Detailed Analysis of Late Adverse Effects of Stereotactic Radiosurgery for Dural Arteriovenous Fistulas: A 20-Year Single-Center Study.

Abstract

Dural arteriovenous fistula (DAVF) is characterized by an abnormal vascular connection located within the dura mater. Stereotactic radiosurgery (SRS) offers favorable outcomes for DAVF, with high obliteration rates and low adverse effects. Although short- to mid-term SRS outcomes for DAVFs and long-term outcomes for arteriovenous malformations have been well documented, the long-term outcomes of SRS for DAVF remain unclear. The aim of this study was to elucidate the late radiation-induced complications (LRICs) of SRS for DAVF based on our long-term observational data. Especially, chronic encapsulated hematoma (CEH), which is defined as an organized intraparenchymal hematoma surrounded by a fibrous capsule, was highlighted as a subtype of LRICs. We enrolled 30 consecutive patients with 32 DAVFs who underwent SRS at our institution between 1998 and 2017. Cumulative DAVF obliteration and LRICs rates and associated risk factors were analyzed using the Kaplan-Meier method. Post-SRS signal changes were defined as edematous lesions with high T2 signal intensity that appeared after SRS. The median observation period after the SRS was 99 months. Two asymptomatic CEHs occurred in our cohort and were treated conservatively. The cumulative rates for LRICs after SRS were 5.3% at 8 years and 11.1% at 10 years. Post-SRS signal changes were significantly associated with the occurrence of CEH (25.0% vs 0.0% at 8 years; P = .005; log-rank test). Although SRS is effective in treating DAVFs, it poses a risk for LRICs. Post-SRS signal changes may be useful predictors of LRIC occurrence.