Northeast Florida Medicine
Vol. 66, No. 3 2015
33
Endovascular Neurosurgery
Introduction
SDAVFs represent the most common subset of a broader
group of pathology known as spinal vascular malformations.
Spinal vascular malformations are a complex and diverse set
of lesions that are a challenge to diagnose and treat.They can
affect upper and lowermotor neurons and thusmanifest with
a wide array of signs and symptoms that mimic other, more
prevalent spinal pathology. As a result, patients with a spinal
vascular malformation often go months or years before the
lesion is found.Moreover, many undergo unnecessary spinal
procedures for conditions unrelated to their true diagnosis. If
left untreated, lesions can cause progressive disability leading
to weakness, incontinence, or total paralysis. Patients who
are successfully diagnosed and treated often feel immediate
improvement in numbness, pain, weakness, or balance.
There is a broad range of spinal vascular malformations,
with SDAVFs being the most common type of lesion.
General Pathophysiology
and Classification
In broad terms, spinal vascular malformations represent
an abnormal connection of an artery to a vein without an
intervening capillary bed.Thus, high pressure arterial blood
is transmitted directly to the venous system resulting in
anatomic changes and physical exam findings. Symptoms
can arise from mass effect of engorged veins, ischemia due
to vascular steal, venous hypertension, or, rarely, hemor-
rhage. All of these phenomena can affect upper or lower
motor neurons depending on the location of the lesion.
Historically, the most common classification scheme for
spinal vascular malformations has been theType I-IV classi-
fication.
1-3
More recently, an effort has beenmade to classify
these lesions based on the location of their respective nidus.
Table 1 summarizes the classification system proposed by
Spetzler, et al in 2002, with the corresponding Type I-IV
designations.
4
As seen in the table, SDAVFs are known as
Type I or dorsal intradural fistulas.
Spinal Dural Arteriovenous Fistulas
By Benjamin Brown, MD
Address correspondence to:
Benjamin L. Brown, MD
Cerebrovascular and Endovascular Neurosurgery
Mayo Clinic
4500 San Pablo Road
Jacksonville, FL 32224
Phone: 904-956-3435
Email:
Abstract:
Spinal dural arteriovenous malformations are the most
common type of spinal vascular malformation. This rare and diverse
group of lesions can pose challenges for clinicians in both diagnosis
and treatment. However, recent advances in endovascular techniques
have provided an alternative to surgical treatment of spinal dural
arteriovenous fistulas (SDAVFs).
Table 1. Summary of the classification scheme proposed by Spetzler, et al in 2002
with corresponding classic Type I-IV nomenclature.
Extradural
Dorsal
Intradural
Ventral
Intradural
Intramedullary Extradural-
Intradural
Conus
Medullaris
Pathophysiology
Compression, ve-
nous congestion,
vascular steal
Venous conges-
tion
Compression,
hemorrhage,
vascular steal
Compression,
vascular steal,
hemorrhage
Compression,
vascular steal,
hemorrhage
Compression,
vascular steal,
hemorrhage
Presentation
Myelopathy
Myelopathy
Myelopathy
Pain, acute
myelopathy
Pain, myelopathy Myelopathy,
radiculopathy
Flow
High
Low
High
High
High
Variable
Nidus
Extradural artery
and vein
Radicular artery
to medullary
vein at root
sleeve
Pial surface
Spinal cord
parenchyma
Diffuse: Extra-
dural, intradural,
parenchymal,
muscle, bone
Multiple feeders
from anterior
and posterior
spinal arteries
Alternate
nomenclature
Epidural fistula Type IA, Spinal
dural AVF
Type IV, angerior
intradural AVF,
or Perimedullary
AVF
Type II, Classic
AVM, or Glo-
mus
Type III,
Metameric, or
Juvenile
None
