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 » Introduction
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Table of Contents    
CASE REPORT
Year : 2012  |  Volume : 60  |  Issue : 4  |  Page : 415-418

Open surgical disconnection for congenital, multi-hole, pial arteriovenous fistulae in non-eloquent cortex


Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA

Date of Submission24-Mar-2012
Date of Decision17-Apr-2012
Date of Acceptance29-Jun-2012
Date of Web Publication6-Sep-2012

Correspondence Address:
Robert J Singer
Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
USA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.100705

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 » Abstract 

Intracranial pial arteriovenous fistulae (pAVFs), a direct shunt between a feeding artery and a venous channel with the absence of a true nidus characteristic of other types of arteriovenous malformations, are rare. We report a seven-year-old girl with an incidental intracranial pAVF. Following partial embolization with a combination of platinum coils and liquid embolic material, this lesion was surgically disconnected and a definitive cure was achieved. Based on the particular characteristics of this lesion-multiple, small arterial feeders, superficial location, and proximity to the non-eloquent cortex-we feel this vascular lesion represents a subset of pAVFs that may be most reasonably and safely treated by open surgery. While staged embolization has recently gained popularity as a treatment option, the additive risk of multiple embolizations as well as repeated exposure to ionizing radiation should not be understated, especially in the pediatric population. Furthermore, given the paucity of data on the long-term effectiveness of embolization, surgery remains an elegant and durable treatment option for pAVFs in carefully selected patients.


Keywords: Arteriovenous fistula, embolization, onyx, pediatric, pial, surgical disconnection


How to cite this article:
Tomycz L, Maris AS, Ghiassi M, Singer RJ. Open surgical disconnection for congenital, multi-hole, pial arteriovenous fistulae in non-eloquent cortex. Neurol India 2012;60:415-8

How to cite this URL:
Tomycz L, Maris AS, Ghiassi M, Singer RJ. Open surgical disconnection for congenital, multi-hole, pial arteriovenous fistulae in non-eloquent cortex. Neurol India [serial online] 2012 [cited 2019 Sep 16];60:415-8. Available from: http://www.neurologyindia.com/text.asp?2012/60/4/415/100705



 » Introduction Top


Intracranial pial arteriovenous fistulae (pAVFs), a direct shunt between a feeding artery and a venous channel are rare vascular lesions. [1] The arterial supply may come from one or multiple feeders, and the venous drainage is typically extremely ecstatic [Figure 1]. Unlike dural AVFs that arise from the middle meningeal artery or other dural vessels, pAVFs are derived from branches of cortical, pial arteries. Pediatric pAVFs are typically congenital and have been associated with both Rendu-Osler-Weber and Klippel-Trenaunay- Weber syndrome More Detailss. [2] Treatment options for pAVFs have traditionally included open surgery. [3],[4] While resection of the fistula and associated varices has historically been performed, it is now widely accepted that simple surgical disconnection is sufficient to obliterate the fistulous point and eliminate shunting. [3] Recently, however, there has been a shift towards endovascular methods. Liquid embolic agents such as nBCA (Trufill, Cordis Neurovascular, Inc.) and Onyx (ev3, Inc.) have been used to endovascularly interrupt the fistulous connection. Detachable coils have also been used, alone or as an adjunctive measure.
Figure 1: An artist's rendition of this patient's pAVF reveals the lesion's multiple arterial feeders and superficial location

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 » Case Report Top


A seven-year-old female with bilateral congenital nasolacrimal duct obstruction was evaluated after a closed head injury. No loss of consciousness was reported. At presentation she was neurologically intact. Non-contrast computed tomography (CT) of head revealed an area of relative hyperdensity in the right frontal lobe [Figure 2] and magnetic resonance imaging (MRI) was done [Figure 3]. Time of flight magnetic resonance angiography and venography images revealed a high-flow signal in the right middle frontal gyrus, findings consistent with AVF. Venous drainage of the AVF appeared to be superficial only. The dilated venous pouch was estimated to be 1.5 cm in diameter. Arterial feeders were observed coming from the anterior cerebral artery (ACA) circulation. No mass effect or edema was noted. Cerebral angiography revealed a high-flow pAVF fed by a large branch of the left ACA and multiple tiny branches of the right middle cerebral artery (MCA) [Figure 4].
Figure 2: Non-contrast, axial CT scan reveals a small lesion of hyperdensity in the right frontal convexity

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Figure 3: T2-weighted, axial MRIs revealing abnormally dilated venous varices draining a right frontal pAVF

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Figure 4: AP (left) and lateral (right) angiograms of the arterial phase. The pAVF is observed to be supplied by a relatively large ACA branch and multiple smaller MCA branches

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Endovascular and surgical procedures

A microcatheter/micro-guidewire system (Marathon and Mirage, ev3, Inc.) was navigated through the largest arterial feeder originating from the right A2 system. Microcatheter injection was performed with the catheter tip just proximal to the fistulous point; no en passage vessels were observed [Figure 5]. Because of the high-flow features of this particular fistula, Onyx 34 was selected for embolization because of its higher viscosity. Unfortunately, after a small amount of Onyx was delivered, the liquid embolic was observed to immediately traverse to the venous side of the fistula and enter into the superior sagittal sinus (SSS). Embolization was immediately stopped [Figure 6]. A second microcatheter (SL-10, Boston Scientific) was navigated to the same point and a nest of detachable coils was deposited, slowing the flow through the shunt. Onyx 34 was delivered to reinforce the nest of coils. Embolization eliminated flow from the ACA pedicle but was terminated before complete obliteration of the fistula due to concerns about premature venous occlusion. Transit time through the fistula was significantly reduced, but there was still shunting through several tiny right MCA feeders [Figure 7]. Venous outflow was preserved.
Figure 5: AP (left) and lateral (right) views of a microcatheter injection demonstrate positioning of the catheter tip at the fistulous point without obvious vessels feeding the normal adjacent cortex

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Figure 6: Lateral angiogram of a microcatheter injection navigated as far as possible through the MCA feeders. Opacification of normal cortical vessels is seen and thus embolization from this position was deemed unsafe and the procedure was aborted

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Figure 7: AP (left) and lateral (right) angiograms show deposition of a nest of coils reinforced with Onyx 34 effectively eliminating flow through the large ACA feeding artery

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Two months after initial embolization, the lesion was localized with a Stealth (Medtronic) system. Dura was opened in a trapdoor fashion with its base over the SSS. A large venous varix was identified in the right mesial frontal region [Figure 8]. Circumferential dissection of the venous varix was carefully initiated. Disconnection of the multiple, small arterial pedicles was achieved. The venous sac was completely disconnected from arterial inflow. Total operative time was 187 min. No drains were placed. Intraoperative angiography demonstrated obliteration of the lesion without evidence of residual fistula. Regional angio-architecture was well preserved. Patient remained neurologically intact postoperatively and at two months' follow-up.
Figure 8: Intraoperative photograph of the brain surface showing a large venous pouch of the fistula which ultimately drains into the midline superior sagittal sinus

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 » Discussion Top


There is little to guide the management of a child with an incidentally discovered, asymptomatic, congenital pAVF. A single case of spontaneous closure has been reported, as well as three cases of patients with pAVFs and minor symptoms who were managed conservatively with no events throughout the study. [5],[6] In one series, however, symptomatic pAVFs that were observed rather than treated caused death in five of eight patients. [7] In our case, given the non-eloquent region of the brain involved, the age of the patient, and the assumption that symptoms would eventually develop from either continuous venous dilation or ischemia, treatment was recommended.

Surgical disconnection is an effective way to achieve durable obliteration of these rare lesions. Especially in the case of multi-hole fistulae, most endovascular series describe the necessity of multiple, staged embolizations to accomplish angiographic obliteration. In another series, 34 of 35 pAVFs were treated by endovascular methods. [8] However, in nearly half of the cases, two to three sessions were required and in 17% of the cases, four to five sessions were necessary. The arterial feeders can often be tiny and difficult to access, and the cumulative risk of multiple, staged embolization procedures may exceed the risk of craniotomy for superficial lesions.

Especially in the young, repeated exposure to ionizing radiation from multiple angiograms should also be considered. Complications related to repeated femoral access are also more common in the pediatric population due to the small vessel caliber. Surgery in this child involved a relatively small craniotomy. Opening the dura immediately revealed the lesion. Retraction was minimal, and all brain tissue was non-eloquent. Bipolar cautery facilitated simple and rapid disconnection of numerous, tiny arterial feeders. Direct visualization permitted preservation of en passage vessels. For high-flow fistulae, partial embolization if feasible, may be pursued to decrease the volume of shunted blood, and can help the patient more gradually adjust to the alteration in blood flow expected following complete surgical disconnection.

 
 » References Top

1.Lasjaunias P, Manelfe C, Chiu M. Angiographic architecture of intracranial vascular malformations and fistulas - Pretherapeutic aspects. Neurosurg Rev 1986;9:253-63.  Back to cited text no. 1
[PUBMED]    
2.Garcia-Monaco R, Taylor W, Rodesch G, Alvarez H, Burrows P, Coubes P, et al. Pial arteriovenous fistula in children as presenting manifestation of Rendu-Osler-Weber disease. Neuroradiology 1995;37:60-4.  Back to cited text no. 2
    
3.Hoh BL, Putman CM, Budzik RF, Ogilvy CS. Surgical and endovascular flow disconnection of intracranial pial single-channel arteriovenous fistulae. Neurosurgery 2001;49:1351-63.  Back to cited text no. 3
[PUBMED]    
4.Yamashita K, Ohe N, Yoshimura S, Iwama T. Intracranial pial arteriovenous fistula - Case report. Neurol Med Chir (Tokyo) 2007;47:550-4.  Back to cited text no. 4
[PUBMED]    
5.Santosh C, Teadale E, Molyneux A. Spontaneous closure of an intracranial middle cerebral arteriovenous fistula. Neuroradiology 1991;33:65-6.  Back to cited text no. 5
    
6.Wang YC, Wong HF, Yeh YS. Intracranial pial arteriovenous fistulas with single-vein drainage. J Neurosurg 2004;100(2 Suppl Pediatrics):201-5.  Back to cited text no. 6
    
7.Nelson K, Nimi Y, Lasjaunias P, Berenstein A. Endovascular embolization of congenital intracranial pial fistulas. Neuroimag Clin North Am 1992;2:309-17.  Back to cited text no. 7
    
8.Weon YC, Yoshida Y, Sachet M, Mahadevan J, Alvarez H, Rodesch G, et al. Supratentorial cerebral arteriovenous fistulas (AVFs) in children: Review of 41 cases with 63 non choroidal single-hole AVFs. Acta Neurochir (Wien) 2005;147:17-31.  Back to cited text no. 8
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]



 

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