Repeat stereotactic radiosurgery for high-grade and large intracranial arteriovenous malformations

Background: The treatment of large and high-grade (Spetzler-Martin III-V) AVMs remains a challenge. There is a paucity of literature addressing the efficacy of radiosurgery in this group. We retrospectively analyze our experience with repeat radiosurgery with such AVMs. Methods: Between 1989 and 2004, 14 patients with large and high-grade AVMs deemed to be nonoperative candidates were treated with repeat radiosurgery. Patients were treated either on a LINAC or γ knife-based system at 2- to 3-year intervals with targeting of the entire nidus with each treatment. Patients who did not receive their full treatment course or follow-up at the institution were excluded. Results: Mean follow-up was 18 months. The complete obliteration rate was 35.7%, with a mean volume reduction of 53% in the remaining lesions. Twenty percent of grade III and 50% of grade IV lesions experienced cure. Complications included persistent headaches (2 patients). Statistical analysis revealed no difference between obliterated and partially obliterated groups with regard to mean pretreatment volume (24.87 cm³), median Spetzler-Martin grade (IV), mean follow-up (30.5 months), total delivered dose (3550 cGy), mean dose per stage (13 Gy), median number of stages (2), or mean interval between treatment stages (40 months). Conclusion: The present study demonstrates the potential role of repeat radiosurgery in the treatment of this cohort in the context of our short follow-up. The benefits of repeat therapy could be derived from using lower doses per session and repeat targeting of the lesion in an effort to increase response and decrease complication rates.