Spinal Vascular Shunts: A Patterned Approach

Abstract

Spinal vascular shunts, including fistulas and malformations, are rare and complex vascular lesions for which multiple classification schemes have been proposed. The most widely adopted scheme consists of 4 types: type I, dural AVFs; type II, intramedullary glomus AVMs; type III, juvenile/metameric AVMs; and type IV, intradural perimedullary AVFs. MR imaging and angiography techniques permit detailed assessment of spinal arteriovenous shunts, though DSA is the criterion standard for delineating vascular anatomy and treatment planning. Diagnosis is almost exclusively based on imaging, and features often mimic more common pathologies. The radiologist's recognition of spinal vascular shunts may improve outcomes because patients may benefit from early intervention.

FIG 1.

A, Normal arterial anatomy: 1, intramedullary branches; 2, sulcal artery; 3, anterior spinal artery; 4, radial perforators; 5, pial arterial plexus; 6, posterior spinal arteries; 7, segmental artery; 8, spinal artery; 9, dorsal branch of the dorsospinal artery; 10, ventral branch of dorsospinal artery; 11, ventral epidural plexus; 12, dorsal epidural plexus; 13, dural artery; 14, radicular artery; 15, ventral radicular artery; 16, dorsal radicular artery; 17, medullary artery. B, Normal venous anatomy: 1, Intramedullary veins; 2, sulcal vein; 3, radial veins; 4, pial venous plexus; 5, anterior spinal vein; 6, posterior spinal veins; 7, medullary vein; 8, ventral radicular vein; 9, dorsal radicular vein; 10, emissary vein; 11, intervertebral vein; 12, branches from ventral epidural venous plexus; 13, branches from dorsal epidural venous plexus.

FIG 2.

A, Type I spinal dural AVF: 1, Intercostal artery; 2, spinal artery; 3, dorsal/muscular branch; 4, radicular artery, ventral branch; 5, radicular artery, dorsal branch; 6, radicular vein; 7, engorged perimedullary vein; 8, dural AVF. B, Type II spinal glomus AVM: 1, anterior spinal artery; 2, feeding arterial branch; 3, intramedullary glomus/nidus; 4, draining branch to pial venous network; 5, posterior spinal veins; 6, pial venous network. C, Type III spinal juvenile/metameric AVM: 1, normal cord tissue within the nidal interstices; 2, intramedullary elements of AVM; 3, extramedullary elements of AVM. D, Type IV IPAVF: 1, anterior spinal artery; 2, fistula; 3, multiple dilated perimedullary veins; 4, multiple contributing arterial feeders; 5, medullary artery; 6, ventral and dorsal radicular arteries.

FIG 3.

A 79-year-old man with a type I spinal dural AVF. A, Sagittal T2 MR imaging of the thoracic spine shows extensive intramedullary edema as signal hyperintensity (white arrow) throughout the cord. The thin peripheral hypointense rim (yellow rectangle) may reflect deoxyhemoglobin within dilated peripheral capillaries. Serpiginous perimedullary flow voids (blue arrow) are most conspicuous along the dorsal aspect of the thoracic cord. B, Frontal view DSA injection of the left L3 segmental artery (white arrow) shows early filling of an ectatic spinal vein (black arrow).

FIG 4.

A 45-year-old man with a type II spinal glomus AVM. A, Sagittal T2 MR imaging of the cervical spine shows serpiginous intramedullary and perimedullary flow voids (white arrow), with adjacent cord hyperintensity (blue arrow). B, Frontal view DSA injection of the right vertebral artery (red arrow) shows opacification of a feeding arterial branch (black arrow) and nidal elements (dashed outline). C, Lateral view DSA shows early filling of ectatic perimedullary veins (blue arrow).

FIG 5.

A 14-year-old girl with a type III spinal juvenile/metameric AVM. A, Sagittal T2 MR imaging of the lumbar spine shows numerous ectatic perimedullary and intramedullary flow voids (blue/white arrow). B, Frontal view DSA injection of the right L2 lumbar artery shows opacification of a prominent anterior spinal artery (red arrow), intramedullary and extramedullary nidal elements (black arrow), and early filing of an ectatic perimedullary vein (blue arrow).

FIG 6.

An 11-year-old boy with a type IV intradural-perimedullary spinal AVF. A, Sagittal T2 MR imaging of the thoracic spine shows enlarged, predominantly ventral, perimedullary flow voids (white arrow) indenting the ventral cord (yellow arrow). B and C, Sequential frontal view DSA images from injection of the left T9 segmental artery show contrast progression through the ASA (red arrow), nidus (black arrow), ectatic left radiculomedullary vein (blue arrow), left common iliac vein (green arrow), and inferior vena cava (white arrow). D, Frontal magnified DSA shows a catheter traversing the opacified ASA (red arrow) and embolization coil (black arrow) and Onyx (Covidien) (yellow arrow) material within the nidus. The draining vein no longer opacifies as a result of shunt obliteration.

FIG 7.

A, A 41-year-old woman with normal CSF flow-related signal voids. Sagittal T2 MR imaging of the thoracic spine shows multiple prominent CSF flow voids (green arrows), mimicking the perimedullary vascular flow voids characteristic of spinal vascular shunts. B, A 71-year-old man with spinal stenosis. Sagittal T2 MR imaging of the lumbar spine shows multiple tortuous, redundant-appearing cauda equina nerve roots (yellow arrow) mimicking the perimedullary flow voids of a spinal vascular shunt above the levels of thecal sac stenoses (white and blue arrows).

FIG 8.

A, A 61-year-old man with a cavernous malformation of the cervical cord. Sagittal T2 MR imaging of the cervical spine shows a small intramedullary mass with central hyperintense signal (white arrow) and a peripheral rim of low signal (black arrow), indicative of blood products in various stages of degradation. There is normal signal in the adjacent cord (yellow arrow). B, A 42-year-old woman with a history of Von Hippel-Lindau disease and cervical cord hemangioblastomas. Sagittal T2 MR imaging shows a small intramedullary mass (yellow arrow) with heterogeneous hyperintense internal signal and surrounding cord edema with cord expansion (blue arrow). C, Sagittal contrast-enhanced T1 with fat saturation depicts intense enhancement (white arrows) within multiple lesions.