Radiosurgery For Cerebral Arteriovenous Malformations Research Articles

The Role of Biological Effective Dose in Predicting Obliteration After Stereotactic Radiosurgery of Cerebral Arteriovenous Malformations

ObjectiveTo determine whether biological effective dose (BED) was predictive of obliteration after stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVMs). Patients and MethodsWe studied patients undergoing single-session AVM SRS between January 1, 1990, and December 31, 2014, with at least 2 years of imaging follow-up. Excluded were patients with syndromic AVM, previous SRS or embolization, and patients treated with volume-staged SRS. Biological effective dose was calculated using a mono-exponential model described by Jones and Hopewell. The primary outcome was likelihood of total obliteration defined by digital subtraction angiography or magnetic resonance imaging (MRI). Variables were analyzed as continuous and dichotomous variables based on the maximum value of (sensitivity–[1–specificity]). ResultsThis study included 352 patients (360 AVM, median follow-up, 5.9 years). The median margin dose prescribed was 18.75 Gy (interquartile range [IQR]: 18 to 20 Gy). Two hundred fifty-nine patients (71.9%) had obliteration shown by angiography (n=176) or MRI (n=83) at a median of 36 months after SRS (IQR: 26 to 44 months). Higher BED was associated with increased likelihood of obliteration in univariate Cox regression analyses, when treated as either a dichotomous (≥133 Gy; hazard ratio [HR],1.52; 95% confidence interval [CI], 1.19 to 1.95; P<.001) or continuous variable (HR, 1.00, 95% CI, 1.0002 to 1.005; P=.04). In multivariable analyses including dichotomized BED and location, BED remained associated with obliteration (P=.001). ConclusionBiological effective dose ≥133 Gy was predictive of AVM obliteration after single-session SRS within the prescribed margin dose range 15 to 25 Gy. Further study is warranted to determine whether BED optimization should be considered as well as treatment dose for AVM SRS planning.

Imaging Artifacts of Nonadhesive Liquid Embolic Agents in Conventional and Cone-beam CT in a\xa0Novel in Vitro AVM Model

BackgroundA major drawback of liquid embolic agents (LEAs) is the generation of imaging artifacts (IA), which may represent a crucial obstacle for the detection of periprocedural hemorrhage or subsequent radiosurgery of cerebral arteriovenous malformations (AVMs). This study aimed to compare the IAs of Onyx, Squid and PHIL in a novel three-dimensional in vitro AVM model in conventional computed tomography (CT) and cone-beam CT (CBCT).MethodsTubes with different diameters were configured in a container resembling an AVM with an artificial nidus at its center. Subsequently, the AVM models were filled with Onyx 18, Squid 18, PHIL 25% or saline and inserted into an imaging phantom (n = 10/LEA). Afterwards CT and CBCT scans were acquired. The degree of IAs was graded quantitatively (Hounsfield units in a defined region of interest) and qualitatively (feasibility of defining the nidus)—Onyx vs. Squid vs. PHIL vs. saline, respectively.ResultsQuantitative density evaluation demonstrated more artifacts for Onyx compared to Squid and PHIL, e.g. 48.15 ± 14.32 HU for Onyx vs. 7.56 ± 1.34 HU for PHIL in CT (p < 0.001) and 41.88 ± 7.22 density units (DU) for Squid vs. 35.22 ± 5.84 DU for PHIL in CBCT (p = 0.044). Qualitative analysis showed less artifacts for PHIL compared to Onyx and Squid in both imaging modalities while there was no difference between Onyx and Squid regarding the definition of the nidus (p > 0.999).ConclusionIn this novel three-dimensional in vitro AVM model, IAs were higher for the EVOH/tantalum-based LEAs Onyx and Squid compared to iodine-based PHIL. Onyx induced the highest degree of IAs with only minor differences to Squid.

Late complications of radiosurgery for cerebral arteriovenous malformations: report of 5 cases of chronic encapsulated intracerebral hematomas and review of the literature

BackgroundChronic encapsulated intracerebral hematomas (CEIHs) are a rare, late complication of radiosurgery for intracranial AVM. We present 5 cases treated mostly by surgical excision and review the literature.MethodsPatients (age 39, 42, 36, 31, 62) presented with headache, paresthesia, hemiparesis or were asymptomatic. CEIHs presented 10 to 13 years (median 12 years) post radiosurgery. Three patients had demonstrated early radiation induced changes post radiosurgery. Angiographic cure, assessed with DSA, was present in all cases except 1 case with a small nidus remnant. MRI demonstrated mixed lesions with a solid enhancing part, organized hematoma and extensive surrounding edema while three cases had also a cystic component.ResultsExcision of the CEIHs with complete or partial removal of the capsule was performed in 4 patients and resulted in marked clinical improvement. One patient was managed conservatively with administration of steroids as surgery was judged excessively hazardous with eventual stabilization of his symptoms.ConclusionsCEIHs are rare, late complications of radiosurgery for cranial AVM. They may be asymptomatic or provoke symptoms and may be preceded by early radiation induced changes. Complete removal of CEIHS is an effective treatment. Because of the long latency period of CEIHs, patients who had radiosurgery for brain AVMs should be followed by MRI at least 10 years even after complete obliteration.

Radiosurgery for Cerebral Arteriovenous Malformation (AVM) : Current Treatment Strategy and Radiosurgical Technique for Large Cerebral AVM.

Arteriovenous malformations (AVMs) are congenital anomalies of the cerebrovascular system. AVM harbors 2.2% annual hemorrhage risk in unruptured cases and 4.5% annual hemorrhage risk of previously ruptured cases. Stereotactic radiosurgery (SRS) have been shown excellent treatment outcomes for patients with small- to moderated sized AVM which can be achieved in 80–90% complete obliteration rate with a 2–3 years latency period. The most important factors are associated with obliteration after SRS is the radiation dose to the AVM. In our institutional clinical practice, now 22 Gy (50% isodose line) dose of radiation has been used for treatment of cerebral AVM in single-session radiosurgery. However, dose-volume relationship can be unfavorable for large AVMs when treated in a single-session radiosurgery, resulting high complication rates for effective dose. Thus, various strategies should be considered to treat large AVM. The role of pre-SRS embolization is permanent volume reduction of the nidus and treat high-risk lesion such as AVM-related aneurysm and high-flow arteriovenous shunt. Various staging technique of radiosurgery including volume-staged radiosurgery, hypofractionated radiotherapy and dose-staged radiosurgery are possible option for large AVM. The incidence of post-radiosurgery complication is varied, the incidence rate of radiological post-radiosurgical complication has been reported 30–40% and symptomatic complication rate was reported from 8.1% to 11.8%. In the future, novel therapy which incorporate endovascular treatment using liquid embolic material and new radiosurgical technique such as gene or cytokine-targeted radio-sensitization should be needed.

Abstract TP490: Long Term Clinical Results of Linear Accelerator Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations: A Single Institution Experience of 18 Years

Introduction: Cerebral arteriovenous malformation (AVM) is an intracranial pial vascular lesion which is treated with microsurgery, endovascular treatment or stereotactic radiosurgery (SRS). We introduce the long-term clinical results of linear accelerator (LINAC) stereotactic radiosurgery for cerebral AVM which is treated in single institution for 18 years period. Methods: Retrospective chart review was held in cerebral AVM patients treated with Novalis (BrainLAB AG, Heimstetten, Germany) stereotactic radiotherapy from 2001 to 2018. Clinical results such as obliteration rate, hemorrhage rate after SRS, and radiosurgery related adverse event was analyzed. Furthermore, predictors for obliteration and symptomatic radiosurgery induced adverse event was analyzed with multivariate logistic regression test. Results: Among 117 patients with cerebral AVMs treated with LINAC-based SRS, 72 were included in study. Total obliteration rate was 80.6% (58/72) for mean 57.0±48.3 months follow up period. Post-SRS hemorrhage and mortality rate was 6.9% (4/72) and 1.4% (1/72), respectively. Mean radiation dose and volume was 22.8Gy and 3.7cc, respectively. Independent predictive factors for nidus obliteration was: (1) radiation dose (OR 1.43, 95% CI 1.04-2.08, p=0.0374), (2) Ruptured AVM (OR 12.18, 95% CI 2.38-86.47, p=0.0054), (3) Virginia AVM score (OR 0.21, 95% CI 0.07-0.53, p=0.0028), and (4) follow up period months (OR 1.03, 95% CI 1.01-1.06, p=0.0261). Independent risk factors for symptomatic radiosurgery related adverse event was radiation volume (OR 1.61, 95% CI 1.09-2.65, p=0.0326). Conclusion: LINAC-based SRS is effective and relatively safe method for treatment of cerebral AVMs. Independent predictive factors for obliteration was high radiation dosage, ruptured status, low Virginia AVM score, and long follow up period. High radiation volume was related to symptomatic radiation induced adverse event.

Letter: Clinical Outcomes of Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations in Pediatric Patients: Systematic Review and Meta-Analysis.

Letter: Clinical Outcomes of Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations in Pediatric Patients: Systematic Review and Meta-Analysis.

Seizure control after radiosurgery for cerebral arteriovenous malformations: a 25-year experience.

Seizures are the second-most common presenting symptom in patients with lobar arteriovenous malformations (AVMs). However, few studies have assessed the long-term effect of stereotactic radiosurgery (SRS) on seizure control. The authors of this study assess the outcome of SRS for these patients to identify prognostic factors associated with seizure control. Patients with AVM who presented with a history of seizure and underwent SRS at the authors' institution between 1987 and 2012 were retrospectively assessed. The total cohort included 155 patients with a mean follow-up of 86 months (range 6-295 months). Primary outcomes assessed were seizure frequency, antiepileptic drug regimen, and seizure freedom for 6 months prior to last follow-up. Seizure-free status was achieved in 108 patients (70%), with an additional 23 patients (15%) reporting improved seizure frequency as compared to their pre-SRS status. The median time to seizure-free status was estimated to be 12 months (95% CI 0-27 months) as evaluated via Kaplan-Meier survival analysis. The mean seizure frequency prior to SRS was 14.2 (95% CI 5.4-23.1) episodes per year. Although not all patients tried, the proportion of patients successfully weaned off all antiepileptic drugs was 18% (28/155 patients). On multivariate logistic regression, focal impaired awareness seizure type (also known as complex partial seizures) and superficial venous drainage were significantly associated with a decreased odds ratio for seizure-free status at last follow-up (OR 0.37 [95% CI 0.15-0.92] for focal impaired awareness seizures; OR 0.36 [95% CI 0.16-0.81] for superficial venous drainage). The effects of superficial venous drainage on seizure outcome were nonsignificant when excluding patients with < 2 years of follow-up. AVM obliteration did not correlate with long-term seizure freedom (p = 0.202, chi-square test). This study suggests that SRS improves long-term seizure control and increases the likelihood of being medication free, independently of AVM obliteration. Patients with focal impaired awareness seizures were less likely to obtain long-term seizure relief.

In Reply: Clinical Outcomes of Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations in Pediatric Patients: Systematic Review and Meta-Analysis.

In Reply: Clinical Outcomes of Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations in Pediatric Patients: Systematic Review and Meta-Analysis.

Clinical Outcomes of Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations in Pediatric Patients: Systematic Review and Meta-Analysis

Arteriovenous malformations (AVMs) in pediatric patients exhibit remarkable differences in terms of management and outcomes. Owing to a paucity of relevant data pertaining to AVMs in pediatric patients, special interest and investigation are required for an improved understanding of the available evidence by clinicians. To determine the clinical outcomes of single-session stereotactic radiosurgery (SRS) for AVMs in pediatric patients. A systematic literature review was performed to identify studies that reported the outcomes of SRS for AVMs in pediatric patients. Data pertaining to variables such as obliteration rate, post-SRS new hemorrhage rate, post-SRS new neurological deficit rate, and mortality rate were extracted and analyzed using meta-analysis techniques. Based on pooled data from 20 studies with 1212 patients, single-session SRS resulted in complete obliteration in 65.9% (95% confidence interval [CI], 60.5%-71.1%; I2=66.5%) patients. Overall complication rate (including new hemorrhage, new neurodeficit, and mortality) was 8.0% (95% CI, 5.1%-11.5%; I2=66.4%). Post-SRS new neurological deficit rate was 3.1% (95% CI, 1.3%-5.4%; I2=59.7%), and post-SRS hemorrhage rate was 4.2% (95% CI, 2.5%-6.3%; I2=42.7%). There was no significant difference between studies disaggregated by treatment method (Gamma Knife [Elekta AB] vs other), treatment year (before year 2000 vs after year 2000), median AVM volume reported (≥3 vs<3 cm3), median dose reported (≥20 vs<20 Gy), or follow-up period (≥36 vs<36 mo). Single-SRS is a safe treatment alternative that achieves high obliteration rates and acceptable complication rates for AVMs in pediatric patients.

Is Biological Effective Dose (BED) Predictive of Outcomes After Radiosurgery for Cerebral Arteriovenous Malformations?

Abstract INTRODUCTION Reports have shown that radiation dose directly correlates with the chance of nidus obliteration after stereotactic radiosurgery (SRS) for arteriovenous malformations (AVMs). However, recent studies have shown that the rate of obliteration was greater in patients having SRS before 2000. As the effect of radiation on cell viability is both dose- and time-dependent, one explanation may be that contemporary SRS, which utilizes more isocenters of radiation to improve dose conformality, takes longer to deliver the same radiation dose, thereby reducing its effectiveness. Biological effective dose (BED) is a metric that incorporates both dose and treatment time and has been shown to correlate with enhanced cell kill in Vitro, as well as normal tissue toxicity in animal models. METHODS A retrospective study of patients having single-session AVM SRS between 1990 and 2009 with a minimum of 2 yr follow-up. Excluded were patients having prior radiation or embolization, as well as patients having volume-staged SRS. BED was calculated using the mono-exponential model described by Jones and Hopewell. The primary outcomes of the study were time to obliteration and chance of excellent outcome (nidus obliteration with no new deficits). RESULTS Three hundred twenty-one patients (328 AVMs) met inclusion criteria (median follow-up, 6.7 yr). BED was associated with both decreased time to obliteration and excellent outcome in univariate Cox regression analyses, both when treated as a dichotomous (P = .002, HR = 1.51 for obliteration; P = .001, HR = 1.61 for outcome) or continuous variable (P = .049, HR = 1.002 for obliteration; P = .01, HR = 1.00 for outcome). In multivariable analyses including dichotomized BED and modified Radiosurgery-Based Arteriovenous Malformation Score as covariates, BED remained significantly associated with both time to obliteration (P = .01, HR = 1.46) and excellent outcome (P = .04, HR = 1.40). CONCLUSION BED was predictive of outcomes after AVM SRS. Further study is warranted to determine whether BED optimization should be considered as well as a prescribed treatment dose for SRS treatment planning.

Venous Stenosis and Hemorrhage After Radiosurgery for Cerebral Arteriovenous Malformations

The risk of hemorrhage remains after radiosurgery for patients with arteriovenous malformations (AVMs), especially during the latency period. The effect of venous outflow stenosis on postradiosurgery AVM hemorrhage has been understudied. The present study sought to clarify the effect of venous stenosis on postradiation hemorrhage. We retrospectively reviewed the records of patients with AVM seen at our institution from 1990 to 2015. Patients who had undergone radiosurgery were included, and those without sufficient data were excluded. We performed multivariable Cox regression to evaluate the predictors of postradiosurgery hemorrhage, with specific emphasis on venous stenosis. Patients were censored from the first radiosurgery to hemorrhage or the last follow-up visit. The baseline and angiographic characteristics were compared between those with venous stenosis and those without to address potential confounders. The present study included 240 patients, of whom 29 (12.1%) had venous stenosis. The venous stenosis cohort included more patients with venous varices (P= 0.009) and fewer with deep venous drainage (P= 0.048) compared with those without venous stenosis. Most patients had grade III or higher AVMs (63.2%), with an obliteration rate of 32.9%. In an all-inclusive multivariable Cox regression, hemorrhage risk was associated with venous stenosis (hazard ratio [HR], 3.70; P= 0.034), age (HR, 1.05; P= 0.002), AVM volume (HR, 1.04; P= 0.004), and hemorrhage before treatment (HR, 4.11; P= 0.014). Male gender was protective (HR, 0.31; P= 0.036) against hemorrhage. We identified statistically significant risk factors for postradiosurgery AVM hemorrhage, which included advanced age, female gender, the presence of venous stenosis, a larger AVM volume, and previous hemorrhage. We recommend cautious selection of patients for radiosurgery with close follow-up after treatment, especially for patients with these risk factors.

Surgical Management of Adverse Radiation Effects After Gamma Knife Radiosurgery for Cerebral Arteriovenous Malformations: A Population-Based Cohort Study.

The goal of this study is to report our experience in the surgical treatment of cerebral arteriovenous malformations (cAVMs) related permanent symptomatic adverse radiation effects (PSAREs), to clarify an appropriate surgical management and to identify the risk factors related to their development. We evaluated 549 patients treated with Gamma Knife radiosurgery (GKRS) for cAVMs with a follow-up of at least 8 years. Univariate and multivariate analyses were used to test different risk factors related to the development of PSARE. We retrospectively reviewed the records of these patients to analyze the clinical outcome. Fourteen patients (2.5%) developed PSARE and were submitted to surgery. Higher average treated volume represents a significant risk factors for the development of PSARE (P < 0.05); on the other hand, older age and higher average dose reduce the risk of PSARE (P<0.05). A favorable clinical outcome was achieved in 13 patients (93%) after surgery; in 1 patient, the unfavorable outcome was due to hemorrhage that occurred months after GKRS. Serial MRI scans following either surgical removal of the nodule or Ommaya reservoir positioning showed progressive reduction of brain edema in all cases. The management of PSARE is controversial, especially for cAVMs treated with SRS. Surgical removal is rarely needed, but-if unavoidable-it can be a valuable option in experienced hands. A careful preoperative planning is always necessary to detect pathologic blood flow through the PSARE.

Does Advanced Age Affect the Outcomes of Stereotactic Radiosurgery for Cerebral Arteriovenous Malformation?

Stereotactic radiosurgery (SRS) is generally considered a minimally invasive treatment modality. However, definitive evidence of the efficacy of SRS in the elderly population is still not available. The outcomes of 561 elderly and nonelderly patients who underwent SRS for AVM at our institution between 1990 and 2013 were reviewed, analyzed, and compared. Elderly patients were defined as those age ≥60 years at the time of SRS. The elderly cohort comprised 55 patients; the nonelderly cohort, 506. In the elderly cohort, the median age was 65 years, and the duration of follow-up was 91 months. The actuarial obliteration rates were 47% at 3 years, 70% at 4 years, and 76% at 5 years in the elderly cohort, and 57% at 3 years, 76% at 4 years, and 83% at 5 years in the nonelderly cohort. In the elderly cohort, the hemorrhage rates during the post-SRS latent phase were 5.2%/year in patients with hemorrhagic onset and 0%/year in those with nonhemorrhagic onset, and event-free survival (EFS) was 93% at 6 years and 89% at 12 years. The obliteration rate, mortality, and EFS rate were not significantly different between the 2 cohorts, whereas the rate of perifocal edema was significantly lower (P= 0.021) in the elderly cohort. The pre-SRS and post-SRS hemorrhage rates were slightly higher in the elderly cohort, albeit without statistical significance. Therapeutic effects and outcomes of SRS are similar in elderly and nonelderly patients. Treatment-related neurologic deficits are rare, and longer EFS can be expected.

373 Risk of Hemorrhage Following Radiosurgery for Cerebral Arteriovenous Malformations (AVMs) Is Associated with Venous Stenosis

Abstract INTRODUCTION Approximately 6% of all patients who undergo radiosurgery experience subsequent hemorrhage, even in those with obliterated lesions. Little information has been presented in existing literature about risk modifiers of post-radiosurgery hemorrhage. Associated aneurysms, venous drainage pattern, size of AVM and prescription dose were previously reported as risk factors. Here, we aim to elucidate the effect of venous stenosis on risk of hemorrhage after radiosurgery. METHODS We retrospectively reviewed medical records of all AVM patients evaluated at our institution from 1990–2015, and those who were treated with radiosurgery were included. We excluded patients without baseline or follow-up data, nor information about treatment and angiographic results. Baseline and angiographic characteristics were compared between those with venous stenosis and those without to elicit confounding factors. We then proceeded with univariable and multivariable Cox regression analysis looking at predictors of post-radiosurgery hemorrhage, with inclusion of confounding factors. Patients were censored from first radiosurgery to hemorrhage or to last follow-up. RESULTS &gt;We included 240 patients in this study. Twenty-nine (12.1%) had venous stenosis; there were more AVMs with venous varices(P = 0.009) and fewer with deep venous drainage (P = 0.048) compared to those without venous stenosis. Univariable analysis on post-radiosurgery hemorrhage showed age, gender, AVM volume, venous stenosis, and unrelated aneurysm were associated with increased risk of hemorrhage. In an all-inclusive model multivariable Cox regression, increased risk of hemorrhage was associated with venous stenosis (HR:3.70, P = 0.034), age (HR:1.05, P = 0.002), AVM volume (HR:1.04, P = 0.004), and hemorrhage before treatment (HR:4.11, P = 0.014). Male gender appears protective (HR:0.31, P = 0.036) against hemorrhage. CONCLUSION We found multiple factors associated with increased risk of AVM hemorrhage after radiosurgery. We recommend that selection of radiosurgery should proceed with caution with close follow-up after treatment, especially in patients with venous stenosis combined with advanced age, female gender, large AVM volume, and previous rupture.

Results of Treatment With Radiosurgery in Cerebral Arteriovenous Malformations: An 18-Year Retrospective Study

Results of Treatment With Radiosurgery in Cerebral Arteriovenous Malformations: An 18-Year Retrospective Study

Using a Machine Learning Approach to Predict Outcomes after Radiosurgery for Cerebral Arteriovenous Malformations.

Predictions of patient outcomes after a given therapy are fundamental to medical practice. We employ a machine learning approach towards predicting the outcomes after stereotactic radiosurgery for cerebral arteriovenous malformations (AVMs). Using three prospective databases, a machine learning approach of feature engineering and model optimization was implemented to create the most accurate predictor of AVM outcomes. Existing prognostic systems were scored for purposes of comparison. The final predictor was secondarily validated on an independent site’s dataset not utilized for initial construction. Out of 1,810 patients, 1,674 to 1,291 patients depending upon time threshold, with 23 features were included for analysis and divided into training and validation sets. The best predictor had an average area under the curve (AUC) of 0.71 compared to existing clinical systems of 0.63 across all time points. On the heldout dataset, the predictor had an accuracy of around 0.74 at across all time thresholds with a specificity and sensitivity of 62% and 85% respectively. This machine learning approach was able to provide the best possible predictions of AVM radiosurgery outcomes of any method to date, identify a novel radiobiological feature (3D surface dose), and demonstrate a paradigm for further development of prognostic tools in medical care.

Radiosurgery for Cerebral Arteriovenous Malformations with Associated Arterial Aneurysms

The radiosurgical outcomes for cerebral arteriovenous malformations (AVM) with AVM-associated arterial aneurysms (AAA) are poorly understood, because many AAAs are embolized before nidal intervention. The aim of this retrospective case-control study is to determine the effect of AAAs on AVM radiosurgery outcomes. We evaluated an institutional AVM radiosurgery database from 1989 to 2013. AAAs were classified as intranidal (type I) or prenidal (type II). The case cohort comprised AVMs with patent type I or II AAAs. The control cohort comprised AVMs without AAAs and matched 2:1 to the case cohort. The case cohort comprised 51 AVMs, including 23 with type I and 28 with type II AAAs. The control cohort comprised 102 AVMs without AAAs. The cumulative AVM obliteration, annual postradiosurgery hemorrhage, and radiologically evident radiation-induced changes rates were 67%, 3.3%, and 28%, respectively, for the case cohort, compared with 70%, 2.0%, and 35%, respectively, for the control cohort. The presence of an AAA was not significantly associated with obliteration (P = 0.293), postradiosurgery hemorrhage (P = 0.209), or radiation-induced changes (P = 0.323). The rates of type II AAA occlusion at 3, 5, and 10 years were 46%, 77%, and 95%, respectively. The type II AAA occlusion rate was significantly higher in obliterated AVMs (P = 0.002). Patent intranidal or prenidal AAAs do not significantly affect AVM radiosurgical outcomes. Occlusion of distal prenidal AAAs commonly occurs after radiosurgery. These findings may support a more conservative stance for embolization before radiosurgery for AVMs with AAAs.

Radiosurgery for Cerebral Arteriovenous Malformations in Elderly Patients: Effect of Advanced Age on Outcomes After Intervention

Cerebral arteriovenous malformations (AVM) are infrequently diagnosed and treated in elderly patients (age, >60 years). We hypothesize that, in contrast to AVM surgical outcomes, radiosurgery outcomes are not adversely affected by increased age. The goals of this case-control study are to analyze the radiosurgery outcomes for elderly patients with AVMs and determine the effect of elderly age on AVM radiosurgery outcomes. We evaluated a prospective database of patients with AVMs treated with radiosurgery from 1989 to 2013. Elderly patients with AVM (age, ≥ 60 years) with radiologic follow-up of ≥ 2 years or nidus obliteration were selected for analysis, and matched, in a 1:1 fashion and blinded to outcome, to adult nonelderly patients with AVM (age, <60 years). Statistical analyses were performed to determine actuarial obliteration rates and evaluate the relationship between elderly age and AVM radiosurgery outcomes. The matching processes yielded 66 patients in each of the elderly and nonelderly AVM cohorts. In the elderly AVM cohort, the actuarial AVM obliteration rates at 3, 5, and 10 years were 37%, 65%, and 77%, respectively; the rates of radiologically evident, symptomatic, and permanent radiation-induced changes were 36%, 11%, and 0%, respectively; the annual hemorrhage risk after radiosurgery was 1.1%, and the AVM-related mortality rate was 1.5%. Elderly age was not significantly associated with AVM obliteration, radiation-induced changes, or hemorrhage after radiosurgery. Advanced age does not appear to confer appreciably worse AVM radiosurgery outcomes, unlike its negative effect on AVM surgical outcomes. Thus, when an AVM warrants treatment, radiosurgery may be the preferred treatment for elderly patients.

Predictors of Seizure Improvement Following Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations in a Prospective Cohort of 229 Patients with AVM-associated Epilepsy (P1.001)

Predictors of Seizure Improvement Following Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations in a Prospective Cohort of 229 Patients with AVM-associated Epilepsy (P1.001)

Frameless Hypofractionated Robotic Radiosurgery for Cerebral Arteriovenous Malformations: Early Clinical Report on Obliteration Rate, Bleeding Risk, and Toxicity

analyses the independent prognostic factors according to the histology of the primary tumor are as follows: Breast e KPS < 70% (HR Z 1.84); no PTC (HR Z 1.47), no chemotherapy [CT] (HR Z 1.49); no RS (HR Z 2.34). Lung e KPS < 70% (HR Z 1.80); no PTC (HR Z 2.10); no FT (HR Z 2.90 for RS and 1.72 for SG, respectively). Melanoma e no FT (HR Z 4.38 for RS and 2.28 for SG, respectively). GI e no SG (HR Z 4.19). All tumors e KPS < 70% (HR Z 1.70); no PTC (HR Z 1.42); no CT (HR Z 1.42), no FT (HR Z 2.48 for RS and 2.11 for SG, respectively); ECM (HR Z 1.48). *All p value < 0.05. Conclusions: Comparing our data to DS-GPA we observe differences in prognostic factors for breast cancer (PTC, CT and FT), lung cancer (PTC and FT), melanoma (FT) and GI (FT). ECM was just significant when it was analyzed all tumor types together and the number of BM was not an independent factor in this study. The FT was correlated with improved survival in all tumor histology. The inclusion of new prognostic factors could further refine DS-GPA. Author Disclosure: M.G. Silva: None. D.F.G. Neves: None. F.L.C. Faustino: None. D.F. Ferreira: None. A.C.A. Pellizon: None. R.C. Fogaroli: None. D.G. Castro: None. M.J. Chen: None.