Application of single-stage stereotactic radiosurgery for cerebral arteriovenous malformations >10 cm3.

BACKGROUND AND PURPOSE Stereotactic radiosurgery (SRS) is a safe and effective treatment for small arteriovenous malformations (AVMs), the use of this modality for the treatment of large AVMs is still controversial, although it has been used in difficult cases. The aim of this study was to evaluate the treatment outcomes of patients who underwent single-stage SRS for large AVMs and to discuss the role of SRS in the treatment of these challenging lesions. METHODS Between 1998 and 2010, 65 patients with AVMs >10 cm(3) underwent single-stage SRS using the Leksell Gamma Knife. Patients who had prospective volume-staged SRS were excluded from this series. Outcomes including the rates of obliteration, hemorrhage after treatment, and adverse events were retrospectively evaluated. RESULTS The mean nidus volume was 14.9 cm(3) (±3.8 cm(3)), and a mean margin dose of 20 Gy (±1.5 Gy) was applied. The mean observation period was 60 months (range, 7-178 months). The nidus obliteration rates after SRS were 44%, 76%, and 81% at 3, 5, and 6 years, respectively. The annual hemorrhage rate after SRS was 1.94% and permanent adverse events were observed in 2 patients (3%). CONCLUSIONS For large AVMs <20 cm(3), single-stage radiosurgery by applying >16 Gy marginal dose presented favorable obliteration rates with relatively low rate of morbidity. Further accumulation of cases is awaited to fully evaluate the results of single-stage radiosurgery for large AVMs.