Volume-staged radiosurgery for large arteriovenous malformations: an evolving paradigm

Area of Science:

• Neurosurgery
• Radiation Oncology
• Radiosurgery

Background:

• Large arteriovenous malformations (AVMs) present significant treatment challenges.
• Optimal treatment parameters for volume-staged stereotactic radiosurgery (VS-SRS) for large AVMs remain undefined.
• Previous VS-SRS approaches for AVMs larger than 10 ml require optimization.

Purpose of the Study:

• To compare VS-SRS treatment outcomes for AVMs exceeding 10 ml between two distinct treatment eras.
• To evaluate the impact of modified treatment parameters on AVM obliteration and cure rates.
• To assess complication rates associated with different VS-SRS strategies for large AVMs.

Main Methods:

• Retrospective review of 63 patients who completed VS-SRS for AVMs larger than 10 ml.
• Comparison of treatment outcomes between Era 1 (1992-2004) and Era 2 (2004-2008).
• Era 2 featured prospectively decreased AVM treatment volume per stage, increased dose per stage, and shortened intervals between stages.

Main Results:

• Near or complete AVM obliteration was significantly more common in Era 2 (68% at 5 years) compared to Era 1 (21% at 5 years).
• Higher radiation dose per stage (≥ 17 Gy) and smaller AVM volume per stage (≤ 8 ml) were strong predictors of obliteration.
• The overall probability of cure, including salvage therapy, was significantly higher in Era 2 (41% at 5 years) versus Era 1 (0% at 5 years), with a lower complication rate (13% vs. 29%).

Conclusions:

• VS-SRS is a viable treatment option for large AVMs, offering obliteration or downsizing.
• Reducing AVM treatment volume per stage to ≤ 8 ml enhances dose delivery, accelerates response, and improves obliteration and cure rates.
• This refined VS-SRS approach facilitates improved outcomes for large AVMs without increasing complications, potentially enabling surgical intervention for cure.