Introduction: Stereotactic radiosurgery is an effective treatment modality for small arteriovenous malformations (AVMs) of the brain. For larger AVMs, the treatment dose is often lowered to reduce potential complications, but this decreases the likelihood of cure. One strategy is to divide large AVMs into smaller anatomic volumes and treat each volume separately.
Methods: Eighteen patients underwent prospective staged volume radiosurgery over a 13-year period. All AVMs had volumes greater than 15 mls. Separate anatomical volumes were irradiated at 3 to 9 month intervals. At 4 years, patients with residual disease on their follow-up angiograms underwent retreatment.
Results: Fourteen patients have been followed for a minimum of 3 years. Initial follow-up angiography revealed complete occlusion in 5 of the 14 patients (35.7%). Seven patients showed residual disease and underwent retreatment. Six of 7 showed angiographic closure of their AVMs after retreatment. Angiographic closure increases to 78.6% by 7 years. To date, we have achieved angiographic closure in 11 of the 18 patients for an overall occlusion rate of 61.1%. Five patients (27.8%) had a hemorrhage after radiosurgery for an overall hemorrhage rate of 4.2% per patient years. Four of 18 patients (22%) developed transient new symptoms not related to hemorrhage that subsequently resolved. One patient (5.6%) developed a new permanent deficit not related to hemorrhage. One patient declined further treatment after undergoing 2 of 4 planned treatments and subsequently expired from a hemorrhage for an overall mortality of 5.6%.
Conclusions: Staged volume radiosurgery for AVMs larger than 15 mls is a viable treatment strategy. The long-term occlusion rate is high while the radiation related complication rate is low. Hemorrhage during the “lag period” remains the greatest source of morbidity and mortality.
Patient Care: Protocol seems effective in treating large AVMs that historically have been difficult to treat using conventional methods.
Learning Objectives: To prospectively assess the long term efficacy and complications associated with staged volume radiosurgical treatment of large, symptomatic AVMs.