Transvenous embolization of a pediatric pial arteriovenous fistula
- Department of Radiology and Biomedical Imaging, University of California San Francisco, California, USA
- Correspondence to Dr D Cooke, Radiology and Biomedical Imaging, 505 Parnassus Avenue, San Francisco, CA 94143, USA;
Contributors JT, HF, RH and CD helped in the preparation and editing of the manuscript. VH and DC performed the procedures.
- Received 17 March 2011
- Revised 28 May 2011
- Accepted 1 June 2011
- Published Online First 7 July 2011
Pial arteriovenous fistulas (AVFs) are a rare, although clinically significant, vascular anomaly affecting the pediatric population. There are few retrospective case series describing their epidemiological, clinical and radiographic characteristics as well as technical elements of treatment. Combined transarterial and transvenous embolization of a 12 month old female with a multi-hole pial AVF is described. The patient underwent treatment in a staged fashion and without neurological complication.
Pial arteriovenous fistulas (AVFs) represent approximately 4% of pediatric cerebral vascular anomalies comprised primarily of arteriovenous malformations (AVMs) and vein of Galen malformations (VAGMs).1 2 They are angiographically distinct from the aforementioned groups in that they do not have a true vascular nidus nor do they communicate directly with the vein of Galen, respectively. A small number of case reports and retrospective series exist, the largest by Weon et al, describing the clinical and radiographic features and treatment methods.1 3 4 Clinically, these patients present with symptoms similar to the VAGM population—namely, cardiac insufficiency, seizures (often seen in the setting of hemorrhage) and macrocrania.1 2 4 5 They have a higher associated frequency with hereditary hemorrhagic telangiectasia than the AVM population and their presence necessitates further workup to exclude hereditary hemorrhagic telangiectasia.2 6 7 Transarterial embolization is the primary method of treatment although open surgery and radiosurgery have also been employed.1 2
We describe herein a combined transfermoral, transarterial and transvenous embolization of a 12 month old female in a staged fashion. We detail the clinical presentation, imaging findings and technical elements involved in the patient's care.
The patient was a 36 week female twin diagnosed with an intracranial vascular anomaly during prenatal and postnatal ultrasound (figure 1A, B). At 9 months the patient had developmental delay and mild congestive heart failure Neurological examination was non-focal and without evidence of bulging anterior fontanelle or bruit, cardiac murmur or hepatosplenomegaly. Digital subtraction angiography (DSA) and transarterial coil embolization were performed with the patient under general anesthesia, and a sterile technique was used throughout the case. DSA demonstrated a multi-hole pial AVF centered in a dilated right basal vein of Rosenthal (BVR) and supplied by enlarged posterior temporal and posterior choroidal branches of the posterior cerebral artery (PCA) (figure 2A–D), insular branches of the right middle cerebral artery (figure 2E, F) and posterior communicating and anterior choroidal arteries (figure 2E–H). Venous outflow was into a dilated vein of Galen and falcine sinus (figure 2). During subselective navigation, a large arteriovenous connection, 4 mm in size, was encountered and it was elected to use detachable platinum coils to occlude the connection, which resulted in substantial reduction in flow. This was thought to be sufficient to allow enough reduction in flow to permit the child to grow and to allow delayed embolization at a later age.
Embolization was undertaken via a 4 F Terumo guide catheter (Terumo Medical Corp, Somerset, New Jersey, USA) and a Prowler 14 non-select microcatheter (Codman Inc, Raynam, Massachusetts, USA). A Synchro 2 microwire (Boston Scientific Inc, Natick, Massachusetts, USA) was used to select the right posterior temporal branch. Embolization of the right posterior temporal branch was performed using 12 detachable GDC coils (Boston Scientific Inc). The patient had an uncomplicated immediate postoperative course and was discharged with a plan for a secondary embolization. The second planned treatment was to be done depending on clinical symptoms at a later date when the child was larger, the same strategy used for staging VAGM. The first embolization closed several enormous connections and dramatically reduced the amount of shunting, which we felt would allow improvement in the presenting symptoms.
At 3 months following the initial embolization the patient presented to an outside hospital after becoming increasingly fussy with associated vomiting and eventual loss of consciousness. CT (figure 3A) demonstrated intraventricular hemorrhage and associated hydrocephalus while MR angiography (figure 3B,C) demonstrated persistence of the pial AVF.
The hemorrhage prompted a second and more aggressive attempt at cure. The feeding vessels arising from a temporal branch of the PCA were much smaller in caliber compared with the original treatment, which permitted usage of Onyx. Transarterial embolization was performed via a 5 F MPC guide catheter positioned within the left vertebral artery. A Marathon microcatheter (ev3 Inc, Irvine, California, USA) was primed with a Mirage 0.008 inch microwire (ev3 Inc). The microcatheter was then positioned within the mid-segment of an enlarged right PCA feeder to the BVR varix. Onyx 18 (ev3 Inc) was then administered through the microcatheter antegrade flow of the Onyx cast toward the arteriovenous fistula and venous varix. The remaining plethora of small feeders (figure 4A,C) was not safe to permit arterial embolization so transvenous techniques were employed.
Transvenous embolization was performed via 5 F MPC guide catheter positioned within the distal right internal jugular vein. A Prowler Select Plus microcatheter (Codman Inc) was primed with a Sychro-2 pre-shaped microwire (Boston Scientific Inc). The microcatheter system was used to access the right BVR. With the transvenous catheter within the proximal venous varix, 30 GDC detachable coils (Boston Scientific Inc) were deployed. Post-embolization DSA demonstrated no residual filling of the pial AVF (figure 4). At 6 months following the secondary embolization, the patient was without focal neurological deficit and met age appropriate developmental milestones.
To the authors' knowledge, this case represents the first transvenous embolization on a non-Galenic AVF. Transarterial embolization is the firstline method, as also in this case, to treat pial AVFs because it preserves vein patency of the expected physiological venous outflow. In the setting, however, where a transarterial approach is limited secondary to difficulty related to arterial branch catheterization and/or risk of potential embolization of a parent vessel, transvenous embolization provides an alternative to surgical ligation or radiosurgery.
The transfemoral, transvenous method has been described in the treatment VAGMs and has proved effective with associated morbidity not significantly different from a conventional transarterial approach.5 8–10 Transvenous treatment of true VAGMs has become an accepted treatment in many instances and is the preferred treatment of choroidal-type VAGMs at our institution. However, the vast majority of vein of Galen dilatations are from an upstream adjacent AVM where transvenous occlusion of the draining veins would produce catastrophic hemorrhage. This case is unique as the rare anatomy of a multi-hole pial fistula involving only the single draining BVR permitted safe coil occlusion. The senior author has utilized transvenous coil occlusion in hundreds of fistulas involving shunts in the dural sinuses, although in this case the technique was considered a last option after occluding the larger and safer PCA feeders given the fragility, tortuosity and significant length of the venous access required to reach the recipient BVR varix. The use of fibered coils was considered, although in light of the large caliber dural sinus and enlarged vein of Galen, we felt dense packing with the stiffer fibered coils was not permissible without pushing the catheter out of the desired position. Furthermore, the smaller caliber of the anterior BVR receiving the plethora of tiny feeders from the anterior choroidal and posterior communicating arteries favored the use of more accurate, soft and smaller detachable non-fibered coils.
Pediatric pial AVFs remain a rare and incompletely understood subset of cerebrovascular anomalies whose early identification and treatment is essential in the preserve of neurological function. The therapeutic goal, as with other vascular anomalies, is obliteration of the shunt while preserving patency of the physiological venous drainage. In the setting of limitations of transarterial therapy, a transvenous approach may prove successful in reducing or eradicating the shunt without increased morbidity.
Competing interests None.
Patient consent Obtained.
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