Letter to the Editor: “Cured” intracranial dural arteriovenous fistulas

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TO THE EDITOR: We read with great interest the recent paper by Ambekar and colleagues1 (Ambekar S, Gaynor BG, Peterson EC, et al: Long-term angiographic results of endovascularly “cured” intracranial dural arteriovenous fistulas. J Neurosurg 124:1123–1127, April 2016). The authors report their center's experience with Onyx embolization of 26 dural arteriovenous fistulas (DAVFs) from 2006 to 2013. They define angiographic “cure” as occlusion of a fistula with the absence of early venous drainage immediately postembolization. They report exceptional short-term results as they found that all 26 lesions met their criteria for postembolization cure. The authors then determined that their overall rate of DAVF recurrence following initial complete occlusion was 14.3%, according to repeat angiography performed on 21 treated DAVFs at a mean time of 14 months postembolization.

We believe that a clear distinction must be drawn between the true recurrence of a cured fistula and the reemergence of a fistula that is only partially occluded but rendered angiographically occult. This distinction is not just semantic but is critically important when comparing the efficacy and long-term durability of the different procedures available for the treatment of DAVFs. It is our opinion that the authors' method of defining “cure” overestimates the success of their initial embolization. In our practice, we do not believe that a DAVF can be deemed “cured” based on an initial postembolization angiogram. We suggest that a repeat angiogram approximately 3 months later would more likely distinguish between a true cure and an initially angiographically occult, but not completely obliterated, DAVF.

The authors' number of initially occluded fistula cases that later demonstrated recurrent shunting is not surprising given the known properties of Onyx. This agent facilitates the successful embolization of DAVFs because of its ability to penetrate the fistulous site from either the arterial or venous side. In some cases, however, Onyx may only angiographically “silence” the fistula while leaving the fistulous point and draining vein patent. Onyx laminates along the vessel circumference as it is pushed forward. As this occurs, the central lumen is not initially obliterated, but rather small channels persist. This quality of Onyx allows for very effective radial distribution, as emphasized by the authors. However, as Onyx is not exquisitely prothrombotic (in contrast to N-butyl cyanoacrylate), any remaining channels through the fistula may serve to recruit additional arterial supply, resulting in perceived recurrence of an initially angiographically occult fistula.3 This also explains the observation of a recanalized fistula when incomplete penetration into the draining vein is initially observed.

Authors of several recent series have examined the recurrence rate of cranial DAVFs embolized with Onyx. There remains a lack of standardization in follow-up imaging among endovascular centers, with most studies reporting a single follow-up angiogram obtained at various intervals. For instance, Panagiotopoulos et al. reported on a series of 11 patients who exhibited immediate postembolization DAVF occlusion and a similar 11% rate of residual DAVF on follow-up angiograms obtained at a mean of 3 months. However, this group noted a lower rate of venous penetration during the first embolization attempt.4 Few studies have examined cases occluded at 3 months that remain so at a later time point, but our suspicion is that the number of such true recurrences would be vanishingly small when framed in this context. This is exemplified by Chandra et al.'s study of 41 consecutive DAVFs. Immediate angiographic occlusion was 95%. Of the 35 patients who exhibited initial angiographic occlusion, 6% were found to harbor a residual DAVF at a median 4-month follow-up. The other 33 patients exhibited persistent occlusion of their fistula when they underwent repeat angiography at a median of 28 months.2

References

  • 1

    Ambekar SGaynor BGPeterson ECElhammady MS: Long-term angiographic results of endovascularly “cured” intracranial dural arteriovenous fistulas. J Neurosurg 124:112311272016

  • 2

    Chandra RVLeslie-Mazwi TMMehta BPYoo AJRabinov JDPryor JC: Transarterial onyx embolization of cranial dural arteriovenous fistulas: long-term follow-up. AJNR Am J Neuroradiol 35:179317972014

  • 3

    Nelson PKRussell SMWoo HHAlastra AJVidovich DV: Use of a wedged microcatheter for curative transarterial embolization of complex intracranial dural arteriovenous fistulas: indications, endovascular technique, and outcome in 21 patients. J Neurosurg 98:4985062003

  • 4

    Panagiotopoulos VMöller-Hartmann WAsgari SSandalcioglu IEForsting MWanke I: Onyx embolization as a first line treatment for intracranial dural arteriovenous fistulas with cortical venous reflux. Rofo 181:1291382009

Disclosures

The authors report no conflict of interest.

Response

No response was received from the authors of the original article.

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Article Information

INCLUDE WHEN CITING Published online September 2, 2016; DOI: 10.3171/2016.6.JNS161353.

© AANS, except where prohibited by US copyright law.

Headings

References

  • 1

    Ambekar SGaynor BGPeterson ECElhammady MS: Long-term angiographic results of endovascularly “cured” intracranial dural arteriovenous fistulas. J Neurosurg 124:112311272016

  • 2

    Chandra RVLeslie-Mazwi TMMehta BPYoo AJRabinov JDPryor JC: Transarterial onyx embolization of cranial dural arteriovenous fistulas: long-term follow-up. AJNR Am J Neuroradiol 35:179317972014

  • 3

    Nelson PKRussell SMWoo HHAlastra AJVidovich DV: Use of a wedged microcatheter for curative transarterial embolization of complex intracranial dural arteriovenous fistulas: indications, endovascular technique, and outcome in 21 patients. J Neurosurg 98:4985062003

  • 4

    Panagiotopoulos VMöller-Hartmann WAsgari SSandalcioglu IEForsting MWanke I: Onyx embolization as a first line treatment for intracranial dural arteriovenous fistulas with cortical venous reflux. Rofo 181:1291382009

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