Gamma Knife surgery for arteriovenous malformations in children

Pediatric cranial stereotactic radiosurgery: Meta-analysis and international stereotactic radiosurgery society practice guidelines

BACKGROUND

There are limited data on the use of stereotactic radiosurgery (SRS) for pediatric patients. The aim of this systematic review was to summarize indications and outcomes specific to pediatric cranial SRS to inform consensus guidelines on behalf of the International Stereotactic Radiosurgery Society.

METHODS

A systematic review, using the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analyses, analyzed English-language articles on SRS, published between 1989 and 2021, that included outcomes for at least 5 pediatric patients. MEDLINE database terms included tumor types and locations, and radiosurgical and age-specific terms. We excluded nonclinical reports, expert opinions, commentaries, and review articles. Meta-regressions for associations with local control were performed for medulloblastoma, craniopharyngioma, ependymoma, glioma, and arteriovenous malformation (AVM).

RESULTS

Of the 113 articles identified for review, 68 met the inclusion criteria. These articles described approximately 400 pediatric patients with benign and malignant brain tumors and 5119 with AVMs who underwent cranial SRS. The rates of local control for benign tumors, malignant tumors, and AVMs were 89% (95% CI, 82%-95%), 71% (95% CI, 59%-82%), and 65% (95% CI, 60%-69%), respectively. No significant associations were identified for local control with the patient-, tumor-, or treatment-related variables.

CONCLUSIONS

This review is the first to summarize outcomes specific to SRS for pediatric brain tumors and AVMs. Although data reporting is limited for pediatric patients, SRS appears to provide acceptable rates of local control. We present ISRS consensus guidelines to inform the judicious use of cranial SRS for pediatric patients.

Radiation-induced malignancies after stereotactic radiosurgery for brain arteriovenous malformations: a large single-center retrospective study and systematic review

Stereotactic radiosurgery (SRS) is widely utilized to treat small- and medium-sized brain arteriovenous malformations (BAVMs); however, radiation-induced malignancies (RIMs) have been reported as extremely rare yet potentially life-threatening complications of SRS. This study aimed to investigate the risk of RIMs after SRS for BAVMs. The outcomes of patients who underwent single-session SRS for BAVMs at our institution and were followed for ≥ 5 years were analyzed to calculate the incidence of RIMs. In addition, a systematic review was conducted using the existing literature reporting RIMs after SRS for BAVMs in compliance with the PRISMA guideline. Regarding the in-hospital analysis, only one (0.18%) RIM (gliosarcoma) was observed among 569 patients, with a median follow-up period of 151 months (interquartile range, 103-255 months). The 15, 20, and 25-year cumulative incidences of RIMs were 0%, 0%, and 1.01%, respectively, whereas the overall incidence rate was 0.12 per 1,000 patient-years. In the systematic review, 14 studies were included, with the incidence of RIMs ranging from 0.00 to 0.24%. Eight patients with RIMs were identified, and the most common pathology was glioblastoma. The median time until the diagnosis of RIM was 7.1 years (range, 4-19 years) after SRS, and their clinical courses were largely dismal, with the post-diagnosis survival periods being 1-10 months. RIM constitutes an extremely rare but potentially fatal complication following SRS for BAVMs, with its incidence rate being at most 0.24%.

Long-Term Outcomes After Stereotactic Radiosurgery for Pediatric Brain Arteriovenous Malformations: A Systematic Review

BACKGROUND

The long-term outcomes after stereotactic radiosurgery (SRS) for pediatric brain arteriovenous malformations (AVMs) remain poorly understood given the paucity of longitudinal studies. A systematic review was conducted to pool cumulative incidences for all outcomes.

METHODS

PubMed, Embase, and Web of Science were queried to systematically extract potential references. The articles relating to AVMs treated via SRS were required to be written in English, involve pediatric patients (<18 years of age), and include a mean follow-up period of >5 years. Individual patient data were obtained to construct a pooled Kaplan-Meier plot on obliteration rates over time.

RESULTS

Among the 6 studies involving 1315 pediatric patients averaging a follow-up period of 86.6 months (range, 6-276), AVM obliteration was observed in 66.1% with cumulative probabilities of 48.28% (95% confidence interval [CI], 41.89-54.68), 76.11% (95% CI, 67.50-84.72), 77.48% (95% CI, 66.37-88.59) over 3, 5, and 10 years, respectively. The cumulative incidence of post-SRS hemorrhage, tumors, cysts, and de novo seizures was 7.2%, 0.3%, 1.6%, and 1.5%, respectively. The cumulative incidence of radiation-induced necrosis, edema, radiologic radiation-induced changes (RICs), symptomatic RICs, and permanent RICs were 8.0%, 1.4%, 28.0%, 8.7%, and 4.9%, respectively.

CONCLUSIONS

Studies assessing long-term outcomes after SRS are moderate in quality and retrospective. Thus, interpretation with caution is advised given the variable degree of loss to follow-up, which suggests that complication rates may be higher than the values stated in the literature. Future prospective studies are needed to validate these findings.

Biologically Effective Dose and Prediction of Obliteration of Arteriovenous Malformations in Pediatric Patients Treated by Gamma Knife Radiosurgery

BACKGROUND AND OBJECTIVES

Stereotactic radiosurgery (SRS) represents an effective treatment for pediatric arteriovenous malformations (AVMs). Biological effective dose (BED) has shown promising results in 2 previous studies as a predictive variable for outcomes in adults, but its role has never been studied in pediatric outcomes.

METHODS

Retrospective data for patients 18 years or younger treated with a single-session SRS for AVMs were collected from 1989 to 2019. BED calculations were performed using an α/β ratio of 2.47. Kaplan-Meier analysis was used to evaluate obliteration, new hemorrhage, and radiation-induced changes (RIC). Cox-regression analysis was used for obliteration prediction using 2 models (margin dose vs BED).

RESULTS

One hundred ninety-seven patients (median age = 13.1 years, IQR = 5.2) were included; 72.6% (143/197) of them presented initially with spontaneous hemorrhage. A median margin dose of 22 Gy (IQR = 4.0) with a median BED of 183.2 Gy (IQR = 70.54) was used to treat AVM with a median volume of 2.8 cm 3 (IQR = 2.9). After SRS, obliteration was confirmed in 115/197 patients (58.4%) using magnetic resonance imaging and angiography at a median follow-up of 2.85 years (IQR = 2.26). The cumulative obliteration probability was 43.6% (95% CI = 36.1-50.3), 60.5% (95% CI+ = 2.2-67.4), and 66.0% (95% CI = 56.0-73.7) at 3, 5, and 10 years, respectively. In Cox multivariate analysis, a BED >180 Gy (hazard ratio [HR] = 2.11, 95% CI = 1.30-3.40, P = .002) in model 1 and a margin dose >20 Gy (HR = 1.90, 95% CI = 1.15-3.13, P = .019) in model 2 were associated with obliteration. An AVM nidus volume >4 cm 3 was associated with lower obliteration rates in both models. The probability of symptomatic RIC at 10 years was 8.6% (95% CI = 3.5-13.4). Neither BED nor margin dose was associated with RIC occurrence, with the only predictive factor being deep AVM location (HR = 3, 95% CI = 1-9.1, P = .048).

CONCLUSION

This study confirms BED as a predictor for pediatric AVM obliteration. Optimization of BED in pediatric AVM SRS planning may improve cumulative obliteration rates.

Natural history and treatment of deep-seated brain arteriovenous malformations in pediatric patients

OBJECTIVE

Pediatric deep brain arteriovenous malformations (bAVMs) represent a unique management challenge given their higher cumulative risk of hemorrhage as well as a higher risk of treatment. Better understanding of hemorrhage risk in this patient population will lead to a better decision-making process for patient management.

METHODS

The authors retrospectively reviewed their institutional bAVM database from 1990 to 2019 and included patients younger than 21 years who had deep-seated bAVMs. They present the annual hemorrhage risk, during the natural history and after treatment, and functional outcomes.

RESULTS

Thirty-one pediatric patients were included in this study (13 males and 18 females) with a mean age of 11.8 (SD 4.4) years. The most frequent presenting symptoms were headache (54.8%), weakness (38.7%), and seizure (22.6%). The mean follow-up duration was 13.14 (SD 12.5) years, during which 7 (22.6%) AVMs were obliterated, 10 (32.3%) individuals experienced hemorrhage, and the modified Rankin Scale score worsened in 8 (25.8%) patients. The annual natural history risk of hemorrhage was 3.24% per patient, and the overall annual hemorrhage risk after treatment was 1.98% per patient. In particular, the risk was reduced to 0.64% per patient in the stereotactic radiosurgery (SRS) group. Non-White race showed a trend of higher rupture at presentation (OR 5 [95% CI 0.84-41.68], p = 0.09). Female sex was associated with higher odds (OR 13.076 [95% CI 1.424-333.591], p = 0.048) and SRS was associated with lower odds (OR 0.122 [95% CI 0.011-0.862], p = 0.049) of follow-up hemorrhage.

CONCLUSIONS

Given the substantial cumulative risk of lifelong hemorrhagic stroke in pediatric patients, timely definitive treatment is warranted. SRS may be beneficial when the risk-benefit profile is deemed acceptable.

Return of the lesion: a meta-analysis of 1134 angiographically cured pediatric arteriovenous malformations

OBJECTIVE

Brain arteriovenous malformations (AVMs) carry a risk of rupture and subsequent morbidity or mortality unless fully treated. AVMs in pediatric patients are known to occasionally recur after obliteration. The objective of this study was to characterize the risk of AVM recurrence following angiographically confirmed obliteration in children.

METHODS

Consecutive pediatric AVMs treated at a single center were identified from a prospective database. Patients with angiographically confirmed AVM obliteration following treatment were included in this study. Associations between AVM recurrence and patient or procedural factors were characterized using the two-tailed Fisher exact test or Mann-Whitney U-test. A literature search was conducted using PubMed, Scopus, Embase, and the Clarivate Web of Science with defined search criteria, and eligible studies were included alongside this study cohort in a meta-analysis. Rates of AVM recurrence following obliteration were pooled across studies with a random-effects model and reported with 95% confidence intervals (CIs).

RESULTS

Recurrence after angiographic confirmation of AVM obliteration was observed in 10.4% (7/67) of pediatric AVMs treated at the authors' center. Patients with recurrent AVMs were significantly younger than those without recurrence (p = 0.002). In the meta-analysis, which included 1134 patients across 24 studies, the rate of recurrence was 4.8% (95% CI 3.0%-6.7%). The rate of AVM recurrence following radiosurgery was 0.7% (95% CI 0%-1.6%), which was significantly lower than the 8.5% rate (95% CI 5.0%-12.0%) following microsurgery.

CONCLUSIONS

Recurrence of obliterated brain AVMs is common in children. Recurrence is more common in young children and following microsurgery.

Effect of Prior Embolization on Outcomes After Stereotactic Radiosurgery for Pediatric Brain Arteriovenous Malformations: An International Multicenter Study

BACKGROUND

Pediatric brain arteriovenous malformations (AVMs) are a significant cause of morbidity but the role of multimodal therapy in the treatment of these lesions is not well understood.

OBJECTIVE

To compare the outcomes of stereotactic radiosurgery (SRS) with and without prior embolization for pediatric AVMs.

METHODS

We retrospectively evaluated the International Radiosurgery Research Foundation pediatric AVM database. AVMs were categorized, based on use of pre-embolization (E + SRS) or lack thereof (SRS-only). Outcomes were compared in unadjusted and inverse probability weight (IPW)-adjusted models. Favorable outcome was defined as obliteration without post-SRS hemorrhage or permanent radiation-induced changes (RIC).

RESULTS

The E + SRS and SRS-only cohorts comprised 91 and 448 patients, respectively. In unadjusted models, the SRS-only cohort had higher rates of obliteration (68.5% vs 43.3%,  < .001) and favorable outcome (61.2% vs 36.3%, P < .001) but a lower rate of symptomatic RIC (9.0% vs 16.7%, P = .031). The IPW-adjusted rates of every outcome were similar between the 2 cohorts. However, cumulative obliteration rates at 3, 5, 8, and 10 yr remained higher in the absence of prior embolization (46.3%, 64.6%, 72.6%, and 77.4% for SRS-only vs 24.4%, 37.2%, 44.1%, and 48.7% for E + SRS cohorts, respectively; SHR = 0.449 [0.238-0.846], P = .013).

CONCLUSION

Embolization appears to decrease cumulative obliteration rates after SRS for pediatric AVMs without affecting the risk of post-treatment hemorrhage or adverse radiation effects arguing against the routine use of pre-SRS embolization. While endovascular therapy can be considered for occlusion of high-risk angioarchitectural features prior to SRS, future studies are necessary to clarify its role.

Surgical management of pediatric rolandic arteriovenous malformations: a single-center case series

OBJECTIVE

Pediatric rolandic arteriovenous malformations (AVMs) present a treatment challenge given the lifetime risk of hemorrhage, rehemorrhage, and associated long-term morbidity. Microsurgical resection has been recommended as the optimal treatment for AVMs in general, but there is no dedicated literature on the outcomes of resection of pediatric rolandic AVMs. Here, the study objective was to review the outcomes of microsurgical resection of pediatric rolandic AVMs in the modern era, together with the utilization of surgical adjuncts including navigation, intraoperative angiography, and neurophysiological monitoring.

METHODS

The authors performed a retrospective review of patients 18 years of age and younger with cerebral AVMs microsurgically treated between January 2000 and May 2016 at The Hospital for Sick Children. Only those patients with an AVM whose nidus was located within the rolandic region were analyzed. A descriptive analysis was performed to identify patient demographics, preoperative AVM characteristics, and postoperative obliteration rates and neurological complications.

RESULTS

A total of 279 AVMs were evaluated in the study period. Twenty-three of these AVMs were rolandic, and the median age in the 11 microsurgically treated cases was 11 years (range 1-17 years). AVM hemorrhage was the most common presentation, occurring in 8 patients (73%). Lesions were either Spetzler-Martin grade II (n = 8, 73%) or grade III (n = 3, 27%). The postoperative obliteration rate of AVMs was 100%. The mean imaging follow-up duration was 33 months (range 5-164 months). There was no documented recurrence of an AVM during follow-up. One patient developed a transient postoperative hemiparesis, while another patient developed right fingertip hyperesthesia.

CONCLUSIONS

Microsurgical resection of rolandic pediatric AVMs yields excellent AVM obliteration with minimal neurological morbidity in selected patients. The incorporation of surgical adjuncts, including neurophysiological monitoring and neuronavigation, allows accurate demarcation of functional cortex and enables effective resection.

Early obliteration of pediatric brain arteriovenous malformations after stereotactic radiosurgery: an international multicenter study

OBJECTIVE

Stereotactic radiosurgery (SRS) is a treatment option for pediatric brain arteriovenous malformations (AVMs), and early obliteration could encourage SRS utilization for a subset of particularly radiosensitive lesions. The objective of this study was to determine predictors of early obliteration after SRS for pediatric AVMs.

METHODS

The authors performed a retrospective review of the International Radiosurgery Research Foundation AVM database. Obliterated pediatric AVMs were sorted into early (obliteration ≤ 24 months after SRS) and late (obliteration > 24 months after SRS) responders. Predictors of early obliteration were identified, and the outcomes of each group were compared.

RESULTS

The overall study cohort was composed of 345 pediatric patients with obliterated AVMs. The early and late obliteration cohorts were made up of 95 (28%) and 250 (72%) patients, respectively. Independent predictors of early obliteration were female sex, a single SRS treatment, a higher margin dose, a higher isodose line, a deep AVM location, and a smaller AVM volume. The crude rate of post-SRS hemorrhage was 50% lower in the early (3.2%) than in the late (6.4%) obliteration cohorts, but this difference was not statistically significant (p = 0.248). The other outcomes of the early versus late obliteration cohorts were similar, with respect to symptomatic radiation-induced changes (RICs), cyst formation, and tumor formation.

CONCLUSIONS

Approximately one-quarter of pediatric AVMs that become obliterated after SRS will achieve this radiological endpoint within 24 months of initial SRS. The authors identified multiple factors associated with early obliteration, which may aid in prognostication and management. The overall risks of delayed hemorrhage, RICs, cyst formation, and tumor formation were not statistically different in patients with early versus late obliteration.

Hemorrhagic Cerebrovascular Pathology in the Pediatric Population

Hemorrhagic cerebrovascular disease in the pediatric population can have devastating and long-term effects. Progress in the fields of genetics, neuroimaging, pharmacology, and surgical techniques has led to improved diagnosis and management of pediatric cerebrovascular diseases. In this review we discuss the current etiologies and medical and surgical treatments of hemorrhagic cerebrovascular pathology affecting infants and children. A special emphasis is placed on neuroendovascular treatment options. Increased knowledge about this unique pathology and the medical and therapeutic options will empower practitioners to more quickly and accurately identify and accurately treat hemorrhagic diseases in the pediatric population.

Decision-Making for Patients With Cerebral Arteriovenous Malformations

Cerebral arteriovenous malformations (AVMs) are a complex and heterogeneous pathology which require an understanding of the natural history of these lesions, as well as the potential treatment options in order to manage them safely. While treatment is the agreed upon strategy for most ruptured AVMs, the management of unruptured AVMs continues to be debated. More recently, this debate has been fueled by the A Randomized Trial of Unruptured Arteriovenous Malformations (ARUBA) trial which attempts to define the natural history and treatment risk of AVMs. However, the trial has significant shortcomings which limit its broad applicability. In addition, the breadth, efficacy, and safety of potential treatment options continue to improve. This review focuses on defining the natural history of cerebral AVMs, an overview of the ARUBA trial, and the most current treatment paradigm for cerebral AVMs.

[Arteriovenous malformations of the brain in children: treatment results for 376 patients]

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Cerebral arteriovenous malformations (AVM) are increasingly detected in children.

Objective

To estimate the risk of hemorrhage in children with AVM before and after treatment and evaluate the outcomes of various methods of AVM management in children.

Material and methods

This study included 376 patients with various cerebral AVM under the age of 18 years. There were 273 patients with intracranial hemorrhage (72.6%).

Results

Recurrent hemorrhages within the first month were registered in 1.1% of patients with angiomatous AVM prior to treatment and in 15.4% of patients with fistulous AVM. Microsurgical resection of AVM was performed in 135 (35.9%) patients. Total resection was achieved in 97.8% of cases. There were no mortality after microsurgical procedures. Endovascular treatment was applied in 79 (21%) patients. Total embolization was achieved in 29.1% of patients. One patient (1.3%) died after endovascular procedure. Radiosurgery was performed in 140 (37.2%) patients with total obliteration after a single fraction in 64.4% of patients. Favorable long-term outcomes (GOS grades V-IV) were achieved in 89.6% of patients with available follow-up data (n=182). Recurrent hemorrhages were registered in 6% of patients (3.3% after radiosurgery, 2.7% after endovascular treatment). One patient with recurrent hemorrhage died after radiosurgery.

Conclusion

Early relapses of hemorrhage are not characteristic for children with cerebral AVM. Therefore, there are no indications for urgent surgery except for cases of intracerebral hematoma. In children, microsurgical treatment is preferred for angiomatous AVM, endovascular treatment - for fistulous AVM. Radiosurgery also ensures favorable outcomes. However, it is unreasonable to postpone AVM radiosurgical treatment in children with increased risk of recurrent hemorrhage considering relatively long period of post-radiation obliteration of AVM.

What is the best therapeutic approach to a pediatric patient with a deep-seated brain AVM?

Although brain arteriovenous malformations (bAVMs) account for a very small proportion of cerebral pathologies in the pediatric population, they are the cause of roughly 50% of spontaneous intracranial hemorrhages. Pediatric bAVMs tend to rupture more frequently and seem to have higher recurrence rates than bAVMs in adults. Thus, the management of pediatric bAVMs is particularly challenging. In general, the treatment options are conservative treatment, microsurgery, endovascular therapy (EVT), gamma knife radiosurgery (GKRS), proton-beam stereotactic radiosurgery (PSRS), or a combination of the above. In order to identify the best approach to deep-seated pediatric bAVMs, we performed a systematic review, according to the PRISMA guidelines. None of the options seem to offer a clear advantage over the others when used alone. Microsurgery provides the highest obliteration rate, but has higher incidence of neurological complications. EVT may play a role when used as adjuvant therapy, but as a stand-alone therapy, the efficacy is low and the long-term side effects of radiation from the multiple sessions required in deep-seated pediatric bAVMs are still unknown. GKRS has a low risk of complication, but the obliteration rates still leave much to be desired. Finally, PSRS offers promising results with a more accurate radiation that avoids the surrounding tissue, but data is limited due to its recent introduction. Overall, a multi-modal approach, or even an active surveillance, might be the most suitable when facing deep-seated bAVM, considering the difficulty of their management and the high risk of complications in the pediatric population.

Long-Term Outcomes for Pediatric Patients with Brain Arteriovenous Malformations Treated with Gamma Knife Radiosurgery, Part 2: The Incidence of Cyst Formation, Encapsulated Hematoma, and Radiation-Induced Tumor

OBJECTIVE

Long-term data about the incidence of late adverse radiation effects (AREs) in pediatric brain arteriovenous malformations (AVMs) treated with Gamma Knife radiosurgery (GKRS) are lacking. This study addresses the incidence of late AREs, including cyst formation (CF), chronic encapsulated hematoma (CEH), and radiation-induced tumor, in pediatric patients with AVM treated with GKRS.

METHODS

This is a single-institutional study involving pediatric patients with AVM who underwent GKRS between 1991 and 2014. Among 201 pediatric patients with AVM (age ≤15 years), 189 who had at least 12 months of follow-up were assessed in this study. The median treatment volume was 2.2 cm³, and the median marginal dose was 20 Gy.

RESULTS

The mean follow-up period was 136 months. During the follow-up period, symptomatic radiation-induced perilesional edema was found in 5 patients (3%), CFs in 7 patients (4%), CEHs in 7 patients (4%), and radiation-induced tumors in 2 patients (1%). The cumulative incidences of late AREs including CF, CEH, and radiation-induced tumor were 1.2% at 5 years, 5.2% at 8 years, 6.1% at 10 years, 7.2% at 15 years, and 17.0% at 20 years. In the multivariate analysis, treatment volume alone was a significant factor for late AREs (P < 0.001; hazard ratio, 1.111).

CONCLUSIONS

GKRS is a reasonable treatment option for pediatric AVMs to prevent future intracranial hemorrhages, particularly in the eloquent regions. However, considerable attention should be paid to late AREs such as CFs, CEHs, and radiation-induced tumors because of longer life expectancy in pediatric patients.

Long-Term Outcomes for Pediatric Patients with Brain Arteriovenous Malformations Treated with Gamma Knife Radiosurgery, Part 1: Analysis of Nidus Obliteration Rates and Related Factors

OBJECTIVE

Little is known about long-term outcomes for pediatric brain arteriovenous malformations (AVMs) treated with Gamma Knife radiosurgery (GKRS). This study investigated annual hemorrhage rates and nidus obliteration rates, and the factors affecting them, in pediatric AVMs treated with GKRS.

METHODS

We examined 189 pediatric AVM patients (age ≤15 years) who underwent GKRS and had at least 12 months of follow-up. The Spetzler-Martin (S-M) grade was I in 29 patients (15%), II in 57 (30%), III in 82 (43%), IV in 16 (9%), and V in 5 (3%). The median treatment volume was 2.2 cm³, and the median marginal dose was 20 Gy.

RESULTS

The mean follow-up period was 136 months. During a cumulative latency period to nidus obliteration of 813 years, 23 hemorrhages occurred, resulting in an annual post-GKRS hemorrhage rate of 2.8%. The cumulative hemorrhage rates after GKRS were 3.3%, 8.5%, and 11.9% at 3, 5, and 10 years, respectively. Higher S-M grade was significantly associated with intracranial hemorrhages during the latency period (P < 0.001). The actuarial nidus obliteration rates with repeated GKRS were 64% and 81% at 5 and 10 years, respectively. Absence of pre-GKRS embolization (P = 0.023) and higher marginal dose (P = 0.029) were significant factors predicting nidus obliteration.

CONCLUSIONS

GKRS is a reasonable treatment option in pediatric AVMs to prevent future hemorrhages. Because higher S-M grade AVMs are more likely to hemorrhage during the latency period, a combined therapy with endovascular embolization should be considered to prevent AVM rupture.

The factors associated with hemorrhagic presentation in children with untreated brain arteriovenous malformation: a meta-analysis

OBJECTIVE Rupture of arteriovenous malformations (AVMs) would result in high mortality and prevalence of disability in pediatric patients. Decisions regarding the treatment of AVMs need to weigh the risk of rupture over the course of their natural history against the possibility of creating a lesion during treatment. Multiple factors have been proposed to predict hemorrhagic presentation of pediatric patients with AVMs. The aim of this meta-analysis was to evaluate the predictors of hemorrhagic presentation in pediatric patients with AVMs. METHODS The authors searched the PubMed and EMBASE databases. Studies reporting the predictors of hemorrhagic presentation in children with untreated brain AVMs were included. The predictive ability of identified predictors was assessed by odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS A higher risk of hemorrhagic presentation was found in AVMs with smaller size (< 3 cm, OR 2.97, 95% CI 1.94–4.54, p < 0.00001), deep venous drainage (OR 2.28, 95% CI 1.55–3.36, p < 0.0001), a single draining vein (OR 2.23, 95% CI 1.27–3.92, p = 0.005), a single feeder (OR 3.72, 95% CI 1.31–10.62, p = 0.01), a deep location (OR 1.82, 95% CI 1.22–2.72, p = 0.004), an infratentorial location (OR 2.25, 95% CI 1.19–4.26, p = 0.01), and diffuse morphology (OR 8.94, 95% CI 3.01–26.55, p < 0.0001). In addition, the AVMs with draining vein ectasia (OR 0.35, 95% CI 0.13–0.97, p = 0.04) and high Spetzler-Martin (SM) grade (OR 0.53, 95% CI 0.36–0.78, p = 0.001) had a lower risk of hemorrhagic presentation in pediatric patients. CONCLUSIONS Smaller AVMs, deep venous drainage, a single draining vein, a single feeder, deep/infratentorial location, diffuse morphology, and high SM grade were identified as positive predictors for hemorrhagic presentation. Particularly, patients with diffuse AVMs have a higher risk of hemorrhagic presentation than other factors and may need active treatments. However, factors such as age, sex, draining vein stenosis, and associated aneurysms were not associated with hemorrhagic presentation. ABBREVIATIONS AVM = arteriovenous malformation; CI = confidence interval; NOS = Newcastle-Ottawa Scale; OR = odds ratio; SM = Spetzler-Martin.

Radiosurgical treatment of arteriovenous malformations in a retrospective study group of 33 children: the importance of radiobiological scores

PURPOSE

Arteriovenous malformations' (AVMs) obliteration depends on several factors; among the many factors that must be considered to obtain a high rate of obliteration and a low rate of complications, Flickinger-Pollock Score (FPS) seems to have an important role but still have to be validated in the pediatric population while Paddick-Conformity Index (PCI) still has no demonstration of its utility on the outcome and is considered only as a treatment quality marker.

METHODS

We retrospectively analyzed 33 consecutive children (2-18 years) with an AVM, treated with stereotactic radiosurgery Gamma Knife (SRS-GK) from 2001 to 2014 in our institution. We assess angiographic (DSA) Obliteration Rate (OR) as well FPS and PCI to draw conclusions.

RESULTS

DSA-OR was 60.6% with a rate of hemorrhage of 0%. median target volume (TV) was 3.60 cc (mean 4.32 ± 3.63; range 0.15-14.2), median PD was 22 Gy (mean 21.4 ± 2.6; range 16.5-25). Median percentage of coverage was 98% (mean 97 ± 3; range 84-100). The median modified FPS was 0.78 (mean 0.89 ± 0.52; range 0.21-2.1) and highly correlate with OR (p = 0.01). The median PCI was 0.65 (mean 0.65 ± 0.14; range 0.34-0.95) A PCI lower than 0.57 highly correlates with final OR (p = 0.02).

CONCLUSION

SRS-GK was safe and gradually effective in children. A prescription dose-like that used in adult population (i.e. > 18 and between 20 and 25 Gy) is essential to achieve obliteration. A PD of 23 Gy and 22 Gy did impact OR, respectively (p = 0.02) and (p = 0.05). FPS and PCI are valuable scores that seem to correlate with the OR also in the pediatric population although further prospective studies are needed to confirm these observations.

Comparison of the Long-term Efficacy and Safety of Gamma Knife Radiosurgery for Arteriovenous Malformations in Pediatric and Adult Patients

It is debated whether the efficacy and long-term safety of gamma knife radiosurgery (GKRS) for arteriovenous malformations (AVMs) differs between adult and pediatric patients. We aimed to clarify the long-term outcomes of GKRS in pediatric patients and how they compare to those in adult patients. We collected data for 736 consecutive patients with AVMs treated with GKRS between 1990 and 2014 and divided the patients into pediatric (age < 20 years, n = 144) and adult (age ≥ 20 years, n = 592) cohorts. The mean follow-up period in the pediatric cohort was 130 months. Compared to the adult patients, the pediatric patients were significantly more likely to have a history of hemorrhage (P < 0.001). The actuarial rates of post-GKRS nidus obliteration in the pediatric cohort were 36%, 60%, and 87% at 2, 3, and 6 years, respectively. Nidus obliteration occurred earlier in the pediatric cohort than in the adult cohort (P = 0.015). The actuarial rates of post-GKRS hemorrhage in the pediatric cohort were 0.7%, 2.5%, and 2.5% at 1, 5, and 10 years, respectively. Post-GKRS hemorrhage was marginally less common in the pediatric cohort than in the adult cohort (P = 0.056). Cyst formation/encapsulated hematoma were detected in seven pediatric patients (4.9%) at a median post-GKRS timepoint of 111 months, which was not significantly different from the rate in the adult cohort. Compared to adult patients, pediatric patients experience earlier therapeutic effects from GKRS for AVMs, and this improves long-term outcomes.

Clinical outcomes and radiosurgical considerations for pediatric arteriovenous malformation: influence of clinical features on obliteration rate

PURPOSE

Gamma knife radiosurgery (GKRS) is an established treatment modality for brain arteriovenous malformation (AVM), but there have been few published studies examining the relationship between clinical features of AVM and successful obliteration with GKRS in pediatric patients. In the current study, we investigate the outcomes of GKRS for pediatric patients with brain AVM and analyze the variables that influence obliteration.

METHODS

We analyzed 68 pediatric patients (≤ 18 years) with a mean follow-up period of 61.9 months (range 6-215 months). The following parameters were analyzed to determine their influence on obliteration of AVM treated by GKRS: age, sex, target volume, irradiation dose, prior treatment, location of AVM, nidus structure, velocity of AVM, location of venous drainage, number of feeding arteries, and initial presenting symptoms. Also, we estimated clinical factors which should be considered during the follow-up period.

RESULTS

Of the 68 patients, complete obliteration was confirmed in 26 (38.2%) by cerebral angiography. The response rate of AVM for GKRS was 92.6%. No significant association was observed between any of the parameters investigated and the obliteration of AVM, with the exception of number of feeding arteries, which exhibited a statistically significant difference by univariate analysis (p = 0.003). However, on multivariate analysis, nidus structure (p = 0.007), velocity of the main arterial phase (p = 0.013), velocity of the feeding artery phase (p = 0.004), and the number of feeding arteries (p = 0.018) showed statistical significance.

CONCLUSION

GKRS yielded good long-term clinical outcomes in most pediatric patients. Multiple arterial feeding vessels, diffuse nidus structure, and fast flow of AVM were specific factors associated with a low rate of obliteration in pediatric AVMs.

Stereotactic body radiotherapy for pediatric hepatocellular carcinoma with central biliary obstruction

Here, we present the case of a pediatric patient with newly diagnosed hepatocellular carcinoma causing central biliary obstruction and persistently elevated bilirubin of 3.0-4.3 mg/dl despite placement of bilateral internal-external biliary drains. The tumor was not resectable, and the patient was not a candidate for liver transplant due to nodal disease, for chemotherapy due to hyperbilirubinemia, or for local therapies aside from stereotactic body radiotherapy (SBRT). In this report, we discuss the successful use of SBRT in the management of this patient, and its role in allowing the patient to become a candidate for additional therapies.

Cyst formation after stereotactic radiosurgery for brain arteriovenous malformations: a systematic review

OBJECTIVE Cyst formation can occasionally occur after stereotactic radiosurgery (SRS) for brain arteriovenous malformations (AVMs). Given the limited data regarding post-SRS cyst formation in patients with AVM, the time course, natural history, and management of this delayed complication are poorly defined. The aim of this systematic review was to determine the incidence, time course, and optimal management of cyst formation after SRS for AVMs. METHODS A literature review was performed using PubMed to identify studies reporting cyst formation in AVM patients treated with SRS. Baseline and outcomes data, including the incidence and management of post-SRS cysts, were extracted from each study that reported follow-up duration. The mean time to cyst formation was calculated from the subset of studies that reported individual patient data. RESULTS Based on pooled data from 22 studies comprising the incidence analysis, the overall rate of post-SRS cyst formation was 3.0% (78/2619 patients). Among the 26 post-SRS cyst patients with available AVM obliteration data, nidal obliteration was achieved in 20 (76.9%). Of the 64 cyst patients with available symptomatology and management data, 21 (32.8%) were symptomatic; 21 cysts (32.8%) were treated with surgical intervention, whereas the remaining 43 (67.2%) were managed conservatively. Based on a subset of 19 studies reporting individual time-to-cyst-formation data from 63 patients, the mean latency period to post-SRS cyst formation was 78 months (6.5 years). CONCLUSIONS Cyst formation is an uncommon complication after SRS for AVMs, with a relatively long latency period. The majority of post-SRS cysts are asymptomatic and can be managed conservatively, although enlarging or symptomatic cysts may require surgical intervention. Long-term follow-up of AVM patients is crucial to the appropriate diagnosis and management of post-SRS cysts.

International multicenter cohort study of pediatric brain arteriovenous malformations. Part 2: Outcomes after stereotactic radiosurgery

OBJECTIVE Pediatric patients (age < 18 years) harboring brain arteriovenous malformations (AVMs) are burdened with a considerably higher cumulative lifetime risk of hemorrhage than adults. Additionally, the pediatric population was excluded from recent prospective comparisons of intervention versus conservative management for unruptured AVMs. The aims of this multicenter, retrospective cohort study are to analyze the outcomes after stereotactic radiosurgery for unruptured and ruptured pediatric AVMs. METHODS We analyzed and pooled AVM radiosurgery data from 7 participating in the International Gamma Knife Research Foundation. Patients younger than 18 years of age who had at least 12 months of follow-up were included in the study cohort. Favorable outcome was defined as AVM obliteration, no post-radiosurgical hemorrhage, and no permanently symptomatic radiation-induced changes (RIC). The post-radiosurgery outcomes of unruptured versus ruptured pediatric AVMs were compared, and statistical analyses were performed to identify predictive factors. RESULTS The overall pediatric AVM cohort comprised 357 patients with a mean age of 12.6 years (range 2.8-17.9 years). AVMs were previously treated with embolization, resection, and fractionated external beam radiation therapy in 22%, 6%, and 13% of patients, respectively. The mean nidus volume was 3.5 cm³, 77% of AVMs were located in eloquent brain areas, and the Spetzler-Martin grade was III or higher in 59%. The mean radiosurgical margin dose was 21 Gy (range 5-35 Gy), and the mean follow-up was 92 months (range 12-266 months). AVM obliteration was achieved in 63%. During a cumulative latency period of 2748 years, the annual post-radiosurgery hemorrhage rate was 1.4%. Symptomatic and permanent radiation-induced changes occurred in 8% and 3%, respectively. Favorable outcome was achieved in 59%. In the multivariate logistic regression analysis, the absence of prior AVM embolization (p = 0.001) and higher margin dose (p < 0.001) were found to be independent predictors of a favorable outcome. The rates of favorable outcome for patients treated with a margin dose ≥ 22 Gy vs < 22 Gy were 78% (110/141 patients) and 47% (101/216 patients), respectively. A margin dose ≥ 22 Gy yielded a significantly higher probability of a favorable outcome (p < 0.001). The unruptured and ruptured pediatric AVM cohorts included 112 and 245 patients, respectively. Ruptured AVMs had significantly higher rates of obliteration (68% vs 53%, p = 0.005) and favorable outcome (63% vs 51%, p = 0.033), with a trend toward a higher incidence of post-radiosurgery hemorrhage (10% vs 4%, p = 0.07). The annual post-radiosurgery hemorrhage rates were 0.8% for unruptured and 1.6% for ruptured AVMs. CONCLUSIONS Radiosurgery is a reasonable treatment option for pediatric AVMs. Obliteration and favorable outcomes are achieved in the majority of patients. The annual rate of latency period hemorrhage after radiosurgery for both ruptured and unruptured pediatric AVM patients conveys a significant risk until the nidus is obliterated.

Long-term hemorrhagic risk in pediatric patients with arteriovenous malformations

OBJECTIVE Compared with the general population, the specific natural history of arteriovenous malformations (AVMs) in pediatric patients is less well understood. Furthermore, few pediatric studies have compared posttreatment hemorrhagic risk and functional outcome across different treatment modalities. The objective of this study was to elucidate these points. METHODS The authors retrospectively reviewed all pediatric patients with AVMs evaluated at their institution between 1990 and 2013. The AVM natural history was represented by hemorrhagic risk during the observation period. For treated patients, the observation period was defined as the interval between diagnosis and treatment. Posttreatment hemorrhagic risk and functional outcomes were also assessed. RESULTS A total of 124 pediatric patients with AVMs were evaluated, and 90 patients (72.6%) were retained through follow-up. The average patient age was 13.3 ± 3.8 years, with a mean follow-up period of 9.95 years. The overall AVM obliteration rate was 59.7%. Radiosurgery had an obliteration rate of 49.0%. Thirteen patients were managed conservatively. Four patients under observation hemorrhaged during a total interval of 429.4 patient-years, translating to an annual risk of 0.9%. Posttreatment hemorrhagic risk by treatment modalities were categorized as follows: surgery ± embolization (0.0%), radiosurgery ± embolization (0.8%), embolization alone (2.8%), surgery + radiosurgery ± embolization (3.5%), and observation (0.8%). A significantly higher risk of posttreatment hemorrhage was observed for patients with hemorrhagic presentation (p = 0.043) in multivariate analysis. Seizure presentation, frontal lobe location, nonheadache presentation, and treatment modality were significantly associated with increased risk of poor functional outcomes. CONCLUSIONS In this study of pediatric patients with AVMs, the natural history of hemorrhage was relatively low at 0.9%. Resection remained the optimal management for hemorrhage control and functional outcome perseverance in these pediatric patients with AVMs. AVM obliteration is a valid treatment goal, especially for patients with ruptured presentation, to prevent further hemorrhages later in life.

Arteriovenous Malformations in the Pediatric Population: Review of the Existing Literature

Arteriovenous malformations (AVMs) in the pediatric population are relatively rare but reportedly carry a higher rate of rupture than in adults. This could be due to the fact that most pediatric AVMs are only detected after rupture. We aimed to review the current literature regarding the natural history and the clinical outcome after multimodality AVM treatment in the pediatric population, as optimal management for pediatric AVMs remains controversial. A multidisciplinary approach using multimodality therapy if needed has been proved to be beneficial in approaching these lesions in all age groups. Microsurgical resection remains the gold standard for the treatment of all accessible pediatric AVMs. Embolization and radiosurgery should be considered as an adjunctive therapy. Embolization provides a useful adjunct therapy to microsurgery by preventing significant blood loss and to radiosurgery by decreasing the volume of the AVM. Radiosurgery has been described to provide an alternative treatment approach in certain circumstances either as a primary or adjuvant therapy.

Leksell Gamma Knife for pediatric and adolescent cerebral arteriovenous malformations: results of 100 cases followed up for at least 36 months

OBJECT

The goal of this study was to evaluate advantages, risks, and failures of Gamma Knife radiosurgery (GKRS) in a large series of pediatric and adolescent patients with cerebral arteriovenous malformations (cAVMs) who were followed up for at least 36 months.

METHODS

Since February 1993, 100 pediatric and adolescent patients (≤ 18 years of age) with cAVMs have undergone GKRS at the authors' institution and were followed up for at least 36 months. Forty-six patients were boys and 54 were girls; the mean age was 12.8 years (range 3-18 years). Hemorrhage, either alone or combined with seizure, was the clinical onset in 70% of cases. The mean pre-GK cAVM volume was 2.8 ml; 92% of cAVMs were Spetzler-Martin (S-M) Grades I-III. Most lesions (94%) were in eloquent or deep-seated brain regions, according to S-M classification. The parameters for mean and range in treatment planning were prescription isodose 53.8% (40%-90%); prescription dose (PD) 20.2 Gy (9.0-26.4 Gy); maximal dose (MD) 37.8 Gy (18-50 Gy); and number of shots 4.7 (1-17). On the day of GKRS, stereotactic CT or stereotactic MRI and digital subtraction angiography were used.

RESULTS

Obliteration rate (OR) was angiographically documented in 75 of 84 cases (89.3%) after single-session GKRS, with actuarial ORs at 3 and 5 years of 68.0% and 88.1%, respectively. A repeat treatment was performed in 7 patients (6 with obliteration), and 16 patients with cAVMs underwent staged treatment (9 of them were angiographically cured). Thus, the overall OR was 90%, with actuarial ORs at 3, 5, and 8 years of 59.0%, 76.0%, and 85.0%, respectively. Permanent symptomatic GK-related complications were observed in 11% of cases, with surgical removal of enlarged mass seen on post-RS imaging needed in 5 cases. Hemorrhage during the latency period occurred in 9% of patients, but surgical evacuation of the hematoma was required in only 1 patient. One patient died due to rebleeding of a brainstem cAVM. Radiosurgery outcomes varied according to cAVM sizes and doses: volumes ≤ 10 ml and PDs > 16 Gy were significantly associated with higher ORs and lower rates of permanent complication and bleeding during the latency period.

CONCLUSIONS

The data from this study reinforce the conclusion that GKRS is a safe and effective treatment for pediatric and adolescent cAVMs, yielding a high OR with minimal permanent severe morbidity and no mortality. The very low frequency of severe hemorrhages during the latency period further encourages a widespread application of RS in such patients. Univariate analysis found that modified RS-based cAVM score, nidus volume, PD, integral dose, S-M grade, and preplanned treatment (the last 2 parameters were also confirmed on multivariate analysis) significantly influenced OR. Lower S-M grades and single-session planned treatments correlated with shorter treatment obliteration interval on univariate analysis. This statistical analysis suggests that a staged radiosurgical treatment should be planned when nidus volume > 10 ml and/or when the recommended PD is ≤ 16 Gy.

The long-term outcomes of radiosurgery for arteriovenous malformations in pediatric and adolescent populations

OBJECT Although stereotactic radiosurgery (SRS) has been accepted as a therapeutic option for arteriovenous malformations (AVMs) in children and adolescents, substantial data are still lacking regarding the outcomes of SRS for AVMs in this age group, especially long-term complications. This study aimed to clarify the long-term outcomes of SRS for the treatment of AVM in pediatric patients aged ≤ 18 years. METHODS Outcomes of 116 patients who were aged 4-18 years when they underwent SRS between 1990 and 2009 at the study institute were analyzed retrospectively. RESULTS The median follow-up period after SRS was 100 months, with 6 patients followed up for more than 20 years. Actuarial obliteration rates at 3 and 5 years after SRS were 68% and 88%, respectively. Five hemorrhages occurred in 851 patient-years of follow-up. The annual bleeding rate after SRS before obliteration was calculated as 1.3%, which decreased to 0.2% after obliteration. Shorter maximum nidus diameter (p = 0.02) and higher margin dose (p = 0.03) were associated with a higher obliteration rate. Ten patients experienced adverse events after SRS. Of them, 4 patients presented with delayed complications years after SRS (range 9-20 years after SRS). CONCLUSIONS SRS can reduce the risk of hemorrhage in pediatric and adolescent AVMs, with an acceptable risk of complications in the long term. However, adverse events such as expanding hematoma and radiation necrosis that can occur after substantial follow-up should be taken into account at the time that treatment decisions are made and informed consent is obtained.

Transvenous embolization: a report of 4 pediatric cases

The treatment of brain arteriovenous malformations (AVMs) in children has always been a challenge for interventionalists, neurosurgeons, and radiosurgeons. Endovascular embolization is usually performed through transarterial access, but in selected cases the transvenous approach can be considered. The authors of this report aimed to evaluate the efficacy of transvenous embolization in very selected pediatric cases. They describe 4 children treated using transvenous embolization for AVMs that were small, had a single drainage vein, and were deeply located or had a difficult arterial access. The 6-month angiographic and clinical follow-ups are reported as well. In all cases, complete occlusion of the AVM was achieved with no side effects for the patient. Transvenous embolization may represent a promising alternative therapeutic option in very selected cases.

Radiosurgery for unruptured cerebral arteriovenous malformations in pediatric patients

BACKGROUND

Unruptured cerebral arteriovenous malformations (AVMs) in pediatric patients (age <18 years) were excluded from A Randomized Trial of Unruptured AVMs (ARUBA). Therefore, the efficacy of radiosurgery for unruptured pediatric AVMs is poorly understood. The goal of this study is to determine the outcomes and define the predictors of obliteration following radiosurgery for unruptured AVMs in pediatric patients.

METHODS

We evaluated a prospective database, from 1989 to 2013, of AVM patients treated with radiosurgery at our institution. Patients with age less than 18 years at the time of radiosurgery, unruptured nidi, and at least 2 years of radiologic follow-up or AVM obliteration were selected for analysis. Statistical analyses were performed to determine actuarial obliteration rates and identify factors associated with obliteration.

RESULTS

In the 51 unruptured pediatric AVM patients included for analysis, the median age was 13 years, and the most common presentation was seizure in 53 %. The median nidus volume and radiosurgical margin dose were 3.2 cm(3) and 21.5 Gy, respectively. The median radiologic follow-up was 45 months. The actuarial AVM obliteration rates at 3, 5, and 10 years were 29 %, 54 %, and 72 %, respectively. In the multivariate Cox proportional hazards regression analysis, higher margin dose (P = 0.002), fewer draining veins (P = 0.038), and lower Virginia Radiosurgery AVM Scale (P = 0.003) were independent predictors of obliteration. Obliteration rates were significantly higher with a margin dose of at least 22 Gy (P = 0.003) and for nidi with 2 or fewer draining veins (P = 0.001). The incidences of radiologically evident, symptomatic, and permanent radiation-induced changes were 55 %, 16 %, and 2 %, respectively. The annual post-radiosurgery hemorrhage rate was 1.3 %, and the incidence of post-radiosurgery cyst formation was 2 %.

CONCLUSION

Radiosurgery affords a favorable risk to benefit profile for unruptured pediatric AVMs. Pediatric patients with unruptured AVMs merit further study to define an optimal management approach.

Radiosurgery for ruptured intracranial arteriovenous malformations

Object

Ruptured intracranial arteriovenous malformations (AVMs) are at a significantly greater risk for future hemorrhage than unruptured lesions, thereby necessitating treatment in the majority of cases. In a retrospective, single-center study, the authors describe the outcomes after radiosurgery in a large cohort of patients with ruptured AVMs.

Methods

From an institutional review board–approved, prospectively collected AVM radiosurgery database, the authors identified all patients with a history of AVM rupture. They analyzed obliteration rates in all patients in whom radiological follow-up data were available (n = 639). However, to account for the latency period associated with radiosurgery, only those patients with more than 2 years of radiological follow-up and those with earlier AMV obliteration were included in the analysis of prognostic factors related to obliteration and complications. This resulted in a cohort of 565 patients with ruptured AVMs for whom data were analyzed; these patients had a median radiological follow-up of 57 months and a median age of 29 years. Twenty-one percent of the patients underwent preradiosurgery embolization. The median volume and prescription dose were 2.1 cm3 and 22 Gy, respectively. The Spetzler-Martin grade was III or higher in 56% of patients, the median radiosurgery-based AVM score was 1.08, and the Virginia Radiosurgery AVM Scale (RAS) score was 3 to 4 points in 44%. Survival and regression analyses were performed to determine obliteration rates over time and predictors of obliteration and complications.

Results

In the overall population of 639 patients with ruptured AVMs, the obliteration rate was 11.1% based on MRI only (71 of 639 patients), 56.0% based on angiography (358 of 639), and 67.1% based on combined modalities (429 of 639 patients). In the cohort of patients with 2 years of follow-up or an earlier AVM obliteration, the cumulative obliteration rate was 76% and the actuarial obliteration rates were 41% and 64% at 3 and 5 years, respectively. Multivariate analysis identified the absence of preradiosurgery embolization (p < 0.001), increased prescription dose (p = 0.001), the presence of a single draining vein (p = 0.046), no postradiosurgery-related hemorrhage (p = 0.007), and lower Virginia RAS score (p = 0.020) as independent predictors of obliteration. The annual risk of a hemorrhage occurring during the latency period was 2.0% and the rate of hemorrhage-related morbidity and mortality was 1.6%. Multivariate analysis showed that decreased prescription dose (p < 0.001) and multiple draining veins (p = 0.003) were independent predictors of postradiosurgery hemorrhage. The rates of symptomatic and permanent radiation-induced changes were 8% and 2.7%, respectively. In the multivariate analysis, a single draining vein (p < 0.001) and higher Virginia RAS score (p = 0.005) were independent predictors of radiation-induced changes following radiosurgery.

Conclusions

Radiosurgery effectively treats ruptured AVMs with an acceptably low risk-to-benefit ratio. For patients with ruptured AVMs, favorable outcomes are more likely when preradiosurgical embolization is avoided and a higher prescription dose can be delivered.

Stereotactic radiosurgery at a low marginal dose for the treatment of pediatric arteriovenous malformations: obliteration, complications, and functional outcomes

OBJECT.: Stereotactic radiosurgery (SRS) is an established treatment modality for brain arteriovenous malformations (AVMs) in children, but the optimal treatment parameters and associated treatment-related complications are not fully understood. The authors present their single-institution experience of using SRS, at a relatively low marginal dose, to treat AVMs in children for nearly 20 years; they report angiographic outcomes, posttreatment hemorrhage rates, adverse treatment-related events, and functional outcomes.

METHODS

The authors conducted a retrospective review of 2 cohorts of children (18 years of age or younger) with AVMs treated from 1991 to 1998 and from 2000 to 2010.

RESULTS

A total of 80 patients with follow-up data after SRS were identified. Mean age at SRS was 12.7 years, and 56% of patients had hemorrhage at the time of presentation. Median target volume was 3.1 cm(3) (range 0.09-62.3 cm(3)), and median prescription marginal dose used was 17.5 Gy (range 12-20 Gy). Angiograms acquired 3 years after treatment were available for 47% of patients; AVM obliteration was achieved in 52% of patients who received a dose of 18-20 Gy and in 16% who received less than 18 Gy. At 5 years after SRS, the cumulative incidence of hemorrhage was 25% (95% CI 16%-37%). No permanent neurological deficits occurred in patients who did not experience posttreatment hemorrhage. Overall, good functional outcomes (modified Rankin Scale Scores 0-2) were observed for 78% of patients; for 66% of patients, functional status improved or remained the same as before treatment.

CONCLUSIONS

A low marginal dose minimizes SRS-related neurological deficits but leads to low rates of obliteration and high rates of hemorrhage. To maximize AVM obliteration and minimize posttreatment hemorrhage, the authors recommend a prescription marginal dose of 18 Gy or more. In addition, SRS-related symptoms such as headache and seizures should be considered when discussing risks and benefits of SRS for treating AVMs in children.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Treatment for brain arteriovenous malformation in the 1998-2011 period and review of the literature

PURPOSE

The results of the treatment of pial AVM provided at our neurosurgical centre are presented. Based on these results and on an overview of literary data on the efficacy and complications of each therapeutic modality, the algorithm of indications, as used at our institution, is presented. COHORT OF PATIENTS: The series comprises 195 patients, aged 9 to 87 years and treated in the years 1998-2011. The surgical group consists of 76 patients; of these, 49 patients solely received endovascular treatment, 25 were consulted and referred directly to the radiosurgical unit, and the remaining 45 were recommended to abide by the strategy of "watch and wait".

RESULTS

In the surgical group, serious complications were 3.9 %, at a 96.1 % therapeutic efficacy. As for AVM treated with purely endovascular methods, serious procedural complications were seen in 4.1 % of patients, with efficacy totalling 32.7 %. One observed patient suffered bleeding, resulting in death. For comparison with literary data for each modality, a survival analysis without haemorrhage following monotherapy for AVM with each particular modality was carried out.

CONCLUSIONS

Based on our analysis, we have devised the following algorithm of treatment: 1. We regard surgical treatment as the treatment of choice for AVM of Spetzler-Martin (S-M) grades I and II, and only for those grade III cases that are surgically accessible. 2. Endovascular intervention should mainly be used for preoperative embolisation, as a curative procedure for lower-grade AVM in patients with comorbidities, and as palliation only for higher-grade cases. 3. Stereotactic irradiation with Leksell Gamma Knife (LGK) is advisable, mainly for poorly accessible, deep-seated grade-III AV malformations. In the case of lower grades, the final decision is left to the properly informed patient. 4. Observation should be used as the method of choice in AVM of grades IV and V, where active therapy carries greater risk than the natural course of the disease.

Gamma knife surgery for pediatric arteriovenous malformations: a 25-year retrospective study

OBJECT

The authors present their 25-year experience in treating pediatric arteriovenous malformations (AVMs) to allow comparisons with other historic studies and data in adults.

METHODS

Data were collected from a prospectively maintained departmental database selected for age and supplemented by case note review and telephone interviews as appropriate.

RESULTS

Three hundred sixty-three patients, ages 1-16 years (mean ± SD, 12 ± 3.2 years), underwent 410 treatments; 4 had planned 2-stage treatments and 43 were retreated subsequent to an initial partial response. Fifty-eight percent received general anesthesia for the procedure. Sixteen percent had previously undergone embolization. The most common presenting symptoms were as follows: hemorrhage (80.2%), epilepsy (8.3%; overall seizure prevalence 19.9%), and migrainous headaches (6.3%). Only 0.28% of the AVMs were incidental findings. The mean lesion volume was 3.75 ± 5.3 cm3 (range 0.01-32.8 cm3), with a median Spetzler-Martin grade of III (range I-V). The mean peripheral (therapeutic) dose was 22.7 ± 2.3 Gy (range 15-25 Gy), corresponding to a mean maximum dose of 43.6 ± 6 Gy (range 25-51.4 Gy). The obliteration rate was 71.3% in patients who received one treatment and 62.5% for retreated patients, with a mean obliteration time of 32.4 and 79.6 months, respectively. The overall obliteration rate was 82.7%. No follow-up data are as yet available for the 4 patients who underwent the staged treatments. Only 4 patients received peripheral doses below 20 Gy, and the AVM was obliterated in 3 of these patients. The other patients received 20, 22.5, or 25 Gy and had obliteration rates of 82.6%, 77.7%, and 86.3%, respectively. The bleeding rate postradiosurgery was 2.2%, and the cumulative complication rate was 3.6%, with radionecrosis being the most common complication (1.1%).

CONCLUSIONS

Surprisingly, there was no correlation (p = 0.43) between outcome and radiosurgical dose when that dose was between 20 and 25 Gy, thus suggesting that the lower of these 2 doses may be effective. Radiosurgery for pediatric AVM is safe and effective.

Stereotactic radiosurgery of cranial arteriovenous malformations and dural arteriovenous fistulas

Cranial arteriovenous malformations (AVM) and cranial dural arteriovenous fistulas (AVF) carry a significant risk of morbidity and mortality when they hemorrhage. Current treatment options include surgery, embolization, radiosurgery, or a combination of these treatments. Radiosurgery is thought to reduce the risk hemorrhage in AVMs and AVFs by obliterating of the nidus of abnormal vasculature over the course of 2 to 3 years. Success in treating AVMs is variable depending on the volume of the lesion, the radiation dose, and the pattern of vascular supply and drainage. This article discusses the considerations for selecting radiosurgery as a treatment modality in patients who present with AVMs and AVFs.

Stereotactic radiosurgery for arteriovenous malformations, part 2: management of pediatric patients

OBJECT

The authors conducted a study to define the long-term outcomes and risks of stereotactic radiosurgery (SRS) for pediatric arteriovenous malformations (AVMs).

METHODS

Between 1987 and 2006, the authors performed Gamma Knife surgery in 996 patients with brain AVMs; 135 patients were younger than 18 years of age. The median maximum diameter and target volumes were 2.0 cm (range 0.6-5.2 cm) and 2.5 cm(3) (range 0.1-17.5 cm(3)), respectively. The median margin dose was 20 Gy (range 15-25 Gy).

RESULTS

The actuarial rates of total obliteration documented by angiography or MR imaging at 71.3 months (range 6-264 months) were 45%, 64%, 67%, and 72% at 3, 4, 5, and 10 years, respectively. The median time to complete angiographically documented obliteration was 48.9 months. Of 81 patients with 4 or more years of follow-up, 57 patients (70%) had total obliteration documented by angiography. Factors associated with a higher rate of documented AVM obliteration were smaller AVM target volume, smaller maximum diameter, and larger margin dose. In 8 patients (6%) a hemorrhage occurred during the latency interval, and 1 patient died. The rates of AVM hemorrhage after SRS were 0%, 1.6%, 2.4%, 5.5%, and 10.0% at 1, 2, 3, 5, and 10 years, respectively. The overall annual hemorrhage rate was 1.8%. Larger volume AVMs were associated with a significantly higher risk of hemorrhage after SRS. Permanent neurological deficits due to adverse radiation effects developed in 2 patients (1.5%) after SRS, and in 1 patient (0.7%) delayed cyst formation occurred.

CONCLUSIONS

Stereotactic radiosurgery is a gradually effective and relatively safe management option for pediatric patients in whom surgery is considered to pose excessive risks. Although hemorrhage after AVM obliteration did not occur in the present series, patients remain at risk during the latency interval until obliteration is complete. The best candidates for SRS are pediatric patients with smaller volume AVMs located in critical brain regions.