Open microsurgery required to address failed endovascular embolization for a spinal dural arteriovenous fistula.

[BACKGROUND] "Endovascular treatment (EVT)-first" strategies have been increasingly used to treat spinal dural arteriovenous fistulas (SDAVFs). Nevertheless, when EVT fails to penetrate the fistulous point and proximal draining vein, conversion to an open microsurgical approach is warranted.

[CASE DESCRIPTION] A 52-year-old male presented with progressive myelopathy. The magnetic resonance imaging (MRI) showed spinal cord edema and dorsal flow voids at the T9 level; formal angiography demonstrated an SDAVF supplied by a radiculomeningeal artery and a single dorsal draining vein. Three-dimensional digital subtraction angiography (DSA) revealed a clear T-sign and caliber change suggesting a reachable shunt. However, when transarterial glue embolization was attempted, the embolic agent could not get past the nerve root sleeve, and, therefore, endovascularly, we could not reach the shunt. Further, we identified an additional new feeder originating from T8. Therefore, EVT was abandoned, and an open microsurgical approach was performed. Once the durotomy was completed, congested intradural "red vein" was identified; it was coagulated and ligated near its dural origin, resulting in complete fistula obliteration. Postoperatively, symptoms improved, and the MRI confirmed occlusion of the SDAVF with resolution of vascular congestion findings.

[CONCLUSION] Even when 3D-DSA indicates good access to a SDAVF shunt, penetration may be limited by root-sleeve anatomy and flow dynamics. When attempted embolization results in feeder occlusion without venous penetration, the procedure should be stopped, and early conversion to open microsurgical intervention should be considered as it is typically highly effective.