Retrograde Cannulation of the Draining Vein for Embolization of Filum Terminale Arteriovenous Fistula in the Lower Sacral Region

BACKGROUND: Filum terminale arteriovenous fistulae (FTAVFs) are rare entities. For those with the fistulous point located in the lower sacral region (below S2), neither surgical nor endovascular strategies are the optimal treatment. CASE DESCRIPTION: We describe 2 FTAVF cases with the fistulous point below S2: one had the anterior spinal artery (ASA) as a single feeder with a long distance to the fistula and the other developed an inaccessible feeder after the initial non-ASA feeder embolization. In a hybrid operating room, through an L4 laminectomy, we surgically exposed and cannulated the cephalad draining vein, other than the feeding arteries, to retrograde occlude the proximal draining vein along with the fistulous point and feeders using Onyx. All shunt points were obliterated with the help of intraoperative digital subtraction angiography. CONCLUSIONS: Retrograde embolization of the draining vein to obliterate FTAVFs in the lower sacral region is feasible and complete. This technique may provide a new treatment option for FTAVFs.