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|Year : 2020 | Volume
| Issue : 4 | Page : 821-823
Radiosurgery for Dural Arteriovenous Fistulas: Bet on the Jockey, not on the Horse
Department of Neurosurgery, Gamma Knife Radiosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
|Date of Web Publication||26-Aug-2020|
Dr. Manjul Tripathi
Department of Neurosurgery, Neurosurgery Office, Nehru Hospital, 5th Floor, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Tripathi M. Radiosurgery for Dural Arteriovenous Fistulas: Bet on the Jockey, not on the Horse. Neurol India 2020;68:821-3
Radiosurgery for dural arteriovenous fistula (DAVF) and cavernoma is often seen with a dismal prognosis. Contrary to popular belief, radiosurgery for DAVF is a natural extension of radiosurgery. It is a valuable alternative treatment modality, but the management should be individualized based on the clinical presentation, location, angioarchitecture, the anticipated natural course of the lesion, and the inherent risks and benefits of the treatment modality [Figure 1]. The main challenge for the neurosurgeon is the uncertain nature history of the disease. The literature is not sure what factors predispose any fistula for its progression or involution. Broadly, the annual hemorrhage risk is approximately 1.5% per year for an unruptured DAVF and 7.4–8.1% for ruptured DAVF with the mortality rate of 10.4%.
|Figure 1: Strategic management of dural arteriovenous fistulas (DAVF: dural arteriovenous fistulas; DSA: digital subtraction angiography; GKRS: gamma knife radiosurgery; ICH: intracranial hematoma; MRI: magnetic resonance imaging)|
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The Borden classification is an ideal classification scheme to decide the need for the treatment and the modality of management. In the published article, authors have shared their experience with the radio surgical management of Borden grade I (GI) DAVF. For DAVF with antegrade sinus drainage (Borden GI) and no progressive neurological deficit, observation is sufficient unless the patient's symptomatology, such as headache or pulsatile tinnitus, gets intolerable. Grade I DAVFs mostly follow a benign course, and spontaneous obliteration has been reported notably in the cavernous sinus location DAVF. Spontaneous regression is rare in transverse sinus sigmoid sinus junction DAVF (less than 5% cases). Nearly 2% of patients may show a change in angioarchitecture from antegrade to retrograde venous drainage leading to a higher risk of new neurological deficits or hemorrhage. Fistulas are angiographically evolving lesions with a change in the venous pattern and delayed recruitment of the arterial feeders (sump effect). Borden grade I DAVFs treated using radiosurgery show a high angiographic obliteration rate preserving the functional dural venous sinus. That remains an added advantage of radiosurgery with the best long-term outcome. In its comparison, sacrificing a functional dural sinus by trans venous intervention or surgery is not justified. Transarterial embolization alone is not an ideal treatment approach due to the frequently complex and tortuous course of the arterial supply of any DAVF. Incomplete closure of DAVF may lead to persistent sinus hypertension, local tissue ischemia, and overexpression of vascular endothelial growth factor. Hence, any modality only with the intention of palliation rather than cure is not a justified approach.
Borden G II/III fistulas have a more aggressive course with the risk of future hemorrhage as high as 35% in the first weeks after the initial episode of intracranial bleeding. Such patients are better treated by endovascular intervention or surgery as initial treatment. Endovascular approaches are suitable for palliative management and early symptomatic improvement; however, it fails to achieve complete and permanent obliteration of the fistula in ≥50% of the cases. There are high chances of recanalization of the fistula. Surgery is an effective and permanent treatment modality with the limited direct artery to vein fistulas, especially in anterior cranial fossa locations. Due to technical limitations, surgery carries a higher risk in other intracranial locations. The overall risk of direct surgical intervention is higher than stereotactic radiosurgery (SRS)/SRS and endovascular combination. Radiosurgery in Borden G II-III DAVFs as a single treatment modality should be used only in patients with no or limited cortical venous drainage, patients with mild symptoms, and patients with poor vascular access for embolization. Combined embolization and radiosurgery is a more effective management strategy for the same. An important question is the timing of embolization concerning radiosurgery. Radiosurgery is best performed before endovascular intervention because the previous embolization could hamper the visualization of the entire DAVF target. While embolization provides symptomatic relief and mitigates the chances of immediate intracranial bleed, radiosurgery facilitates late and long-term closer minimizing the chances of remote recanalization and the risk of bleeding. DAVF is a complex disease, and patients are best managed at a center of excellence, well-equipped in all the three treatment modalities. Radiosurgery reduces the chances of interval bleed until complete angiographic obliteration.
The authors' contribution to this topic is an important addition to the literature from the radio surgical community of India. Authors have highlighted the fact that the average latency interval for the fistula closure is nearly 2 years, while for an arteriovenous malformation, it ranges from 3 to 5 years. Apart from Borden grade, another significant factor is the location of the fistula. In literature, cavernous sinus location fistulas respond better than other locations. In the authors' series, only once a patient has a fistula in cavernous sinus location. This report highlights that DAVF in other locations also responds well to gamma knife radiosurgery. Radiosurgery is a valuable adjunct in the successful management of DAVF.
Sincere thanks to Dept. of Radiotherapy for supporting Gamma knife radiosurgery services.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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