful proteins in predicting the risk of cerebral hemorrhage.

Methods:

Immunohistochemical analysis was conducted on specimens from twenty patients with cAVM diagnosed via magnetic resonance imaging and digital subtraction angiography and twenty primary epilepsy controls using antibodies against vascular endothelial growth factor receptor-2 (VEGFR-2), matrix metalloproteinase-9 (MMP-9), vascular cell adhesion molecule (VCAM-1), and endothelial nitric oxide synthase (eNOS). Western blotting and real-time fluorescent quantitative polymerase chain reaction (PCR) were performed to determine protein and mRNA expression levels. Student's t-test was used for statistical analysis.

Results:

VEGFR-2, MMP-9, VCAM-1, and eNOS expression levels increased in patients with cAVM compared with those in normal cerebral vascular tissue, as determined by immunohistochemical analysis. In addition, Western blotting and real-time PCR showed that the protein and mRNA expression levels of VEGFR-2, MMP-9, VCAM-1, and eNOS were higher in the cAVM group than in the control group, all the differences mentioned were statistically significant (P < 0.05).

Conclusions:

VEGFR-2, MMP-9, VCAM-1, and eNOS are upregulated in patients with cAVM and might play important roles in angiogenesis, vascular remodeling, and migration in patients with cAVM. MMP-9, VEGFR-2, VCAM-1, and eNOS might be potential excellent group proteins in predicting the risk of cerebral hemorrhage at arteriovenous malformation.

Embolization of feeding arteries and symptom alleviation of mixed dural-pial arteriovenous malformations

Background

To examine whether embolization of dural or pial blood supply branch is more efficient for symptom alleviation for unruptured mixed dural-pial arteriovenous malformations (DPAVMs).

Methods

We retrospectively reviewed 30 DPAVM patients from a database of 425 consecutive cerebral arteriovenous malformation (CAVM) patients who underwent endovascular embolization between January 2010 and December 2015 at our institution. Demographics, angioarchitectural characteristics, endovascular embolization details and patients clinical outcomes were recorded. The modified Rankin Scale (mRS), Engel‘s classification and Visual Analogue pain scale (VAS) were used to assess clinical outcomes.

Results

The single center cohort data shows that the incidence of DPAVM is 7.1%. Among the 30 DPAVM patients, 9 (30.0%) are ruptured and 21 (70.0%) are unruptured. Four (19.0%) of the 21 unruptured DPAVM patients are failed to follow-up, leaving 17 to analysis the clinical outcomes. Clinical presentations of the 17 unruptured DPAVM patients are epilepsy (n = 10), headache (n = 5) and focal neurological dysfunction (n = 2). Six patients have DPAVMs occluded via pial blood supply branches, 4 via dural branches and 7 via both pial and dural branches. Unruptured DPAVM patients with nidus occluded via dural blood supply branches, or both pial and dural branches have higher symptom alleviation rate than patients with nidus occluded via pial branches (100%/85.7% vs 66.7%).

Conclusions

For DPAVM patients presented with epilepsy, headache and FND, embolization via dural blood supply branches may be more efficient for symptom alleviation. Large cohort study is needed to confirm the generalizability.

A proposed classification for assessing rupture risk in patients with intracranial arteriovenous malformations

Background:

Whether cerebral arteriovenous malformations (AVMs) should be treated remains an ongoing debate. Nevertheless, there is a need for predictive factors that assist in labelling lesions as low or high risk for future rupture. Our aim was to design a new classification that would consider hemodynamic and anatomic factors in the rapid assessment of rupture risk in patients with AVMs.

Methods:

This was a retrospective study that included 639 patients with ruptured and unruptured AVMs. We proposed a new classification score (1–4 points) for AVM rupture risk using three factors: feeding artery mean velocity (Vm), nidus size, and type of venous drainage. We employed descriptive statistics and logistic regression analysis.

Results:

A total of 639 patients with cerebral AVMs, 388 (60%) had unruptured AVMs and 251 (40%) had ruptured AVMs. Logistic regression analysis revealed a significant effect of Vm, nidus size, and venous drainage type in accounting for the variability of rupture odds (P = 0.0001, R² = 0.437) for patients with AVMs. Based in the odds ratios, grades 1 and 2 of the proposed classification were corresponded to low risk of hemorrhage, while grades 3 and 4 were associated with hemorrhage: 1 point OR = (0.107 95% CI; 0.061–0.188), 2 point OR = (0.227 95% CI; 0.153–0.338), 3 point OR = (3.292 95% CI; 2.325–4.661), and 4 point OR = (23.304 95% CI; 11.077–49.027).

Conclusion:

This classification is useful and easy to use, and it may allow for the individualisation of each cerebral AVM and the assessment of rupture risk based on a model of categorisation.

Cerebral arteriovenous malformation draining vein stenosis is associated with atherosclerotic risk factors

OBJECTIVE

The pathogenesis of venous outflow stenosis associated with cerebral arteriovenous malformation (AVM) draining veins is poorly understood. We sought to determine the relationship between venous stenosis and atherosclerotic risk factors.

MATERIALS AND METHODS

All patients with an AVM seen at our institution between 1990 and 2016 were retrospectively reviewed. Patients <18 years of age were excluded. Patients were classified into two groups based on the presence or absence of venous stenosis. Patient charts were reviewed for the following atherosclerotic risk factors: age >50 years, sex, race, hypertension, type 2 diabetes mellitus, hyperlipidemia, coronary artery disease, chronic kidney disease stage III, and cigarette smoking. The relationship between venous stenosis and atherosclerotic risk factors was assessed using univariate and multivariate analyses.

RESULTS

278 patients were included (mean age 41 years, 55% men). Venous stenosis was present in 87 patients (31% of the cohort). The presence of venous stenosis was significantly associated with age >50 years (P=0.05), hypertension (P=0.05), diabetes (P=0.02), and hyperlipidemia (P=0.001). Multivariate analysis showed that hyperlipidemia (P=0.05) was predictive of draining vein stenosis.

CONCLUSIONS

Venous stenosis is associated with several atherosclerotic risk factors, suggesting that cerebral AVM venous outflow stenosis occurs by a degenerative process. Additional studies can show whether these modifiable risk factors may be targeted to prevent draining vein stenosis and AVM rupture.

Delayed Venous Drainage in Ruptured Arteriovenous Malformations Based on Quantitative Color-Coded Digital Subtraction Angiography

OBJECTIVE

Clinically applicable hemodynamic risk factors to predict arteriovenous malformation (AVM) rupture are missing in the literature. The aim of this study was to use catheter angiography to identify hemodynamic parameters in ruptured and unruptured AVMs.

METHODS

Patients with frontal and temporal AVMs and Siemens syngo iFlow color-coding angiography were included in this study (n = 71). Clinical and radiologic data (age, sex, Spetzler-Martin [SM] and supplemented SM grade, and rupture status), and hemodynamic features (contrast mean transit time [MTT] of feeding arteries, draining veins, AVM nidus, and the cerebral circulation time [CCT]) were analyzed. Univariable analysis was performed to compare findings between ruptured and unruptured AVMs.

RESULTS

In total, 35 ruptured and 36 unruptured AVMs were analyzed. Clinical characteristics and AVM grades were comparable between ruptured and unruptured AVMs. Ipsilateral CCT (5.2 vs. 4.0 seconds; P = 0.035), MTT between Tmax of the ipsilateral internal carotid artery and Tmax of sinus entry of the draining vein (3.2 vs. 2.0 seconds; P < 0.001), and MTT between Tmax at the start of venous outflow and Tmax of sinus entry (1.6 vs. 0.7 seconds; P < 0.0001) were significantly longer in ruptured compared with unruptured AVMs. MTTs of nidus, between the internal carotid and feeding arteries, of the venous sinus passage as well as contralateral CCT and controlled ipsilateral CCT were comparable between both groups.

CONCLUSIONS

Ruptured AVMs have significantly prolonged venous drainage times compared with unruptured AVMs; this suggests restricted AVM drainage and increased blood pressure within the AVM nidus. Prospective studies are needed to determine the predictive power of these measurements.

Outcomes after intracerebral hemorrhage from arteriovenous malformations

OBJECTIVE

To compare outcomes after intracerebral hemorrhage (ICH) from cerebral arteriovenous malformation (AVM) rupture and other causes of ICH.

METHODS

We performed a retrospective population-based study using data from the Nationwide Inpatient Sample. We used standard diagnosis codes to identify ICH cases from 2002 to 2011. Our predictor variable was cerebral AVM. Our primary outcomes were inpatient mortality and home discharge. We used logistic regression to compare outcomes between patients with ICH with and without AVM while adjusting for demographics, comorbidities, and hospital characteristics. In a confirmatory analysis using a prospective cohort of patients hospitalized with ICH at our institution, we additionally adjusted for hematoma characteristics and the Glasgow Coma Scale score.

RESULTS

Among 619,167 ICH hospitalizations, the 4,485 patients (0.7%, 95% confidence interval [CI] 0.6-0.8) with an AVM were younger and had fewer medical comorbidities than patients without AVM. After adjustment for confounders, patients with AVM had lower odds of death (odds ratio [OR] 0.5, 95% CI 0.4-0.7) and higher odds of home discharge (OR 2.0, 95% CI 1.4-3.0) than patients without AVM. In a confirmatory analysis of 342 patients with ICH at our institution, the 34 patients (9.9%, 95% CI 7.2-13.6) with a ruptured AVM had higher odds of ambulatory independence at discharge (OR 4.4, 95% CI 1.4-13.1) compared to patients without AVM.

CONCLUSIONS

Patients with ICH due to ruptured AVM have more favorable outcomes than patients with ICH from other causes.

Contemporary Imaging of Cerebral Arteriovenous Malformations

OBJECTIVE

Brain arteriovenous malformation (AVM) rupture results in substantial morbidity and mortality. The goal of AVM treatment is eradication of the AVM, but the risk of treatment must be weighed against the risk of future hemorrhage.

CONCLUSION

Imaging plays a vital role by providing the information necessary for AVM management. Here, we discuss the background, natural history, clinical presentation, and imaging of AVMs. In addition, we explain advances in techniques for imaging AVMs.

Endovascular management of arteriovenous malformations

Arteriovenous malformation (AVM) embolization can serve as a crucial adjunct before surgical resection, a partial approach to target high-risk features, or, rarely, as a curative approach for high-risk, surgically inaccessible lesions. Specifically, embolization is a welcome surgical adjunct to reduce the size of medium to large AVMs, to target perforator supply, and/or to target the deep portion of a nidus. In addition, a crucial role for embolization is the targeting of associated aneurysms, particularly in the setting of a ruptured lesion, regardless of the subsequent therapeutic modality. Rarely, a deep, small ruptured AVM that cannot be accessed surgically may be embolized with intent to cure. This chapter will review patient selection, technical nuances, and published results for AVM embolization. With appropriate patient selection and well-defined goals of embolization, the risk of procedural morbidity can be outweighed by its benefit.

The natural history of cerebral arteriovenous malformations

Cerebral arteriovenous malformations (AVMs) are composed of a complex tangle of abnormal arteries and veins and are a significant source of cerebral hemorrhage and consequent morbidity and mortality in young adults, representing a diagnostic and therapeutic challenge. Current natural-history studies of cerebral AVMs report overall annual rates of 1% and 3% for the risk of epilepsy and hemorrhage, respectively. Unruptured AVMs have an annual hemorrhage rate of 2.2% while ruptured lesions have an annual hemorrhage rate of 4.5%. These hemorrhage rates are can change over time, particularly for hemorrhagic lesions, with the rebleed rate ranging from 6% to 15.8% in the first year after rupture across several studies. Besides hemorrhage, other significant risk factors for AVM hemorrhage include deep location, deep venous drainage, associated aneurysms, and pregnancy. Other factors include patient age, sex, and small AVM size, which are not currently considered significant risk factors for AVM hemorrhage. In addition to hemorrhage risk and seizure risk, the natural history of an AVM also encompasses the daily psychologic burden that a patient must endure knowing that he or she possesses an untreated AVM. This chapter reviews the epidemiology, clinical features, and natural history of cerebral AVMs.

Subsequent haemorrhage in children with untreated brain arteriovenous malformation: Higher risk with unbalanced inflow and outflow angioarchitecture

OBJECTIVES

Children with brain arteriovenous malformations (bAVMs) are at risk of life-threatening haemorrhage in their early lives. Our aim was to analyse various angioarchitectural features of bAVM to predict the risk of subsequent haemorrhage during follow-up in children.

METHODS

We identified all consecutive children admitted to our institution for bAVMs between July 2009 and September 2015. Children with at least 1 month of treatment-free follow-up after diagnosis were included in further analysis. Annual rates of AVM rupture as well as several potential risk factors for subsequent haemorrhage were analysed using Kaplan-Meier analyses and Cox proportional hazards regression models.

RESULTS

We identified 110 paediatric patients with a mean follow-up period of 2.1 years (range, 1 month-15.4 years). The average annual risk of haemorrhage from untreated AVMs was 4.3 % in children. No generalised venous ectasia in conjunction with fast arteriovenous shunt was predictive of subsequent haemorrhage (RR, 7.55; 95 % CI 1.96-29.06). The annual rupture risk was 11.1 % in bAVMs without generalised venous ectasia but with fast arteriovenous shunt.

CONCLUSIONS

bAVM angiographic features suggesting unbalanced inflow and outflow might be helpful to identify children at higher risk for future haemorrhage.

KEY POINTS

• Haemorrhage risk stratification is important for children with untreated brain AVM. • Angiographic features suggesting unbalanced inflow and outflow predict paediatric brain AVM haemorrhage. • Identifying AVMs with high rupture risk help patient selection and tailoring treatment.

Outcomes and Complications After Endovascular Treatment of Brain Arteriovenous Malformations: A Prognostication Attempt Using Artificial Intelligence

PURPOSE

To identify factors influencing outcome in brain arteriovenous malformations (BAVM) treated with endovascular embolization. We also assessed the feasibility of using machine learning techniques to prognosticate and predict outcome and compared this to conventional statistical analyses.

METHODS

A retrospective study of patients undergoing endovascular treatment of BAVM during a 22-year period in a national neuroscience center was performed. Clinical presentation, imaging, procedural details, complications, and outcome were recorded. The data was analyzed with artificial intelligence techniques to identify predictors of outcome and assess accuracy in predicting clinical outcome at final follow-up.

RESULTS

One-hundred ninety-nine patients underwent treatment for BAVM with a mean follow-up duration of 63 months. The commonest clinical presentation was intracranial hemorrhage (56%). During the follow-up period, there were 51 further hemorrhagic events, comprising spontaneous hemorrhage (n = 27) and procedural related hemorrhage (n = 24). All spontaneous events occurred in previously embolized BAVMs remote from the procedure. Complications included ischemic stroke in 10%, symptomatic hemorrhage in 9.8%, and mortality rate of 4.7%. Standard regression analysis model had an accuracy of 43% in predicting final outcome (mortality), with the type of treatment complication identified as the most important predictor. The machine learning model showed superior accuracy of 97.5% in predicting outcome and identified the presence or absence of nidal fistulae as the most important factor.

CONCLUSIONS

BAVMs can be treated successfully by endovascular techniques or combined with surgery and radiosurgery with an acceptable risk profile. Machine learning techniques can predict final outcome with greater accuracy and may help individualize treatment based on key predicting factors.

Relationship of pulsatility and resistance indices to cerebral arteriovenous malformation angioarchitectural features and hemorrhage

The role that hemodynamics plays in the pathophysiology of cerebral arteriovenous malformation (AVM) hemorrhage remains unclear. Here, we examine the relationship of pulsatility and resistance indices to AVM angioarchitectural features and hemorrhage. Records of patients with cerebral AVMs evaluated at our institution between 2007-2014 and with flows obtained before treatment using quantitative magnetic resonance angiography (QMRA) were retrospectively reviewed. Flow volume rate and flow velocity were measured in primary arterial feeders and compared to their contralateral counterparts. Pulsatility index (PI)=[(systolic flow velocity-diastolic flow velocity)/mean flow velocity] and resistance index (RI)=[(systolic flow velocity-diastolic flow velocity)/systolic flow velocity] were calculated for each feeder and compared to the normal contralateral vessel. Relationships between PI, RI and AVM clinical and angioarchitectural features were assessed using linear regression. Seventy-two patients with a total of 101 feeder arteries were included. PI and RI were significantly lower in AVM arterial feeders compared to normal vessels, thereby resulting in significantly higher flow volume rates and flow velocities in feeder vessels. There was no significant association of PI and RI with hemorrhagic presentation, exclusive deep venous drainage, venous stenosis, single draining vein, or deep location. In conclusion, PI and RI can be measured using QMRA and are lower in AVM arterial feeders compared to normal vessels. Although we found no significant correlation between PI, RI, and AVM angioarchitectural characteristics thought to be associated with increased hemorrhage risk, future studies with larger sample sizes may better elucidate this relationship.

Dormant micro arteriovenous malformations lead to recurrent cerebral haemorrhage

Introduction

Some micro arteriovenous malformations (AVMs) located in deep brain are undetectable. How to choose a proper timing to detect these AVMs remains unclear.

Case description

A 21-year-old male patient was admitted to our center for intraventricular haematoma. Digital subtraction angiographies (DSAs) were performed one week and one month respectively after his haemorrhage, but no positive results were obtained. The patient was hospitalized for re-haemorrhage six years later. A micro AVM with two diffused niduses was detected and embolised three months after his re-haemorrhage. The patient recovered without any neurological deficit.

Discussion and evaluation

Compressive effects of haematoma and spontaneous obliteration of AVMs might play pivotal roles in negative DSA results.

Conclusions

Strategic and timely use of DSA could identify some dormant re-haemorrhagic AVMs.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-016-2615-5) contains supplementary material, which is available to authorized users.

Hemodynamic Perturbations in Cerebral Arteriovenous Malformations and Management Implications

Cerebral AVMs have high flow, low resistance shunts that induce regional hemodynamic disturbances and possibly neural derangements. A better understanding of these mechanisms may help treatment planning and the management of complications after endovascular or surgical treatment.

Although the precise mechanisms of hemodynamic perturbation are still relatively unclear, the presence of chronic cerebral hypoperfusion is central and widely believed to be associated with both neurological deficits at presentation (‘steal‘) and ‘hyperemic’ complications following shunt obliteration. The ‘normal perfusion pressure breakthrough‘ (NPPB) theory states that chronic hypoperfusion around AVMs induces the loss of autoregulatory capability; following AVM shunt obliteration, perfusion pressure elevation induces an increase in flow, due to ‘vasomotor paralysis’, which can cause hemorrhage. The ‘dissociative vasoparalysis' theory suggests that vasodilation is preserved but not vasoconstriction. However, pharmacologic exploration of cerebral autoregulation with induced vasoconstriction (phenylephrine) and vasodilatation (acetazolamide) helps identify 3 patterns of autoregulatory behavior. The vast majority of AVM patients appear to retain autoregulatory capability, despite low arterial feeding pressures, consistent with a “shift to the left” of the autoregulation curve. Pronounced hypotension may “exhaust” cerebrovascular reserve in some patients, predisposing to hemorrhagic complications in the post-operative period. Lastly, “vasoparalysis” may coexist with a combination of vascular insult and marked hypotension.

Clinical presentation, AVM angioarchitecture and peri-operative physiologic data (especially feeding artery and venous outflow pressures) may assist patient management. Patients can be identified in whom staged treatment is recommended initially. Following AVM obliteration, the patient's hemodynamic response, which may range from a minimal increase in A-V pressure gradient to significant CBF increase may be predicted, and blood pressure, fluid and ICP management adjusted accordingly, as the monitoring of post-operative cerebral hemodynamics remains difficult. Extreme attention to endovascular and operative technique must be exercised, as technical problems can be devastating.

Although incompletely understood, hemodynamic derangements associated with cerebral AVMs increasingly appear to be associated with intact cerebral autoregulation in most patients. As cerebral hemodynamics monitoring remains challenging, clinical, angiographic and physiologic data from interventional/operative monitoring must be used to guide patient management.

Angioarchitecture Predicting Hemorrhage in Cerebral Arteriovenous Malformations

To find out lesions responsible for hemorrhage in arteriovenous malformations (AVMs), a retrospective study of angioarchitecture around the nidus was conducted in 27 patients who underwent conservative treatment. Comparison of angiograms revealed disappearance of an intranidal aneurysmal dilatation after the hemorrhagic events in two cases. The hematomas were adjacent to the dilatation, and no subarachnoid hemorrhage was evident. Obstruction of venous drainage, noticed in a case of spontaneous regression of AVM, was not demonstrated in the cases of hemorrhage.

The intranidal aneurysmal dilatation is likely to have caused the hemorrhage in our cases. Careful endavascular embolization using proper materials should be indicated for an intranidal aneurysmal dilatation to prevent subsequent hemorrhage.

Histopathological Features of Brain Arteriovenous Malformations in Japanese Patients

Clinical features of high risk brain arteriovenous malformations (BAVMs) are well characterized. However, pathological evidences about the differences that are possessed by high risk patients are still lacking. We reviewed archived routine hematoxylin-eosin specimens from a total of 54 surgical treated BAVMs. The histopathological features in nidus were semi-quantitatively analyzed. We obtained the pathological differences of BAVMs nidus between several clinical features. Among the analyzed pathological features, the significant differences were observed in degree of venous enlargement and intimal hyperplasia. Juvenile, female, diffuse nidus, high Spetzler-Martin grade, and low flow patients had a lesser degree of those parameters compared to adult, male, compact nidus, low Spetzler-Martin grade and high flow patients. High risk profiles of BAVMs patients were well-reflected in the nidus pathology. Therefore, juvenile, female, diffuse nidus, and low flow in Japanese BAVMs patients might have different vascular remodeling process that predispose to higher tendency of hemorrhage.

Therapeutic management of cerebral arteriovenous malformations: a review

The therapeutic management of cerebral arteriovenous malformations has undergone significant change over the past 40 years. Embolization, radiosurgery, advanced imaging modalities, neuropsychological testing and advances in surgical technique has both significantly improved our ability to treat patients, as well as confounding the landscape as to what constitutes best medical practice. Variability in natural history provides additional challenges in that it is challenging to determine an accurate estimate of the risk of hemorrhage, morbidity and mortality. It is clear that the complexity of the treatment of these lesions demands a multidisciplinary approach. The need for a team of neurosurgeons, interventional and diagnostic neuroradiologists, neurologists, radiation oncologists and neuropsychologists will improve outcomes and aid in determining best therapy for patients.

The Clinical Characteristics and Treatment of Cerebral Microarteriovenous Malformation Presenting with Intracerebral Hemorrhage: A Series of 13 Cases

Object. The aim of this report was to explore the clinical presentation, radiological features, treatment methods, and outcome of micro-AVMs presenting with intracerebral hemorrhage. Methods. The clinical data, radiological features, treatment, and follow-up results for a consecutive series of 13 cases with micro-AVMs were retrospectively analyzed. Results. All 13 patients presented with intracerebral hemorrhage. Ten cases were confirmed by enhanced thin layer CT scanning and CTA, and the other 3 cases were confirmed by DSA. Treatment consisted of surgical removal in 10 cases, endovascular embolization in 1, and radiosurgery in 2. The modified GOS score was achieved in the third month after discharge: 10 cases were rated with 5 points (good recovery), 1 case was rated with 4 points (mild disability), and 2 cases were rated with 3 points (severe disability). During follow-up, No case of rebleeding was reported. Conclusions. Intracerebral hemorrhage is the main clinical manifestation of micro-AVMs. It is beneficial to find a tiny nidus of dense vessels located on hematoma wall on enhanced thin layer CT scanning for a clear diagnosis and to detect any abnormal feeding artery or venous drainage for an indirect diagnostic evidence. Resection is the main method of treatment for micro-AVMs.

Acute rupture of a feeding artery aneurysm after embolization of a brain arteriovenous malformation

BACKGROUND

Staged endovascular embolization of large arteriovenous malformations (AVMs) is frequently performed to gradually reduce flow and prevent abrupt hemodynamic changes. While feeding artery aneurysms have been associated with increased risk of hemorrhage in the setting of AVMs, decisions regarding if and when to treat these aneurysms vary. Acute, fatal rupture of a feeding artery aneurysm following embolization of a large, unruptured AVM has been infrequently reported in the literature.

CASE DESCRIPTION

A 69-year-old female presented with headache and mild left hemiparesis referable to a 5 cm right fronto-parieto-temporal AVM with surrounding vasogenic edema. The AVM was associated with numerous bilateral feeding artery aneurysms (the largest was a 2 cm right middle cerebral artery (MCA) bifurcation aneurysm). There was also a large, partially thrombosed venous varix. Staged embolization of the AVM was performed. Several hours after the third stage of her embolization, she became obtunded, with a fixed and dilated right pupil. Head computed tomography (CT) showed a large intraparenchymal hemorrhage with midline shift in the right sylvian fissure, remote from the AVM nidus. She was taken to surgery for a decompressive craniectomy and hematoma evacuation. The MCA aneurysm was confirmed to be the source of hemorrhage and it was clipped. Despite aggressive medical and surgical treatments, the patient died.

CONCLUSIONS

An increase in AVM feeding artery pressure following endovascular embolization may contribute to the rupture of a feeding artery aneurysm. For this reason, treatment of large arterial aneurysms on feeding pedicles should be considered prior to embolization of the AVM nidus.

Usefulness of repetitive intraoperative indocyanine green-based videoangiography to confirm complete obliteration of micro-arteriovenous malformations

Background:

It is difficult to intraoperatively confirm the total disappearance of arteriovenous (AV) shunts during surgery for microarteriovenous malformations (micro-AVMs), especially when the nidus is extremely small or diffuse on preoperative angiography. Although intraoperative angiography is effective for evaluating residual shunts, procedure-related risks raise important concerns. The purpose of this study was to assess the usefulness of intraoperative indocyanine green-based videoangiography (ICG–VA) to determine complete disappearance of micro-AVMs during surgery.

Methods:

We retrospectively analyzed eight patients with ruptured micro-AVMs who were treated using craniotomy with ICG–VA at our institution.

Results:

Two patients underwent emergency partial evacuation of hematoma and external decompression before the diagnostic angiography. While three patients had a nidus smaller than 1 cm, five patients had only early draining veins without an appreciable nidus. The draining veins were superficial in six cases and deep in two cases. The average interval from onset to surgery was 33 days (range, 2–57). ICG–VA was repetitively conducted until disappearance of the AV shunt was confirmed. No residual AV shunt was observed on postoperative radiological examinations. In all cases, the diagnosis of AVM was confirmed from the results of postoperative pathological examination.

Conclusions:

ICG–VA could detect early draining veins more clearly in situ than diagnostic angiography. Although it is not as effective for visualizing lesions with deep draining veins, repetitive ICG–VA was safe and effective for confirming the disappearance of AV shunts with superficial drainage.

Diagnosis and evaluation of intracranial arteriovenous malformations

BACKGROUND

Ideal management of intracranial arteriovenous malformations (AVMs) remains poorly defined. Decisions regarding management of AVMs are based on the expected natural history of the lesion and risk prediction for peritreatment morbidity. Microsurgical resection, stereotactic radiosurgery, and endovascular embolization alone or in combination are all viable treatment options, each with different risks. The authors attempt to clarify the existing literature's understanding of the natural history of intracranial AVMs, and risk-assessment grading scales for each of the three treatment modalities.

METHODS

The authors conducted a literature review of the existing AVM natural history studies and studies that clarify the utility of existing grading scales available for the assessment of peritreatment risk for all three treatment modalities.

RESULTS

The authors systematically outline the diagnosis and evaluation of patients with intracranial AVMs and clarify estimation of the expected natural history and predicted risk of treatment for intracranial AVMs.

CONCLUSION

AVMs are a heterogenous pathology with three different options for treatment. Accurate assessment of risk of observation and risk of treatment is essential for achieving the best outcome for each patient.

Brainstem arteriovenous malformations: anatomical subtypes, assessment of "occlusion in situ" technique, and microsurgical results

OBJECT

The surgical management of brainstem arteriovenous malformations (AVMs) might benefit from the definition of anatomical subtypes and refinements of resection techniques. Many brainstem AVMs sit extrinsically on pia mater rather than intrinsically in the parenchyma, allowing treatment by occluding feeding arteries circumferentially, interrupting draining veins after arteriovenous shunting is eliminated, and leaving the obliterated nidus behind. The authors report here the largest series of brainstem AVMs to define 6 subtypes, assess this "occlusion in situ" technique, and analyze the microsurgical results.

METHODS

Brainstem AVMs were categorized as 1 of 6 types: anterior midbrain, posterior midbrain, anterior pontine, lateral pontine, anterior medullary, and lateral medullary AVMs. Data from a prospectively maintained AVM registry were reviewed to evaluate multidisciplinary treatment results.

RESULTS

During a 15-year period, the authors treated 29 patients with brainstem AVMs located in the midbrain (1 anterior and 6 posterior), pons (6 anterior and 7 lateral), and medulla (1 anterior and 8 lateral). The nidus was pial in 26 cases and parenchymal in 3 cases. Twenty-three patients (79%) presented with hemorrhage. Brainstem AVMs were either resected (18 patients, 62%) or occluded in situ (11 patients, 38%). All lateral pontine AVMs were resected, and the occlusion in situ rate was highest with anterior pontine AVMs (83%). Angiography confirmed complete obliteration in 26 patients (89.6%). The surgical mortality rate was 6.9%, and the rate of permanent neurological deterioration was 13.8%. At follow-up (mean 1.3 years), good outcomes (modified Rankin Scale [mRS] score ≤ 2) were observed in 18 patients (66.7%) and poor outcomes (mRS score of 3-5) were observed in 9 patients (33.3%). The mRS scores in 21 patients (77.8%) were unchanged or improved. The best outcomes were observed with lateral pontine (100%) and lateral medullary (75%) AVMs, and the rate of worsening/death was greatest with posterior midbrain and anterior pontine AVMs (50% each).

CONCLUSIONS

Brainstem AVMs can be differentiated by their location in the brainstem (midbrain, pons, or medulla) and the surface on which they are based (anterior, posterior, or lateral). Anatomical subtypes can help the neurosurgeon determine how to advise patients, with lateral subtypes being a favorable surgical indication along with extrinsic pial location and hemorrhagic presentation. Most AVMs are dissected with the intention to resect them, and occlusion in situ is reserved for those AVMs that do not separate cleanly from the brainstem, that penetrate into the parenchyma, or are more anterior in location, where it is difficult to visualize and preserve perforating arteries (anterior pontine and lateral medullary AVMs). Although surgical morbidity is considerable, surgery results in a better obliteration rate than nonoperative management and is indicated in highly selected patients with high rerupture risks.

Normal perfusion pressure breakthrough theory: a reappraisal after 35 years

The intrinsic ability of the brain to maintain constant cerebral blood flow (CBF) is known as cerebral pressure autoregulation. This ability protects the brain against cerebral ischemia and hyperemia within a certain range of blood pressures. The normal perfusion pressure breakthrough (NPPB) theory described by Spetzler in 1978 was adopted to explain the edema and hemorrhage that sometimes occur after resection of brain arteriovenous malformations (AVMs). The underlying pathophysiology of edema and hemorrhage after AVM resection still remains controversial. Over the last three decades, advances in neuroimaging, CBF, and cerebral perfusion pressure (CPP) measurement have both favored and contradicted the NBBP theory. At the same time, other theories have been proposed, including the occlusive hyperemia theory. We believe that both theories are related and complementary and that they both explain changes in hemodynamics after AVM resection. The purpose of this work is to review the current status of the NBBP theory 35 years after its original description.

Pseudoephedrine-induced Hemorrhage Associated with a Cerebral Vascular Malformation

Background:

Sympathomimetic-related intracerebral hemorrhage is well-documented. Most cases are associated with phenylpropanolamine use.

Case Report:

We report a case of intracerebral hemorrhage occurring in a middle-aged man who suffered from chronic sinusitis and had been ingesting pseudoephedrine daily for one year. This patient was previously well with no known cardiovascular risk factors. Clinical examination revealed no evidence of vasculitis nor coagulopathy and initial neuroimaging (i.e., computed tomography, angiography, magnetic resonance imaging) demonstrated no features consistent with aneurysm, arteriovenous malformation (AVM), cavernoma, nor cerebral metastases. A follow-up cerebral angiogram demonstrated a small AVM arising off a branch of the pericallosal artery and a small arteriovenous fistula arising off the costal marginal branch. The AVM was embolized without incident, however, the AVF was not accessible.

Conclusions:

Sympathomimetics have long been associated with intracerebral hemorrhage. Since 1979, over 30 published case reports have documented the relationship between phenylpropanolamine and stroke. Only one report links phenylpropanolamine consumption to an intracerebral hemorrhage in a patient with an AVM. There is a paucity of literature etiologically inculpating other ephedra alkaloids in the causation of intracerebral hemorrhage. This is a case of pseudoephedrine-induced intracerebral hemorrhage in a patient with an underlying vascular malformation.

Factors Determining the Clinical Complications of Radiosurgery for AVM

Purpose:

To identify the predictors of symptomatic post-radiation T2 signal change in patients with arteriovenous malformations (AVM) treated with radiosurgery.

Materials and Methods:

The charts of 211 consecutive patients with arteriovenous malformations treated with either gamma knife radisurgery or linear accelerator radiosurgery between 2000-2009 were retrospectively reviewed. 168 patients had a minimum of 12 months of clinical and radiologic follow-up following the procedure and complete dosage data. Pretreatment characteristics and dosimetric variables were analyzed to identify predictors of adverse radiation effects.

Results:

141 patients had no clinical symptomatic complications. 21 patients had global or focal neurological deficits attributed to symptomatic edema. Variables associated with development of symptomatic edema included a non-hemorrhagic symptomatic presentation compared to presentation with hemorrhage, p=0.001; OR (95%CI) = 6.26 (1.99, 19.69); the presence of venous rerouting compared to the lack of venous rerouting, p=0.031; OR (95% CI) = 3.25 (1.20, 8.80); radiosurgery with GKS compared to linear accelerator radiosurgery p = 0.012; OR (95% CI) = 4.58 (1.28, 16.32); and the presence of more than one draining vein compared to a single draining vein p = 0.032; OR (95% CI) = 2.82 (1.06, 7.50).

Conclusions:

We postulated that the higher maximal doses used with gamma knife radiosurgery may be responsible for the greater number of adverse radiation effects with this modality compared to linear accelerator radiosurgery. We found that AVMs with greater venous complexity and therefore instability resulted in more adverse treatment outcomes, suggesting that AVM angioarchitecture should be considered when making treatment decisions.

Endovascular management of arteriovenous malformations of the brain

Arteriovenous malformations (AVMs) of the brain are rare, complex, vascular lesions that can result in significant morbidity and mortality. Modern treatment of brain AVMs is a multimodality endeavor, requiring a multidisciplinary team with expertise in cerebrovascular neurosurgery, endovascular intervention, and radiation therapy in order to provide all therapeutic options and determine the most appropriate treatment regimen depending on patient characteristics and AVM morphology. Current therapeutic options include microsurgical resection, radiosurgery (focused radiation), and endovascular embolization. Endovascular embolization is primarily used as a preoperative adjuvant before microsurgery or radiosurgery. Palliative embolization has been used successfully to reduce the risk of hemorrhage, alleviate clinical symptoms, and preserve or improve neurological function in inoperable or nonradiosurgical AVMs. Less frequently, embolization is used as 'primary therapy' particularly for smaller, surgically difficult lesions. Current embolic agents used to treat brain AVMs include both solid and liquid agents. Liquid agents including N-butyl cyanoacrylate and Onyx are the most commonly used agents. As newer embolic agents become available and as microcatheter technology improves, the role of endovascular treatment for brain AVMs will likely expand.

Safety and efficacy using a detachable tip microcatheter in the embolization of pediatric arteriovenous malformations

PURPOSE

The treatment of deep-seeded pediatric brain arteriovenous malformations (AVMs) remains a challenging task. We describe our experience using a new detachable tip microcatheter in the embolization of brain arteriovenous malformations, pial arteriovenous fistulas, and vein of Galen malformations. We describe the safety and efficacy using a new detachable tip microcatheter in the treatment of pediatric deep brain arteriovenous malformations, pial malformations, and vein of Galen malformations.

METHODS

During a period of 9 months from March 2013 through January 2014, 11 pediatric patients in 14 procedures with 27 total injections were selected for treatment with a detachable tip under Food and Drug Administration (FDA) compassionate use exemption and were admitted to our department for treatment of their brain AVM using a liquid embolic agent and a detachable tip microcatheter. The ages of the patients ranged from 3 months to 18 years old.

RESULTS

Of the 27 total injections done, the tip detached in seven cases. For the 16 n-BCA injections, the tip detached six times (37.5 %), and for the 11 Onyx injections, the tip detached one time (9 %). There were no cases of premature microcatheter detachment during normal vessel navigation.

CONCLUSIONS

The introduction of these detachable tip microcatheters allows for a safe and relaxed injection that permits a true circumferential occlusion, and may further permit filling a larger amount of angioarchitecture without the risk of distal migration, or vessel damage during the usual rapid removal of non detachable micocatheters.

Brain parenchymal signal abnormalities associated with developmental venous anomalies in children and young adults

BACKGROUND AND PURPOSE

Abnormal signal in the drainage territory of developmental venous anomalies has been well described in adults but has been incompletely investigated in children. This study was performed to evaluate the prevalence of brain parenchymal abnormalities subjacent to developmental venous anomalies in children and young adults, correlating with subject age and developmental venous anomaly morphology and location.

MATERIALS AND METHODS

Two hundred eighty-five patients with developmental venous anomalies identified on brain MR imaging with contrast, performed from November 2008 through November 2012, composed the study group. Data were collected for the following explanatory variables: subject demographics, developmental venous anomaly location, morphology, and associated parenchymal abnormalities. Associations between these variables and the presence of parenchymal signal abnormalities (response variable) were then determined.

RESULTS

Of the 285 subjects identified, 172 met inclusion criteria, and among these subjects, 193 developmental venous anomalies were identified. Twenty-six (13.5%) of the 193 developmental venous anomalies had associated signal-intensity abnormalities in their drainage territory. After excluding developmental venous anomalies with coexisting cavernous malformations, we obtained an adjusted prevalence of 21/181 (11.6%) for associated signal-intensity abnormalities in developmental venous anomalies. Signal-intensity abnormalities were independently associated with younger subject age, cavernous malformations, parenchymal atrophy, and deep venous drainage of developmental venous anomalies.

CONCLUSIONS

Signal-intensity abnormalities detectable by standard clinical MR images were identified in 11.6% of consecutively identified developmental venous anomalies. Signal abnormalities are more common in developmental venous anomalies with deep venous drainage, associated cavernous malformation and parenchymal atrophy, and younger subject age. The pathophysiology of these signal-intensity abnormalities remains unclear but may represent effects of delayed myelination and/or alterations in venous flow within the developmental venous anomaly drainage territory.

Angiographic features help predict outcome after stereotactic radiosurgery for the treatment of pediatric arteriovenous malformations

PURPOSE

Arteriovenous malformations (AVMs) are a frequent cause of hemorrhagic stroke in children. Stereotactic radiosurgery (SRS) is an established treatment for these lesions, particularly those that are surgically inaccessible. Because only complete AVM obliteration is believed to protect against the future risk of hemorrhage, identifying lesion characteristics that predict response to therapy is an important objective. The goal of this study is to evaluate the influence of angiographic features of AVMs on the rate of obliteration following treatment with SRS.

METHODS

This is a retrospective cohort study of pediatric patients (age ≤18 years) treated with Gamma Knife SRS for cerebral AVMs between 2000 and 2012. Detailed angiographic data at the time of initial angiographic evaluation were prospectively recorded by experienced neurointerventional radiologists. The primary outcome was the rate of obliteration on a 3-year follow-up angiogram.

RESULTS

We identified 42 pediatric patients treated with SRS for cerebral AVMs. Twenty-seven patients completed 3-year angiographic follow-ups. Complete obliteration was seen in 30%, partial response in 67%, and no response in 4%. Higher SRS dose was associated with complete obliteration. Larger AVM diameter, presence of multiple draining veins, and presence of multiple draining veins reaching a sinus were associated with partial response. In this small cohort, diffuse AVM borders, presence of aneurysm, and pre-SRS embolization were not associated with obliteration.

CONCLUSIONS

Our study identifies AVMs in the pediatric population with a nidus diameter of <2.5 cm and a solitary draining vein as the most likely to undergo complete obliteration after SRS treatment.