Brain arteriovenous malformations

Complete seizure-free rates following interventional treatment of intracranial arteriovenous malformations: a systematic review and meta-analysis

Seizures are common presenting symptoms of intracranial arteriovenous malformations (AVMs). This systematic review and meta-analysis aims to assess the current evidence regarding complete seizure freedom rates following surgical resection, stereotactic radiosurgery (SRS), and/or endovascular embolization of intracranial AVMs. A systematic review of PubMed, Ovid MEDLINE, and Ovid EMBASE was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included manuscripts were methodically scrutinized for quality, spontaneous AVM-associated or hemorrhage-associated seizures, complete seizure-free rates following each interventional treatment, follow-up duration; determination methods of seizure outcomes, and average time-to-onset of recurrent seizures after each treatment. Manuscripts that described patients with nondisabling seizures or reduced seizure frequency in their seizure-free calculations were excluded. Seizure freedom rates following surgical resection, SRS, and endovascular embolization were compared via random-effect analysis. Thirty-four studies with a total of 1765 intracranial AVM patients presenting with spontaneous AVM-associated seizures and 408 patients presenting with hemorrhage-associated seizures were qualitatively analyzed. For patients presenting with AVM-associated seizures, the complete seizure-free rates were 73.0% (321/440 patients; 95% CI 68.8-77.1%) following surgical resection, 60.5% (376/622 patients; 95% CI 56.6-64.3%) following SRS, and 44.6% (29/65 patients; 95% CI 32.5-56.7%) following endovascular embolization alone. For patients presenting with either AVM-associated or hemorrhage-associated seizures, the complete seizure-free rates were 73.0% (584/800 patients; 95% CI 69.9-76.1%) following surgical resection, 46.4% (572/1233 patients; 95% CI 43.6-49.2%) following SRS, and 44.6% (29/65 patients; 95% CI 32.5-56.7%) following embolization. For patients presenting with either AVM-associated or hemorrhage-associated seizures, the overall improvements in seizure outcomes regardless of complete seizure freedom were 82.6% (661/800 patients; 95% CI 80.0-85.3%), 70.6% (870/1233 patients; 95% CI 68.0-73.1%), and 70.8% (46/65 patients; 95% CI 59.7-81.1%) following surgical resection, SRS, and embolization, respectively. No study reported information about the time-to-onset for recurrent seizures in any patient following treatment, as seizure outcomes were only described at the last follow-up visit. The available data suggests that surgical resection results in the highest rate of complete seizure freedom. The rate of seizure improvement following surgery increased further to 82.3% when including patients who had improved seizure frequency without achieving true seizure freedom. Complete seizure-free rates following SRS or embolization were more ambiguous and lower when compared to surgical resection. There is a need for high quality studies evaluating AVM treatment modalities and clearly defined seizure outcomes, as the current literature consists mostly of heterogenous patient populations.

[Relationship between the features of venous drainage of supratentorial arteriovenous malformations and the risk of intracranial hemorrhage]

BACKGROUND

Intracranial hemorrhage is the most common complication of cerebral arteriovenous malformations (AVM). In recent years, most studies devoted to the features of AVM functioning consider venous drainage as important factor influencing the rupture of malformation.

OBJECTIVE

To review the literature data on the relationship between the features of venous drainage of cerebral arteriovenous malformations and intracranial hemorrhage.

MATERIAL AND METHODS

We found 43 studies discussing the features of AVM venous drainage for the period from 1982 to 2020. Most of reports were published between 2005 and 2020.

RESULTS

Deep venous drainage and a single drainage vein were the most significant factors influencing the risk of hemorrhage. Venous ectasia, reflux, stenosis, number, length and tortuosity of drainage veins were less important for the risk of AVM rupture.

CONCLUSION

Analysis of the features of AVM venous drainage can make it possible to predict the natural course of disease and risk of intracranial hemorrhage. These aspects are essential for neurosurgical treatment.

Segmentation techniques of brain arteriovenous malformations for 3D visualization: a systematic review

BACKGROUND

Visualization, analysis and characterization of the angioarchitecture of a brain arteriovenous malformation (bAVM) present crucial steps for understanding and management of these complex lesions. Three-dimensional (3D) segmentation and 3D visualization of bAVMs play hereby a significant role. We performed a systematic review regarding currently available 3D segmentation and visualization techniques for bAVMs.

METHODS

PubMed, Embase and Google Scholar were searched to identify studies reporting 3D segmentation techniques applied to bAVM characterization. Category of input scan, segmentation (automatic, semiautomatic, manual), time needed for segmentation and 3D visualization techniques were noted.

RESULTS

Thirty-three studies were included. Thirteen (39%) used MRI as baseline imaging modality, 9 used DSA (27%), and 7 used CT (21%). Segmentation through automatic algorithms was used in 20 (61%), semiautomatic segmentation in 6 (18%), and manual segmentation in 7 (21%) studies. Median automatic segmentation time was 10 min (IQR 33), semiautomatic 25 min (IQR 73). Manual segmentation time was reported in only one study, with the mean of 5-10 min. Thirty-two (97%) studies used screens to visualize the 3D segmentations outcomes and 1 (3%) study utilized a heads-up display (HUD). Integration with mixed reality was used in 4 studies (12%).

CONCLUSIONS

A golden standard for 3D visualization of bAVMs does not exist. This review describes a tendency over time to base segmentation on algorithms trained with machine learning. Unsupervised fuzzy-based algorithms thereby stand out as potential preferred strategy. Continued efforts will be necessary to improve algorithms, integrate complete hemodynamic assessment and find innovative tools for tridimensional visualization.

Cerebral Revascularization for the Management of Symptomatic Pure Arterial Malformations

Background: Pure arterial malformations (PAMs) are extremely rare abnormalities defined as dilated, overlapping, and tortuous arteries with a coil-like appearance in the absence of venous components. Over the last half century, only seven published reports have described cases of patients with PAMs who received treatment. Methods: Here, we report two cases of women with PAMs who received surgical treatment, and we present a systematic review of the literature. We searched the PubMed, Embase, Web of Science, and Medline databases (up until October 1, 2021) for relevant publications. We performed independent-sample t-tests and Fisher's exact tests to compare continuous and categorical characteristics among the available cases. Results: Our first patient was a 43-year-old woman with PAM of the left internal carotid artery (ICA), who received an ICA-radial artery (RA)-M2 bypass. Post-operative digital subtraction angiography (DSA) revealed the disappearance of the left ICA PAM without ischemic events during follow-up. The second patient was a 53-year-old woman with PAMs of the right ICA and posterior cerebral artery. The P1 lesion was treated by proximal occlusion combined with a superficial temporal artery-P2 bypass. During the 12-month follow-up period, the size of the PAMs decreased significantly as indicated by the post-operative DSA showing the absence of hemorrhages. Our systematic review, which includes 56 PAMs, shows that the reported PAMs were more common in the anterior circulation (33/56, 58.9%) than in the posterior circulation (11/56, 19.7%). Bilateral PAMs were more likely to affect bilateral anterior cerebral arteries (ACA) (ACAbilateral vs. ACAunilateral: 63.6 vs. 26.2%, p = 0.02). In addition, PAMs involving the anterior circulation were likely to affect multiple arteries (anteriormulti vs. posteriormulti: 30.3 vs. 0%, p = 0.038). Conclusion: We found very few reports on treated PAMs; further studies with large sample sizes and long follow-up periods are required to explore the appropriate treatment strategy for PAMs.

Radiomics Analysis for Predicting Epilepsy in Patients With Unruptured Brain Arteriovenous Malformations

Objectives: To investigate the association between radiomics features and epilepsy in patients with unruptured brain arteriovenous malformations (bAVMs) and to develop a prediction model based on radiomics features and clinical characteristics for bAVM-related epilepsy.

Methods: This retrospective study enrolled 176 patients with unruptured bAVMs. After manual lesion segmentation, a total of 858 radiomics features were extracted from time-of-flight magnetic resonance angiography (TOF-MRA). A radiomics model was constructed, and a radiomics score was calculated. Meanwhile, the demographic and angioarchitectural characteristics of patients were assessed to build a clinical model. Incorporating the radiomics score and independent clinical risk factors, a combined model was constructed. The performance of the models was assessed with respect to discrimination, calibration, and clinical usefulness.

Results: The clinical model incorporating 3 clinical features had an area under the curve (AUC) of 0.71. Fifteen radiomics features were used to build the radiomics model, which had a higher AUC of 0.78. Incorporating the radiomics score and clinical risk factors, the combined model showed a favorable discrimination ability and calibration, with an AUC of 0.82. Decision curve analysis (DCA) demonstrated that the combined model outperformed the clinical model and radiomics model in terms of clinical usefulness.

Conclusions: The radiomics features extracted from TOF-MRA were associated with epilepsy in patients with unruptured bAVMs. The radiomics-clinical nomogram, which was constructed based on the model incorporating the radiomics score and clinical features, showed favorable predictive efficacy for bAVM-related epilepsy.

Endovascular treatment of brain arteriovenous malformations involving the anterior cerebral artery

To date, at least to the best of our knowledge, there are only limited studies available on the endovascular treatment (EVT) of brain arteriovenous malformations (BAVMs) involving the anterior cerebral artery (ACA), thus termed ACA-BAVMs. The present study retrospectively examined 60 patients with ACA-BAVMs treated with EVT. The patients were aged between 10 and 72 years (mean age, 35.4±7.0 years) and included 28 females (46.7%, 28/60). The ACA-BAVMs were divided into three types: Type I BAVMs were those located below and in front of the corpus callosum genu, type II BAVMs were those located at the upper area of the corpus callosum from the genu to the anterior portion of corpus callosum body, and type III BAVMs were those located from the anterior portion of corpus callosum body to the splenium of the corpus callosum. There were 9 (15%, 9/60), 15 (25%, 15/60) and 36 (60%, 36/60) patients with type I, II and III ACA-BAVMs, respectively. Statistical analysis revealed that the posterior cerebral artery (PCA) tended to be involved in type II and III BAVMs. All patients were treated using EVT. During EVT, there were 3 cases of intraoperative bleeding (5%, 3/60), which tended to occur in type I and II ACA-BAVMs. The other 57 cases (95%, 57/60) had no complications and new neurological deficits. At the time of discharge, 48 (80%, 48/60) patients had a Glasgow Outcome Scale score of 5. During the clinical follow-up period, 47 patients were classified according to the modified Rankin Scale (mRS) score; 39 (83%, 39/47) patients presented with an mRS score of 0. On the whole, the present study demonstrated that EVT may be a safe treatment for ACA-BAVMs.

Angioarchitectural features amongst patients with unruptured brain arteriovenous malformations presenting with headache: findings from a single center retrospective review of 76 patients

Background

Brain arteriovenous malformations (AVMs) consist of abnormal connections between arteries and veins via an interposing nidus. While hemorrhage is the most common presentation, unruptured AVMs can present with headaches, seizures, neurological deficits, or be found incidentally. It remains unclear as to what AVM characteristics contribute to pain generation amongst unruptured AVM patients with headaches.

Methods

To assess this relationship, the current study evaluates angiographic and clinical features amongst patients with unruptured brain AVMs presenting with headache. Loyola University Medical Center medical records were queried for diagnostic codes corresponding to AVMs. In patients with unruptured AVMs, we analyzed the correlation between the presenting symptom of headache and various demographic and angiographic features.

Results

Of the 144 AVMs treated at our institution between 1980 and 2017, 76 were unruptured and had sufficient clinical data available. Twenty-three presented with headaches, while 53 patients had other presenting symptoms. Patients presenting with headache were less likely to have venous stenosis compared to those with a non-headache presentation (13 % vs. 36 %, p = 0.044).

Conclusions

Our study suggests that the absence of venous stenosis may contribute to headache symptomatology. This serves as a basis for further study of correlations between AVM angioarchitecture and symptomatology to direct headache management in AVM patients.

The role of mural cells in hemorrhage of brain arteriovenous malformation

Brain arteriovenous malformation (bAVM) is the most common cause of intracranial hemorrhage (ICH), particularly in young patients. However, the exact cause of bAVM bleeding and rupture is not yet fully understood. In bAVMs, blood bypasses the entire capillary bed and directly flows from arteries to veins. The vessel walls in bAVMs have structural defects, which impair vascular integrity. Mural cells are essential structural and functional components of blood vessels and play a critical role in maintaining vascular integrity. Changes in mural cell number and coverage have been implicated in bAVMs. In this review, we discussed the roles of mural cells in bAVM pathogenesis. We focused on 1) the recent advances in human and animal studies of bAVMs; 2) the importance of mural cells in vascular integrity; 3) the regulatory signaling pathways that regulate mural cell function. More specifically, the platelet-derived growth factor-B (PDGF-B)/PDGF receptor-β (PDGFR-β), EphrinB2/EphB4, and angiopoietins/tie2 signaling pathways that regulate mural cell-recruitment during vascular remodeling were discussed in detail.

SMASH-U aetiological classification: A predictor of long-term functional outcome after intracerebral haemorrhage

BACKGROUND

SMASH-U is a systematic aetiological classification system for intracerebral haemorrhage (ICH) proven to be a predictor of post-ICH haematoma expansion and mortality. However, its role in predicting functional outcome remains elusive. Therefore, we aimed to investigate whether SMASH-U is associated with long-term functional outcome after ICH and improves the accuracy of prediction when added to max-ICH score.

METHODS

Consecutive acute ICH patients from 2012 to 2018 from the neurology department of Tongji Hospital were enrolled. ICH aetiology was classified according to the SMASH-U system. The association of SMASH-U with 12-month functional outcome after ICH and the predictive value were evaluated.

RESULTS

Of 1938 ICH patients, the aetiology of 1295 (66.8%) patients were classified as hypertension, followed by amyloid angiopathy (n = 250, 12.9%), undetermined (n = 159, 8.2%), structural lesions (n = 149, 7.7%), systemic disease (n = 74, 3.8%) and medication (n = 11, 0.6%). The baseline characteristics were different among the six aetiologies. In multivariate analysis, SMASH-U was proven to be a predictor of 12-month unfavourable functional outcome. When adding the SMASH-U system, the predictive performance of max-ICH score was improved (area under the receiver operating characteristic curve from 0.802 to 0.812, p = 0.010) and the predictive accuracy was enhanced (integrated discrimination improvement [IDI]: 1.60%, p < 0.001; continuous net reclassification improvement [NRI]: 28.16%, p < 0.001; categorical NRI: 3.34%, p = 0.004).

CONCLUSIONS

SMASH-U predicted long-term unfavourable functional outcomes after acute ICH and improved the accuracy of prediction when added to max-ICH score. Integrating the aetiology to a score model to predict the post-ICH outcome may be meaningful and worthy of further exploration.

Progress and prospects of mechanotransducers in shear stress-sensitive signaling pathways in association with arteriovenous malformation

Arteriovenous malformations are congenital vascular lesions characterized by a direct and tangled connection between arteries and veins, which disrupts oxygen circulation and normal blood flow. Arteriovenous malformations often occur in the patient with hereditary hemorrhagic telangiectasia. The attempts to elucidate the causative factors and pathogenic mechanisms of arteriovenous malformations are now still in progress. Some studies reported that shear stress in blood flow is one of the factors involved in arteriovenous malformations manifestation. Through several mechanotransducers harboring the endothelial cells membrane, the signal from shear stress is transduced towards the responsible signaling pathways in endothelial cells to maintain cell homeostasis. Any disruption in this well-established communication will give rise to abnormal endothelial cells differentiation and specification, which will later promote arteriovenous malformations. In this review, we discuss the update of several mechanotransducers that have essential roles in shear stress-induced signaling pathways, such as activin receptor-like kinase 1, Endoglin, Notch, vascular endothelial growth factor receptor 2, Caveolin-1, Connexin37, and Connexin40. Any disruption of these signaling potentially causes arteriovenous malformations. We also present some recent insights into the fundamental analysis, which attempts to determine potential and alternative solutions to battle arteriovenous malformations, especially in a less invasive and risky way, such as gene treatments.

Intracranial Vascular Abnormalities in Children

Intracranial vascular abnormalities rarely are encountered in primary care. Many of the pathologies are occult and prognosis varies widely between inconsequential variants of anatomy to acutely life-threatening conditions. Consequently, there often is a great deal of anxiety associated with any potential diagnosis. This article reviews anatomic intracranial vascular lesions, including vascular malformations (arteriovenous malformations/arteriovenous fistulae and cavernous malformations), structural arteriopathies (aneurysms and moyamoya), and common developmental anomalies of the vasculature. The focus includes a general overview of anatomy, pathology, epidemiology, and key aspects of evaluation for the primary care provider and a review of common questions encountered in practice.

Current concepts and perspectives on brain arteriovenous malformations: A review of pathogenesis and multidisciplinary treatment

Brain arteriovenous malformations (bAVMs) are unusual vascular pathologies characterized by the abnormal aggregation of dilated arteries and veins in the brain parenchyma and for which the absence of a normal vascular structure and capillary bed leads to direct connections between arteries and veins. Although bAVMs have long been believed to be congenital anomalies that develop during the prenatal period, current studies show that inflammation is associated with AVM genesis, growth, and rupture. Interventional treatment options include microsurgery, stereotactic radiosurgery, and endovascular embolization, and management often comprises a multidisciplinary combination of these modalities. The appropriate selection of patients with brain arteriovenous malformations for interventional treatment requires balancing the risk of treatment complications against the risk of hemorrhaging during the natural course of the pathology; however, no definitive guidelines have been established for the management of brain arteriovenous malformations. In this paper, we comprehensively review the current basic and clinical studies on bAVMs and discuss the contemporary status of multidisciplinary management of bAVMs.

Cerebral Arteriovenous Malformation Recurrence After Complete Surgical Excision in an Adult: Case Report and Review of the Literature

Angiographically confirmed complete surgical excision of brain arteriovenous malformations (bAVMs) is conventionally considered curative. Recurrence in adults is rarely encountered; only 18 cases have been reported in the English literature over the past 30 years. The potential for recurrence and consequent need for routine long-term follow-up are important considerations in the management of these lesions. We report a case of a 23-year-old female with a recurrent bAVM discovered incidentally on routine imaging three years after complete surgical excision. We review the existing literature and discuss the options for surveillance and management.

Intracerebral and subarachnoid hemorrhage in pregnancy

Maternal stroke occurs in around 34 out of every 100,000 deliveries and is responsible for around 5%-12% of all maternal deaths. It is most commonly hemorrhagic, and women are at highest risk for developing pregnancy-related hemorrhage during the early postpartum period through 6 weeks following the delivery. The most common causes of hemorrhagic stroke in pregnant patients are arteriovenous malformations and cerebral aneurysms. Management is similar to that for acute hemorrhagic stroke in the nonpregnant population with standard use of computed tomography and judicious utilization of intracranial vessel imaging and contrast. The optimal delivery method is evaluated on a case-by-case basis, and cesarean delivery is not always required. As most current studies are limited by retrospective design, relatively small sample sizes, and heterogeneous study term definitions, strong and comprehensive evidence-based guidelines on the management of acute hemorrhagic stroke in pregnant patients are still lacking. In the future, multicenter registries and prospective studies with uniform definitions will help improve management strategies in this complex patient population.

Intermediate-grade brain arteriovenous malformations and the boundary of operability using the supplemented Spetzler-Martin grading system

OBJECTIVE

Supplemented Spetzler-Martin grading (Supp-SM), which is the combination of Spetzler-Martin and Lawton-Young grades, was validated as being more accurate than stand-alone Spetzler-Martin grading, but an operability cutoff was not established. In this study, the authors surgically treated intermediate-grade AVMs to provide prognostic factors for neurological outcomes and to define AVMs at the boundary of operability.

METHODS

Surgically treated Supp-SM intermediate-grade (5, 6, and 7) AVMs were analyzed from 2011 to 2018 at two medical centers. Worsened neurological outcomes were defined as increased modified Rankin Scale (mRS) scores on postoperative examinations. A second analysis of 2000-2011 data for Supp-SM grade 6 and 7 AVMs was performed to determine the subtypes with improved or unchanged outcomes. Patients were separated into three groups based on nidus size (S1: < 3 cm, S2: 3-6 cm, S3: > 6 cm) and age (A1: < 20 years, A2: 20-40 years, A3: > 40 years), followed by any combination of the combined supplemented grade: low risk (S1A1, S1A2, S2A1), intermediate risk (S2A2, S1A3, S3A1, or high risk (S3A3, S3A2, S2A3).

RESULTS

Two hundred forty-six patients had intermediate Supp-SM grade AVMs. Of these patients, 102 had Supp-SM grade 5 (41.5%), 99 had Supp-SM grade 6 (40.2%), and 45 had Supp-SM grade 7 (18.3%). Significant differences in the proportions of patients with worse mRS scores at follow-up were found between the groups, with 24.5% (25/102) of patients in Supp-SM grade 5, 29.3% (29/99) in Supp-SM grade 6, and 57.8% (26/45) in Supp-SM grade 7 (p < 0.001). Patients with Supp-SM grade 7 AVMs had significantly increased odds of worse postoperative mRS scores (p < 0.001; OR 3.7, 95% CI 1.9-7.3). In the expanded cohort of 349 Supp-SM grade 6 AVM patients, a significantly higher proportion of older patients with larger Supp-SM grade 6 AVMs (grade 6+, 38.6%) had neurological deterioration than the others with Supp-SM grade 6 AVMs (22.9%, p = 0.02). Conversely, in an expanded cohort of 197 Supp-SM grade 7 AVM patients, a significantly lower proportion of younger patients with smaller Supp-SM grade 7 AVMs (grade 7-, 19%) had neurological deterioration than the others with Supp-SM grade 7 AVMs (44.9%, p = 0.01).

CONCLUSIONS

Patients with Supp-SM grade 7 AVMs are at increased risk of worse postoperative neurological outcomes, making Supp-SM grade 6 an appropriate operability cutoff. However, young patients with small niduses in the low-risk Supp-SM grade 7 group (grade 7-) have favorable postoperative outcomes. Outcomes in Supp-SM grade 7 patients did not improve with surgeon experience, indicating that the operability boundary is a hard limit reflecting the complexity of high-grade AVMs.

The efficacy and deficiency of contemporary treatment for spinal cord arteriovenous shunts

Contemporary treatments for spinal cord arteriovenous shunts are only based on clinicians' treatment experiences and expertise due to its rarity. We reviewed the clinical course of the largest multi-cantered cohort to evaluate the efficacy and deficiency of contemporary interventional treatments for spinal cord arteriovenous shunts. The clinical features, treatment results and clinical outcomes of 463 spinal cord arteriovenous shunts patients were retrospectively assessed. The main outcome was the neurological deterioration that was evaluated based on the modified Aminoff and Logue scale. According to post-treatment DSA, complete obliteration was defined as disappearance of the intradural lesion, whereas partial obliteration was defined as any residual intradural lesion remaining visible and was further categorized as shunt-reduction obliteration (the nidus or shunt points was reduced) or palliative obliteration (only obliterated aneurysms or feeders). Cure rate was 40.6% for whole cohort, 58.5% after microsurgery, and 26.4% after embolization. The curative resection was associated with non-metameric lesions, lesions with a maximum diameter < 3 cm and lesions without anterior sulcal artery supply. The curative embolization was associated with fistula-type lesions, non-metameric lesions, and main drainage diameter < 1.5 mm. Permanent treatment-related neurological deficits rate was 11.2% for the whole cohort, 16.1% after microsurgery, and 5.6% after embolization. The pre-treatment clinical deterioration rate was 32.5%/year, which decreased to 9.3%/year after clinical interventions. After partial treatment, the long-term acute and gradual deterioration rate were 5.3%/year and 3.6%/year, respectively. The acute deteriorations were associated with metameric lesions, craniocervical lesions, lesions with a maximum diameter ≥2 cm and residual aneurysm. Residual aneurysm was the only predictor of acute deterioration for non-metameric spinal cord arteriovenous shunts. The gradual deteriorations were associated with palliative obliteration, absence of pre-treatment acute deterioration and intact main drainage. Although clinical risks of spinal cord arteriovenous shunts were reduced after clinical interventions, contemporary treatments for spinal cord arteriovenous shunt remains associated with considerable risks and incomplete efficacy. Individualized treatment plans should be adopted according to the angioarchitectural features and major clinical risks of specific lesions. There is a higher opportunity for complete obliteration for lesions with simple angioarchitecture. However, regarding most of spinal cord arteriovenous shunts with complex vascular anatomy, partial treatment is the only choice. For these patients, palliative obliteration targeting the aneurysms is recommended for reducing hemorrhagic risk, whereas shunt-reduction obliteration is necessary for non-haemorrhagic myelopathy. Contemporary treatment is ineffective in reducing hemorrhagic risk of incurable metameric spinal cord arteriovenous shunts.

Clinical Characteristics, Angioarchitecture and Management of Tectum Mesencephali Arteriovenous Malformations : A Retrospective Case Series

PURPOSE

Tectum mesencephali arteriovenous malformations (TM-AVMs) are rare lesions deeply located close to eloquent structures making them challenging to treat. We aimed to present clinical presentation, angiographic features and treatment strategies of TM-AVMs through a single center retrospective case series.

METHODS

A TM-AVMs is defined as a nidus located in the parenchyma or on the pia mater of the posterior midbrain. Records of consecutive patients admitted with TM-AVMs over a 21-year period were retrospectively analyzed. Vascular anatomy of the region is also reviewed.

RESULTS

In this study 13 patients (1.63% of the complete cohort; 10 males), mean age 48 years, were included. All patients presented with intracranial hemorrhage and two patients (15%) died after an early recurrent bleeding. Mean size of the TM-AVMs was 10.1 ± 5 mm. Multiple arterial feeders were noted in every cases. Of the patients 11 underwent an exclusion treatment, 8 via embolization (6 via arterial access and 2 via venous access) and 4 via stereotactic radiosurgery (SRS) (1 patient received both). Overall success treatment rate was 7/11 patients (64% overall; 63% in the embolization group, 25% in the SRS group). Two hemorrhagic events led to a worsened outcome, one during embolization and one several years after SRS. All other patients remained clinically stable or improved.

CONCLUSION

The TM-AVMs are rare but stereotypic lesions found in a hemorrhagic context. Multiple arterial feeders are always present. Endovascular treatment seems to be an effective technique with relatively low morbidity; SRS had a low success rate but was only use in a limited number of patients.

Preradiosurgery embolization in reducing the postoperative hemorrhage rate for patients with cerebral arteriovenous malformations: a systematic review and meta-analysis

Few studies have examined the postoperative hemorrhage rate of cerebral arteriovenous malformations (AVMs) treated by embolization prior to stereotactic radiosurgery. The objective of this analysis was to compare the postoperative hemorrhage rate between AVMs treated with and those treated without preradiosurgery embolization. A systematic search of the PubMed and Embase databases was performed with no restriction on the publication period. Based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we included studies with sufficient baseline and outcome data. The analysis was performed using Comprehensive Meta-Analysis (CMA) 2.0. Eleven studies comprising 2591 patients were eligible for analysis. There was no significant difference in the postoperative hemorrhage rate between patients who had undergone embolization followed by SRS and those who had undergone SRS alone (OR 1.140, 95% CI 0.851-1.526, p = 0.38). The obliteration rate was significantly lower in the E + SRS group than in the SRS group (OR 0.586, 95% CI 0.398-0.863, p = 0.007). No significant difference in permanent neurological deficits was identified between patients who had undergone embolization followed by SRS and those who had undergone SRS alone (OR 1.175, 95% CI 0.626-2.206, p = 0.616). Available data suggested that preradiosurgery embolization did not reduce the postoperative hemorrhage rate and resulted in a significantly lower obliteration rate than treatment with SRS alone.

Conventional and advanced MRI evaluation of brain vascular malformations

Vascular malformations (VMs) of the central nervous system (CNS) include a wide range of pathological conditions related to intra and extracranial vessel abnormalities. Although some VMs show typical neuroimaging features, other VMs share and overlap pathological and neuroimaging features that hinder an accurate differentiation between them. Hence, it is not uncommon to misclassify different types of VMs under the general heading of arteriovenous malformations. Thorough knowledge of the imaging findings of each type of VM is mandatory to avoid these inaccuracies. Conventional MRI sequences, including MR angiography, have allowed the evaluation of CNS VMs without using ionizing radiation. Newer MRI techniques, such as susceptibility-weighted imaging, black blood sequences, arterial spin labeling, and 4D flow imaging, have an added value of providing physiopathological data in real time regarding the hemodynamics of VMs. Beyond MR images, new insights using 3D printed models are being incorporated as part of the armamentarium for a noninvasive evaluation of VMs. In this paper, we briefly review the pathophysiology of CNS VMs, focusing on the MRI findings that may be helpful to differentiate them. We discuss the role of each conventional and advanced MRI sequence for VMs assessment and provide some insights about the value of structured reports of 3D printing to evaluate VMs.

Homocysteine Level and Risk of Hemorrhage in Brain Arteriovenous Malformations

Objective

We aimed to investigate the risk factors associated with hemorrhage and clarify the relation of homocysteine (Hcy) with brain arteriovenous malformations (bAVMs).

Method

We retrospectively reviewed bAVM patients from Beijing Tiantan Hospital between January 2019 and December 2019. Clinical and laboratory variables were analyzed in enrolled patients with bAVMs. Potential predictors associated with hemorrhage were evaluated by logistic regression analysis.

Results

A total of 143 bAVM patients were identified in the study, including 69 unruptured and 74 ruptured cases. Patients with hemorrhage were less likely to have hyperhomocysteinemia (P = 0.023). Logistic regression analysis showed that increased maximum diameter of bAVM lesions (odds ratio (OR) 0.634, 95% confidence intervals (CI) 0.479-0.839; P = 0.001) and serum Hcy level (OR 0.956, 95% CI 0.920-0.993; P = 0.021) were associated with lower risk of hemorrhage in bAVMs.

Conclusion

The present study provided evidence regarding the association between serum Hcy and hemorrhage in patients with bAVMs. Higher Hcy level was correlated with a lower risk of rupture. Detection of factors for subsequent hemorrhage is necessary to develop therapeutic strategies for bAVMs preferably.

Ultrasound-visualized, site-specific vascular embolization using magnetic protein microcapsules

Imaging-guided vascular embolization is frequently performed on patients with advanced hepatocellular carcinoma (HCC) to alleviate symptoms and extend their survival time. Current operation procedures are not only painful for patients, but are also inaccurate in tumor targeting after the release of embolic agents from the catheter, leading to injury to healthy tissues simultaneously. In this study, we developed an ultrasound-visualized, site-specific vascular embolization strategy with magnetic protein microcapsules (MPMs). MPMs were fabricated using a rapid emulsification method, giving it a smooth surface and a core-shell structure. Their diameters could be controlled within 10 μm, allowing them to pass through capillaries. The core-shell structure and loading of magnetic Fe3O4 endowed MPMs with good contrast under ultrasound imaging and magnetically inducible targeting properties, as well as aggregation response even under flowing conditions. In vitro cytotoxicity and hemolysis evaluation demonstrated good biocompatibility of the MPMs. Furthermore, mock embolization showed that cell death could be induced by aggregation of the MPMs. Such a combination of real-time monitoring using ultrasound and control on targeted vascular embolization might be a breakthrough in the treatment of advanced HCC.

CTCFL expression is associated with cerebral vascular abnormalities

CTCFL is expressed in testis, oocytes and embryonic stem cells, and is aberrantly expressed in malignant cells, and is classified as a cancer-testis gene. We have previously shown by using a tetracycline-inducible Ctcfl transgene that inappropriate expression of Ctcfl negatively impacts fetal development and causes early postnatal lethality in the mouse. The affected pups displayed severe vascular abnormalities and localized hemorrhages in the brain evocative of cerebral cavernous malformations (CCM) and arteriovenous malformations (AVM) in humans. Thus, we aim to analyze; a) the presence of CCM-related proteins CCM1/KRIT1, CCM2/malcavernin and CCM3/PDCD10 in Ctcfl transgenic animals and, b) whether there is CTCFL expression in human CCM and AVM tissues. Ctcfl transgenic animals exhibited increased CD31 expression in vascular areas of the dermis and periadnexal regions but no difference was observed for vWF and α-SMA expressions. CCM-related proteins CCM1/KRIT1, CCM2/malcavernin and CCM3/PDCD10 were aberrantly expressed in coronal sections of the head in transgenic animals. We also observed CTCFL expression in human CCMs and AVMs. The induced expression of CTCFL resulting in vascular brain malformations in mice combined with the presence of CTCFL in human vascular malformations provide new insights into the role of this gene in vascular development in humans.

Imaging Characteristics and Endovascular Treatment of Brain Arteriovenous Malformations Mainly Fed by the Posterior Cerebral Artery

Background: A BAVM that is mainly supplied by the posterior cerebral artery (PCA) lies deeply in the middle of the bilateral posterior hemispheres. Few studies have investigated the imaging characteristics and endovascular treatment (EVT) of brain arteriovenous malformations (BAVMs) in this area.

Methods: A retrospective study was performed for patients who were diagnosed with PCA-BAVMs from January 2015 to December 2019. The PCA-BAVMs were divided into type I and type II according to their feeding arteries. Type I PCA-BAVMs were supplied by the posterior choroidal artery (PchA) from the PCA. They could be further subdivided into type Ia and type Ib. Type II PCA-BAVMs were supplied by the temporal or occipital branch from the PCA. They could also be further subdivided into type IIa and IIb. Targeted embolization of the risk factors was the main aim of EVT.

Results: Forty-two patients were identified, with age ranging from 6 to 63 years. Twenty-four cases belonged to type I (57.1%, 24/42), including 6 Ia cases and 18 Ib cases. Eighteen cases belonged to type II (42.9%, 18/42), including 7 IIa cases and 11 IIb cases. Immediate complete or nearly complete embolization was achieved in 17 (40.5%, 17/42) cases. Partial embolization was achieved in 25 (59.5%, 25/42) cases. Two (4.8%, 2/42) patients experienced intraoperative or postoperative bleeding. The GOS scores at discharge were 3, 4, and 5 in 2 (4.8%, 2/42), 2 (4.8%, 2/42), and 38 (90.4%, 38/42) cases, respectively. There was no statistical difference between patients in type I and type II groups regarding age, BAVM rupture, SM grade, immediate extent of obliteration, and prognosis. Deep venous drainage was more common in patients of the type I group (P < 0.001).

Conclusions: Our classification of the PCA-BAVMs was based on the segmentation of the PCA, which is a reasonable approach and could guide the strategy of EVT. EVT is a reasonable option for the PCA-BAVMs. The main aim of EVT is to secure the weak structures. A targeted EVT aimed at the ruptured part of the BAVM can reduce the risk of early rebleeding.

Unruptured Arteriovenous Malformations: Do We Have an Answer After the Final Follow-Up of ARUBA? A Bayesian Viewpoint

Brain arteriovenous malformations (bAVMs) are vascular lesions that carry significant morbidity and mortality risk upon rupture. bAVM rupture causes either intracerebral or intraventricular hemorrhage, or both. In 2014, the first results of the ARUBA trial (A Randomized Trial of Unruptured Brain Arteriovenous Malformations) were published in The Lancet, causing a paradigm shift in clinical practice and suggesting the superiority of medical treatment in terms of mortality or stroke compared with any intervention designed to obliterate the AVM. In 2020, the final results of the ARUBA trial were published. In this Viewpoint, we critically review the clinical equipoise behind the trial, highlight issues regarding external validity, and place the results of the trial in the context of other results in scientific literature of bAVMs using Bayesian inference. ARUBA is a trial of decision-making, and only proper knowledge of the nuances of its interpretation within the broader context of bAVM research can lead to proper decision-making when confronted with patients with unruptured bAVMs.

Early Outcomes and Complications of Endovascular Treatment of Cerebral Arteriovenous Malformations in Pediatric Patients

INTRODUCTION

Arteriovenous malformations (AVMs) are the commonest cause of hemorrhagic stroke in children. Endovascular embolization is a feasible treatment modality, but cure rates are heterogenous from one series to another. We aimed to describe the immediate obliteration rates and periprocedural complications of embolization of pediatric AVMs.

METHODS

Between 2011 and 2019, participants below 18 years of age with AVMs treated by the same neurosurgeon at a single center were included. The clinical features, immediate angiographic results, and periprocedural complications were retrospectively collected from the clinical records.

RESULTS

Thirty-four embolization sessions were performed on 20 children (12 females with a mean age of 13). Intracranial hemorrhage was the most common presentation (75%), and the majority were frontal (30%) and basal ganglia (30%) lesions. An immediate complete angiographic obliteration was achieved in 9 patients (45%) with low-grade lesions (Spetzler-Martin grade I and II). NBCA was the most common embolic agent used (52.9%). Complications were reported in 3 (8.8%) out of 34 sessions. Two of them were intraoperative perforations with clinical consequences. A slight cortical hemorrhage during the procedure was observed in 1 patient without clinical repercussions.

DISCUSSION

This single-surgeon single-center experience suggests that endovascular treatment is a safe and efficient treatment for pediatric AVMs. Pediatric prognostic scores for a suitable selection of candidates are needed. Further studies are required to validate these results.

Brain vascular biology

The complex development of the brain vascular system can be broken down by embryonic stages and anatomic locations, which are tightly regulated by different factors and pathways in time and spatially. The adult brain is relatively quiescent in angiogenesis. However, under disease conditions, such as trauma, stroke, or tumor, angiogenesis can be activated in the adult brain. Disruption of any of the factors or pathways may lead to malformed vessel development. In this chapter, we will discuss factors and pathways involved in normal brain vasculogenesis and vascular maturation, and the pathogenesis of several brain vascular malformations.

Management of Intracerebral Hemorrhage: JACC Focus Seminar

Intracerebral hemorrhage (ICH) accounts for a disproportionate amount of stroke-related morbidity and mortality. Although chronic hypertension and cerebral amyloid angiopathy are the underlying cerebral vasculopathies accounting for the majority of ICH, there are a broad range of potential causes, and effective management requires accurate identification and treatment of the underlying mechanism of hemorrhage. Magnetic resonance imaging and vascular imaging techniques play a critical role in identifying disease mechanisms. Modern treatment of ICH focuses on rapid stabilization, often requiring urgent treatment of mass effect, aggressive blood pressure reduction and correction of contributing coagulopathies to achieve hemostasis. We discuss management of patients with ICH who continue to require long-term anticoagulation, the interaction of ICH with neurodegenerative diseases, and our approach to prognostication after ICH. We close this review with a discussion of novel medical and surgical approaches to ICH treatment that are being tested in clinical trials.

Stereotactic Radiosurgery for Spetzler-Martin Grade I and II Arteriovenous Malformations: International Society of Stereotactic Radiosurgery (ISRS) Practice Guideline

BACKGROUND

No guidelines have been published regarding stereotactic radiosurgery (SRS) in the management of Spetzler-Martin grade I and II arteriovenous malformations (AVMs).

OBJECTIVE

To establish SRS practice guidelines for grade I-II AVMs on the basis of a systematic literature review.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant search of Medline, Embase, and Scopus, 1986-2018, for publications reporting post-SRS outcomes in ≥10 grade I-II AVMs with a follow-up of ≥24 mo. Primary endpoints were obliteration and hemorrhage; secondary outcomes included Spetzler-Martin parameters, dosimetric variables, and “excellent” outcomes (defined as total obliteration without new post-SRS deficit).

RESULTS

Of 447 abstracts screened, 8 were included (n = 1, level 2 evidence; n = 7, level 4 evidence), representing 1102 AVMs, of which 836 (76%) were grade II. Obliteration was achieved in 884 (80%) at a median of 37 mo; 66 hemorrhages (6%) occurred during a median follow-up of 68 mo. Total obliteration without hemorrhage was achieved in 78%. Of 836 grade II AVMs, Spetzler-Martin parameters were reported in 680: 377 were eloquent brain and 178 had deep venous drainage, totaling 555/680 (82%) high-risk SRS-treated grade II AVMs.

CONCLUSION

The literature regarding SRS for grade I-II AVM is low quality, limiting interpretation. Cautiously, we observed that SRS appears to be a safe, effective treatment for grade I-II AVM and may be considered a front-line treatment, particularly for lesions in deep or eloquent locations. Preceding publications may be influenced by selection bias, with favorable AVMs undergoing resection, whereas those at increased risk of complications and nonobliteration are disproportionately referred for SRS.

One-Stage Treatment in a Hybrid Operation Room to Cure Brain Arteriovenous Malformation: A Single-Center Experience

OBJECTIVE

To report the principles and techniques of using a hybrid operation room in the treatment of brain arteriovenous malformation (BAVM).

METHODS

From October 1, 2016 to December 31, 2018, we treated 54 consecutive patients with nonemergent BAVM in a hybrid operation room. The clinical data, radiologic images, and outcomes were collected to establish a prospective database for evaluation.

RESULTS

Thirty-two male and 22 female patients were enrolled with a mean age of 32.6 ± 13.1 years (range, 10-61 years). Bleeding (n = 32, 59.3%) was the main clinical presentation, followed by headache (n = 27, 50.0%), seizures (n = 14, 25.9%), neurofunctional deficits (n = 16, 29.6%), and no symptoms (n = 2, 3.7%). Thirty-one patients (57.4%) accepted resection without intraoperative embolization, 18 (33.3%) were treated with combined embolization and resection, and 5 (9.3%) were cured with intraoperative embolization and resection was cancelled. All patients achieved total BAVM obliteration confirmed with intraoperative angiography. There were no significant differences in outcomes between low-grade (Spetzler-Martin grades I, II, and modified grade III-) and high-grade (Spetzler-Martin grades ≥IV and modified grade III+) groups, except that the high-grade group had more blood loss (667.9 ± 647.5 vs. 284.3 ± 148.6 mL; P = 0.046) and longer postoperative hospitalization (17.1 ± 9.1 vs. 10.8 ± 5.4 days; P = 0.026). At discharge, 52 patients (96.3%) had favorable outcomes (Glasgow Outcome Scale score ≥4). Forty-three patients (79.6%) received 1 year follow-up after treatment; 97.7% (n = 42) of these had ongoing favorable outcomes. However, 4 patients with low-grade BAVM had recurrence.

CONCLUSIONS

The hybrid operation room can ensure safe, comprehensive treatment of BAVM, offering the opportunity for a favorable curative treatment in 1 stage.

Ruptured Brain Arteriovenous Malformations: Surgical Timing and Outcomes-A Retrospective Study of 25 Cases

Background  One important problem in treatment of ruptured brain arteriovenous malformations (bAVMs) is surgical timing. The aim of the study was to understand which parameters affect surgical timing and outcomes the most. Materials and Methods  Between January 2010 and December 2018, 25 patients underwent surgery for a ruptured bAVM at our institute. Intracerebral hemorrhage (ICH) score was used to evaluate hemorrhage severity, while Spetzler-Martin scale for AVM architecture. We divided patients in two groups: "early surgery" and "delayed surgery." The modified Rankin Scale (mRS) evaluated the outcomes. Results   Eleven patients were in the "early surgery" group: age 38 ± 18 years, Glasgow Coma Scale (GCS) 7.64 ± 2.86, ICH score 2.82 ± 0.71, hematoma volume 45.55 ± 23.21 mL. Infratentorial origin of hemorrhage was found in 27.3% cases; AVM grades were I to II in 82%, III in 9%, and IV in 9% cases. Outcome at 3 months was favorable in 36.4% cases and in 54.5% after 1 year. Fourteen patients were in the "delayed surgery" group: age 41 ± 16 years, GCS 13.21 ± 2.39, ICH score 1.14 ± 0.81, hematoma volume 29.89 ± 21.33 mL. Infratentorial origin of hemorrhage was found in 14.2% cases; AVM grades were I to II in 50% and III in 50%. Outcome at 3 months was favorable in 78.6% cases and in 92.8% after 1 year. Conclusions  The early outcome is influenced more by the ICH score, while the delayed outcome by Spetzler-Martin grading. These results suggest that it is better to perform surgery after a rest period, away from the hemorrhage when possible. Moreover, this study suggests how in young patient with a high ICH score and a low AVM grade, early surgery seems to be a valid and feasible therapeutic strategy.

Association between draining vein diameters and intracranial arteriovenous malformation hemorrhage: a multicentric retrospective study

PURPOSE

Intracranial arteriovenous malformations (AVMs) cause hemorrhage, and the role of draining vein diameters in rupture risk is controversial. The aims of the present study were to investigate the variables related with intracranial AVM rupture and to examine the association of draining vein diameters and AVM hemorrhage.

METHODS

Two hundred three patients were included in this study, of which 117 (57%) had unruptured AVMs, and 86 (43%) had ruptured AVMs.

RESULTS

In an adjusted (multivariate) analysis, the variables significantly associated with AVM hemorrhagic presentation were age (OR per year increase 0.97, 95%CI 0.95-0.99, p = 0.007), a deep nidus compared with superficial nidus (OR 3.21, 95%CI 1.13-9.06, p = 0.028), the nidus diameter (OR per each mm increase 0.95, 95%CI 0.92-0.97, p < 0.001), a single draining vein compared with multiple draining veins (OR 2.14, 95%CI 1.02-4.50, p = 0.044), the draining vein diameter (OR per mm increase 1.52, 95%CI 1.26-1.83, p < 0.001), and a draining vein diameter ≥ 5 mm compared with < 5 mm (OR 5.80, 95%CI 2.70-12.47, p < 0.001).

CONCLUSION

In this study, after adjusted analysis, the variables associated with intracranial AVM hemorrhagic presentation were a young age, a small nidus diameter, a deeply located nidus, a single draining vein, and large draining vein diameters. A draining vein diameter cutoff ≥ 5 mm was positively associated with the risk of AVM rupture. A large and prospective study is now necessary to confirm if draining vein diameter is a risk factor for AVM hemorrhage.

Artery of Percheron as a Rare Feeder of Hemorrhagic Thalamic Arteriovenous Malformation: A Case Report and Literature Review

Arteriovenous malformation (AVM) fed by the artery of Percheron (AOP) is extremely rare, with only one case described in the literature to date. We herein present a case of a 43-year-old female with hemorrhagic thalamic AVM mainly supplied by the AOP, who subsequently underwent conservative management and recovered well except for mild right hemiparesis. This case highlights that the AOP is a rarely recognized but clinically significant entity and should be identified when dealing with AOP-associated neurovascular disorder as described.

Angiographically occult and spontaneously thrombosed large brain arteriovenous malformation

Treatment for brain arteriovenous malformations (AVM) include combinations of surgery, radiosurgery and embolization. Very rarely, spontaneous obliteration may occur, especially among small lesions with single superficial vein drainage and prior bleeding. We report the case of a large symptomatic AVM, without history of hemorrhage or prior treatment, in which self-obliteration was noted at surgery. Although MRI suggested the presence of an AVM, no evidence of arterial anomaly was observed in the brain angiography. At surgery, a large cortical nidus with tortuous arterial vessels, resembling that of an AVM but without blood flow, was identified. Complete resection was easily performed without relevant bleeding. The histopathologic study confirmed the diagnosis of a thrombosed AVM. Despite the low probability of recanalization, surgical resection of a suspected spontaneously obliterated AVM may be warranted, in order to reach a definitive diagnosis and to avoid the risk of an eventual bleeding, especially among younger patients.

Surgical selection and outcomes among elderly patients with brain arteriovenous malformations

OBJECTIVE

Studies of resection of brain arteriovenous malformations (AVMs) in the elderly population are scarce. This study examined factors influencing patient selection and surgical outcome among elderly patients.

METHODS

Patients 65 years of age and older who underwent resection of an unruptured or ruptured brain AVM treated by two surgeons at two centers were identified. Patient demographic characteristics, AVM characteristics, clinical presentation, and outcomes measured using the modified Rankin Scale (mRS) were analyzed. For subgroup analyses, patients were dichotomized into two age groups (group 1, 65-69 years old; group 2, ≥ 70 years old).

RESULTS

Overall, 112 patients were included in this study (group 1, n = 61; group 2, n = 51). Most of the patients presented with hemorrhage (71%), a small nidus (< 3 cm, 79%), and a low Spetzler-Martin (SM) grade (grade I or II, 63%) and were favorable surgical candidates according to the supplemented SM grade (supplemented SM grade < 7, 79%). A smaller AVM nidus was statistically significantly more likely to be present in patients with infratentorial AVMs (p = 0.006) and with a compact AVM nidus structure (p = 0.02). A larger AVM nidus was more likely to be treated with preoperative embolization (p < 0.001). Overall outcome was favorable (mRS scores 0-3) in 71% of the patients and was statistically independent from age group or AVM grading. Patients with ruptured AVMs at presentation had significantly better preoperative mRS scores (p < 0.001) and more favorable mRS scores at the last follow-up (p = 0.04) than patients with unruptured AVMs.

CONCLUSIONS

Outcomes were favorable after AVM resection in both groups of patients. Elderly patients with brain AVMs treated microsurgically were notable for small nidus size, AVM rupture, and low SM grades. Microsurgical resection is an important treatment modality for elderly patients with AVMs, and supplemented SM grading is a useful tool for the selection of patients who are most likely to achieve good neurological outcomes after resection.

ABBREVIATIONS

AVM = arteriovenous malformation; BNI = Barrow Neurological Institute; LY = Lawton-Young; mRS = modified Rankin Scale; SM = Spetzler-Martin; supp-SM = supplemented SM; UCSF = University of California, San Francisco.

Brain arteriovenous malformations: A review of natural history, pathobiology, and interventions

Brain arteriovenous malformations (AVMs) are anomalous direct shunts between cerebral arteries and veins that convalesce into a vascular nidus. The treatment strategies for AVMs are challenging and variable. Intracranial hemorrhage and seizures comprise the most common presentations of AVMs. However, incidental AVMs are being diagnosed with increasing frequency due to widespread use of noninvasive neuroimaging. The balance between the estimated cumulative lifetime hemorrhage risk vs the risk of intervention is often the major determinant for treatment. Current management options include surgical resection, embolization, stereotactic radiosurgery (SRS), and observation. Complete nidal obliteration is the goal of AVM intervention. The risks and benefits of interventions vary and can be used in a combinatorial fashion. Resection of the AVM nidus affords high rates of immediate obliteration, but it is invasive and carries a moderate risk of neurologic morbidity. AVM embolization is minimally invasive, but cure can only be achieved in a minority of lesions. SRS is also minimally invasive and has little immediate morbidity, but AVM obliteration occurs in a delayed fashion, so the patient remains at risk of hemorrhage during the latency period. Whether obliteration can be achieved in unruptured AVMs with a lower risk of stroke or death compared with the natural history of AVMs remains controversial. Over the past 5 years, multicenter prospective and retrospective studies describing AVM natural history and treatment outcomes have been published. This review provides a contemporary and comprehensive discussion of the natural history, pathobiology, and interventions for brain AVMs.

Microsurgical approach for symptomatic brain AVMs - single center experience

Objectives: Brain arteriovenous malformations (AVMs) represent high-flow vascular lesions made up of a complex network of feeding arteries and draining veins interposed by a nidus and without a capillary bed. The management of the AVMs represents a challenge, and the optimal treatment should be considered based on the particularities of each AVM. This paper aims to provide outcome data for the cohort of patients with AVMs that underwent surgical treatment. Methods: A retrospective review of patients who presented with AVMs between 2001 and 2019 was conducted. Patients were included if they underwent surgery, preoperative and postoperative angiographic studies were available. Results: 91 patients were included. The SM grade was 1 in 16 cases (17,6%), 2 in 27 patients (29.7%), 3 in 29 patients (31,9%), 4 in 12 cases (13.2%) and grade 5 in 7 cases (7.7%). In 58 (63.7%) cases the AVMs were ruptured. Complete microsurgical resection was achieved in 82 cases (90.1%). Unruptured AVM (87.9% vs. 63.8% for ruptured AVMs; p = 0.015), low-grade AVM (86% vs. 60.4% for grade III-V AVMs; p = 0.006) and cortical location (79.5% vs. 30.8% for deep AVM; p < 0.0001) were the factors associated with a good outcome on mRS scale. Conclusions: Microsurgical resection is the curative treatment for AVMs and offers a good functional outcome if selection criteria are met.

Intracranial calcifications in childhood: Part 2

This article is the second of a two-part series on intracranial calcification in childhood. In Part 1, the authors discussed the main differences between physiological and pathological intracranial calcification. They also outlined histological intracranial calcification characteristics and how these can be detected across different neuroimaging modalities. Part 1 emphasized the importance of age at presentation and intracranial calcification location and proposed a comprehensive neuroimaging approach toward the differential diagnosis of the causes of intracranial calcification. Pathological intracranial calcification can be divided into infectious, congenital, endocrine/metabolic, vascular, and neoplastic. In Part 2, the chief focus is on discussing endocrine/metabolic, vascular, and neoplastic intracranial calcification etiologies of intracranial calcification. Endocrine/metabolic diseases causing intracranial calcification are mainly from parathyroid and thyroid dysfunction and inborn errors of metabolism, such as mitochondrial disorders (MELAS, or mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes; Kearns-Sayre; and Cockayne syndromes), interferonopathies (Aicardi-Goutières syndrome), and lysosomal disorders (Krabbe disease). Specific noninfectious causes of intracranial calcification that mimic TORCH (toxoplasmosis, other [syphilis, varicella-zoster, parvovirus B19], rubella, cytomegalovirus, and herpes) infections are known as pseudo-TORCH. Cavernous malformations, arteriovenous malformations, arteriovenous fistulas, and chronic venous hypertension are also known causes of intracranial calcification. Other vascular-related causes of intracranial calcification include early atherosclerosis presentation (children with risk factors such as hyperhomocysteinemia, familial hypercholesterolemia, and others), healed hematoma, radiotherapy treatment, old infarct, and disorders of the microvasculature such as COL4A1- and COL4A2-related diseases. Intracranial calcification is also seen in several pediatric brain tumors. Clinical and familial information such as age at presentation, maternal exposure to teratogens including viruses, and association with chromosomal abnormalities, pathogenic genes, and postnatal infections facilitates narrowing the differential diagnosis of the multiple causes of intracranial calcification.

Exome sequencing of 112 trios identifies recessive genetic variants in brain arteriovenous malformations

BACKGROUND

Brain arteriovenous malformation (BAVM) is a main cause of cerebral hemorrhage and hemorrhagic stroke in adolescents. Morphologically, a BAVM is an abnormal connection between cerebrovascular arteries and veins. The genetic etiology of BAVMs has not been fully elucidated. In this study, we aim to investigate potential recessive genetic variants in BAVMs by interrogation of rare compound heterozygous variants.

METHODS

We performed whole exome sequencing (WES) on 112 BAVM trios and analyzed the data for rare and deleterious compound heterozygous mutations associated with the disease.

RESULTS

We identified 16 genes with compound heterozygous variants that were recurrent in more than one trio. Two genes (LRP2, MUC5B) were recurrently mutated in three trios. LRP2 has been previously associated with BAVM pathogenesis. Fourteen genes (MYLK, HSPG2, PEAK1, PIEZO1, PRUNE2, DNAH14, DNAH5, FCGBP, HERC2, HMCN1, MYH1, NHSL1, PLEC, RP1L1) were recurrently mutated in two trios, and five of these genes (MYLK, HSPG2, PEAK1, PIEZO1, PRUNE2) have been reported to play a role in angiogenesis or vascular diseases. Additionally, abnormal expression of the MYLK protein is related to spinal arteriovenous malformations.

CONCLUSION

Our study indicates that rare recessive compound heterozygous variants may underlie cases of BAVM. These findings improve our understanding of BAVM pathology and indicate genes for functional validation.

The current clinical picture of cerebral proliferative angiopathy: systematic review

BACKGROUND

Cerebral proliferative angiopathy (CPA) is a rare subset of arteriovenous malformations (AVM). It has unique clinical presentation, angiographic characteristics, and pathophysiology which often brings challenges for the treatment. We aimed to define its epidemiology, pathophysiology are unknown, and best management strategies.

METHODS

A systematic review was conducted according to the PRISMA guidelines. MEDLINE was searched for articles regarding CPA. Extracted data included epidemiological, clinical, and angiographical characteristics, treatment, and outcomes. Treatment was classified as conservative, radiosurgery, endovascular, decompression, and indirect vascularization. A meta-analytical approach was employed for description of the data as study-size adjusted percentages or weighted means, as appropriate.

RESULTS

Thirty-three studies were analyzed, rendering a total 95 cases-half of which came from a single study. Patients were predominantly young (mean 23 years old) and female (60.0%) presenting with headaches (44.9%), seizures (37.1%), or transient ischemic attacks (33.7%). Hemorrhage was present in 18.0%, but rebleeding rates were as high as 67%. The majority of nidus were > 6 cm (52.5%) with hemispheric extension (73.0%). Capillary angioectatic appearance (85.7%), transdural supply (62.5%), and deep venous drainage (73.0%) were also frequent features. Most patients were treated conservatively (54.4%), followed by endovascular (34.2%). Indirect vascularization and radiosurgery were attempted in five and two patients, respectively. Mean follow-up was 110.8 patient-years. Neurological status improved in 50.7%, remained stable in 40.2%, and worsened in 9.0%.

CONCLUSIONS

Conservative and endovascular treatments seem adequate interventions, despite limited evidence. Complementary techniques can be used in patients throughout disease history, according to symptom-based, individualized approach. More studies are required for choosing interventions based on reliable long-term results.

Somatic Gain of KRAS Function in the Endothelium Is Sufficient to Cause Vascular Malformations That Require MEK but Not PI3K Signaling

Supplemental Digital Content is available in the text.

Rationale:

We previously identified somatic activating mutations in the KRAS (Kirsten rat sarcoma viral oncogene homologue) gene in the endothelium of the majority of human sporadic brain arteriovenous malformations; a disorder characterized by direct connections between arteries and veins. However, whether this genetic abnormality alone is sufficient for lesion formation, as well as how active KRAS signaling contributes to arteriovenous malformations, remains unknown.

Objective:

To establish the first in vivo models of somatic KRAS gain of function in the endothelium in both mice and zebrafish to directly observe the phenotypic consequences of constitutive KRAS activity at a cellular level in vivo, and to test potential therapeutic interventions for arteriovenous malformations.

Methods and Results:

Using both postnatal and adult mice, as well as embryonic zebrafish, we demonstrate that endothelial-specific gain of function mutations in Kras (G12D or G12V) are sufficient to induce brain arteriovenous malformations. Active KRAS signaling leads to altered endothelial cell morphogenesis and increased cell size, ectopic sprouting, expanded vessel lumen diameter, and direct connections between arteries and veins. Furthermore, we show that these lesions are not associated with altered endothelial growth dynamics or a lack of proper arteriovenous identity but instead seem to feature exuberant angiogenic signaling. Finally, we demonstrate that KRAS-dependent arteriovenous malformations in zebrafish are refractory to inhibition of the downstream effector PI3K but instead require active MEK (mitogen-activated protein kinase kinase 1) signaling.

Conclusions:

We demonstrate that active KRAS expression in the endothelium is sufficient for brain arteriovenous malformations, even in the setting of uninjured adult vasculature. Furthermore, the finding that KRAS-dependent lesions are reversible in zebrafish suggests that MEK inhibition may represent a promising therapeutic treatment for arteriovenous malformation patients.

Mesenchymal Behavior of the Endothelium Promoted by SMAD6 Downregulation Is Associated With Brain Arteriovenous Malformation Microhemorrhage

BACKGROUND AND PURPOSE

In unruptured brain arteriovenous malformations (bAVMs), microhemorrhage portends a higher risk of future rupture and may represent a transitional state along the continuum of destabilization. Exploration of the molecular and cellular mechanisms of microhemorrhage will provide a possible target for medical treatment to prevent bAVM bleeding.

METHODS

We performed RNA sequencing analysis on 34 unruptured bAVM surgical samples. Functional pathway analysis was performed to identify potential signals associated with the microhemorrhagic phenotype. Candidate gene was then investigated in bAVM specimens by immunohistochemical staining. Several functional assays were used to investigate the effects of candidate genes on the phenotypic properties of cultured human umbilical vein endothelial cells. Then, Masson trichrome staining and immunofluorescence staining were used to evaluate the phenotypic and molecular changes in bAVM tissue.

RESULTS

Via RNA sequencing, we identified differential gene expression between 18 microhemorrhagic bAVMs and 16 nonmicrohemorrhagic bAVMs. TGFβ (transforming growth factor-beta)/BMP (bone morphogenetic protein) signaling was associated with the bAVM microhemorrhage group when SMAD6 (SMAD family member 6) was downregulated. Immunohistochemical staining showed that the vascular endothelium of microhemorrhagic bAVMs exhibited decreased SMAD6 expression. Functional assays revealed that SMAD6 downregulation promoted the formation of endothelial cell tubes with deficient cell-cell junctions and facilitated the acquisition of mesenchymal behavior by endothelial cells. Masson trichrome and immunofluorescence staining demonstrated that mesenchymal phenotype of endothelial cells is promoted in microhemorrhagic bAVMs.

CONCLUSIONS

TGFβ/BMP signaling mediated by SMAD6 in vascular endothelial cells is associated with microhemorrhagic bAVMs, and mesenchymal behavior of endothelial cells induced by SMAD6 downregulation is related with bAVM microhemorrhage.

Neuroimaging of Pediatric Intracerebral Hemorrhage

Hemorrhagic strokes account for half of all strokes seen in children, and the etiologies of these hemorrhagic strokes differ greatly from those seen in adult patients. This review gives an overview about incidence and etiologies as well as presentation of children with intracerebral hemorrhage and with differential diagnoses in the emergency department. Most importantly it describes how neuroimaging of children with intracerebral hemorrhage should be tailored to specific situations and clinical contexts and recommends specific imaging protocols for acute and repeat imaging. In this context it is important to keep in mind the high prevalence of underlying vascular lesions and adapt the imaging protocol accordingly, meaning that vascular imaging plays a key role regardless of modality. Magnetic resonance imaging (MRI), including advanced sequences, should be favored whenever possible at the acute phase.

Clinical and radiographic adverse events after Gamma Knife radiosurgery for brainstem lesions: A dosimetric analysis

OBJECTIVES

To analyze the association between dosvolume relationships and adverse events in brainstem lesions treated with Gamma Knife radiosurgery (GKRS).

METHODS

Treatment plans were generated on BrainLab Elements and GammaPlan software. Dosimetric data were analyzed as continuous variables for patients who received GKRS to brain metastases or arteriovenous malformations (AVM) within or abutting the brainstem. Adverse events were classified as clinical and/or radiographic. Logistic and cox regression were used to assess the relationship between dosimetric variables and adverse events.

RESULTS

Sixty-one patients who underwent single fraction GKRS for brain metastases or AVM were retrospectively analyzed. Median age was 62 years (range: 12-92 years) and the median prescription dose was 18 Gy (range: 13-25 Gy). Median follow-up was 6months. Clinical and radiographic complications were seen in ten (16.4%) and 17 (27.9%) patients, respectively. On logistic regression, increasing D_05% was found to be associated with an increased probability of developing a clinical complication post-GKRS (OR: 1.18; 95% CI: 1.01-1.39; p = 0.04). Furthermore, mean brainstem dose (HR: 1.43; 95% CI: 1.05-1.94; p < 0.02), D_05% (HR: 1.09; 95% CI: 1.01-1.18; p = 0.03), and D_95% (HR: 2.37; 95% CI: 0.99-5.67; p = 0.05) were associated with an increased hazard of experiencing post-GKRS complications over time.

CONCLUSIONS

Increasing D_05% to the brainstem is associated with an increased risk of developing clinical complications. Clinicians may consider this parameter in addition to fractionated stereotactic radiation therapy when well-established dose constraints are not met in this patient population. Additional data are needed to further validate these findings.