Spinal Extramedullary Arteriovenous Fistulas: A 15-Year Endovascular Treatment Experience in a Tertiary Care Hospital in Thailand

Abstract

Background: Spinal arteriovenous shunts are rare diseases. Different classifications have been proposed, but the most widely used are those classified by locations. Different locations (i.e., intramedullary and extramedullary) have different treatment outcomes and different posttreatment angiographical results. Our study presents the 15-year endovascular treatment outcomes of patients who had spinal extramedullary arteriovenous fistulas (AVFs) at Ramathibodi Hospital, which is a tertiary care hospital in Thailand.

Methods: A retrospective medical record and imaging review of all patients with spinal extramedullary AVFs, which were confirmed by a diagnostic spinal angiogram in our institute from January 2006 to December 2020, were performed. The angiographic complete obliteration rate in the first session of endovascular treatment, clinical outcomes of the patients, and complications of the procedures for all eligible patients were analyzed.

Results: Sixty-eight eligible patients were included in the study. The most common diagnosis was spinal dural AVF (45.6%). The most common presenting symptoms were weakness, numbness, and bowel-bladder involvement (70.6%, 67.6%, and 57.4%, respectively). Ninety-four percent had spinal cord edema in preoperative magnetic resonance imaging. All patients had pial venous reflux. Sixty-four patients (94.1%) received endovascular treatment as the first option. The complete obliteration rate in the first session of endovascular treatment was 75% and was high in all subgroups except for the perimedullary AVF group. The overall intraoperative complication of endovascular treatment was 9.4%. Follow-up imaging showed no residual AVF in 50 patients (87.7%). Most of the patients (57.4%) had improvement of neurological functions at 3- to 6-month follow-up.

Conclusion: Treatment results of spinal extramedullary AVFs were good in terms of angiographic aspects and clinical outcomes. This may have resulted from the locations of the AVFs, which mostly did not involve the spinal cord arterial supply, with the exception of perimedullary AVFs. Although perimedullary AVF is difficult to treat, it can be cured by careful catherization and embolization.

Keywords: Spinal arteriovenous shunts; angiographic complete obliteration rate; endovascular treatment.

Figure 1

Example of spinal epidural arteriovenous fistula (AVF). (a–b) Pretreatment sagittal T2-weighted magnetic resonance image (MRI) of cervical and thoracolumbar spine shows hyperintense T2 cord signal change from craniocervical junction to conus medullaris with venous pouch at T12/L1 level (white arrowhead). (c) Early epidural venous pouch is fed by left L4 segmental artery (white arrow). (d) Epidural venous pouch drains into 2 radicular veins (white arrowhead). (e) Coronal reformatted image of flat panel computed tomography after transarterial glue embolization shows glue cast in venous pouch, confirming the position of venous pouch is in the epidural space. (f–g) Posttreatment sagittal T2-weighted MRI of cervical and thoracolumbar spine shows resolution of hyperintense T2 change of the spinal cord with hemosiderin deposit at the previously seen venous pouch (white arrowhead).

Figure 2

Example of a spinal dural arteriovenous fistula (AVF) at the T12 spinal level that is fed by 2 segmental arteries. (a) Left T11 segmental arterial injection shows the radiculomeningeal artery that runs along the dura (white arrowhead) before opening into the AVF (white arrow). (b) Left T12 segmental arterial injection shows the radiculomeningeal artery feeding the AVF (white arrow). (c) Coronal reformatted view of 3-dimensional rotational angiography before embolization shows the radiculomeningeal artery that runs along the dura.

Figure 3

Example of perimedullary arteriovenous fistula (AVF) at the C5 spinal level. (a) Pretreatment sagittal T2-weighted magnetic resonance image (MRI) of the cervical spine shows a hyperintense T2 cord signal change from the craniocervical junction to the T4 level with a venous pouch at the C5 level (white arrow). (b) Anterior-posterior view of left vertebral artery injection shows an AVF that is fed by the left lateral spinal artery (white arrow). (c) Lateral view of the left vertebral artery injection shows an AVF draining into the posterior perimedullary vein (white arrowhead). (d) Posttreatment sagittal T2-weighted MRI of the cervical spine shows resolution of the hyperintense T2 cord signal change with hemosiderin deposition along the spinal cord at C2 to the T4 levels.

Figure 4

Example of radicular arteriovenous fistula (AVF) at the T11 spinal level. (a) Pretreatment sagittal T2-weighted magnetic resonance image (MRI) of the thoracolumbar spine shows hyperintense T2 cord signal change from T7 to the conus medullaris levels with dilated perimedullary veins. (b) Left T11 segmental arterial injection shows the AVF being fed by the radicular artery (white arrow). (c) Coronal reformatted image of flat panel computed tomography after transarterial glue embolization shows glue cast along the distal segment of left T11 radicular artery and the proximal segment of the radicular vein. (d) Posttreatment sagittal T2-weighted MRI of the thoracolumbar spine shows complete resolution of the hyperintense T2 cord signal change without visualization of the dilated perimedullar veins.

Figure 5

Example of filum terminale arteriovenous fistula (AVF). (a) Right T9 segmental arterial injection shows the radiculomedullary artery and contributing anterior spinal artery, which runs downward to the conus medullaris. (b) Filum terminale artery (white arrowhead) that is a caudal continuation of the anterior spinal artery feeding the AVF (white arrow), and the filum terminale vein runs upward along the filum terminale (black arrowhead). (c) Sagittal reformatted image of flat panel computed tomography after transarterial glue embolization shows glue cast in the filum terminale vein.