Hidden Triplets: Coexisting Spinal Epidural and Dural Arteriovenous Fistulae - A Rare Case Report and Literature Review.

A Spinal epidural and dural Arteriovenous Fistula is a rare vascular malformation that rarely presents as multiple synchronous lesions. We report a rare case of three synchronous lumbar spinal arteriovenous shunts in a 22-year-old male presenting with subarachnoid hemorrhage (SAH) symptoms. Angiographic evaluation revealed a complex vascular pathology consisting of one anterior epidural arteriovenous fistula (AVF) fed by the L3 radiculomedullary branch and two smaller dural AVFs at L4-L5 levels. Initial cranial imaging was unremarkable, but spinal MRI demonstrated intrathecal hemorrhage with perimedullary flow voids. The dominant epidural fistula, characterized by a large venous pouch draining into medullary veins, was successfully treated with endovascular embolization, fistula and staged management was planned for the remaining lesions. This case highlights three important clinical aspects: (1) the coexistence of epidural and dural spinal shunts represents a distinct pathological entity from classic spinal dural AVFs; (2) hemorrhagic presentation may occur in spinal AVFs with epidural venous drainage; and (3) comprehensive spinal angiography is crucial when evaluating SAH of unknown origin. The anatomical and hemodynamic differences between these fistula types underscore the need for precise angiographic characterization to guide appropriate management.