Objective: This study was undertaken to determine which factors were statistically predictive of radiological and clinical outcomes in the radiosurgical treatment of arteriovenous malformations (AVMs).
Methods: The computerized dosimetric and clinical data for 269 patients were reviewed. The AVM nidus was hand-contoured on successive enhanced computed tomographic slices through the nidus, to allow detailed determinations of nidus volume, target miss, normal brain tissue treated, dose conformality, and dose gradient. In addition, a number of patient and treatment factors, including Spetzler-Martin grade, presenting symptoms, dose, number of isocenters, radiological outcome, and clinical outcome, were subjected to multivariate analysis.
Results: Two hundred twenty-five patients were treated with radiosurgery for the first time, and 44 patients underwent radiosurgical retreatment. One hundred forty-three patients had AVMs located in or near "eloquent" brain areas and 126 patients did not. Seventy patients demonstrated preoperative neurological findings related to the AVM and 199 did not. Twenty-six patients had previously undergone endovascular treatment and 10 patients had previously undergone surgical treatment of their AVMs. Of the 269 patients studied, 228 experienced no complication, 10 (3.7%) experienced a transient radiation-induced complication, 3 (1%) experienced a permanent radiation-induced complication, and 28 (10%) experienced posttreatment hemorrhage.
Conclusion: None of the analyzed factors was predictive of hemorrhage after radiosurgery in this study. The 12-Gy volume was predictive of permanent radiation-induced complications. Eloquent AVM location and 12-Gy volume were correlated with the occurrence of transient radiation-induced complications. Better conformality was correlated with a reduced incidence of transient complications. Lower Spetzler-Martin grades, higher doses, and steeper dose gradients were correlated with radiological success.