Stereotactic Radiosurgery versus Observation for Intracranial Low-grade Dural Arteriovenous Fistulas

Introduction: Given the low hemorrhagic risk of intracranial low-grade dural arteriovenous fistulas (dAVFs), the benefits of routine intervention remain controversial. Stereotactic radiosurgery (SRS) has a low-risk profile that may be favorable for these lesions, which have a lower tolerance for complications. However, its efficacy and safety as an upfront treatment have not been adequately assessed against their natural history. In this study, we directly compare the outcomes of patients with low-grade dAVFs treated with SRS versus those managed conservatively.

Methods: Multi-center retrospective study analyzing data from the Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR) and the International Radiosurgery Research Foundation (IRRF). The inclusion criteria were: (1) confirmed diagnosis of an intracranial low-grade dAVF by catheter-based angiography, (2) no prior dAVF-related intracranial hemorrhage, and (3) management with upfront SRS or observation. The study cohort comprised 135 patients from CONDOR and 169 patients from IRRF.

Results: Among 304 patients who had a mean follow-up of 46.7 months (SD 45.5), 169 (55.6%) were females, and the mean age was 56 years (SD 13.5). Of these, 135 (44.4%) patients were managed conservatively and 169 (55.6%) had upfront SRS. Compared to the observation group, symptomatic improvement was more likely in the intervention group (95.1% vs 58.5%; OR=13.75 [5.61-33.69], p< 0.001), which remained significant after multiple imputation and adjustment for baseline differences. The rate of complete dAVF obliteration, hemorrhage, and functional independence were similar between groups. No dAVF up-conversions were observed during follow-up. All-cause mortality rate was 5.4% (n=16), all unrelated to the dAVF or treatment. Five (3.0%) SRS-related complications were reported and resolved during the follow-up period.

Conclusion : SRS treatment was associated with an increased symptomatic improvement rate for patients with intracranial low-grade dAVFs compared to conservative management. SRS was associated with a low complication risk and did not appear to alter rates of dAVF obliteration, hemorrhage, and functional independence. Future prospective trials focusing on SRS as the first-line intervention for symptomatic low-grade dAVFs should be considered.