Imaging And Outcomes In The Treatment Of Sacral Dural Arteriovenous Fistulas.

OBJECTIVE

Spinal dural arteriovenous fistulas (DAVFs) in the sacral region are extremely rare and their intradural retrograde draining system has not been investigated in detail. The aim of this study was to characterize the venous drainage patterns of sacral DAVFs based on our clinical experience in treating patients with this condition.

METHODS

We retrospectively reviewed the clinical data of patients with sacral DAVFs treated at our institution from January 2016 to January 2024. Preoperative spinal angiography was used to evaluate the positional relationship between the shunt point of sacral DAVF and the vertebral midline. We proposed that if the location of the shunt point was located on the midline, the draining vein would be the filum terminale vein (FTV); if the shunt point was located off the midline, the draining vein would be the radiculomedullary vein (RMV).

RESULTS

A total of 17 sacral DAVFs patients treated with direct surgery were included in this study. All patients presented with lower extremity weakness and numbness. Sphincter dysfunction was present in 15 patients (88.2%). The mean interval from symptom onset to diagnosis was 14.1 months (range 1-96 months). Preoperative magnetic resonance imaging(MRI) detected T2 hyperintensity at the level of the conus medullaris and intradural flow voids in all patients. Spinal angiography confirmed the diagnosis of sacral DAVF in all cases, and complete fistula occlusion was achieved with surgical ligation in all patients. Intraoperatively, 4 patients with the midline location of the shunt point were confirmed to have FTV as the draining vein, while the other 13 patients with off-midline shunt point were confirmed to have RMV as the draining vein. The intraoperative findings were completely consistent with the preoperative assessment of the draining veins based on the location of the shunt point.

CONCLUSIONS

The draining veins of sacral DAVFs are not always the FTVs, in fact, most sacral DAVFs drain via the RMV. With our simple imaging-based method, the two different types of draining veins in sacral DAVFs can be preliminarily identified before surgery.