Background: Stereotactic radiosurgery (RS) is an effective tool in treating brain AVMs. Careful study of AVM angiographic characteristics may improve results.
Objective: To report the long-term outcomes of Gamma Knife radiosurgery (GKRS) in brain AVMs focusing on how the angioarchitectural and hemodynamic parameters of AVMs impact the post-radiosurgery results.
Methods: Retrospective longitudinal study of 697 consecutive GKRS treatments of brain AVMs in 662 patients, performed at a single center between 1993 and 2005. Mean age: 37 years, median AVM volume: 3.6cc, mean follow-up: 11 years. 45% of patients presented with intracranial hemorrhage, 44% underwent embolization, and 7% multiple RS. AVM characteristics in the RS-planning angiograms were analyzed and their relationship to the post-RS obliteration rate was determined by univariate and multivariate analysis.
Results: The obliteration rate after a single RS was 69.3%, after multiple RS 75%. Positive predictors of obliteration included: compact nidus (OR=3.16, 95%CI: 1.92-5.22), undilatated feeders (OR=0.36, 95%CI: 0.23-0.57), smaller AVM volume (OR=0.95, 95%CI: 0.92-0.99), and higher marginal dose (OR=1.16, 95%CI: 1.06-1.27). Improvement or clinical stability was observed in 89.3% of patients, post-procedure bleeding in 6.1%, and clinical worsening attributable to RS in 3.8%. The annual risk of hemorrhage in the four years following RS was 1.2%.
Conclusion: GKRS yielded a good long-term clinical outcome in most patients. Certain angiographic features of brain AVMs, such as a well-defined nidus and undilatated feeder arteries, contribute to AVM occlusion by RS. GKRS can be regarded as the treatment of choice for AVMs smaller than 6 cc, even after bleeding.
Copyright (C) by the Congress of Neurological Surgeons