Dorsal Spinal Subdural Hematoma: A Rare Case of Dorsal Spinal Pial Arteriovenous Fistula

Introduction: Spinal pial arteriovenous fistulas (spAVFs), or intradural perimedullary AVFs, comprise of a direct anastomotic shunt from an intradural artery and spinal veins. They commonly have a hemorrhagic presentation, and though they usually have an anterior spinal artery supply, there have been rare instances of dorsal spAVFs with posterior spinal artery as the primary feeder. Here we present a patient with a spontaneous dorsal spinal subdural hemorrhage (SDH) with intraoperative findings suggestive of a dorsal spAVF.

Methods: This case illustration includes follow-up data for a 1-year period following surgical evacuation for a spinal subdural hematoma along with clipping of a suspected dorsal spAVF. Evaluation of this case included review of CT, MRI, MRA, Diagnostic Spinal Angiogram (DSA), and direct surgical video including with microscopy and intraoperative ultrasound.

Results: A 41-year-old male presented with sudden onset severe headache, back, leg, neck, and retro-orbital pain, followed by transient complete paralysis of his bilateral lower extremities lasting for several hours. He presented to our emergency department the following day with persistent right leg weakness and difficulty ambulating. MRI revealed an extensive SDH tracking along the dorsal spine from T7 to the cauda equina, causing spinal cord compression at T10-11. Pre-operative MRA was negative for an obvious vascular malformation and patient was taken urgently for a laminectomy, subdural hematoma evacuation, and intradural exploration.

Intraoperative findings included SDH with engorged dorsal spinal veins and the appearance of a dorsolateral spAVF at T10. The visualized suspected fistulous point was clipped. No definitive vascular malformation was identified on post-operative DSA and MRA. Despite continued proximal right leg weakness, the patient is now independently ambulatory.

Conclusion : spAVFs remain a hereterogenous and challenging pathology. We present a case of spontaneous spinal SDH caused by a rare dorsal spAVF.