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Show EDITORIAL Endovascular Treatment of Dural Carotid Cavernous Sinus Fistulas Ajay K. Wakhloo, MD, PhD With the introduction of newer embolization materials and flat panel detectors to the surgical angiography unit and refinement of endovascular techniques, we are witnessing rapid improvement in the safety and efficacy of treatment of direct and dural carotid-cavernous sinus fistulas (CCFs). In this issue of the Journal of Neuro-Ophthalmology, Gemmete et al (1) provide an overview on the clinical presentations, Barrow classification, and typical CT and MRI findings of CCFs. The authors then focus on the history of endovascular CCF treatment and introduce us to transarterial, transvenous, and combined transarterial-transvenous approaches. They point out that treatment options range from manual compression of the carotid artery, radiation therapy, stent and stent grafts (predominantly for direct CCFs), placement of detachable balloons or coils within the arteriovenous connection, and infusion of embolic materials into the CCF. Depending on the experience and preference of the treating physician, embolic materials are frequently combined. The articles by Gandhi et al (2) and Bhatia et al (3) describe the use of Onyx for dural CCF. Recently approved by the Food and Drug Administration (FDA) for preoperative embolization of brain arteriovenous malformations (bAVMs), Onyx is an ethylene vinyl alcohol copolymer in a dimethyl sulfoxide solvent. This liquid embolic mixture also contains suspended tantalum powder that gives it radioopacity and its trademark black color. Onyx is a nonadhesive polymer that precipitates in the vessel as the solvent is diluted and washed out. The authors emphasize the safety profile of Onyx resulting from the nonadhesive nature of the material, which permits a long and controlled infusion and a significant reduction in procedure time and radiation exposure. Although a controlled and long injection is desirable, it entails the risk of occluding pial arteries through dural anastomoses. Unlike cyanoacrylates, which are mixed with iodinated oil and well visible (4), Onyx may be poorly visualized in smaller vessels owing to sedimentation of tantalum powder within the delivery microcatheter. This feature demands advanced knowledge of ‘‘dangerous'' preexisting extracranial-intracranial anastomoses frequently not visible before embolization. Gandhi et al (2) and Bhatia et al (3) emphasize the danger of Onyx infusion into preexisting collateral vessels. To avoid reflux of the embolic agent, use of a nondetachable temporary balloon within the internal carotid artery is recommended if the pretreatment angiogram shows that the fistula is substantially supplied by the meningohypophyseal trunk. Although 6 patients treated successfully is a small number, the authors provide evidence that Onyx is a promising new embolic agent for treatment of dural CCFs. Several studies have now been published on the successful use of Onyx alone or in conjunction with coils and stents for direct and dural CCFs and other dural arteriovenous fistulas (AVFs) (5-10). Although cure of dural CCFs and other AVFs is reported in most treated patients with no major periprocedure morbidity, large series demonstrate that the treatment of AVMs remains challenging (5-11). Although use of Onyx was initially promising, larger case series show that cure of bAVMs with Onyx is achieved in only 2%-28% of patients, and Division of NeuroImaging and Intervention, Department of Radiology, University of Massachusetts, Worcester, Massachusetts. Address correspondence to Ajay K. Wakhloo, MD, PhD, Division of NeuroImaging and Intervention, Department of Radiology, University of Massachusetts, 55 Lake Avenue North, Worcester, MA 01655. E-mail: ajay.wakhloo@umassmemorial.org J Neuro-Ophthalmol, Vol. 29, No. 1, 2009 1 J Neuro-Ophthalmol, Vol. 29, No. 1, 2009 Editorial there is permanent morbidity and mortality of 3% to 11%. In experienced hands, an increased cure rate may be attainable, but the complication rate remains comparable to that of formerly used liquid embolic agents (11,12). As Bhatia et al (3) discuss, endovascular treatment of dural CCFs can be lengthy and may involve significant radiation exposure owing to the time needed to place the microcatheter in hard-to-access dural CCFs rather than to the time needed to deploy embolic materials. As the numbers of x-ray-based endovascular procedures increase, there is a growing concern about long fluoroscopy exposure (13,14). The goal remains to avoid skin injuries and damage to the lens from increased radiation exposure. In a recent study, the surface doses recorded during endovascular procedures were equivalent to a dose of 1.5 Gy, which may increase the risk of inducing meningiomas, gliomas, and nerve sheath tumors (15). Experience over the past 3 decades has shown that endovascular treatment of CCFs is safe and should be considered the primary option. However, as with any new technology, caution is warranted with the latest embolic material until more patients have been treated. Long-term clinical and angiographic data on Onyx are needed to verify the permanency of CCF occlusion. As with cyanoacrylates, Onyx seems to generate a chronic inflammatory response, which may be important for lasting obliteration of any type of arteriovenous fistula (16,17). REFERENCES 1. Gemmete JJ, Ansari SA, Gandhi D. Endovascular techniques for treatment of carotid-cavernous fistula. J Neuroophthamol 2009;29:62-71. 2. Gandhi D, Ansari SA, Cornblath WT. Successful transarterial embolization of a barrow type D dural carotid-cavernous fistula with ethylene vinyl alcohol copolymer (Onyx). J Neuroophthalmol 2009;29:9-12. 3. Bhatia KD, Wang L, Parkinson RJ, et al. Successful treatment of six cases of indirect dural carotid-cavernous fistulas with ethylene vinyl alcohol copolymer (Onyx) transvenous embolization. J Neuroophthalmol 2009;29:3-8. 4. Wakhloo AK, Perlow A, Linfante I, et al. Transvenous n-butyl-cyanoacrylate infusion for complex dural carotid cavernous fistulas: technical considerations and clinical outcome. AJNR Am J Neuro-radiol. 2005;26:1888-97. 5. He HW, Jiang CH, Wu ZX, et al. Transvenous embolization with a combination of detachable coils and Onyx for a complicated cavernous dural arteriovenous fistula. Chin Med J (Engl) 2008;121:1651-5. 6. Suzuki S, Lee DW, Jahan R, et al. Transvenous treatment of spontaneous dural carotid-cavernous fistulas using a combination of detachable coils and Onyx. AJNR Am J Neuroradiol 2006;27: 1346-9. 7. Shi ZS, Qi TW, Gonzalez NR, et al. Combined covered stent and Onyx treatment for complex dural arteriovenous fistula involving the clivus and cavernous sinus. Surg Neurol [May 13, 2008 epub ahead of print]. 8. Gomez F, Escobar W, Gomez AM, et al. Treatment of carotid cavernous fistulas using covered stents: midterm results in seven patients. AJNR Am J Neuroradiol 2007;28:1762-8. 9. Cognard C, Januel AC, Silva NA Jr, et al. Endovascular treatment of intracranial dural arteriovenous fistulas with cortical venous drainage: new management using Onyx. AJNR Am J Neuroradiol 2008;29:235-41. 10. Nogueira RG, Dabus G, Rabinov JD, et al. Preliminary experience with Onyx embolization for the treatment of intracranial dural arteriovenous fistulas. AJNR Am J Neuroradiol 2008;29:91-7. 11. Jayaraman MV, Marcellus ML, Hamilton S, et al. Neurologic complications of arteriovenous malformation embolization using liquid embolic agents. AJNR Am J Neuroradiol 2008;29:242-6. 12. Jayaraman M, Cloft HJ. Embolization of brain arteriovenous malformations for cure: because we could or because we should? AJNR Am J Neuroradiol 2008;39:107-8. 13. Velat GJ, Reavey-Cantwell JF, Sistrom C, et al. Comparison of N-butyl cyanoacrylate and Onyx for the embolization of intracranial arteriovenous malformations: analysis of fluoroscopy and procedure times. Neurosurgery 2008;63:ONS73-80. 14. Suzuki S, Furui S, Matsumaru Y, et al. Patient skin dose during neuroembolization by multiple-point measurement using a radiosensitive indicator. AJNR Am J Neuroradiol 2008;29:1076-81. 15. Lekovic GP, Kim LJ, Gonzalez LF, et al. Radiation exposure during endovascular procedures. Neurosurgery 2008;63:ONS81-5. 16. Sadato A, Wakhloo AK, Hopkins LN. Effects of a mixture of a low concentration of n-butylcyanoacrylate and Ethiodol on tissue reactions and the permanence of arterial occlusion after embolization. Neurosurgery 2000;47:1197-203. 17. Jahan R, Murayama Y, Gobin YP, et al. Embolization of arteriovenous malformations with Onyx: clinicopathological experience in 23 patients. Neurosurgery 2001;48:984-95. 2 q 2009 Lippincott Williams & Wilkins |
