Systematic review of brain arteriovenous malformation grading systems evaluating microsurgical treatment recommendation

The application of machine learning for treatment selection of unruptured brain arteriovenous malformations: A secondary analysis of the ARUBA trial data

OBJECTIVE

To build a supervised machine learning (ML) model that selects the best first-line treatment strategy for unruptured bAVMs.

METHODS

A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) trial data was obtained from the National Institute of Neurological Disorders and Stroke (NINDS). A team of five clinicians examined the demographic, clinical, and radiological details of each patient at baseline and reached a consensus on the best first-line treatment for bAVMs. Their treatment choice was used to train an automated supervised ML (autoML) model to select treatments for bAVMs for the training dataset. The accuracy and AUC of the algorithm in selecting the treatment strategy were measured for the test dataset, and feature importance scores of the included variables were calculated.

RESULTS

Among the 100,000 combinations of supervised ML algorithms and their hyperparameters attempted by autoML, gradient boosting classifier had the best predictive performance with an overall accuracy of 0.74 and an area under the curve (AUC) of 0.88. The treatment-specific accuracies were 0.96, 0.85, 0.84, and 0.82; and AUCs were 0.75, 0.95, 0.80, and 0.88 for medical management, surgery, endovascular embolization, and gamma-knife radiosurgery, respectively. Spetzler-Martin score, followed by eloquent AVM location and AVM size, were the three most important features in determining treatments.

CONCLUSION

ML could reliably select the best first-line treatment strategy for bAVMs as per multidisciplinary expert consensus. This study can be replicated for larger population-based AVM registries, with the inclusion of outcome data, thus helping address the bias involved in the management of unruptured bAVMs.

The middle meningeal artery Patency After Coil Embolization (PACE) score: A novel descriptor of angiographic occlusion

INTRODUCTION

A scoring system to characterize the efficacy of middle meningeal artery (MMA) embolization is lacking and would help predict the likelihood of subdural hematoma resolution.

METHODS

We developed a simple angiographic classification system ranging from 0 to 3 for quantifying MMA Patency After Coil Embolization (PACE) based residual flow distal to the embolization. MMA embolizations using coils at our institution were used to validate the PACE score system using procedural angiograms. Follow-up CT scans following embolization were reviewed for acute blood products, and to characterize long-term resolution.

RESULTS

60 patients were included in the study, with a total of 80 subdural hematomas with follow-up imaging that were available for analysis. 37 patients had a PACE score of 0, 18 had a PACE score of 1, 4 had a PACE score of 2, and 1 had a PACE score of 3. The presence of acute blood products was significantly lower in PACE 0 compared to PACE 1, 2, or 3. The cross-sectional area of the chronic subdural collections was statistically lower on follow-up CT scans after coil embolization.

CONCLUSIONS

Coil embolization of the MMA may reduce the incidence of acute blood products after embolization and decrease the cross-sectional area of chronic subdural hematoma on long-term follow-up. Lower PACE scores may correlate with lower rates of acute blood products after the procedure and increased resolution of chronic subdural hematoma on follow-up. A larger cohort is required to characterize the superiority between the PACE scores.

Renal Clear Cell Carcinoma Masquerading As Brain Arteriovenous Malformation: A Case Report and Review of the Literature

Cerebral arteriovenous malformations (AVMs) are tangles of abnormal vessels with early arteriovenous (AV) shunting that can lead to intracerebral hemorrhage, seizures, neurologic deficit, or headache. To date, only a few cases of carcinomas metastasizing to pre-existing cerebral AVMs have been reported in the literature. However, renal clear cell carcinoma (RCC) brain metastases that exhibit early AV shunting, where AVM pathology is not present, are extremely rare. We report a very rare case of early AV shunting phenomenon in RCC brain metastasis. This is a case of a 57-year-old man with no prior medical history who presented to the emergency department with an acute onset headache and speech difficulties. Contrast-enhanced computed tomography of the head revealed a left temporal intracerebral hemorrhage with a vascular nidus adjacent to the hematoma. A diagnostic cerebral angiogram (DSA) showed a Spetzler-Martin grade II AVM in the left para-Sylvian region, supplied by middle cerebral arteries with a superficial draining vein. Gadolinium-enhanced brain MRI revealed evolving methemoglobin and a small compact nidus adjacent to the hematoma in the distal left Sylvian fissure. The patient was stable until day 17 after hospital admission, when he deteriorated due to an interval repeat hemorrhage, requiring surgical excision of the AVM and the hematoma. Postoperative DSA revealed no residual shunting and complete resection of the AVM. However, there was a further re-bleed postoperatively, necessitating a second surgery. Pathology revealed an RCC without any specific pathological features indicative of an AVM. The patient recovered to his baseline but died in less than a year due to the progression of metastatic disease. In conclusion, RCC can exhibit an early AV shunting phenomenon, with the presence of enlarged, tortuous, pathologic nidal-like tumor-feeding vessels, which can mimic an AVM, which is extremely rare. This phenomenon poses significant treatment challenges, as the treatment goals are completely different for AVMs and metastatic disease.

Location-based clinical and angiographic profile of brain arteriovenous malformations - a single-center observational study

BACKGROUND

The location of brain arteriovenous malformations (bAVM) is one of the most relevant prognostic factors included in surgical, endovascular and radiosurgical scores. However, their characteristics according to location are seldom described. The goal of this study was to describe the clinical and angiographic characteristics of bAVM classified according to their location.

METHODS

This retrospective observational study included patients diagnosed with bAVM and attending a national referral hospital during the period 2010-2020. Data regarding clinical and angiographic variables were extracted, including characteristics on nidus, arterial afferents, venous drainage and associated aneurysms. BAVM were classified in 8 groups according to their location: frontal, temporal, parieto-occipital, periventricular, deep, cerebellar, brainstem and mixed. Data distribution for each group was determined and between-group differences were assessed.

RESULTS

A total of 269 bAVM (in 258 patients) were included. The most frequent location was parieto-occipital; and the least frequent, brainstem. Statistically significant differences were observed between groups for most studied variables, including: clinical presentation, functional status at admission; nidus size and density, classification according to the Spetzler-Martin, Buffalo and modified Pollock-Flickinger scales; number, diameter, origin and type of afferents; number, diameter, type and direction of venous drainage, retrograde venous flow; and presence and size of flow-related aneurysms.

CONCLUSION

The clinical and angiographic differences observed between brain AVM groups allow the formulation of profiles according to their location.

A Case of Cerebral Arteriovenous Malformation and Malformation of the Lower Limbs

The case involves a 37-year-old female who was diagnosed with undifferentiated immunodeficiency and protein-losing gastroenteropathy at the age of 26 and was under outpatient care in the gastroenterology department while taking Prednisolone 15mg. At the age of 37, she experienced loss of consciousness and was diagnosed with a right occipital lobe arteriovenous malformation upon investigation. Although initially managed conservatively, she presented the following month with a right-sided headache and vomiting and was urgently transported to our hospital. Imaging with contrast-enhanced CT revealed bleeding from the arteriovenous malformation. Emergency craniotomy was performed, followed by ventricular drainage. Two weeks later, she underwent transcatheter arterial embolization of the main feeder via the right femoral artery approach, followed by excision of the arteriovenous malformation the next day. Subsequently, she had an uneventful recovery. A confirmation CT angiography before discharge revealed severe stenosis of the right common femoral artery, leading to a referral to the cardiovascular surgery department. The stenosis was attributed to the Pro-Glide used for hemostasis during the embolization procedure. Repair surgery was performed, during which CT angiography revealed arteriovenous malformations in both the popliteal fossae and the foot.

Current and Future Applications of Arterial Spin Labeling MRI in Cerebral Arteriovenous Malformations

Arterial spin labeling (ASL) has emerged as a promising noninvasive tool for the evaluation of both pediatric and adult arteriovenous malformations (AVMs). This paper reviews the advantages and challenges associated with the use of ASL in AVM assessment. An assessment of the diagnostic workup of AVMs and their variants in both adult and pediatric populations is proposed. Evaluation after treatments, whether endovascular or microsurgical, was similarly examined. ASL, with its endogenous tracer and favorable safety profile, offers functional assessment and arterial feeder identification. ASL has demonstrated strong performance in identifying feeder arteries and detecting arteriovenous shunting, although some studies report inferior performance compared with digital subtraction angiography (DSA) in delineating venous drainage. Challenges include uncertainties in sensitivity for specific AVM features. Detecting AVMs in challenging locations, such as the apical cranial convexity, is further complicated, demanding careful consideration due to the risk of underestimating total blood flow. Navigating these challenges, ASL provides a noninvasive avenue with undeniable merits, but a balanced approach considering its limitations is crucial. Larger-scale prospective studies are needed to comprehensively evaluate the diagnostic performance of ASL in AVM assessment.

Factors Associated with Unfavorable Clinical Presentations in Patients with Ruptured BrainArteriovenous Malformations

BACKGROUND

Rupture of brain arteriovenous malformations (bAVMs) carries potentially devastating consequences. For patients presenting with ruptured bAVMs, several clinical grading systems have been shown to predict long-term patient morbidity and may be taken into consideration when making clinical decisions. Unfortunately, use of these scoring systems is typically limited to their prognostic value and offer little to patients in therapeutic benefit. Tools are needed not only to predict prognosis for patients experiencing ruptured bAVMs but to gain insight into what characteristics predispose patients to poor long-term outcomes before they rupture. Our objective was to find clinical, morphologic, and demographic variables that correlate with unfavorable clinical grades on presentation in patients with ruptured bAVMs.

METHODS

We retrospectively reviewed a cohort of patients with ruptured bAVMs. Linear regression models were used to test whether Glasgow Coma Scale (GCS) and Hunt-Hess scores on presentation(outcomes) were associated with patient and arteriovenous malformation (AVM) characteristics (predictors) individually.

RESULTS

GCS and Hunt-Hess were assessed following bAVM rupture for 121 brain cases. The median age at rupture was 28.5 years, and 62 (51%) were female. Smoking history was associated with worse GCS; current and past smokers had GCS scores 1.33 points lower on average than nonsmokers (95% confidence interval [CI] -2.59 to -0.07, P = 0.039) and had worse Hunt-Hess scores (0.42, 95% CI 0.07-0.77, P = 0.019). Associated aneurysms were associated with worse GCS (-1.60, 95% CI -3.16 to -0.05, P = 0.043) and trended towards worse Hunt-Hess scores (0.42 points, 95% CI -0.01 to 0.86, P = 0.057).

CONCLUSIONS

Patient smoking status and presence of an AVM associated aneurysm were shown to have modest correlations with unfavorable clinical grades (Hunt-Hess, GCS) on presentation, with unfavorable clinical grades being associated with long-term patient prognosis following bAVM rupture. Further investigation using AVM-specific grading scales and external data are needed to determine the utility of these and other variables in clinical practice for patients with bAVM.

Late chronic local inflammation, synaptic alterations, vascular remodeling and arteriovenous malformations in the brains of male rats exposed to repetitive low-level blast overpressures

In the course of military operations in modern war theaters, blast exposures are associated with the development of a variety of mental health disorders associated with a post-traumatic stress disorder-related features, including anxiety, impulsivity, insomnia, suicidality, depression, and cognitive decline. Several lines of evidence indicate that acute and chronic cerebral vascular alterations are involved in the development of these blast-induced neuropsychiatric changes. In the present study, we investigated late occurring neuropathological events associated with cerebrovascular alterations in a rat model of repetitive low-level blast-exposures (3 × 74.5 kPa). The observed events included hippocampal hypoperfusion associated with late-onset inflammation, vascular extracellular matrix degeneration, synaptic structural changes and neuronal loss. We also demonstrate that arteriovenous malformations in exposed animals are a direct consequence of blast-induced tissue tears. Overall, our results further identify the cerebral vasculature as a main target for blast-induced damage and support the urgent need to develop early therapeutic approaches for the prevention of blast-induced late-onset neurovascular degenerative processes.

Brain arteriovenous malformations of the middle cerebral artery region: image characteristics and endovascular treatment based on a new classification system

BACKGROUND

To date, few studies have investigated the use of endovascular treatment (EVT) for brain arteriovenous malformations (BAVMs) in the supplying area of the middle cerebral artery (MCA). Moreover, no suitable classification was aimed at EVT for MCA-BAVMs. Therefore, this study proposed a new classification.

METHODS

This study retrospectively collected 135 MCA‑BAVMs. They were classified into four types: Type I BAVMs located above the M1 segment; Type II BAVMs located in the region around the Sylvian fissure; and Type III BAVMs located in the supplying region of the M4 segment and subdivided into types IIIa and IIIb. The relevance of various types of MCA-BAVMs and their imaging characteristics and EVT outcomes was analyzed by ordinary one-way ANOVA, Tukey's multiple comparisons test and the chi-square test.

RESULTS

The 135 patients averaged 33.8 ± 14.7 years and included 75 females (55.6%, 75/135). Among them, 15 (11.1%, 15/135), 16 (11.9%, 16/135), 54 (40%, 54/135), and 50 (37%, 50/135) MCA-BAVMs were type I, II, IIIa and IIIb, respectively. After EVT, a good outcome was achieved in 97% of patients. Statistical analysis showed that type I BAVMs were smaller than type II and IIIb BAVMs (P value < 0.05), and type IIIb BAVMs were larger than type I and IIIa BAVMs (P value < 0.05). Deep vein involvement in type I and IIIb BAVMs was more common than in other types (P value < 0.05), and intraventricular hemorrhage (IVH) was also more common (P value < 0.05). The normal morphology in type IIIb was less than that in the other types (P value < 0.05). Type IIIa BAVMs had a higher degree than other types (P value < 0.05).

CONCLUSION

The present study demonstrated that the new classification of MCA-BAVMs can be used to evaluate imaging characteristics and EVT outcomes in different types. In addition, EVT may be a safe treatment modality for MCA‑BAVMs.

IV and V grade arteriovenous Malformations: A multicenter surgical experience. Use of multiple grading system to predict surgical risk

OBJECTIVE

The aim of our study is to report a multicenter experience in the treatment of IV and V grade arteriovenous malformations (AVMs) and to apply commonly used grading scales for surgical risk assessment for these vascular high-grade lesions.

METHODS

Between January 2015 and December 2019, a retrospective study was conducted to identify patients undergoing microsurgical intervention for cAVMs at two Italian centers specialized in the treatment of vascular pathologies. Data on patients with Spetzler-Martin IV and V and with a score equal or more than 7 according to Lawton-Young classification were collected. Ruptured AVMs at admission were subsequently classified according to the new proposed AVICH classification.

RESULTS

A total of 20 patients with high grade (IV and V) cAVMs were enrolled in the study and the average follow-up was 36.45 months. The outcome based on mRS was favorable in 65 % of cases. The pre-operative mRS was a factor influencing clinical outcome, as well as the number of bleedings preceding the treatment, age, and nidus characteristics. S-M IV, L-Y 3 and S-M supp 7 scores were associated with good outcome. Based on the AVICH classification, for ruptured cAVMs, having a score of 9 ore less was correlated to a postoperative mRS fewer or equal than 2.

CONCLUSIONS

Surgical management for high-grade AVMs should be considered in highly selected patients with repeated bleeding or disabling symptoms. Classification systems provide an aid in selecting patients for surgery, also in grade IV and V. It is essential to establish common registers for the management of these complex vascular malformations.

Microsurgical Treatment of Deep and Eloquent AVMs

Over the past 30 years, the treatment of deep and eloquent arteriovenous malformations (AVMs) has moved away from microneurosurgical resection and towards medical management and the so-called minimally invasive techniques, such as endovascular embolization and radiosurgery. The Spetzler-Martin grading system (and subsequent modifications) has done much to aid in risk stratification for surgical intervention; however, the system does not predict the risk of hemorrhage nor risk from other interventions. In more recent years, the ARUBA trial has suggested that unruptured AVMs should be medically managed. In our experience, although these eloquent regions of the brain should be discussed with patients in assessing the risks and benefits of intervention, we believe each AVM should be assessed based on the characteristics of the patient and the angio-architecture of the AVM, in particular venous hypertension, which may guide us to treat even high-grade AVMs when we believe we can (and need to) to benefit the patient. Advances in imaging and intraoperative adjuncts have helped us in decision making, preoperative planning, and ensuring good outcomes for our patients. Here, we present several cases to illustrate our primary points that treating low-grade AVMs can be more difficult than treating high-grade ones, mismanagement of deep and eloquent AVMs at the behest of dogma can harm patients, and the treatment of any AVM should be tailored to the individual patient and that patient's lesion.