The Neurosurgical Atlas by Aaron Cohen-Gadol, M.D.
Spinal Vascular Malformations
Last Updated: October 1, 2018
Overview
The spinal vascular malformations are in many ways analogous to
their intracranial counterparts. Lesions characterized by high flow
shunts include spinal arteriovenous fistulas (AVF) and spinal
arteriovenous malformations (AVM). The most common classification
scheme for spinal vascular malformations uses the Type 1 to 4
classification system, though other classification schema exist.
Type 1 lesions are dural AVFs in which a radiculomeningeal artery
forms a fistulous communication with dural veins at the nerve root
sleeve, and result in subsequent arterialization of the perimedullary
venous plexus. Type 2 AVMs have an intramedullary nidus with
variable anterior spinal artery (ASA) and/or posterior spinal artery
contributions. Some authors treat conus medullaris AVMs as
separate entities, though the angioarcitecture is similar. Type 3
lesions are known as juvenile or metameric AVMs with both
extradural and intradural involvement. The classic Cobb syndrome is
limited to metameric-origin malformations involving the spinal cord,
bone, and skin.
The spinal arteriovenous metameric syndrome (SAMS) describes all
forms of metameric malformations, even if the AVM does not involve
the spinal cord. Type 4 spinal AVMs, refer to ventrally-located
perimedullary fistulae on the pial surface, within the subarachnoid
space, primarily receiving arterial contributions from the ASA. These
have been subcategorized into A, B, and C based on size and
complexity; venous hypertension and aneurysms are often
complications of the latter. Other related entities introduced in this
section include extradural (epidural) AVF and vertebral arteriovenous
fistulas (vertebrovenous fistula).
Dural Arteriovenous Fistula (Type I)
Type 1 lesions are dural AVFs in which a dural branch from a
radicular artery (radiculomedullary/radiculomeningeal) forms an
abnormal communication with the dural veins at the nerve root
sleeve, under the pedicle of the vertebral body. Arterialization of the
perimedullary venous plexus results. This is the most common spinal
vascular malformation, accounting for 70% of vascular malformations
of the spine.
Figure 1: 81 year old F with myelopathy. T2W Sagittal MRI
demonstrates hyperintense intramedullary cord signal (black
arrow, left image) and multiple extramedullary hypointense flow
voids representing arterialized perimedullary veins (white
arrows, center image). L4 lumbar artery angiogram
demonstrates a slow flow, spinal dural arteriovenous fistula
arising from the right L4 radicular branch (white arrow, right
image). Venous drainage is cephalad into the perimedullary
venous plexus (black arrows, right image).
Figure 2: 64 year old M with myelopathy. T2W Sagittal MRI
demonstrates hyperintense intramedullary cord signal (white
arrow, left image) and multiple extramedullary hypointense flow
voids representing congested perimedullary veins (white
arrows, center image). Right T11 segmental artery angiogram
demonstrates a dural arteriovenous fistula associated with the
right T11 radicular artery. The intradural component begins at
the right T11 nerve root (bottom arrow, right image), ascends in
the left lateral canal to the superior margin of the T10 vertebral
body (upper arrow, right image)
Figure 3: 62 year old F with spontaneous intracranial
subarachnoid hemorrhage. Left vertebral artery angiography in
LAO projection (left image) and left lateral projection (center
image) demonstrate a dural arteriovenous fistula with arterial
supply from the left C4 radicular branch (white arrows) and
cephalad venous drainage via the anterior spinal vein (black
arrows). Intra-operative angiogram (right image) demonstrates
complete occlusion of cervical spinal dural AV fistula status
post microsurgical ligation (white arrow).
Intramedullary AVMs (Type II)
Intramedullary AVMs are analogous to intracranial AVMs, with nidus
located entirely in the spinal cord parenchyma. The nidus can be
characterized by compact or diffuse angioarchitecture. Single or
multiple feeding arteries from branches of the ASA and/or posterior
spinal artery.
Figure 4: 38-year-old M with rapid onset mid-thoracic Brown-
Sequard syndrome. T2W MRI demonstrates hyperintense
intramedullary cord signal (upper arrow, left image), mid-thoracic
nidus at the T6 vertebral level (arrow head), and serpiginous
intra-dural flow voids (bottom arrow, left image). Left T7
segmental artery angiography in demonstrate a mid-thoracic
intramedullary AVM nidus (large arrow head, center images). The
dominant and most direct supply arises from anterior spinal
arterial feeders (small arrow head) supplied by the left T7
radiculomedullary artery. Several nidal aneurysms are noted.
Tortuous, arterialized perimedullary veins (arrows, right image)
drain the nidus.
Conus Medullaris AVMs
Conus Medullaris AVMs have similar angioarchitecture with classic
type II lesions, typically with multiple feeders from the ASA and
posterior spinal artery, direct arteriovenous shunts, and large dilated
veins. These lesions are generally attributed to a neurulation
abnormality and are often associated with tethered cord
phenomenon. Progressive myeloradiculopathy results with both
upper motor neuron symptoms secondary to venous hypertension
and ischemia as well as lower motor neuron symptoms secondary to
mass effect from hugely dilated venous structures.
Figure 5: 56 year old male with myeloradiculopathy. T2W MRI
demonstrates hyperintense intramedullary cord signal (arrow
head, left image) just above the level of the conus and multiple
serpiginous intra-dural flow voids (white arrows). Left T10
segmental artery angiography (center images) demonstrate a
conus medullaris arteriovenous malformation (arrow head)
supplied by the T10 radicular artery (black arrow head) and
anterior spinal artery which is quite dysplastic (black arrows).
Right internal iliac artery angiogram reveals anterior spinal
arterial supply arising from the artery of Desproges-Gotteron
(black arrows, right image).
Juvenile spinal AVM (Type III), Spinal Arteriovenous
Metameric Syndrome (SAMS), and Cobb Syndrome
Type 3 lesions are metameric AVMs with both extradural and
intradural involvement. The spinal arteriovenous metameric
syndrome (SAMS) describes all forms of metameric malformations,
even if the AVM does not involve the spinal cord. The classic Cobb
syndrome is limited to metameric-origin malformations involving the
spinal cord, bone, and skin. Cutaneous manifestations of Cobb
syndrome are typically port-wine stains (PWS) or angiomas, but
reports exist of angiokeratomas, angiolipomas, and lymphangioma
circumscriptum. Lesions are difficult to treat, often with staged,
multidisciplinary approach. May be more prone to aneurysm
formation and rupture. In general, these conditions are extremely rare
conditions.
Figure 6a: 23 year old male with large midthoracic vascular
birthmark and suspected underlying vascular malformation.
Angiography revealed multilevel metameric spinal arteriovenous
malformations from T7 through T12 with bilateral arterial supply
at these levels, involving the paraspinal soft tissue and osseous
structures, without definite spinal cord involvement.
Representative right T12 segmental artery angiogram
demonstrates dysplastic paraspinal angioarchitecture (arrow
heads).
Figure 6b: 23 year old male with large midthoracic vascular
birthmark and suspected underlying vascular malformation.
Right T9 segmental artery angiogram demonstrates high flow
arteriovenous fistula (white arrow) with large varix (arrow heads).
Figure 6c: 23 year old male with large midthoracic vascular
birthmark and suspected underlying vascular malformation.
Right and left T11 segmental arterial angiograms demonstrating
bilateral supply to the metameric AVM.
Figure 6d: 23 year old male with large midthoracic vascular
birthmark and suspected underlying vascular malformation.
Representative right T9 segmental artery angiograms, pre- and
post-embolization (top row). The right T9 high flow shunt with
large varix (arrow head), was embolized with detachable coils
after the catheter was passed through the fistula into its venous
side. Distal feeders arising beyond the arteriovenous fistula
were embolized with acrylic. Representative right T11 segmental
artery angiogram and unsubtracted image (bottom row). The T11
AV shunt, arising from its proximal intercostal artery was treated
with detachable coils to occlude its varix (arrow head), as well as
a combination of liquid coils and acrylic (arrows). In general, it is
most important to close the lesion itself, such as an aneurysm,
varix, fistula, or nidus, to obtain long-lasting effect. Proximal
feeder occlusion tends to result in an incomplete transient effect
due to parasitized collaterals.
Figure 7: 15 year old female with large vascular birthmark
overlying the right flank and spinal AVM.
T2W MRI demonstrates hyperintense intramedullary cord signal,
serpiginous signal flow voids surrounding the conus (arrows,
right image), with a notably larger signal void at the T12-L1 level
(arrow head). Right T10 segmental artery angiogram
demonstrates a small intramedullary AVM (large arrow heads),
arising from a dysplastic anterior spinal artery (arrows), and T10
radiculomedullary artery (small arrow heads). The ventral AV
fistula and varix are noted.
MRI of the pelvis demonstrates abnormal T1 and T2 signal with
associated post-contrast enhancement of the overlying skin and
subcutaneous tissue of the right flank and lower back as well as
the right erector spinae, piriformis, and gluteus maximus
musculature (white arrow heads). Chemical shift India ink artifact
on out-of-phase imaging confirms the presence of diffuse fat
within the infiltrative vascular lesion. Multiple prominent, dilated
blood vessels drain this region and communicate with the right
iliac venous system. Several of these prominent veins are
located within the right sacral neural foramina, resulting in mass
effect on the right S1 nerve root and near-complete obliteration
of the S2 and S3 neural foramina.
Intradural-Perimedullary AVF (Type IV)
Type 4 spinal AVMs, are ventrally-located perimedullary fistulae on
the pial surface, within the subarachnoid space, primarily receiving
arterial contributions from the ASA. Type 4 lesions can be acquired,
post-traumatic or iatrogenic in etiology. Congenital lesions may be
associated with genetic syndromes Klippel-Trenaunay/Parkes-
Weber syndromes, Hereditary Hemorrhagic Telangiectasia (Osler-
Weber-Rendu syndrome). These have been subcategorized into A,
B, and C based on size and complexity. Venous hypertension and
aneurysms are often complications of the latter.
Figure 8a: 34-year-old male with recent lumbar spine stabbing
injury; L1 laminectomy with exploration of epidural collection
was performed. Increasing paraparesis for 1 month. CT
angiography of the lumbar spine, axial and coronal planes,
demonstrates an ovoid focus of enhancement both ventrally
and centrally located near the conus terminalis, representing a
suspected pseudoaneurysm (arrows). Sagittal T2W and T2W
postcontrast MRI of the thoracolumbar spine, demonstrates a T1
and T2 hypointense, ovoid lesion with central post contrast
enhancement. Also noted are clumped nerve roots with
enhancement indicating arachnoiditis, as well as loculated
subdural enhancing collection (arrow head).
Figure 8b: 34-year-old male with recent lumbar spine stabbing
injury; L1 laminectomy with exploration of epidural collection
was performed. Increasing paraparesis for 1 month. Left T9
segmental artery angiogram. The artery of Adamkiewicz (black
arrows) arises from the left T9 segmental artery. There is a small
arteriovenous fistula at the terminal portion of the descending
ramus, at the level of the conus. There is a small
pseudoaneurysm (arrow heads) at the proximal venous side of
the fistula with early filling of the conus perimedullary venous
plexus (white arrows).
Extradural (Epidural) AVF
Extradural (Epidural) Arteriovenous Fistulas are abnormal
communications between an extradural arterial branch that usually
arises from a branch of a radicular artery and the epidural venous
plexus. Two different types of spinal extradural AVFs have been
described: (A) purely extradural lesions and (B) extradural lesions
with intradural medullary venous drainage, with the fistula site
located distally from the dural penetration site. Combination of upper
motor neuron and lower motor neuron symptoms. Resultant
engorgement of the venous plexus, leads to mass effect on adjacent
nerve roots and spinal cord. Venous hypertension and vascular steal
also may contribute to myelopathic symptoms.
Figure 9: 59 year old female with 1 month onset of
myeloradiculopathy. Sagittal and axial T2W MRI of the
thoracolumbar spine, demonstrated T2 hypointense prominent
spinal surface flow voids along the left lateral epidural space
(arrows). Left T12 artery segmental angiogram in LAO and AP
projections, demonstrates abnormal venous outflow into the left
posterolateral epidural venous plexus (arrows).
Vertebral AVF (Vertebral-Venous Fistula)
Vertebral arteriovenous fistulas (vertebral-venous fistula) are
abnormal connections between the extracranial vertebral artery or its
branches and neighboring veins. Common causes of these fistulas
include: penetrating neck trauma; iatrogenic injuries (ie. insertion of
venous catheters, complications of anterior interbody fusion);
spontaneous/congenital in association with fibromuscular dysplasia
or neurofibromatosis. Symptoms of neck pain, neurologic dysfunction
do to steal phenomenon, venous hypertension, or mechanical
compression.
Figure 10: 33 year old female with neurofibromatosis, history of
neck pain 1 week prior to delivering child, presented with
progressive right cervical radiculopathy and bruit over the right
neck. Axial and sagittal T2 MRI demonstrates a markedly dilated
flow void spanning the right C3-C4 foramen and right
anterolateral epidural venous plexus resulting in cord
compression. DSA, right vertebral artery injection (AP, Lat, Obl
images) demonstrate irregular, fusiform dilatation of the C2
segment of the right vertebral artery with arteriovenous fistula at
C3-C4 level, communicating with a markedly engorged epidural
venous plexus. There is complete “steal” through the fistula with
no antegrade filling of the right vertebral artery beyond the
fistula.
Left vertebral artery injection (AP image, far left) demonstrates a
normal cervical and intracranial left vertebral artery with
retrograde filling of the V4, V3, and distal V2 segments of the
right vertebral artery with subsequent filling of the arteriovenous
fistula. The basilar artery artery and cerebellar branches are
normal.
Contributors: Daniel Murph, MD; Andrew DeNardo, MD; John Scott,
MD and Daniel Sahlein, MD
DOI: https://doi.org/10.18791/nsatlas.v1.04.05
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