Embolization of an epidural arteriovenous fistula of the sacral nerve root with a neural tube defect: A case report

Introduction and importance: Rarely, epidural arteriovenous fistula (AVF) of the sacral neural root may be associated with neural tube defects. Case presentation: A 46-year-old man presented with progressive weakness and numbness in both lower extremities. On physical examination, both lower extremities only had Grade III muscle strength. MRI revealed extensive dilated veins along the spinal cord, edema of the spinal cord, lipomyelomeningocele and tethering of the spinal cord. Angiography revealed an epidural AVF at the sacral neural root with intradural venous drainage. Endovascular treatment (EVT) was performed. First, a microcatheter accessed the AVF; then, another micro- catheter coiled around the feeding artery near the fistula to establish the "pressure cooker" effect; finally, the AVF was obliterated by casting Onyx via the first microcatheter. After EVT, the patient's symptoms improved immediately. Postoperative computed tomography confirmed the presence of defective sacral bone. Based on the patient's physical examination and imaging findings, a neural tube defect with a tethered cord and a lipomyelomeningocele were confirmed. Two months later, the patient recovered well and could walk. The followup MR image revealed a nearly normal spinal cord. Clinical discussion: Microsurgical resection is difficult because of the deep location of such an AVF. EVT by casting Onyx can be a feasible option. To avoid Onyx reflux, the 'pressure cooker' technique can be helpful for obliterating such an AVF. Conclusion: On the basis of this case report, EVT can be effective for epidural AVFs of the sacral neural root in select cases.