Peer-Review ReportThe Evolution of Endovascular Treatment of Carotid Cavernous Fistulas: A Single-Center Experience
Introduction
Carotid-cavernous fistulas (CCFs) are pathologic connections between the carotid artery and cavernous sinus. There are two primary subtypes of these lesions. Direct CCFs (dCCFs) represent a defect in the wall of the cavernous segment of the internal carotid artery. Most dCCFs occur in young men after a blunt or penetrating trauma (10). However, dCCFs also occur spontaneously, related to a ruptured cavernous-carotid aneurysm or in the setting of a collagen vascular disorder. Indirect CCFs (iCCFs) are more appropriately regarded as dural arteriovenous fistulas. These lesions are located in the walls of the cavernous sinus and exhibit multiple connections between the cavernous sinus and meningeal branches of the cavernous carotid artery, the external carotid artery, or both. Indirect fistulas may develop after resolution of cavernous sinus thrombosis (2) and occur most commonly in postmenopausal women (10).
Both classes of CCFs produce increased blood flow into the cavernous sinus, which overwhelms existing means of venous egress. This fistulous flow is typically shunted through the ophthalmic veins, producing the classic symptoms of proptosis, chemosis, conjunctival injection, and diplopia. The resultant increased intraocular pressure may ultimately result in visual compromise. In both classes of fistula, intracranial hemorrhage may occur if significant retrograde venous drainage is present (26).
The various strategies used to treat direct and indirect CCFs relate to differences in the size and anatomic location of the pathologic shunt as well as to variations in arterial inflow dynamics and patterns of venous outflow. Low-flow iCCFs that present with mild symptomatology often are best managed conservatively by manual compression of the ipsilateral carotid artery and jugular vein, in conjunction with close follow-up of intraocular pressure and visual acuity (15). For patients with severe or progressive symptoms and for those who do not respond to conservative management, treatment is warranted. Historically, endovascular treatment strategies have included both transarterial and transvenous routes of access for embolization via the use of detachable balloons, coils, and liquid embolic agents. Some cases require placement of an intravascular stent and may require parent artery occlusion to achieve successful fistula obliteration. These techniques have evolved over time, and safe and effective endovascular strategies are now available for even the most complex CCF.
In the present study, we analyzed our center's experience in managing 100 consecutive patients with CCF and in this work emphasize evolving treatment strategies that incorporate advances in endovascular materials and techniques. We also present several representative cases depicting the various avenues of endovascular treatment to illustrate technical nuances associated with the treatment of these lesions.
Section snippets
Methods
We retrospectively reviewed our prospectively maintained clinical database and identified 100 patients with CCF who underwent evaluation for endovascular treatment between December 1995 and September 2012 at Barrow Neurological Institute of St. Joseph's Hospital and Medical Center in Phoenix, Arizona, USA. Relevant clinical and demographic data were extracted after a review of outpatient clinic and inpatient hospital medical records, operative notes, radiologic reports, and cerebral angiograms.
Direct Fistula
Of the 42 cases of dCCFs, 40 were treated with endovascular techniques (95%). Multiple embolization sessions were performed in 15 of 40 (37.5%) treated patients (mean 1.7 ± 1.1 sessions), ranging from a single session to a maximum of five sessions. In one patient, an inability to catheterize the fistula prompted craniotomy for surgical trapping. In the second patient, no adequate venous access could be accomplished to a very small dCCF that was not amenable to transarterial embolization. The
Endovascular Techniques for Direct Fistulae
Transarterial approaches have historically represented first-line treatment for dCCF. In the United States, detachable silicone balloons were widely and successfully used to treat dCCF. In 2004, however, these devices were withdrawn from market, and neurointerventionalists began to use detachable coils to close fistula. In cases in which the site of the fistula is clear, such as fistulas related to a ruptured cavernous aneurysm with a well-defined neck, coil embolization may be effective in
Conclusions
Treatment strategies for CCF will continue to evolve as endovascular devices and techniques advance. Reconstructive techniques for direct fistulas using both covered stents 18, 25, 29 and flow-diverting stents (20) to facilitate parent vessel preservation will likely gain prominence in the coming years. Increasing experience with the use of EVOH to treat many types of arteriovenous fistulas is likely to expand the treatment armamentarium for CCF. As with other rare cerebrovascular lesions,
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.