High-flow vertebral arteriovenous fistulas (VAVF) are rare complications of cervical spine surgery and characterized by iatrogenic direct-communication of the extracranial vertebral artery (VA) to the surrounding venous plexuses. The authors describe two patients with VAVF presenting with ischemic presentation after C1 pedicle screw insertion for a treatment of C2 fracture and nontraumatic atlatoaxial subluxation. The first patient presented with drowsy consciousness with blurred vision. The diffusion MRI showed an acute infarction on bilateral cerebellum and occipital lobes. The second patient presented with pulsatile tinnitus, dysarthria and a subjective weakness and numbness of extremities. In both cases, digital subtraction angiography demonstrated high-flow direct VAVFs adjacent to C1 screws. The VAVF of the second case occurred near the left posterior inferior cerebellar artery originated from the persistent first intersegmental artery of the left VA. Both cases were successfully treated by complete occlusion of the fistulous portion and the involved segment of the left VA using endovascular coil embolization. The authors reviewed the VAVFs after the upper-cervical spine surgery including C1 screw insertion and the feasibility with the attention notes of its endovascular treatment.
High-flow vertebral arteriovenous fistula (VAVF) can rarely occur by an unintended vertebral artery injury caused by penetrating accidents, injuries of the cervical spine or medical procedures
A 57-year-old woman presented with severe neck pain after a pedestrian traffic accident. The initial neurologic examination showed symmetrical motor power without any sensory changes in the extremities. Plane films and computed tomography of her cervical spine demonstrated a C2 fracture involving the bilateral (mainly left) C2 pedicle and a lateral mass extending into the base of the odontoid process. The preoperative magnetic resonance imaging (MRI) did not demonstrate any abnormal course and relationship of the VA and adjacent structures.
The patient underwent a bilateral pedicle screw fixation between C1, C2, and C3. The operative procedures through posterior approach were uneventfully completed. Six days after operation, she complained of an abrupt and severe nuchal pain and blurred vision. She deteriorated the symptoms and showed dysarthria, right facial palsy and drowsy consciousness. The diffusion MRI of the brain showed a multifocal acute infarction in the bilateral cerebellar hemisphere and the bilateral occipital lobes. The digital subtraction angiography (DSA) demonstrated high-flow VAVF between the V3 segment of the left VA above the pedicle screw located left C1 and the paravertebral venous plexus (
Under local anesthesia, a single microcatheter approached via 5 Fr guiding catheter located the left VA was easily passed from the proximal part of the fistula to the distal V3. The V3 segment of the left VA was complete occluded by four detachable coils and ten pushable coils (
A 45-year-old woman presented with numbness and recurrently transient weakness of her left extremities. The brain MRI showed no ischemic lesions on brain. However, the MRI of the cervical spine revealed an increasing atlanto-dental interval (ADI) with compromising the central canal at the C1 level. A CT angiography (CTA) of the cervical spine revealed an unusual course of the bilateral V3, a so-called persistent first intersegmental artery (PFIA). The horizontal part of the bilateral V3 begun from not C1 vertebral foramen but C2 vertebral foramen and was placed between the C1 and C2 posterior arches. For the stabilization of the atlanto-axial subluxation, the patient underwent a bilateral screw fixation between C1 and C2 using pedicle the screw insertion technique. During the careful dissection of the left C1 lateral mass, a relatively large volume of arterial bleeding was encountered, which was immediately controlled by compression using gelform and bone wax. The remaining surgical procedures were uneventfully finished.
Immediately after the recovery from anesthesia, the patient complained of pulsatile tinnitus on the left ear. Four days later, she additionally presented with vertigo, nausea, dysarthria and subjective weakness and numbness of extremities. The DSA demonstrated a high-flow VAVF between the V3 segment of the left VA and the paravertebral venous plexus (
Under general anesthesia, bilateral femoral arteries were punctured. For using the double-microcatheter technique to approach the distal part of the fistula from right VA and proximal part of the fistula from left VA, two 5 Fr guiding catheter were placed into the proximal segment of the right and left vertebral arteries. The first microcatheter was navigated to the distal portion of the fistula via vertebrobasilar junction from the right VA. Subsequently, the second microcatheter was placed on the proximal portion of the fistula via the left VA. An initial coil-frame was made from one detachable coil inserted through the first microcatheter. The first frame was placed between just the distal segment of the fistula and the left PICA (
VAVFs are rare lesions caused by traumatic or spontaneous origin. Penetrating neck injuries are frequently associated with the lesions; however, a dislocation or fracture of the cervical spine and iatrogenic causes such as central line insertion or cervical spine surgery are also associated
The V3 segment is anatomically complicated and is also associated with several congenital or acquired vascular-anomalies such as PFIA, fenestration of VA, PICA from C1-2 and high-riding VA, etc. Some reports suggest that congenital or acquired disorders such as Down or Klippel-Feil syndrome, neurofibromatosis, fibromuscular dysplasia, atlantoaxial dislocation, or rheumatoid arthritis are predominant risk factors for the presence of such vascular anomalies
Owing to the advantages compared with the surgical repair such as shorter procedure and recovery time, smaller risk of bleeding and infection and immediately obtaining angiographic results after the procedure, EVT have been accepted the first option for VAVFs. From the literature and our cases, EVT provided good clinical and angiographic results without significant morbidity
There are some considerations of EVT for VAVFs. First, the best goal of treatment is to completely occlude the fistula channels and preserve the patency of the VA. However, if the high-flow VAVFs demonstrated a transection of the VA, an extensive damage of the vessel wall or multiple influx channels, preserving the parent artery may be impossible and a vascular sacrifice may be necessary. In the presented two cases, we have chosed trapping the influenced VA for the complete occlusion of the influx channels of VAVFs. In case of a patent contralateral VA or sufficient collateral supplies via posterior communicating artery, an influencing VA can be completely occluded to prevent further complications
The EVT of VAVF is safe and effective in the treatment of the high-flow, complex VAVFs. The detachable coil has its advantages of retrievability, trackability and diversity of its size. Preoperative angiographic studies such as CTA or DSA are essential for understanding the vessel-bone relationships to avoid the risk of VA injury. Furthermore, long-term angiographic follow-ups after the EVT are important for determining the thromboembolic complications and recurrence of fistulas.
Case 1. The pretreatment angiography (A) demonstrates high-flow arteriovenous fistula at the V3 segment of the left vertebral artery above the screw inserted left C1 pedicle. The left V3 segment including the fistulous segment was complete occluded by endovascular coil embolization (B). The posttreatment angiography (C) demonstrates a complete obliteration of the fistula and occlusion of the V3 segment.
Case 2. The pretreatment angiography (A) demonstrates a high-flow arteriovenous fistula with transection between the V3 segment of the left vertebral artery and the paravertebral venous plexus with the venous regurgitations extending into the left sigmoid and inferior petrosal sinus. The 3D image (A, right) reveals the left posterior inferior cerebellar artery (PICA) originating from extradural segment near the fistula. The two microcatheters were navigated to the distal and proximal protion of the fistula for saving the left PICA and supporting coil-frames (B). The posttreatment angiography (C) demonstrates a complete obliteration of the fistula with saving the left PICA.