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 gamma 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 cm(3)), 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.