Vascular

Traumatic Arteriovenous Fistula
of the Posterior Inferior
Cerebellar Artery Treated with
Endovascular Coil Embolization:
Case Report
James K. Liu, M.D.,* David Decker, B.S.,† Michael S. Tenner, M.D.,‡
William T. Couldwell, M.D., Ph.D.,* and Bennie W. Chiles, III, M.D.†
*Department of Neurosurgery, University of Utah, Salt Lake City, Utah, and †Departments
of Neurosurgery and ‡Radiology, New York Medical College, Valhalla,
New York

Liu JK, Decker D, Tenner MS, Couldwell WT, Chiles BW III. Traumatic arteriovenous fistula of the posterior inferior cerebellar
artery treated with endovascular coil embolization: case report.
Surg Neurol 2004;61:255– 61.

KEY WORDS

Arteriovenous fistula, posterior inferior cerebellar artery,
Guglielmi detachable coil embolization, Wallenberg syndrome, skull base fracture.

BACKGROUND

High-flow intracranial arteriovenous (AV) fistulas associated with giant varices are rare lesions. These varices can
present with symptoms from mass effect, spontaneous
hemorrhage, and seizures to cardiac failure. Direct AV
fistulas of the posterior inferior cerebellar artery (PICA)
are extremely rare lesions, with only two cases reported
in the literature.
CASE DESCRIPTION

The authors present an unusual case of a 25-year-old male
with a direct AV fistula of the PICA that resulted from a
fracture of the occipital condyle. This high-flow AV fistula
drained into a giant varix of the vein of the lateral recess
that compressed the brainstem, resulting in a Wallenberg
syndrome. The patient underwent embolization of the proximal PICA feeding the fistula with a Guglielmi detachable coil
(GDC), which resulted in thrombosis of the varix. A postembolization angiogram showed occlusion of the PICA AV fistula and draining varix. A computed tomography (CT) scan
performed at a 10-month follow-up visit showed dramatic
decompression of the brainstem. Although the patient continued to have some sensory changes secondary to Wallenberg syndrome, he was otherwise doing well neurologically.
CONCLUSION

The treatment of this lesion is difficult because of its
location near the brainstem. Postocclusion edema or
hemorrhage can result in mass effect and life-threatening
brainstem compression. Our patient, whose AV fistula
was caused by trauma, was treated effectively with GDC
embolization. © 2004 Elsevier Inc. All rights reserved.

Address reprint requests to: Bennie W. Chiles III, M.D., Department of
Neurosurgery, New York Medical College, Munger Pavilion, Valhalla, NY
10595.
Received May 8, 2002; accepted March 27, 2003.
© 2004 Elsevier Inc. All rights reserved.
360 Park Avenue South, New York, NY 10010 –1710

ntracranial arteriovenous (AV) fistulas are rare lesions that are usually associated with a giant varix
when the fistula is of high flow [2,4,13,25]. These varices can present with symptoms due to mass effect,
spontaneous hemorrhage, seizures, or cardiac failure.
AV fistulas of the vertebrobasilar circulation are extremely rare lesions, with only three cases reported in
the literature [13,25,26]. Two cases occurred spontaneously in the posterior inferior cerebellar artery
(PICA) and were associated with a giant varix. One
was treated surgically [25] and the other by endovascular balloon occlusion [26]. The third case was a
spontaneous intracranial vertebral artery fistula
treated by surgical clipping via a far lateral approach
[13]. The treatment of these lesions is difficult because of their location near the brainstem. Postocclusion edema or hemorrhage can result in mass effect
and life-threatening brainstem compression [24 –26].
We report here a case of a direct AV fistula of the PICA
secondary to trauma, which was occluded with GDC
embolization.

I

Case Report
HISTORY
A 25-year-old male suffered multiple injuries in a
motor vehicle accident, including pelvic fractures,
0090-3019/04/$–see front matter
doi:10.1016/S0090-3019(00)00422-1

256 Surg Neurol
2004;61:255– 61

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Liu et al

CT scan of the base of the skull demonstrating a fracture through the left occipital condyle.

lung contusions, a torn urethra, and a skull base
fracture through the left occipital condyle (Figure
1). He was stabilized and treated at a local hospital
and was transferred to a rehabilitation center. Four
months after the accident, the patient was referred
to our center for evaluation of the stability of the
occipitocervical junction. A magnetic resonance image (MRI) of his cervical spine revealed a large flow
void, presumably a pseudoaneurysm, compressing
the brainstem (Figure 2A, B). The patient stated
that he had occasional double vision, dizziness, and
ringing in his left ear. He also experienced decreased sensation to heat on the left side of his face
and on the right side of his body while showering.
EXAMINATION
The patient was alert and awake. The pupils were
anisocoric (right, 4 mm; left, 3 mm) but reactive to
light. There was noticeable ptosis and miosis on the
left side. The extraocular muscles were intact. The
patient exhibited decreased sensation to pain and
temperature on the left side of the face and on the
right side of the body. The uvula was deviated to
the right, and the tongue was deviated to the left.
A cerebral angiogram revealed an AV fistula arising from the left PICA (Figure 3A–C). The fistula
arose approximately 1 cm from the origin of the
PICA and drained into an extremely dilated varix of

the vein of the lateral recess, which then coursed
into the region of the petrosal and basilar venous
plexus (Figure 3D, E). No distal vessels were seen
beyond the fistulous connection from the PICA.
TREATMENT WITH GDC
EMBOLIZATION
The patient underwent embolization of the AV fistula with a GDC. A microcatheter was advanced into
the left vertebral artery and then into the left PICA.
A single 2 mm ⫻ 2 cm GDC was deposited transversely to the long axis of the PICA, distal to its
origin from the vertebral artery and proximal to the
dilated fistulous vein. The fistula was thrombosed
and occluded. A postembolization angiogram
showed occlusion of the left PICA and AV fistula
with collateral circulation coming from the left anterior inferior cerebellar artery (AICA) feeding the
PICA region (Figure 3F).
POSTEMBOLIZATION COURSE
After occlusion of the fistula, the patient underwent
close monitoring in the intensive care unit for 24
hours. Postembolization CT and MRI showed
thrombosis of the dilated varix with continued compression of the lateral medulla (Figure 4A, B). The
patient remained stable neurologically and was discharged on the third hospital day. At a 10-month

Traumatic PICA AV Fistula

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Surg Neurol 257
2004;61:255– 61

MRI of the cervical spine, sagittal (A) and axial (B) views, revealing the dilated varix, compressing the left lateral
aspect of the brainstem.

follow-up visit, the patient was functioning well;
however, he continued to have a left 12th nerve
palsy and loss of sensation in his ipsilateral face
and contralateral body. A CT angiogram showed
dramatic resolution of the giant draining varix with
decompression of the lateral medulla without evidence of recurrent fistula (Figure 4C, D).

Discussion
AV fistulas are abnormal connections between the
arterial and venous circulations and may occur anywhere in the body. They were first described in
1762 by Hunter, a Scottish anatomist, who noted
that a fistulous connection developed after an artery and vein were simultaneously injured [15].
Their etiology may be spontaneous, iatrogenic, or
posttraumatic. When they occur spontaneously,
they are often associated with fibromuscular dysplasia [21], neurofibromatosis, or congenital abnormalities [11,12,17]. Most iatrogenic causes are from
percutaneous angiography and rarely from intraoperative trauma to the vertebral artery during cervical spine surgery [5,20,28]. Traumatic causes include penetrating and nonpenetrating injuries
[1,3,18].
Direct intracranial AV fistulas are very uncommon. The majority are carotid-cavernous fistulas

that occur as a result of trauma, although some
occur spontaneously as a result of an intracavernous aneurysmal rupture [6,10,27]. Most AV fistulas
of the vertebrobasilar circulation are extracranial,
occurring mostly in the high cervical vertebral artery [12,18,21]. Intracranial varices that are produced by a direct communication between an artery and a draining varix resulting in a high-flow AV
shunt are very rare [25]. These AV fistulas have an
angiographic appearance distinct from that of classic arteriovenous malformations or vein of Galen
malformations. Vinuela et al [26] reported the first
spontaneous AV fistula of the PICA associated with
a large varix that was successfully treated by detachable balloon occlusion. The same authors also
reported a similar case in which the fistula was
surgically ligated [25]. Halliday et al [13] reported
an intracranial vertebral AV fistula that was surgically clipped with a far lateral approach.
Traumatic injury to the intracranial arteries, by
either closed or penetrating head trauma, is an
uncommon event that may result in arterial dissections, pseudoaneurysms, and fistulas [1,14]. Our
patient suffered a fracture of the left occipital condyle, and the fistula developed 1 cm from the origin
of the PICA. The anatomic location of the fracture
suggests that it was probably involved in the formation of the AV fistula.

258 Surg Neurol
2004;61:255– 61

Liu et al

Pre-embolization (A–E) and postembolization (F) angiograms. (A) Lateral view of early arterial phase shows filling
of the large draining varix through a direct fistula that originates from the PICA. (B) and (C) Lateral (B) and oblique
(C) views of the mid-arterial phase show progressive filling of the large draining varix. (D) and (E) Frontal (D) and lateral
(E) venous phase left vertebral angiogram. The dilated vein of the lateral recess is seen to drain into the dilated petrosal
venous system. (F) Postembolization angiogram shows obliteration of the PICA, fistula, and varix from the circulation.

3

The clinical presentation depends on the size and
location of the fistula and draining varix and on the
age of the patient. High-flow intracranial AV fistulas
can cause neurologic symptoms by local mass effect of the expanding varix and/or by a vascular
“steal” phenomenon due to shunting of arterial
blood from neural structures [18,19,21,22]. The patient described here developed a Wallenberg syndrome that was likely caused by compression of the
lateral medulla by the draining varix. The patient
also had a left 12th nerve palsy, which was most
likely caused by the initial fracture through the
occipital condyle. Another possibility for the 12th
nerve palsy, although less likely, may be the dilated
varix compressing the neighboring hypoglossal
nerve rootlets as they exit the medulla and enter
the hypoglossal canal. This anatomic relationship
has been well described [16].
The primary goal of therapy is to occlude the
fistula while preserving distal flow to the artery
[8,14], which has been successfully achieved with

either surgical ligation or endovascular balloon occlusion [13,23,25,26]. In the present case, the PICA
and the fistula were occluded by GDC embolization.
Because of the high-flow fistula in our case, attempts at embolizing the fistula itself may have
resulted in distal embolization into the lungs. Thus,
the PICA was occluded just distal to its origin from
the vertebral artery and before the fistulous connection. When the placement of the coil is confirmed, it is electrolytically detached, and clotting
and occlusion of the fistula proceed. The draining
varix eventually undergoes progressive thrombosis
secondary to venous stasis.
One major concern of sudden occlusion of a highflow AV fistula is the development of acute parenchymal edema and/or hemorrhage, explained by
the normal pressure perfusion breakthrough theory
[24]. By removing the sump effect of an AV fistula,
the acute diversion of blood flow to areas of ischemic cerebral vasculature lacking regional autoregulation may produce substantial vasogenic edema

Traumatic PICA AV Fistula

Surg Neurol 259
2004;61:255– 61

Postembolization CT and MRI scans. Immediate post-embolization axial CT (A) and MRI (B) scans show thrombosis of the varix with continued compression of the lateral medulla. No evidence of edema or hemorrhage is seen
in the parenchyma. At a 10-month follow-up visit, the CT angiogram (C) shows the previously thrombosed varix has
dramatically diminished and the brainstem is adequately decompressed. Three-dimensional reconstruction (D) shows
patency of the left vertebral artery without evidence of flow into the previous varix of the vein of the lateral recess.

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260 Surg Neurol
2004;61:255– 61

and possible hemorrhage [9,12]. Another potential
complication is the increase in mass effect secondary to swelling of the thrombosed varix, which may
compress vital neural structures [26]. In some
cases, acute obliteration of the fistula may lead to
acute cardiac decompensation [7]. These complications may be minimized by performing staged procedures and controlling the blood pressure intraand postoperatively [12,25,26]. Vineula et al [25]
described the “balloon-in-tandem” technique,
where the proximal balloon functions to decrease
local flow through the AV fistula while the distal
balloon is fully inflated to occlude it. This technique
minimizes the risk of embolizing the distal varix and
the lungs by promoting adequate proximal control
of the high-flow AV fistula.
A postembolization angiogram showed that the
PICA region was supplied by collateral feeders from
the AICA (Figure 3F). The patient tolerated the procedure well without complications. Immediately after the procedure, his blood pressure was controlled under close monitoring to prevent a sudden
increase in perfusion pressure. No signs of mass
effect from potential swelling of the thrombosed
varix were noted after embolization.
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