Comparison of 3 Different Types of Spinal Arteriovenous Shunts below the Conus in Clinical Presentation, Radiologic Findings, and Outcomes

Abstract

Background and purpose: Spinal arteriovenous shunts below the conus constitute 3 types of lesions, which have previously been mainly described in case reports, given their rarity, and are sometimes misdiagnosed. The purpose of this study was to describe the features of each type and compare these types as to epidemiologic features, clinical and radiologic presentations, treatment, and outcomes in a consecutive series of 48 cases.

Materials and methods: The prospectively collected data bases of 2 referral centers for spinal vascular lesions were retrospectively reviewed. Spinal arteriovenous shunts below the conus were defined as all dural and intradural shunts below the conus medullaris. Clinical features, radiologic findings, treatment results, and clinical outcomes were assessed.

Results: There were filum terminale arteriovenous fistulas in 11 patients (22.9%), radicular arteriovenous shunts in 7 patients (14.6%), and spinal dural arteriovenous fistulas in 30 patients (62.5%). Radicular arteriovenous shunts presented at a younger age (P = .017) and with a higher incidence of back pain symptoms (P = .037). A tethered spinal cord was found in 54.5% of patients with filum terminale arteriovenous fistulas and 23.3% of patients with spinal dural arteriovenous fistulas. After treatment, the angiographic complete obliteration rate was 89.4% and spinal function was improved significantly (P < .001).

Conclusions: Three groups of spinal arteriovenous shunts below the conus can be differentiated according to clinical and radiologic features. Filum terminale arteriovenous fistulas are frequently associated with dysraphic malformations, which may suggest a particular embryologic origin.

Fig 1.

The radiologic presentation of a 64-year-old man with a FTAVF. A, Spinal angiogram shows the FTAVF at the level of S2 (arrow). Note the faint filum terminale artery (arrowhead) from the T10 intercostal artery, converging with the draining vein upwardly. B, Internal iliac artery angiogram demonstrates the extra supply of the FTAVF lesion in A. Note the same appearance of the drainage vein (arrow) as in A. C, The T1 contrast-enhanced image demonstrates the abnormally dilated and tortuous vessels situated on the surface of the spinal cord (arrow). D, T2-weighted image of the thoracic spine shows cord edema extending to the upper thoracic spinal cord.

Fig 2.

The radiologic presentation of a 34-year-old man with concomitant rAVS and conus AVM. A, Left L3 lumbar artery angiogram shows the nidus-type conus AVM at the level of L1 (arrow). B, Right internal iliac artery angiogram demonstrates an rAVS (arrow), which shares the draining vein of the AVM. C, Spinal CT angiography shows the draining vein of the rAVS and its connection to the conus AVM. D, Cast of liquid embolic agent with complete occlusion of the rAVS from the right internal iliac artery.

Fig 3.

The radiologic presentation of a 64-year-old man with an SDAVF below the conus associated with a tethered cord. A, Left internal iliac artery angiogram shows the SDAVF at the level of S2 (arrow). B, Embolic material cast reveals that the embolic agent is approaching the proximal venous end (arrowhead). C, The patient also has a tethered cord (white arrow) on the T1-weighted MR image.