AngioCT and angioMRI are the initial radiological modalities of suspicion for CCF. They are non-invasive tests that can show indirect signs of CCF, such as orbital congestion and venous engorgement (Table1).
However, DSA is necessary for the confirmation diagnosis, since it gives us the anatomy of the arteriovenous fistula feeding vessels and hemodynamic information on aberrant drainage pathways. This allows us to classify the CCF and plan the treatment of endovascular intervention.
The diagnostic test should include the bilateral selective catheterization of both ICA, ECA and vertebral arteries. Sometimes it can be of great help the realization of complementary series with affected ICA occlusion test to verify the collaterality of the anterior and posterior territory in case it’s needed to sacrifice the ICA.
There are multiple treatment options:
- Conservative:
Indicated in low-flow fistulas, since they have spontaneous remission rates of 5.6-73%.
It is based on pharmacological treatment to reduce intraocular pressure (IOP) and/or carotid-jugular compression in the carotid bulb, causing progressive thrombosis due to intermittent stagnation of blood adjacent to the existing clot. This procedure is not without risks, the maneuver can precipitate a vasovagal attack, ischemic stroke or brachial plexus injury; therefore the cervical ICA disease (atherosclerosis, dissection) is a contraindication for this procedure.
- Endovascular:
Indicated in high-flow fistulas with symptoms and low-flow with progressive symptoms that include proptosis, chemosis, and orbital bruit.
Urgent treatment is relegated to direct CCF with:
- Rapidly developing vision loss
- High intraocular pressure
- Elevated intracranial pressure
- Signs of arterial pseudoaneurysm, venous varices and signs of cortical, deep or brainstem venous reflux
Depending on the type of CC fistulas (Table 2):
- Direct:
The objective is the occlusion of the rupture in the ICA trying to preserve the permeability of the artery. To achieve this, we can use different devices.
- Indirect:
Venous occlusion is the most effective method with success rates of 78% versus 62% for transarterial approaches, with the current trend being the combination of both.
For venous embolization, several different routes to the cavernous sinus may be used, the most commonly used are the IPS and SOV.
As alternative techniques for access, we have a direct puncture of the internal jugular vein, transfemoral facial vein approach, SPS, Sylvian vein, pterygoid plexus and frontal vein.
Regarding the arterial embolization, the occlusion of the nutritional arteries is rarely curative, due to the existence of multiple arterial nurturing branches or collection phenomena, as well as the impossibility of access and embolization security of these branches.
Complete occlusion is essential to prevent the development of new venous drainage routes, complementary techniques can be applied, in a second time: transarterial embolization or radiosurgery.
The results of endovascular treatment in two large recent series are very favorable with a full resolution rate of 90-94.5% of cases.
Morbidity related to the procedure around 0–2.3% due to:
- Paralysis of the cranial nerves (more frequent IV) may be due to the progressive thrombosis of the cavernous sinus, the effect of coils mass or the direct injury of the nerve by the coils. Its resolution is through conservative medical treatment.
- HSA for venous perforation. Resolution by embolization with coils.
- Venous infarcts by redirecting venous drainage.
- Surgical:
When endovascular treatment is unsuccessful or impossible.
The surgical technique involves the ligation or entrapment of arterial segments involved.