Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 2, 2011, pp. 262-265

Neurology India, Vol. 59, No. 2, March-April, 2011, pp. 262-265

Brief Report

Transarterial Onyx embolization of sagittal sinus dural arteriovenous fistulae

Er-qing Chai¹, Jianlin Wang²

¹ Institute of Zoology, School of Life Sciences, Lanzhou University, Lanzhou; Department of Neurosurgery, People's Hospital of Gansu Province, Lanzhou, Gansu, China
² Institute of Zoology, School of Life Sciences, Lanzhou University, Lanzhou, China

Correspondence Address: Jianlin Wang, Tianshui South Road 222, Lanzhou, Gansu, China, jlwang@lzu.edu.cn

Date of Submission: 18-Jul-2010
Date of Decision: 10-Aug-2010
Date of Acceptance: 17-Aug-2010

Code Number: ni11070

PMID: 21483129

DOI: 10.4103/0028-3886.79141

Abstract

Keywords: Dural fistula, sagittal sinus, transarterial embolization

Introduction

Dural arteriovenous fistulae (DAVFs) of the superior sagittal sinus are uncommon. ^[1] Patients with sagittal sinus DAVFs have been mainly treated with surgical excision, and only a very small number of patients have been treated with transarterial and transvenous embolization. ^[2] Recently, embolization of intracranial DAVFs grades III-V using Onyx has been found to be feasible with promising results. ^{[3],[4],[5],[6],[7],[8],[9],[10],[11],[12]} Here, we assess the efficacy and safety of transarterial Onyx embolization in sagittal sinus DAVFs.

Patients and Methods

The charts of 87 consecutive patients with a diagnosis of intracranial DAVF, since 2006, were reviewed. Sagittal sinus DAVF was diagnosed in 4 (4.6%) patients [1 woman and 3 men with a mean age of 38 years (range, 25-45 years)]. All patients underwent four vessel cerebral angiography. Clinical features included intracranial bruit (n=1), seizures (n=1), headache (n=1), and hemorrhage (n=1). An anatomic cure was defined as the disappearance of all symptoms with angiographic demonstration of obliteration of the fistula. The clinical cure group included patients in whom both anatomic cure and the disappearance of all symptoms were achieved despite a persistent shunt.

Arterial embolization technique

All procedures were performed under general anesthesia. An intravenous bolus of 3,000 IU of heparin was administered to each patient after the placement of a 6-French sheath in one of the femoral arteries. A 5-French guiding catheter was then placed at the origin of the external carotid artery supplying the middle meningeal artery (MMA) chosen for DAVF catheterization. A Marathon microcatheter (Micro Therapeutics, Inc., Irvine, CA) was then navigated coaxially to access the DAVF. We initiated embolization procedures with superselective catheterization of the larger arterial pedicle, which supplied the DAVF, to achieve the arteriovenous shunt point. The microcatheter lumen was then flushed with 0.3-mL dimethyl sulfoxide (DMSO, ev3 Inc.). The Onyx-18 injection was followed by biplanar simultaneous subtracted fluoroscopy. Special attention was paid to maintain a gradual and progressive injection rate, while looking for any reflux of the embolizing agent, which would signal the surgeon to interrupt the injection. Once Onyx could not be filled antegradely or the fistula was completely obliterated, the injection was terminated and the heparin was discontinued. An immediate control angiogram was also performed after each procedure.

Results

Patient data are summarized in [Table - 1]. Mean follow-up period of the patients was 19 months.

Anatomy

Of the 4 fistulae, 1 was located in the middle region of the superior sagittal sinus, and 3 were located in the posterior region. All fistulae were supplied by MMAs, with additional suppliers of occipital artery and posterior meningeal artery arising from the vertebral artery. According to the Cognard classification, ^[13] 1 fistula was type I, 1 was type IIb, and 2 were type IV.

Embolization-related results

Four transarterial Onyx embolizations were all performed via MMA. Anatomic cure and clinical cure were achieved in all cases without any complications. Complete obliteration of the fistula was confirmed by immediate angiograms. Clinical cure was achieved at the 19-month follow-up (range, 2-36 months). A control angiogram obtained at 5 months (range, 3-7 months) revealed complete obliteration of the shunt.

Illustrative case

Patient 4

A 37-year-old man presented with intracranial hemorrhage 5 months ago [Figure - 1]. Computed tomography (CT) demonstrated hyperintensity in the left occipital lobe. Subsequent CT angiography revealed a vascular malformation in the left occipital region. The angiogram revealed a type IV DAVF of the superior sagittal sinus fed by bilateral multiple meningeal branches with cortical veins reflux. The right middle meningeal artery was catheterized with a Marathon microcatheter and embolized with Onyx-18. Control angiograms demonstrated complete occlusion of the fistula by the end of the procedure. This patient was found to be asymptomatic at the 32-month follow-up.

Discussion

Sagittal sinus DAVFs account for 4.6% of intracranial DAVFs. The fistulae are located on the wall of the sagittal sinus. If the DAVF drains only into a sinus, the course of the disease is benign, whereas involvement of subarachnoid veins carries the risk of intracranial hemorrhage. ^[14],[15] Patients with sagittal sinus DAVFs may present with intracranial bruits, headache, hemorrhage, ischemic symptoms or dementia. ^[2] The complete eradication of dural fistulae by transvenous embolization using endovascular techniques has been shown to be effective for more than two decades. ^{[2],[16],[17],[18],[19]} The majority of these reports have been of dural fistulae that occur in a dural sinus, and placement of thrombogenic coils into the involved sinus has been often found to result in complete cure. We propose transarterial Onyx embolization of sagittal sinus DAVFs as a potential alternative to transarterial n-butyl-cyanoacrelate (NBCA) embolization, transvenous embolization, surgery, or gamma-knife therapy for such potentially dangerous and complex lesions. Transarterial NBCA embolization will achieve cure in only a minority of DAVFs. Limited data suggest that partial embolization may not protect against the risk of hemorrhage associated with high-risk lesions. ^[16]

Compared with NBCA, Onyx-18 presents a liquid form when injected and a solid form when in contact with blood through precipitation after DMSO evaporates, thus allowing for slower and longer injection rates, which can be better controlled. Furthermore, because of its nonadhesive nature and penetration characteristics, Onyx is a promising embolic agent for endovascular treatment of DAVFs. The transvenous endovascular approach has been generally avoided when treating sagittal sinus DAVFs, especially for the arteriovenous shunts of middle and posterior regions of the sagittal sinus, such as the cases in this series. Occlusion of these venous structures may have disastrous results. In the present study, complete obliteration of the fistula was achieved after embolization of only 1 feeder using a single injection. The anterior branch of the middle meningeal artery is frequently recruited in sagittal sinus DAVFs, and this meningeal artery supply to the shunt is often dilated as visualized on the angiogram. The meningeal arterial access is anatomically more navigable and, consequently, or suitable to microcatheterization. Transarterial navigation allows, in a single approach, a sufficiently distal access for the tip of the microcatheter and the injection of a liquid embolic agent (Onyx). There is a tendency for herniation of Onyx into the right atrium and ventricle from the sinus to the arterialized draining veins, ^[20] but this adverse event did not occur in this series.

Although cure was achieved in all our cases, not all complex sagittal sinus DAVFs would have been cured by transarterial Onyx embolization. Of the 12 patients reported by Halbach et al.,^[21] 9 required surgical excision, 2 were successfully treated using transarterial embolization alone and 1 was successfully treated using transarterial embolization plus intraoperative embolization. We believe that performing transarterial Onyx embolization before performing surgery or transvenous embolization would have added safety. If a vein had ruptured during the embolization, flow would have been very high. We think arterial embolization would have been straightforward and would have made the subsequent approach safer. Surgery also works well for this type of problems and is straightforward. A surgical approach avoids the risk of venous rupture.

References

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