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Robert M. Starke, David J. McCarthy, Ching-Jen Chen, Hideyuki Kano, Brendan J. McShane, John Lee, Mohana Rao Patibandla, David Mathieu, Lucas T. Vasas, Anthony M. Kaufmann, Wei Gang Wang, Inga S. Grills, Christopher P. Cifarelli, Gabriella Paisan, John Vargo, Tomas Chytka, Ladislava Janouskova, Caleb E. Feliciano, Nanthiya Sujijantarat, Charles Matouk, Veronica Chiang, Judith Hess, Rafael Rodriguez-Mercado, Daniel A. Tonetti, L. Dade Lunsford and Jason P. Sheehan

OBJECTIVE

The authors performed a study to evaluate the hemorrhagic rates of cerebral dural arteriovenous fistulas (dAVFs) and the risk factors of hemorrhage following Gamma Knife radiosurgery (GKRS).

METHODS

Data from a cohort of patients undergoing GKRS for cerebral dAVFs were compiled from the International Radiosurgery Research Foundation. The annual posttreatment hemorrhage rate was calculated as the number of hemorrhages divided by the patient-years at risk. Risk factors for dAVF hemorrhage prior to GKRS and during the latency period after radiosurgery were evaluated in a multivariate analysis.

RESULTS

A total of 147 patients with dAVFs were treated with GKRS. Thirty-six patients (24.5%) presented with hemorrhage. dAVFs that had any cortical venous drainage (CVD) (OR = 3.8, p = 0.003) or convexity or torcula location (OR = 3.3, p = 0.017) were more likely to present with hemorrhage in multivariate analysis. Half of the patients had prior treatment (49.7%). Post-GRKS hemorrhage occurred in 4 patients, with an overall annual risk of 0.84% during the latency period. The annual risks of post-GKRS hemorrhage for Borden type 2–3 dAVFs and Borden type 2–3 hemorrhagic dAVFs were 1.45% and 0.93%, respectively. No hemorrhage occurred after radiological confirmation of obliteration. Independent predictors of hemorrhage following GKRS included nonhemorrhagic neural deficit presentation (HR = 21.6, p = 0.027) and increasing number of past endovascular treatments (HR = 1.81, p = 0.036).

CONCLUSIONS

Patients have similar rates of hemorrhage before and after radiosurgery until obliteration is achieved. dAVFs that have any CVD or are located in the convexity or torcula were more likely to present with hemorrhage. Patients presenting with nonhemorrhagic neural deficits and a history of endovascular treatments had higher risks of post-GKRS hemorrhage.

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Robert M. Starke, David J. McCarthy, Ching-Jen Chen, Hideyuki Kano, Brendan McShane, John Lee, David Mathieu, Lucas T. Vasas, Anthony M. Kaufmann, Wei Gang Wang, Inga S. Grills, Mohana Rao Patibandla, Christopher P. Cifarelli, Gabriella Paisan, John A. Vargo, Tomas Chytka, Ladislava Janouskova, Caleb E. Feliciano, Rafael Rodriguez-Mercado, Daniel A. Tonetti, L. Dade Lunsford and Jason P. Sheehan

OBJECTIVE

In this multicenter study, the authors reviewed the results obtained in patients who underwent Gamma Knife radiosurgery (GKRS) for dural arteriovenous fistulas (dAVFs) and determined predictors of outcome.

METHODS

Data from a cohort of 114 patients who underwent GKRS for cerebral dAVFs were compiled from the International Gamma Knife Research Foundation. Favorable outcome was defined as dAVF obliteration and no posttreatment hemorrhage or permanent symptomatic radiation-induced complications. Patient and dAVF characteristics were assessed to determine predictors of outcome in a multivariate logistic regression analysis; dAVF-free obliteration was calculated in a competing-risk survival analysis; and Youden indices were used to determine optimal radiosurgical dose.

RESULTS

A mean margin dose of 21.8 Gy was delivered. The mean follow-up duration was 4 years (range 0.5–18 years). The overall obliteration rate was 68.4%. The postradiosurgery actuarial rates of obliteration at 3, 5, 7, and 10 years were 41.3%, 61.1%, 70.1%, and 82.0%, respectively. Post-GRKS hemorrhage occurred in 4 patients (annual risk of 0.9%). Radiation-induced imaging changes occurred in 10.4% of patients; 5.2% were symptomatic, and 3.5% had permanent deficits. Favorable outcome was achieved in 63.2% of patients. Patients with middle fossa and tentorial dAVFs (OR 2.4, p = 0.048) and those receiving a margin dose greater than 23 Gy (OR 2.6, p = 0.030) were less likely to achieve a favorable outcome. Commonly used grading scales (e.g., Borden and Cognard) were not predictive of outcome. Female sex (OR 1.7, p = 0.03), absent venous ectasia (OR 3.4, p < 0.001), and cavernous carotid location (OR 2.1, p = 0.019) were predictors of GKRS-induced dAVF obliteration.

CONCLUSIONS

GKRS for cerebral dAVFs achieved obliteration and avoided permanent complications in the majority of patients. Those with cavernous carotid location and no venous ectasia were more likely to have fistula obliteration following radiosurgery. Commonly used grading scales were not reliable predictors of outcome following radiosurgery.

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Mohana Rao Patibandla, Dale Ding, Hideyuki Kano, Robert M. Starke, John Y. K. Lee, David Mathieu, Jamie Whitesell, John T. Pierce, Paul P. Huang, Douglas Kondziolka, Caleb Feliciano, Rafael Rodriguez-Mercado, Luis Almodovar, Inga S. Grills, Danilo Silva, Mahmoud Abbassy, Symeon Missios, Gene H. Barnett, L. Dade Lunsford and Jason P. Sheehan

OBJECTIVE

The role of and technique for stereotactic radiosurgery (SRS) in the management of arteriovenous malformations (AVMs) have evolved over the past four decades. The aim of this multicenter, retrospective cohort study was to compare the SRS outcomes of AVMs treated during different time periods.

METHODS

The authors selected patients with AVMs who underwent single-session SRS at 8 different centers from 1988 to 2014 with follow-up ≥ 6 months. The SRS eras were categorized as early (1988–2000) or modern (2001–2014). Statistical analyses were performed to compare the baseline characteristics and outcomes of the early versus modern SRS eras. Favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RICs).

RESULTS

The study cohort comprised 2248 patients with AVMs, including 1584 in the early and 664 in the modern SRS eras. AVMs in the early SRS era were significantly smaller (p < 0.001 for maximum diameter and volume), and they were treated with a significantly higher radiosurgical margin dose (p < 0.001). The obliteration rate was significantly higher in the early SRS era (65% vs 51%, p < 0.001), and earlier SRS treatment period was an independent predictor of obliteration in the multivariate analysis (p < 0.001). The rates of post-SRS hemorrhage and radiological, symptomatic, and permanent RICs were not significantly different between the two groups. Favorable outcome was achieved in a significantly higher proportion of patients in the early SRS era (61% vs 45%, p < 0.001), but the earlier SRS era was not statistically significant in the multivariate analysis (p = 0.470) with favorable outcome.

CONCLUSIONS

Despite considerable advances in SRS technology, refinement of AVM selection, and contemporary multimodality AVM treatment, the study failed to observe substantial improvements in SRS favorable outcomes or obliteration for patients with AVMs over time. Differences in baseline AVM characteristics and SRS treatment parameters may partially account for the significantly lower obliteration rates in the modern SRS era. However, improvements in patient selection and dose planning are necessary to optimize the utility of SRS in the contemporary management of AVMs.

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Mohana Rao Patibandla, Cheng-chia Lee, Athreya Tata, Gokul Chowdary Addagada and Jason P. Sheehan

OBJECTIVE

Research over the past 2 decades has been characterizing the role of stereotactic radiosurgery (SRS) in the treatment of benign intracranial tumors, including meningiomas. However, few studies have examined the long-term outcomes of SRS treatment for posterior fossa meningiomas (PFMs). Furthermore, previous studies have typically used single diameter measurements when reporting outcomes, which can yield misleading results. The authors describe the use of SRS in the treatment of benign WHO grade I PFMs and correlate volumetric analysis with long-term outcomes.

METHODS

This study is a retrospective analysis of a prospectively maintained IRB-approved database. Inclusion criteria were a diagnosis of WHO grade I PFM with subsequent treatment via single-session SRS and a minimum of 3 follow-up MRI studies available. Volumetric analysis was performed on the radiosurgical scan and each subsequently available follow-up scan by using slice-by-slice area calculations of the meningioma and numerical integration with the trapezoid rule.

RESULTS

The final cohort consisted of 120 patients, 76.6% (92) of whom were female, with a median age of 61 years (12–88 years). Stereotactic radiosurgery was the primary treatment for 65% (78) of the patients, whereas 28.3% (34) had 1 resection before SRS treatment and 6.7% (8) had 2 or more resections before SRS. One patient had prior radiotherapy. Tumor characteristics included a median volume of 4.0 cm3 (0.4–40.9 cm3) at treatment with a median margin dose of 15 Gy (8–20 Gy). The median clinical and imaging follow-ups were 79.5 (15–224) and 72 (6–213) months, respectively. For patients treated with a margin dose ≥ 16 Gy, actuarial progression-free survival rates during the period 2–10 years post-SRS were 100%. In patients treated with a margin dose of 13–15 Gy, the actuarial progression-free survival rates at 2, 4, 6, 8, and 10 years were 97.5%, 97.5%, 93.4%, 93.4%, and 93.4%, respectively. Those who were treated with ≤ 12 Gy had actuarial progression-free survival rates of 95.8%, 82.9%, 73.2%, 56.9%, and 56.9% at 2, 4, 6, 8, and 10 years, respectively. The overall tumor control rate was 89.2% (107 patients). Post-SRS improvement in neurological symptoms occurred in 23.3% (28 patients), whereas symptoms were stable in 70.8% (85 patients) and worsened in 5.8% (7 patients). Volumetric analysis demonstrated that a change in tumor volume at 3 years after SRS reliably predicted a volumetric change and tumor control at 5 years (R2 = 0.756) with a p < 0.001 and at 10 years (R2 = 0.421) with a p = 0.001. The authors also noted that the 1- to 5-year tumor response is predictive of the 5- to 10-year tumor response (R2 = 0.636, p < 0.001).

CONCLUSIONS

Stereotactic radiosurgery, as an either upfront or adjuvant treatment, is a durable therapeutic option for WHO grade I PFMs, with high tumor control and a low incidence of post-SRS neurological deficits compared with those obtained using alternate treatment modalities. Lesion volumetric response at the short-term follow-up of 3 years is predictive of the long-term response at 5 and 10 years.

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Mohana Rao Patibandla, Dale Ding, Hideyuki Kano, Zhiyuan Xu, John Y. K. Lee, David Mathieu, Jamie Whitesell, John T. Pierce, Paul P. Huang, Douglas Kondziolka, Caleb Feliciano, Rafael Rodriguez-Mercado, Luis Almodovar, Inga S. Grills, Danilo Silva, Mahmoud Abbassy, Symeon Missios, Gene H. Barnett, L. Dade Lunsford and Jason P. Sheehan

OBJECTIVE

Due to the complexity of Spetzler-Martin (SM) Grade IV–V arteriovenous malformations (AVMs), the management of these lesions remains controversial. The aims of this multicenter, retrospective cohort study were to evaluate the outcomes after single-session stereotactic radiosurgery (SRS) for SM Grade IV–V AVMs and determine predictive factors.

METHODS

The authors retrospectively pooled data from 233 patients (mean age 33 years) with SM Grade IV (94.4%) or V AVMs (5.6%) treated with single-session SRS at 8 participating centers in the International Gamma Knife Research Foundation. Pre-SRS embolization was performed in 71 AVMs (30.5%). The mean nidus volume, SRS margin dose, and follow-up duration were 9.7 cm3, 17.3 Gy, and 84.5 months, respectively. Statistical analyses were performed to identify factors associated with post-SRS outcomes.

RESULTS

At a mean follow-up interval of 84.5 months, favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RIC) and was achieved in 26.2% of patients. The actuarial obliteration rates at 3, 7, 10, and 12 years were 15%, 34%, 37%, and 42%, respectively. The annual post-SRS hemorrhage rate was 3.0%. Symptomatic and permanent RIC occurred in 10.7% and 4% of the patients, respectively. Only larger AVM diameter (p = 0.04) was found to be an independent predictor of unfavorable outcome in the multivariate logistic regression analysis. The rate of favorable outcome was significantly lower for unruptured SM Grade IV–V AVMs compared with ruptured ones (p = 0.042). Prior embolization was a negative independent predictor of AVM obliteration (p = 0.024) and radiologically evident RIC (p = 0.05) in the respective multivariate analyses.

CONCLUSIONS

In this multi-institutional study, single-session SRS had limited efficacy in the management of SM Grade IV–V AVMs. Favorable outcome was only achieved in a minority of unruptured SM Grade IV–V AVMs, which supports less frequent utilization of SRS for the management of these lesions. A volume-staged SRS approach for large AVMs represents an alternative approach for high-grade AVMs, but it requires further investigation.

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Gautam U. Mehta, Georgios Zenonos, Mohana Rao Patibandla, Chung Jung Lin, Amparo Wolf, Inga Grills, David Mathieu, Brendan McShane, John Y. Lee, Kevin Blas, Douglas Kondziolka, Cheng-Chia Lee, L. Dade Lunsford and Jason P. Sheehan

OBJECTIVE

Meningiomas are the most common benign extramedullary lesions of the foramen magnum; however, their optimal management remains undefined. Given their location, foramen magnum meningiomas (FMMs) can cause significant morbidity, and complete microsurgical removal can be challenging. Anterior and anterolateral FMMs carry greater risks with surgery, but they comprise the majority of these lesions. As an alternative to resection, stereotactic radiosurgery (SRS) has been used to treat FMMs in small case series. To more clearly define the outcomes of SRS and to delineate a rational management paradigm for these lesions, the authors analyzed the safety and efficacy of SRS for FMM in an international multicenter trial.

METHODS

Seven medical centers participating in the International Gamma Knife Research Foundation (IGKRF) provided data for this retrospective cohort study. Patients who were treated with Gamma Knife radiosurgery and whose clinical and radiological follow-up was longer than 6 months were eligible for study inclusion. Data from pre- and post-SRS radiological and clinical evaluations were analyzed. Stereotactic radiosurgery treatment variables were recorded.

RESULTS

Fifty-seven patients (39 females and 18 males, with a median age of 64 years) met the study inclusion criteria. Thirty-two percent had undergone prior microsurgical resection. Patients most frequently presented with cranial neuropathy (39%), headache (35%), numbness (32%), and ataxia (30%). Median pre-SRS tumor volume was 2.9 cm3. Median SRS margin dose was 12.5 Gy (range 10–16 Gy). At the last follow-up after SRS, 49% of tumors were stable, 44% had regressed, and 7% had progressed. Progression-free survival rates at 5 and 10 years were each 92%. A greater margin dose was associated with a significantly increased likelihood of tumor regression, with 53% of tumors treated with > 12 Gy regressing. Fifty-two percent of symptomatic patients noted some clinical improvement. Adverse radiation effects were limited to hearing loss and numbness in 1 patient (2%).

CONCLUSIONS

Stereotactic radiosurgery for FMM frequently results in tumor control or tumor regression, as well as symptom improvement. Margin doses > 12 Gy were associated with increased rates of tumor regression. Stereotactic radiosurgery was generally safe and well tolerated. Given its risk-benefit profile, SRS may be particularly useful in the management of small- to moderate-volume anterior and anterolateral FMMs.