The Shunt Point of the Sacral Dural Arteriovenous Fistula: A Case Report and Literature Review

Background The occurrence of sacral dural arteriovenous fistula (dAVF) is rare. The detailed vascular architecture of sacral dAVF, including 3-dimensional (3D) angiographic images with operative findings, has not been evaluated compared with that of the thoracic and lumbar levels. We report a case of sacral dAVF with 3D angiographic examination and operative findings, with a literature review. Case Description A 60-year-old man presented with progressive urinary incontinence and gait disturbance. A sacral dAVF was detected at the S1-2 level. The shunt point was at the medial side of the line between the intermediate sacral crest and the most medial point of the L5 pedicle circle at the anterior posterior view of the angiography; we defined this type as the medial type. After embolization, latent inflow arteries were visualized ipsilaterally and contralaterally. During surgery, because of dAVF recurrence, a vascular tangle was found on the dura. The surgical interruption of the draining vein improved the patient's symptoms. From the literature review, 92% of cases had medial-type shunt point. It is possible for sacral dAVF to have multiple inflow arteries originating ipsilaterally or bilaterally, and a venous pouch. Conclusions The shunt point of sacral dAVF tended to be located medially, not in the sacral foramen. Sacral dAVF has unique angioarchitecture. The differentiation of dAVF from epidural arteriovenous fistula may not be easy in some cases of sacral lesions. Therefore, further studies with a larger number of patients focused on the detailed vascular architecture are needed.