Safety and efficacy of stereotactic radiosurgery for selected borden type III dural arteriovenous fistulas.

Stereotactic radiosurgery (SRS) is a treatment option for intracranial dural arteriovenous fistulas (DAVFs); however, its effectiveness in Borden type III remains unclear. This study aimed to clarify clinical characteristics, indications, and outcomes of SRS for Borden type III DAVFs. Patients who underwent SRS between 1990 and 2024 were retrospectively analyzed, including primary SRS and adjuvant SRS after endovascular treatment (EVT) or surgery. Borden type was determined from pre-SRS angiography. Primary outcome was complete fistula obliteration, and secondary outcomes were post-SRS hemorrhage, improvement of DAVF-related symptoms, and radiation-induced complications. Seventeen patients were included, with a median age of 65 years (interquartile range [IQR] 52-75 years) and follow-up of 30 months (IQR 15-75 months). Among five hemorrhagic-onset patients, four underwent EVT and/or surgery before SRS. Primary SRS was performed in six patients (35.3%) for low-flow shunts, and adjuvant SRS in eleven (64.7%) for remnant/recurrent shunts after previous treatment. The median prescription dose was 18 Gy (IQR 18-20 Gy). Complete fistula obliteration was achieved in 13 patients (76.5%), with cumulative 2- and 5-year rates of 60.3% and 76.2%, and no difference between primary and adjuvant SRS (log-rank test, p = 0.340). DAVF-related symptoms improved in five of six patients (83.3%). No post-SRS hemorrhage or radiation-induced complications occurred. In conclusion, SRS could be a safe and effective treatment option for selected Borden type III DAVFs utilized as primary treatment for low-flow shunts or as adjuvant treatment for remnant/recurrent shunts, when other treatment modalities are not indicated.