Results of volume-staged fractionated Gamma Knife radiosurgery for large complex arteriovenous malformations: obliteration rates and clinical outcomes of an evolving treatment paradigm

Abstract

OBJECTIVEThere are few reported series regarding volume-staged Gamma Knife radiosurgery (GKRS) for the treatment of large, complex, cerebral arteriovenous malformations (AVMs). The object of this study was to report the results of using volume-staged Gamma Knife radiosurgery for patients affected by large and complex AVMs.METHODSData from 20 patients with large AVMs were prospectively included in the authors' AVM database between 2004 and 2012. A staging strategy was used when treating lesion volumes larger than 10 cm3. Hemorrhage and seizures were the presenting clinical feature for 6 (30%) and 8 (40%) patients, respectively. The median AVM volume was 15.9 cm3 (range 10.1–34.3 cm3). The mean interval between stages (± standard deviation) was 15 months (± 9 months). The median margin dose for each stage was 20 Gy (range 18–25 Gy).RESULTSObliteration was confirmed in 8 (42%) patients after a mean follow-up of 45 months (range 19–87 months). A significant reduction (> 75%) of the original nidal volume was achieved in 4 (20%) patients. Engel Class I–II seizure status was reported by 75% of patients presenting with seizures (50% Engel Class I and 25% Engel Class II) after radiosurgery. After radiosurgery, 71.5% (5/7) of patients who had presented with a worsening neurological deficit reported a complete resolution or amelioration. None of the patients who presented acutely because of hemorrhage experienced a new bleeding episode during follow-up. One (5%) patient developed radionecrosis that caused sensorimotor hemisyndrome. Two (10%) patients sustained a bleeding episode after GKRS, although only 1 (5%) was symptomatic. High nidal flow rate and a time interval between stages of less than 11.7 months were factors significantly associated with AVM obliteration (p = 0.021 and p = 0.041, respectively). Patient age younger than 44 years was significantly associated with a greater than 75% reduction in AVM volume but not with AVM obliteration (p = 0.024).CONCLUSIONSAccording to the results of this study, volume-staged GKRS is an effective and safe treatment strategy for large, complex, cerebral AVMs for which microsurgery or endovascular approaches could carry substantially higher risks to the patient. Radiation doses up to 20 Gy can be safely administered. The time interval between stages should be shorter than 11.7 months to increase the chance of obliteration. High nidal flow and a patient age younger than 44 years were factors associated with nidus obliteration and significant nidus reduction, respectively.

Volume-Staged Radiosurgery for Large Arteriovenous Malformation: Retrospective Analysis of 19 Cases

“…For relatively large AVMs >10 ml, two main treatment strategies have been suggested: One is a method in which the entire nidus is irradiated with a low dose, such as 14-16 Gy, and additional irradiation is considered after observing changes after several years (dose-staged radiosurgery: DS-SRS) [4]. Another method is VS-SRS, which divides a large nidus into several compartments and prescribes a reasonable dose to each compartment at intervals [2,3,[5][6][7][8][9]. Ilyas et al conducted a systematic review of VS-SRS and DS-SRS and reported that the average complete obliteration rate was 41.2% for VS-SRS and 32.3% for DS-SRS [10].…”

“…However, for large AVMs, the prescribed dose should be decreased to reduce the risk of radiation damage, but it leads to a decrease in nidus obliteration rates. Therefore, it is very difficult to achieve complete obliteration of large AVMs in a single treatment, and methods using multiple irradiation have been reported previously [2][3][4][5][6][7][8][9]. 1 1…”

“…For relatively large AVMs such as those >10 ml, we divide the nidus into multiple components mainly along the z-axis and irradiate them step by step volume-staged stereotactic radiosurgery (VS-SRS). Although VS-SRS is a classical approach for large AVMs [2,3,[5][6][7][8][9], the optimal dose, irradiated volume, and appropriate interval remain unclear. The study aimed to evaluate our results of VS-SRS for large AVMs >10 ml.…”

Gamma Knife Radiosurgery for Arteriovenous Malformations Using a Four-Dimensional Dynamic Volume Computed Tomography Angiography Planning System as an Alternative to Traditional Catheter Angiogram

“…With the development of the ICON system, gamma knife radiosurgery has experienced its first trend toward frameless treatment strategies, as already embraced by Linac-based platforms [ 26 - 27 ]. As more patients receive treatment via this system, we are likely to see further reduction in the need for frame-based radiosurgery, especially in large lesions already treated with dose- or volume-fractionated SRS [ 28 - 29 ]. In our study, treatment remains a frame-based procedure, but the use of the 4D-CTA as part of the planning process in advance of frame placement demonstrates a significant reduction of “in frame” time.…”

Results of surgical treatment after Gamma Knife radiosurgery for cerebral arteriovenous malformations: patient series

“…Gamma Knife radiosurgery (GKRS) is a safe and effective treatment modality for cerebral arteriovenous malformations (AVMs) that reduces the risk of bleeding, seizure, and some neurological deficits caused by stroke. [1][2][3][4][5][6][7][8][9][10] However, there is a risk of bleeding and radiation-induced perifocal edema and seizure before complete resolution of the nidus can be obtained with GKRS. 1,9,[11][12][13][14][15][16][17][18] Bleeding secondary to GKRS is usually caused by a residual AVM or recanalization of the organized intraluminal thrombus and hemodynamic changes (e.g., thrombosis or narrowing of the draining vein).…”