Multimodal management of arteriovenous malformations of the basal ganglia and thalamus: factors affecting obliteration and outcome

The Efficacy and Disadvantages of Endovascular Therapy for Deep-Seated Cerebral Arteriovenous Malformations: A Long-Term Follow-Up Study

Arteriovenous malformations (AVMs) in the basal ganglia, the thalamus, and the insular lobe of the brain are rare and difficult-to-treat diseases that require integrated multimodal management. This study aimed to determine the safety and disadvantages of embolization as an independent therapy for deep-seated AVMs. The authors reviewed 76 patients from a single center with cerebral deep-seated AVMs from 2010 to 2020. Clinical hemorrhage refers to the initial clinical presentation with bleeding, the first occurrence of bleeding, and delayed postoperative hemorrhage refers to subsequent bleeding following the initial hemorrhage. After interventional therapy, 8 patients experienced delayed postoperative hemorrhage during the total follow-up of 94,631 person-years, with an annual postoperative hemorrhage rate of 3.1%. Compared with the overall clinical hemorrhage rate before treatment (15.9%/person-year), 11 patients experienced clinical hemorrhage during 25,238 person-years, indicating a significantly decreased risk of clinical hemorrhage after treatment. A total of 28.9% (22/76) of patients achieved angiographic obliteration. Multivariate analysis showed that pretreatment limb weakness and a high Spetzler-Martin grade predicted poor clinical outcomes (P = 0.043 and 0.005). Fewer feeding arteries predicted AVMs' obliteration (P = 0.048). Endovascular procedure-related complications, mortality, and morbidity were, respectively, reported in 7.9% (6/76), 1.3% (1/76), and 14.8% (8/54) of patients. Endovascular embolization significantly lowered the risk of clinical deterioration and delayed hemorrhage, indicating it to be a safe and effective therapy for deep-seated AVMs. Lesions with a simple angioarchitecture were more likely to be completely obliterated.

Endovascular Management of Arteriovenous Malformations in the Thalamic and Basal Ganglia: A Systematic Review

Arteriovenous malformations (AVMs) in the thalamic and basal ganglia present significant challenges due to their deep-seated location and complex vessel architecture. This systematic review outlines the efficacy and outcomes of endovascular management of these lesions. A comprehensive analysis of seven studies including 53 patients revealed high technical success rates, with complete obliteration in 46.7-100% of cases, using advanced embolization agents, such as ethylene vinyl-alcohol copolymer, and precipitating hydrophobic injectable liquid. Adjunctive therapies, mainly stereotactic radiosurgery, further improved results in complex cases. The complications were highly variable, and again, the need for the performance of the technique to be as meticulous as possible was pointed out, tailoring the treatment strategies. This review underlines the potential of endovascular interventions in optimizing outcomes in patients with AVMs in these critical brain regions.

Effect of Cobalt-60 Treatment Dose Rate on Arteriovenous Malformation Obliteration After Stereotactic Radiosurgery With Gamma Knife

BACKGROUND AND OBJECTIVES

Stereotactic radiosurgery (SRS) marginal dose is associated with successful obliteration of cerebral arteriovenous malformations (AVM). SRS dose rate-how old the cobalt-60 sources are-is known to influence outcomes for some neurological conditions and benign tumors. The objective of this study was to determine the association between cobalt-60 treatment dose rate and cerebral AVM obliteration in patients treated with SRS.

METHODS

We performed a retrospective cohort study of 361 patients undergoing 411 AVM-directed SRS treatments between 2005 and 2019 at a single institution. Lesion characteristics, SRS details, obliteration dates, and post-treatment toxicities were recorded. Univariate and multivariate regression analyses of AVM outcomes regarding SRS dose rate (range 1.3-3.7 Gy, mean = 2.4 Gy, median = 2.5 Gy) were performed.

RESULTS

At 10 years post-SRS, 68% of AVMs were obliterated on follow-up imaging. Dose rates >2.9 Gy/min were found to be significantly associated with AVM obliteration compared with those <2.1 Gy/min ( P = .034). AVM size, biologically effective dose, and SRS marginal dose were also associated with obliteration, with obliteration more likely for smaller lesions, higher biologically effective dose, and higher marginal dose. Higher dose rates were not associated with the development of post-SRS radiological or symptomatic edema, although larger AVM volume was associated with both types of edema.

CONCLUSION

Patients with cerebral AVMs treated with higher SRS dose rates (from newer cobalt-60 sources) experience higher incidences of obliteration without a significant change in the risk of post-treatment edema.

Endovascular embolization for basal ganglia and thalamic arteriovenous malformations

Background

Basal ganglia and thalamic arteriovenous malformations (AVMs) represent a special subset of malformations. Due to the involvement of vital brain structures and the specifically fine and delicate angioarchitecture of these lesions, it presents unique therapeutic challenges and technical difficulties that require thorough treatment planning, individualized treatment strategies, and advanced techniques for good clinical outcome.

Method

In this study, we presented a series of ruptured basal ganglia and thalamic AVMs embolized via a transarterial, transvenous or combined approach. Herein, we summarized our treatment experience and clinical outcomes to further evaluate the effectiveness and safety of endovascular embolization for these AVMs as well as the indications, therapy strategies, and techniques of embolization procedures.

Results

Twelve patients with basal ganglia and thalamus AVMs were included in the study. Their average age was 23.83 ± 16.51 years (range, 4-57 years) with a female predominance of 67% at presentation. The AVMs were located in the thalamus in 3 (25%) patients, in the basal ganglia in 3 (25%) patients, and in both sites of the brain in 6 (50%) patients. There were 5 AVMs located on the left side and 7 on the right. The mean nidus diameter was 3.32 ± 1.43 cm (range 1.3-6.1 cm). According to the Spetzler-Martin grading classification, 4 (33.3%) brain AVMs were Grade III, 7 (58.3%) were Grade IV, and 1 (8.3%) was Grade V. All of them presented with bleeding at admission: four of these patients presented with an intracerebral hemorrhage (ICH), 8 ICH in combination with intraventricular hemorrhage (IVH), and no patient with subarachnoid hemorrhage (SAH). Among these patients treated with endovascular embolization, 7 patients were treated by the transarterial approach, 4 patients transvenous approach, and 1 patient underwent the combined approach. A single embolization procedure was performed in 6 patients (50%) and the other 6 cases (50%) were treated in a staged manner with up to three procedures. Procedure-related complications occurred only in two patient (16.7%). Complete AVM obliteration was obtained in 7 patients (58.3%), and partial obliteration was in 4 patients (33.3%). Overall, good or excellent outcomes were obtained in 7 patients (58.3%), and poor functional outcome was observed in 5 patients (41.7%) at the last follow-up. All survived patients achieved anatomic stabilization and there was no postoperative bleeding or recurrence in the follow-up.

Conclusion

The management of the basal ganglia and thalamic AVMs is a great challenge, which needs multimodal individualized treatment to improve the chances of radiographic cure and good outcomes. Endovascular therapy is safe and effective in the treatment of cerebral AVMs particularly for deep-seated AVMs such as the basal ganglia and thalamus. Our results demonstrate a high rate of anatomic obliteration with an acceptable rate of complications in the endovascular treatment of these vasculopathies via a transarterial approach or a transvenous approach.

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

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

Transvenous embolization of a ruptured thalamic arteriovenous malformation supplied by the tuberothalamic artery

Background

Basal ganglia and thalamic arteriovenous malformations (AVM) represent 10% of all AVM. They are associated with a high rate of morbidity and mortality due to their high hemorrhagic presentation and eloquence. Radiosurgery has been the first line treatment, whereas surgical removal and endovascular therapy are possible in selected cases. Deep AVM with small niduses and a single draining vein can achieve cure with embolization.

Case Description

A 10-year-old boy with sudden headache and vomiting underwent a brain computed tomography scan that showed a right thalamic hematoma. Cerebral angiography revealed a small ruptured right anteromedial thalamic AVM with a single feeder arising from the tuberothalamic artery and a single drainage to the superior thalamic vein. Transvenous approach using precipitating hydrophobic injectable liquid 25%^® achieved a complete obliteration of the lesion in a single-session. He was discharged home without neurological sequelae and maintained clinically intact at follow-up.

Conclusion

Transvenous embolization of deep-located AVM as a primary treatment is curative in selected cases, with complication rates comparable to other therapeutic strategies.

Non-Oncological Radiotherapy: A Review of Modern Approaches

Despite being usually delivered in oncological patients, radiotherapy can be used as a successful treatment for several non-malignant disorders. Even though this use of radiotherapy has been scarcely investigated since the 1950s, more recent interest has actually shed the light on this approach. Thus, the aim of this narrative review is to analyze the applications of non-oncological radiotherapy in different disorders. Key references were derived from a PubMed query. Hand searching and clinicaltrials.gov were also used. This review contains a narrative report and a critical discussion of non-oncological radiotherapy approaches. In conclusion, non-oncological radiotherapy is a safe and efficacious approach to treat several disorders that needs to be further investigated and used in clinical practice.

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

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

Arteriovenous Malformations-Current Understanding of the Pathogenesis with Implications for Treatment

Arteriovenous malformations are a vascular anomaly typically present at birth, characterized by an abnormal connection between an artery and a vein (bypassing the capillaries). These high flow lesions can vary in size and location. Therapeutic approaches are limited, and AVMs can cause significant morbidity and mortality. Here, we describe our current understanding of the pathogenesis of arteriovenous malformations based on preclinical and clinical findings. We discuss past and present accomplishments and challenges in the field and identify research gaps that need to be filled for the successful development of therapeutic strategies in the future.

3D-printed cranial models simulating operative field depth for microvascular training in neurosurgery

BACKGROUND

The skills required for neurosurgical operations using microsurgical techniques in a deep operating field are difficult to master in the operating room without risk to patients. Although there are many microsurgical training models, most do not use a skull model to simulate a deep field. To solve this problem, 3D models were created to provide increased training in the laboratory before the operating room, improving patient safety.

METHODS

A patient's head was scanned using computed tomography. The data were reconstructed and converted into a standard 3D printing file. The skull was printed with several openings to simulate common surgical approaches. These models were then used to create a deep operating field while practicing on a chicken thigh (femoral artery anastomosis) and on a rat (abdominal aortic anastomosis).

RESULTS

The advantages of practicing with the 3D printed models were clearly demonstrated by our trainees, including appropriate hand position on the skull, becoming comfortable with the depth of the anastomosis, and simulating proper skull angle and rigid fixation. One limitation is the absence of intracranial structures, which is being explored in future work.

CONCLUSION

This neurosurgical model can improve microsurgery training by recapitulating the depth of a real operating field. Improved training can lead to increased accuracy and efficiency of surgical procedures, thereby minimizing the risk to patients.

Radiotherapy of non-tumoral refractory neurological pathologies

Intracranial radiotherapy has been improved, primarily because of the development of stereotactic approaches. While intracranial stereotactic body radiotherapy is mainly indicated for treatment of benign or malignant tumors, this procedure is also effective in the management of other neurological pathologies; it is delivered using GammaKnife® and linear accelerators. Thus, brain arteriovenous malformations in patients who are likely to experience permanent neurological sequelae can be managed by single session intracranial stereotactic body radiotherapy, or radiosurgery, in specific situations, with an advantageous benefit/risk ratio. Radiosurgery can be recommended for patients with disabling symptoms, which are poorly controlled by medication, such as trigeminal neuralgia, and tremors, whether they are essential or secondary to Parkinson's disease. This literature review aims at defining the place of intracranial stereotactic body radiotherapy in the management of patients suffering from non-tumoral refractory neurological pathologies. It is clear that the multidisciplinary collaboration of experienced teams from Neurosurgery, Neurology, Neuroradiology, Radiation Oncology and Medical Physics is needed for the procedures using high precision radiotherapy techniques, which deliver high doses to locations near functional brain areas.