Stereotactic radiosurgery for arteriovenous malformations: The effect of treatment period on patient outcomes

BACKGROUND: Stereotactic radiosurgery (SRS) has been performed on patients with cerebral arteriovenous malformations (AVMs) for over 40 years. OBJECTIVE: To evaluate the impact of treatment period on obliteration, intracranial hemorrhage (ICH), and radiation-induced complications (RICs). METHODS: Retrospective comparison of 381 AVM patients having SRS during a 20-year period (group 1, January 1990 through March 1997, n 160; group 2, April 1997 through December 2009, n 221). The median radiological and clinical follow-up after initial SRS was 77 months and 93 months, respectively. RESULTS: Obliteration was 59.1% at 4 years and 85.1% at 8 years. Obliteration was more common in patients with hemispheric or cerebellar AVMs (P .001), smaller prescription isodose volume (PIV) (P <.001), and group 1 patients (P <.001). The ICH rate was 7.7% at 4 years and 10.6% at 8 years. ICH was more common in older patients (P .02), patients with deep AVM (P .01), and larger PIV (P <.001). There was no difference in the ICH rate between the treatment groups (P .18). The rate of permanent RICs was 4.4% at 4 years and 8.6% at 8 years. RICs were more common with larger PIVs (P <.001) and group 1 patients (P .02). There was no difference in the number of patients having obliteration without new deficits between the 2 treatment periods (68.8% vs 73.3%, P .33). CONCLUSION: Advances in SRS procedures over the past 20 years have resulted in a lower risk of RIC, but fewer patients had AVM obliteration. Increasing the prescription dose for patients with medium- and large-volume AVMs by using current conformal dose-planning techniques may improve the obliteration rate while maintaining a low risk of RICs.