Intramedullary Hemorrhage Caused by Lumbosacral Epidural Arteriovenous Fistula with Dual Retrograde Perimedullary Venous Draining Routes: A Case Report and Review of the Literature

Background Spinal epidural arteriovenous fistulas (SEAVFs) are rare lesions with a low risk of hemorrhage. Most patients with lumbosacral SEAVFs with hemorrhagic events will develop a spinal epidural hematoma from epidural venous pouches. To the best of our knowledge, we have reported the first case of a lumbosacral SEAVF presenting with remote intramedullary hemorrhage in the conus medullaris. Case Description A 56-year-old man presented with sudden-onset severe paraparesis and bowel/bladder dysfunction. Magnetic resonance imaging of the thoracic and lumbosacral spine showed acute intramedullary hemorrhage in the conus medullaris surrounded by spinal cord congestion extending to T8, with perimedullary flow voids along the ventral and dorsal cord surfaces. Magnetic resonance angiography and spinal angiography confirmed the presence of a SEAVF with a large lumbosacral epidural venous lake supplied by dorsal somatic branches of bilateral L4 segmental arteries. Initially, the intradural venous drainage had been misinterpreted as a single route. The patient underwent surgical interruption of the dilated intradural draining vein after embolization of the feeding vessels. Another small intradural venous drainage route was found on the follow-up angiogram. The second operation with occlusion of the initial part of the epidural venous lake was sufficient to cure this lesion. Conclusions With the significant improvement of our patient after treatment of the SEAVF, we speculated that the intramedullary hemorrhage, which had occurred in the area of spinal cord edema, might have resulted from severe venous hypertension, rather than hemorrhagic infarction of the spinal cord. Careful evaluation of the angioarchitecture of SEAVFs is imperative to determine the most effective treatment modality.