Hybrid open-endovascular onyx embolization of spinal type IVb perimedullary spinal arteriovenous fistula through direct posterior spinal vein access: A case report.

Background: Spinal arteriovenous fistulas (SAVFs) are direct communication between arteries and veins without intervening abnormal vessel nidus, which often results in venous congestion and spinal cord dysfunction. Ventrally located SAVF can be challenging to treat through traditional open or endovascular approaches.

Case description: We describe a hybrid (open/endovascular) procedure in a 72-year-old male with a Takai Type IVb SAVF presenting with paraparesis and sphincter dysfunction. Imaging revealed a conus medullaris SAVF in which the main fistulous connection was located ventrally. The conventional endovascular approach was deemed risky, and open surgery failed in the first attempt. The SAVF was resolved using a hybrid approach: under direct visualization, an engorged dorsal vein was punctured with an Angiocath, and a fluoroscopy-guided microcatheter was advanced through it to reach and embolize the ventral perimedullary fistulous connection. After surgery, his progressive neurological decline stabilized, radiographic spinal cord edema improved, and follow-up angiography confirmed obliteration of the fistula. Neurological function remained at the preoperative baseline.

Conclusion: This approach may be a treatment for selected cases of type IVb SAVF. Easily accessible feeding vessels are coagulated and cut; the inaccessible ones can be embolized endovascularly during the same procedure.