Spinal dural arteriovenous fistulas (SDAVFs) cause myelopathy through arterialization of the perimedullary venous plexus and venous congestion of the spinal cord. The authors hypothesized that the craniocaudal extent of engorgement of intrathecal draining veins between the fistula site and the point of drainage out of the thecal sac correlates with the degree of myelopathy.
A retrospective review of the authors' institution's radiology databases identified 31 patients with SDAVFs who had undergone digital subtraction angiography (DSA) and MRI examinations of the spine. The authors counted the number of vertebral body levels of spinal cord enhancement and intrathecal vessel enhancement on T1-weighted postcontrast MRI studies. They also counted the number of levels of cord hyperintensity and intrathecal flow voids on T2-weighted MRI studies. On DSA, the authors identified the number of vertebral body levels of dilated intrathecal draining veins and outflow points from intrathecal veins to epidural veins. Functional status of the patients at the time of diagnosis was assessed using the Aminoff-Logue scale (ALS).
Enlargement of the intrathecal draining veins averaged 10 ± 7.7 spinal levels on DSA. Patients with enlarged draining veins extending 10 or more spinal levels on DSA had worse ALS scores (mean gait 3.4, mean micturition 1.5) than patients with draining veins extending fewer than 10 levels (mean gait 1.8, mean micturition 0.6; p = 0.009 and 0.02, respectively). The number of vertebral body levels of enlarged draining veins correlated with the ALS score (gait r = 0.42, p = 0.009; and micturition r = 0.55, p = 0.0006). More extensive enlarged draining veins were associated with more spinal cord T2 hyperintensity, T2 intrathecal flow voids, and T1 vessel enhancement but not cord enhancement.
The craniocaudal extent of enlarged intrathecal veins draining SDAVF correlates with patient functional status, providing further insight into the pathophysiology of venous hypertensive myelopathy.
Abbreviations used in this paper:ALS = Aminoff-Logue scale; AMV = anterior midline spinal vein; DAVF = dural arteriovenous fistula; DSA = digital subtraction angiography; PMV = posterior midline spinal vein; SDAVF = spinal dural arteriovenous fistula.
AsakawaHYanakaKFujitaKMarushimaAAnnoINoseT: Intracranial dural arteriovenous fistula showing diffuse MR enhancement of the spinal cord: case report and review of the literature. Surg Neurol58:251–2572002
BrunereauLGobinYPMederJFCognardCTubianaJMMerlandJJ: Intracranial dural arteriovenous fistulas with spinal venous drainage: relation between clinical presentation and angiographic findings. AJNR Am J Neuroradiol17:1549–15541996