Treatment of brain arteriovenous malformations with high-flow arteriovenous fistulas: risk and complications associated with endovascular embolization in multimodality treatment

OBJECT: High-flow fistulas associated with brain arteriovenous malformations (AVMs) pose a significant challenge to both stereotactic radiosurgery (SRS) and surgical treatment. The purpose of this study was to examine the outcomes of multimodality treatment of AVMs in association with a large arteriovenous fistula (AVF), with a special focus on endovascular embolization and its associated complications. METHODS: One hundred ninety-two patients harboring cerebral AVMs underwent endovascular treatment in the authors' department between 1997 and 2003. Of these, the authors selected 74 patients presenting with an AVM associated with high-flow AVF(s) for a retrospective analysis based on the findings of superselective angiography. After endovascular embolization, 32 patients underwent resection, 33 underwent either SRS or hypofractionated stereotactic radiotherapy (HSRT), and 3 underwent both surgery and SRS. Six patients underwent embolization only. Immediate and midterm treatment outcomes were analyzed. RESULTS: Fifty-seven (77%) of the 74 patients had AVMs that were Spetzler-Martin Grade III or higher. A complete resection was achieved in all 32 patients. Of patients who underwent SRS/HSRT, 13 patients (39.3%) had either complete or > 90% obliteration of the AVM, and 2 patients (6.1%) had incomplete obliteration. Fourteen patients (42.4%) with residual AVM underwent repeated radiotherapy (and remain under observation). Of the 3 patients who underwent both SRS and resection, resection was complete in 2 and incomplete in one. No follow-up was obtained in 6 patients (8.1%). An endovascular complication was observed in 4 patients (5.4%). Fistula embolization was safely performed in every patient, whereas every endovascular complication was associated with other procedures such as nidus embolization. CONCLUSIONS: Endovascular occlusion of the fistulous component was successfully achieved in every patient; every endovascular complication in this series was related to other procedures such as nidus embolization. The importance of the fistula treatment should be emphasized to minimize the endovascular complications and to maximize the treatment effect when a multimodality therapy is used to treat brain AVMs with large AVF.